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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 09/22] Add a very basic netchannel2 implementation.
This is functional, in the sense that packets can be sent and
received, but lacks any advanced features.
Signed-off-by: Steven Smith <steven.smith@xxxxxxxxxx>
---
drivers/xen/Kconfig | 24 +
drivers/xen/Makefile | 1 +
drivers/xen/netchannel2/Makefile | 12 +
drivers/xen/netchannel2/chan.c | 659 ++++++++++++++++++++++++
drivers/xen/netchannel2/netback2.c | 354 +++++++++++++
drivers/xen/netchannel2/netchan2.c | 32 ++
drivers/xen/netchannel2/netchannel2_core.h | 351 +++++++++++++
drivers/xen/netchannel2/netchannel2_endpoint.h | 63 +++
drivers/xen/netchannel2/netfront2.c | 488 ++++++++++++++++++
drivers/xen/netchannel2/recv_packet.c | 216 ++++++++
drivers/xen/netchannel2/rscb.c | 385 ++++++++++++++
drivers/xen/netchannel2/util.c | 230 +++++++++
drivers/xen/netchannel2/xmit_packet.c | 318 ++++++++++++
include/xen/interface/io/netchannel2.h | 106 ++++
include/xen/interface/io/uring.h | 426 +++++++++++++++
15 files changed, 3665 insertions(+), 0 deletions(-)
create mode 100644 drivers/xen/netchannel2/Makefile
create mode 100644 drivers/xen/netchannel2/chan.c
create mode 100644 drivers/xen/netchannel2/netback2.c
create mode 100644 drivers/xen/netchannel2/netchan2.c
create mode 100644 drivers/xen/netchannel2/netchannel2_core.h
create mode 100644 drivers/xen/netchannel2/netchannel2_endpoint.h
create mode 100644 drivers/xen/netchannel2/netfront2.c
create mode 100644 drivers/xen/netchannel2/recv_packet.c
create mode 100644 drivers/xen/netchannel2/rscb.c
create mode 100644 drivers/xen/netchannel2/util.c
create mode 100644 drivers/xen/netchannel2/xmit_packet.c
create mode 100644 include/xen/interface/io/netchannel2.h
create mode 100644 include/xen/interface/io/uring.h
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index ed4b89b..a081b73 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -210,6 +210,30 @@ config XEN_SCSI_FRONTEND
The SCSI frontend driver allows the kernel to access SCSI Devices
within another guest OS.
+config XEN_NETCHANNEL2
+ tristate "Net channel 2 support"
+ depends on XEN && NET
+ default y
+ help
+ Xen netchannel2 driver support. This allows a domain to act as
+ either the backend or frontend part of a netchannel2 connection.
+ Unless you are building a dedicated device-driver domain, you
+ almost certainly want to say Y here.
+
+ If you say Y or M here, you should also say Y to one or both of
+ ``Net channel2 backend support'' and ``Net channel2 frontend
+ support'', below.
+
+config XEN_NETDEV2_BACKEND
+ bool "Net channel 2 backend support"
+ depends on XEN_BACKEND && XEN_NETCHANNEL2
+ default XEN_BACKEND
+
+config XEN_NETDEV2_FRONTEND
+ bool "Net channel 2 frontend support"
+ depends on XEN_NETCHANNEL2
+ default y
+
config XEN_GRANT_DEV
tristate "User-space granted page access driver"
default XEN_PRIVILEGED_GUEST
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 873e5a3..68eb231 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -30,4 +30,5 @@ obj-$(CONFIG_XEN_GRANT_DEV) += gntdev/
obj-$(CONFIG_XEN_NETDEV_ACCEL_SFC_UTIL) += sfc_netutil/
obj-$(CONFIG_XEN_NETDEV_ACCEL_SFC_FRONTEND) += sfc_netfront/
obj-$(CONFIG_XEN_NETDEV_ACCEL_SFC_BACKEND) += sfc_netback/
+obj-$(CONFIG_XEN_NETCHANNEL2) += netchannel2/
obj-$(CONFIG_XEN_ACPI_WMI_WRAPPER) += acpi-wmi/
diff --git a/drivers/xen/netchannel2/Makefile b/drivers/xen/netchannel2/Makefile
new file mode 100644
index 0000000..bdad6da
--- /dev/null
+++ b/drivers/xen/netchannel2/Makefile
@@ -0,0 +1,12 @@
+obj-$(CONFIG_XEN_NETCHANNEL2) += netchannel2.o
+
+netchannel2-objs := chan.o netchan2.o rscb.o util.o \
+ xmit_packet.o recv_packet.o
+
+ifeq ($(CONFIG_XEN_NETDEV2_BACKEND),y)
+netchannel2-objs += netback2.o
+endif
+
+ifeq ($(CONFIG_XEN_NETDEV2_FRONTEND),y)
+netchannel2-objs += netfront2.o
+endif
diff --git a/drivers/xen/netchannel2/chan.c b/drivers/xen/netchannel2/chan.c
new file mode 100644
index 0000000..e3ad981
--- /dev/null
+++ b/drivers/xen/netchannel2/chan.c
@@ -0,0 +1,659 @@
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/gfp.h>
+#include <linux/etherdevice.h>
+#include <linux/interrupt.h>
+#include <linux/netdevice.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/version.h>
+#include <xen/evtchn.h>
+#include <xen/xenbus.h>
+
+#include "netchannel2_endpoint.h"
+#include "netchannel2_core.h"
+
+static int process_ring(struct napi_struct *napi,
+ int work_avail);
+
+static irqreturn_t nc2_int(int irq, void *dev_id)
+{
+ struct netchannel2_ring_pair *ncr = dev_id;
+
+ if (ncr->irq == -1)
+ return IRQ_HANDLED;
+ if (ncr->cons_ring.sring->prod != ncr->cons_ring.cons_pvt ||
+ ncr->interface->is_stopped)
+ nc2_kick(ncr);
+ return IRQ_HANDLED;
+}
+
+/* Process all incoming messages. The function is given an
+ IRQ-disabled reference for the interface, and must dispose of it
+ (either by enabling the IRQ or re-introducing it to the pending
+ list). Alternatively, the function can stop the ring being
+ processed again by leaking the reference (e.g. when the remote
+ endpoint is misbehaving). */
+/* Returns -1 if we used all the available work without finishing, or
+ the amount of work used otherwise. */
+static int process_messages(struct netchannel2_ring_pair *ncrp,
+ int work_avail,
+ struct sk_buff_head *pending_rx_queue)
+{
+ struct netchannel2_msg_hdr hdr;
+ RING_IDX prod;
+ struct netchannel2 *nc = ncrp->interface;
+ int work_done;
+
+ work_done = 1;
+
+retry:
+ prod = ncrp->cons_ring.sring->prod;
+ rmb();
+ while (work_done < work_avail &&
+ prod != ncrp->cons_ring.cons_pvt) {
+ nc2_copy_from_ring(&ncrp->cons_ring, &hdr, sizeof(hdr));
+ if (hdr.size < sizeof(hdr)) {
+ printk(KERN_WARNING "Other end sent too-small message
(%d)\n",
+ hdr.size);
+ goto done;
+ }
+ if (hdr.size > ncrp->cons_ring.payload_bytes) {
+ /* This one message is bigger than the whole
+ ring -> other end is clearly misbehaving.
+ We won't take any more messages from this
+ ring. */
+ printk(KERN_WARNING "Other end sent enormous message
(%d > %zd)\n",
+ hdr.size,
+ ncrp->cons_ring.payload_bytes);
+ goto done;
+ }
+
+ switch (hdr.type) {
+ case NETCHANNEL2_MSG_SET_MAX_PACKETS:
+ nc2_handle_set_max_packets_msg(ncrp, &hdr);
+ break;
+ case NETCHANNEL2_MSG_PACKET:
+ nc2_handle_packet_msg(nc, ncrp, &hdr,
+ pending_rx_queue);
+ break;
+ case NETCHANNEL2_MSG_FINISH_PACKET:
+ nc2_handle_finish_packet_msg(nc, ncrp, &hdr);
+ break;
+ case NETCHANNEL2_MSG_PAD:
+ break;
+ default:
+ /* Drop bad messages. We should arguably stop
+ processing the ring at this point, because
+ the ring is probably corrupt. However, if
+ it is corrupt then one of the other checks
+ will hit soon enough, and doing it this way
+ should make it a bit easier to add new
+ message types in future. */
+ pr_debug("Bad message type %d from peer!\n",
+ hdr.type);
+ break;
+ }
+ hdr.size = (hdr.size + 7) & ~7;
+ ncrp->cons_ring.cons_pvt += hdr.size;
+
+ work_done++;
+ if (work_done == work_avail)
+ return -1;
+ }
+
+ if (unlikely(prod != ncrp->cons_ring.sring->prod))
+ goto retry;
+
+ /* Dispose of our IRQ-disable reference. */
+done:
+ napi_complete(&ncrp->napi);
+ enable_irq(ncrp->irq);
+
+ if (nc2_final_check_for_messages(&ncrp->cons_ring,
+ prod)) {
+ /* More work to do still. */
+ nc2_kick(ncrp);
+ }
+
+ return work_done;
+}
+
+/* Flush out all pending metadata messages on ring @ncrp, and then
+ update the ring pointers to indicate that we've done so. Fire the
+ event channel if necessary. */
+static void flush_rings(struct netchannel2_ring_pair *ncrp)
+{
+ int need_kick;
+
+ flush_hypercall_batcher(&ncrp->pending_rx_hypercalls,
+ nc2_rscb_on_gntcopy_fail);
+ send_finish_packet_messages(ncrp);
+ if (ncrp->need_advertise_max_packets)
+ advertise_max_packets(ncrp);
+
+ need_kick = 0;
+ if (nc2_finish_messages(&ncrp->cons_ring)) {
+ need_kick = 1;
+ /* If we need an event on the consumer ring, we always
+ need to notify the other end, even if we don't have
+ any messages which would normally be considered
+ urgent. */
+ ncrp->pending_time_sensitive_messages = 1;
+ }
+ if (nc2_flush_ring(&ncrp->prod_ring))
+ need_kick = 1;
+ if (need_kick ||
+ (ncrp->delayed_kick && ncrp->pending_time_sensitive_messages)) {
+ if (ncrp->pending_time_sensitive_messages) {
+ notify_remote_via_irq(ncrp->irq);
+ ncrp->delayed_kick = 0;
+ } else {
+ ncrp->delayed_kick = 1;
+ }
+ ncrp->pending_time_sensitive_messages = 0;
+ }
+}
+
+/* Process incoming messages, and then flush outgoing metadata
+ * messages. We also try to unjam the xmit queue if any of the
+ * incoming messages would give us permission to send more stuff. */
+/* This is given an IRQ-disable reference, and must dispose of it. */
+static int nc2_poll(struct netchannel2_ring_pair *ncrp, int work_avail,
+ struct sk_buff_head *rx_queue)
+{
+ int work_done;
+
+ if (!ncrp->is_attached) {
+ napi_complete(&ncrp->napi);
+ enable_irq(ncrp->irq);
+ return 0;
+ }
+
+ work_done = process_messages(ncrp, work_avail, rx_queue);
+
+ flush_rings(ncrp);
+
+ if (work_done < 0)
+ return work_avail;
+ else
+ return work_done;
+}
+
+/* Like skb_queue_purge(), but use release_tx_packet() rather than
+ kfree_skb() */
+void nc2_queue_purge(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff_head *queue)
+{
+ struct sk_buff *skb;
+
+ while (!skb_queue_empty(queue)) {
+ skb = skb_dequeue(queue);
+ release_tx_packet(ncrp, skb);
+ }
+}
+
+/* struct net_device stop() method. */
+static int nc2_stop(struct net_device *nd)
+{
+ struct netchannel2 *nc = netdev_priv(nd);
+
+ spin_lock_bh(&nc->rings.lock);
+ nc->stats.tx_dropped += skb_queue_len(&nc->pending_skbs);
+ nc2_queue_purge(&nc->rings, &nc->pending_skbs);
+ spin_unlock_bh(&nc->rings.lock);
+
+ return 0;
+}
+
+/* Kick a netchannel2 interface so that the poll() method runs
+ * soon. */
+/* This has semi release-like semantics, so you can set flags
+ lock-free and be guaranteed that the poll() method will eventually
+ run and see the flag set, without doing any explicit locking. */
+void nc2_kick(struct netchannel2_ring_pair *ncrp)
+{
+ if (napi_schedule_prep(&ncrp->napi)) {
+ disable_irq_nosync(ncrp->irq);
+ __napi_schedule(&ncrp->napi);
+ }
+}
+
+static int nc2_open(struct net_device *nd)
+{
+ struct netchannel2 *nc = netdev_priv(nd);
+
+ nc2_kick(&nc->rings);
+ return 0;
+}
+
+/* Rad a mac address from an address in xenstore at @prefix/@node.
+ * Call not holding locks. Returns 0 on success or <0 on error. */
+static int read_mac_address(const char *prefix, const char *node,
+ unsigned char *addr)
+{
+ int err;
+ unsigned mac[6];
+ int i;
+
+ err = xenbus_scanf(XBT_NIL, prefix, node,
+ "%x:%x:%x:%x:%x:%x",
+ &mac[0],
+ &mac[1],
+ &mac[2],
+ &mac[3],
+ &mac[4],
+ &mac[5]);
+ if (err < 0)
+ return err;
+ if (err != 6)
+ return -EINVAL;
+ for (i = 0; i < 6; i++) {
+ if (mac[i] >= 0x100)
+ return -EINVAL;
+ addr[i] = mac[i];
+ }
+ return 0;
+}
+
+/* Release resources associated with a ring pair. It is assumed that
+ the ring pair has already been detached (which stops the IRQ and
+ un-pends the ring). */
+void cleanup_ring_pair(struct netchannel2_ring_pair *ncrp)
+{
+ BUG_ON(ncrp->prod_ring.sring);
+ BUG_ON(ncrp->cons_ring.sring);
+
+ drop_pending_tx_packets(ncrp);
+ nc2_queue_purge(ncrp, &ncrp->release_on_flush_batcher);
+ if (ncrp->gref_pool != 0)
+ gnttab_free_grant_references(ncrp->gref_pool);
+ netif_napi_del(&ncrp->napi);
+}
+
+int init_ring_pair(struct netchannel2_ring_pair *ncrp,
+ struct netchannel2 *nc)
+{
+ unsigned x;
+
+ ncrp->interface = nc;
+ spin_lock_init(&ncrp->lock);
+ ncrp->irq = -1;
+
+ for (x = 0; x < NR_TX_PACKETS - 1; x++)
+ txp_set_next_free(ncrp->tx_packets + x, x + 1);
+ txp_set_next_free(ncrp->tx_packets + x, INVALID_TXP_INDEX);
+ ncrp->head_free_tx_packet = 0;
+
+ skb_queue_head_init(&ncrp->pending_tx_queue);
+ skb_queue_head_init(&ncrp->release_on_flush_batcher);
+
+ if (gnttab_alloc_grant_references(NR_TX_PACKETS,
+ &ncrp->gref_pool) < 0)
+ return -1;
+
+ netif_napi_add(ncrp->interface->net_device, &ncrp->napi,
+ process_ring, 64);
+ napi_enable(&ncrp->napi);
+
+ return 0;
+}
+
+static struct net_device_stats *nc2_get_stats(struct net_device *nd)
+{
+ struct netchannel2 *nc = netdev_priv(nd);
+
+ return &nc->stats;
+}
+
+/* Create a new netchannel2 structure. Call with no locks held.
+ Returns NULL on error. The xenbus device must remain valid for as
+ long as the netchannel2 structure does. The core does not take out
+ any kind of reference count on it, but will refer to it throughout
+ the returned netchannel2's life. */
+struct netchannel2 *nc2_new(struct xenbus_device *xd)
+{
+ struct net_device *netdev;
+ struct netchannel2 *nc;
+ int err;
+ int local_trusted;
+ int remote_trusted;
+ int filter_mac;
+
+ if (!gnttab_subpage_grants_available()) {
+ printk(KERN_ERR "netchannel2 needs version 2 grant tables\n");
+ return NULL;
+ }
+
+ if (xenbus_scanf(XBT_NIL, xd->nodename, "local-trusted",
+ "%d", &local_trusted) != 1) {
+ printk(KERN_WARNING "Can't tell whether local endpoint is
trusted; assuming it is.\n");
+ local_trusted = 1;
+ }
+
+ if (xenbus_scanf(XBT_NIL, xd->nodename, "remote-trusted",
+ "%d", &remote_trusted) != 1) {
+ printk(KERN_WARNING "Can't tell whether local endpoint is
trusted; assuming it isn't.\n");
+ remote_trusted = 0;
+ }
+
+ if (xenbus_scanf(XBT_NIL, xd->nodename, "filter-mac",
+ "%d", &filter_mac) != 1) {
+ if (remote_trusted) {
+ printk(KERN_WARNING "Can't tell whether to filter MAC
addresses from remote domain; filtering off.\n");
+ filter_mac = 0;
+ } else {
+ printk(KERN_WARNING "Can't tell whether to filter MAC
addresses from remote domain; filtering on.\n");
+ filter_mac = 1;
+ }
+ }
+
+ netdev = alloc_etherdev(sizeof(*nc));
+ if (netdev == NULL)
+ return NULL;
+
+ nc = netdev_priv(netdev);
+ memset(nc, 0, sizeof(*nc));
+ nc->magic = NETCHANNEL2_MAGIC;
+ nc->net_device = netdev;
+ nc->xenbus_device = xd;
+
+ nc->remote_trusted = remote_trusted;
+ nc->local_trusted = local_trusted;
+ nc->rings.filter_mac = filter_mac;
+
+ skb_queue_head_init(&nc->pending_skbs);
+ if (init_ring_pair(&nc->rings, nc) < 0) {
+ nc2_release(nc);
+ return NULL;
+ }
+
+ netdev->open = nc2_open;
+ netdev->stop = nc2_stop;
+ netdev->hard_start_xmit = nc2_start_xmit;
+ netdev->get_stats = nc2_get_stats;
+
+ /* We need to hold the ring lock in order to send messages
+ anyway, so there's no point in Linux doing additional
+ synchronisation. */
+ netdev->features = NETIF_F_LLTX;
+
+ SET_NETDEV_DEV(netdev, &xd->dev);
+
+ err = read_mac_address(xd->nodename, "remote-mac",
+ nc->rings.remote_mac);
+ if (err == 0)
+ err = read_mac_address(xd->nodename, "mac", netdev->dev_addr);
+ if (err == 0)
+ err = register_netdev(netdev);
+
+ if (err != 0) {
+ nc2_release(nc);
+ return NULL;
+ }
+
+ return nc;
+}
+
+/* Release a netchannel2 structure previously allocated with
+ * nc2_new(). Call with no locks held. The rings will be
+ * automatically detach if necessary. */
+void nc2_release(struct netchannel2 *nc)
+{
+ netif_carrier_off(nc->net_device);
+
+ unregister_netdev(nc->net_device);
+
+ nc2_detach_rings(nc);
+
+ /* Unregistering the net device stops any netdev methods from
+ running, and detaching the rings stops the napi methods, so
+ we're now the only thing accessing this netchannel2
+ structure and we can tear it down with impunity. */
+
+ cleanup_ring_pair(&nc->rings);
+
+ nc2_queue_purge(&nc->rings, &nc->pending_skbs);
+
+ free_netdev(nc->net_device);
+}
+
+static void _nc2_attach_rings(struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_sring_cons *cons_sring,
+ const volatile void *cons_payload,
+ size_t cons_size,
+ struct netchannel2_sring_prod *prod_sring,
+ void *prod_payload,
+ size_t prod_size,
+ domid_t otherend_id)
+{
+ BUG_ON(prod_sring == NULL);
+ BUG_ON(cons_sring == NULL);
+
+ ncrp->prod_ring.sring = prod_sring;
+ ncrp->prod_ring.payload_bytes = prod_size;
+ ncrp->prod_ring.prod_pvt = 0;
+ ncrp->prod_ring.payload = prod_payload;
+
+ ncrp->cons_ring.sring = cons_sring;
+ ncrp->cons_ring.payload_bytes = cons_size;
+ ncrp->cons_ring.sring->prod_event = ncrp->cons_ring.sring->prod + 1;
+ ncrp->cons_ring.cons_pvt = 0;
+ ncrp->cons_ring.payload = cons_payload;
+
+ ncrp->otherend_id = otherend_id;
+
+ ncrp->is_attached = 1;
+
+ ncrp->need_advertise_max_packets = 1;
+}
+
+/* Attach a netchannel2 structure to a ring pair. The endpoint is
+ also expected to set up an event channel after calling this before
+ using the interface. Returns 0 on success or <0 on error. */
+int nc2_attach_rings(struct netchannel2 *nc,
+ struct netchannel2_sring_cons *cons_sring,
+ const volatile void *cons_payload,
+ size_t cons_size,
+ struct netchannel2_sring_prod *prod_sring,
+ void *prod_payload,
+ size_t prod_size,
+ domid_t otherend_id)
+{
+ spin_lock_bh(&nc->rings.lock);
+ _nc2_attach_rings(&nc->rings, cons_sring, cons_payload, cons_size,
+ prod_sring, prod_payload, prod_size, otherend_id);
+
+ spin_unlock_bh(&nc->rings.lock);
+
+ netif_carrier_on(nc->net_device);
+
+ /* Kick it to get it going. */
+ nc2_kick(&nc->rings);
+
+ return 0;
+}
+
+static void _detach_rings(struct netchannel2_ring_pair *ncrp)
+{
+ spin_lock_bh(&ncrp->lock);
+ /* We need to release all of the pending transmission packets,
+ because they're never going to complete now that we've lost
+ the ring. */
+ drop_pending_tx_packets(ncrp);
+
+ disable_irq(ncrp->irq);
+
+ BUG_ON(ncrp->nr_tx_packets_outstanding);
+ ncrp->max_tx_packets_outstanding = 0;
+
+ /* No way of sending pending finish messages now; drop
+ * them. */
+ ncrp->pending_finish.prod = 0;
+ ncrp->pending_finish.cons = 0;
+
+ ncrp->cons_ring.sring = NULL;
+ ncrp->prod_ring.sring = NULL;
+ ncrp->is_attached = 0;
+
+ spin_unlock_bh(&ncrp->lock);
+}
+
+/* Detach from the rings. This includes unmapping them and stopping
+ the interrupt. */
+/* Careful: the netdev methods may still be running at this point. */
+/* This is not allowed to wait for the other end, because it might
+ have gone away (e.g. over suspend/resume). */
+static void nc2_detach_ring(struct netchannel2_ring_pair *ncrp)
+{
+ if (!ncrp->is_attached)
+ return;
+
+ napi_disable(&ncrp->napi);
+ _detach_rings(ncrp);
+}
+
+/* Trivial wrapper around nc2_detach_ring(). Make the ring no longer
+ used. */
+void nc2_detach_rings(struct netchannel2 *nc)
+{
+ nc2_detach_ring(&nc->rings);
+
+ /* Okay, all async access to the ring is stopped. Kill the
+ irqhandlers. (It might be better to do this from the
+ _detach_ring() functions, but you're not allowed to
+ free_irq() from interrupt context, and tasklets are close
+ enough to cause problems). */
+
+ if (nc->rings.irq >= 0)
+ unbind_from_irqhandler(nc->rings.irq, &nc->rings);
+ nc->rings.irq = -1;
+}
+
+#if defined(CONFIG_XEN_NETDEV2_BACKEND)
+/* Connect to an event channel port in a remote domain. Returns 0 on
+ success or <0 on error. The port is automatically disconnected
+ when the channel is released or if the rings are detached. This
+ should not be called if the port is already open. */
+int nc2_connect_evtchn(struct netchannel2 *nc, domid_t domid,
+ int evtchn)
+{
+ int err;
+
+ BUG_ON(nc->rings.irq >= 0);
+
+ err = bind_interdomain_evtchn_to_irqhandler(domid,
+ evtchn,
+ nc2_int,
+ IRQF_SAMPLE_RANDOM,
+ "netchannel2",
+ &nc->rings);
+ if (err >= 0) {
+ nc->rings.irq = err;
+ nc->rings.evtchn = irq_to_evtchn_port(err);
+ return 0;
+ } else {
+ return err;
+ }
+}
+#endif
+
+#if defined(CONFIG_XEN_NETDEV2_FRONTEND)
+/* Listen for incoming event channel connections from domain domid.
+ Similar semantics to nc2_connect_evtchn(). */
+int nc2_listen_evtchn(struct netchannel2 *nc, domid_t domid)
+{
+ int err;
+
+ BUG_ON(nc->rings.irq >= 0);
+
+ err = bind_listening_port_to_irqhandler(domid,
+ nc2_int,
+ IRQF_SAMPLE_RANDOM,
+ "netchannel2",
+ &nc->rings);
+ if (err >= 0) {
+ nc->rings.irq = err;
+ nc->rings.evtchn = irq_to_evtchn_port(err);
+ return 0;
+ } else {
+ return err;
+ }
+}
+#endif
+
+/* Find the local event channel port which was allocated by
+ * nc2_listen_evtchn() or nc2_connect_evtchn(). It is an error to
+ * call this when there is no event channel connected. */
+int nc2_get_evtchn_port(struct netchannel2 *nc)
+{
+ BUG_ON(nc->rings.irq < 0);
+ return nc->rings.evtchn;
+}
+
+/* @ncrp has been recently nc2_kick()ed. Do all of the necessary
+ stuff. */
+static int process_ring(struct napi_struct *napi,
+ int work_avail)
+{
+ struct netchannel2_ring_pair *ncrp =
+ container_of(napi, struct netchannel2_ring_pair, napi);
+ struct netchannel2 *nc = ncrp->interface;
+ struct sk_buff *skb;
+ int work_done;
+ struct sk_buff_head rx_queue;
+
+ skb_queue_head_init(&rx_queue);
+
+ spin_lock(&ncrp->lock);
+
+ /* Pick up incoming messages. */
+ work_done = nc2_poll(ncrp, work_avail, &rx_queue);
+
+ /* Transmit pending packets. */
+ if (!skb_queue_empty(&ncrp->pending_tx_queue)) {
+ skb = __skb_dequeue(&ncrp->pending_tx_queue);
+ do {
+ if (!nc2_really_start_xmit(ncrp, skb)) {
+ /* Requeue the packet so that we will try
+ when the ring is less busy */
+ __skb_queue_head(&ncrp->pending_tx_queue, skb);
+ break;
+ }
+ skb = __skb_dequeue(&ncrp->pending_tx_queue);
+ } while (skb != NULL);
+
+ flush_rings(ncrp);
+
+ while ((skb = __skb_dequeue(&ncrp->release_on_flush_batcher)))
+ release_tx_packet(ncrp, skb);
+ }
+
+ if (nc->is_stopped) {
+ /* If the other end has processed some messages, there
+ may be space on the ring for a delayed send from
+ earlier. Process it now. */
+ while (1) {
+ skb = skb_peek_tail(&nc->pending_skbs);
+ if (!skb)
+ break;
+ if (prepare_xmit_allocate_resources(nc, skb) < 0) {
+ /* Still stuck */
+ break;
+ }
+ __skb_unlink(skb, &nc->pending_skbs);
+ queue_packet_to_interface(skb, ncrp);
+ }
+ if (skb_queue_empty(&nc->pending_skbs)) {
+ nc->is_stopped = 0;
+ netif_wake_queue(nc->net_device);
+ }
+ }
+
+ spin_unlock(&ncrp->lock);
+
+ receive_pending_skbs(&rx_queue);
+
+ return work_done;
+}
diff --git a/drivers/xen/netchannel2/netback2.c
b/drivers/xen/netchannel2/netback2.c
new file mode 100644
index 0000000..fd6f238
--- /dev/null
+++ b/drivers/xen/netchannel2/netback2.c
@@ -0,0 +1,354 @@
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/vmalloc.h>
+#include <xen/gnttab.h>
+#include <xen/xenbus.h>
+#include <xen/interface/io/netchannel2.h>
+
+#include "netchannel2_core.h"
+#include "netchannel2_endpoint.h"
+
+#define NETBACK2_MAGIC 0xb5e99485
+struct netback2 {
+ unsigned magic;
+ struct xenbus_device *xenbus_device;
+
+ struct netchannel2 *chan;
+
+ struct grant_mapping b2f_mapping;
+ struct grant_mapping f2b_mapping;
+ struct grant_mapping control_mapping;
+
+ int attached;
+
+ struct xenbus_watch shutdown_watch;
+ int have_shutdown_watch;
+};
+
+static struct netback2 *xenbus_device_to_nb2(struct xenbus_device *xd)
+{
+ struct netback2 *nb = xd->dev.driver_data;
+ BUG_ON(nb->magic != NETBACK2_MAGIC);
+ return nb;
+}
+
+/* Read a range of grants out of xenstore and map them in gm. Any
+ existing mapping in gm is released. Returns 0 on success or <0 on
+ error. On error, gm is preserved, and xenbus_dev_fatal() is
+ called. */
+static int map_grants(struct netback2 *nd, const char *prefix,
+ struct grant_mapping *gm)
+{
+ struct xenbus_device *xd = nd->xenbus_device;
+ int err;
+ char buf[32];
+ int i;
+ unsigned nr_pages;
+ grant_ref_t grefs[MAX_GRANT_MAP_PAGES];
+
+ sprintf(buf, "%s-nr-pages", prefix);
+ err = xenbus_scanf(XBT_NIL, xd->otherend, buf, "%u", &nr_pages);
+ if (err == -ENOENT) {
+ nr_pages = 1;
+ } else if (err != 1) {
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err, "reading %s", buf);
+ return err;
+ } else {
+ xenbus_dev_fatal(xd, err, "reading %s as integer",
+ buf);
+ return -EINVAL;
+ }
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ sprintf(buf, "%s-ref-%d", prefix, i);
+ err = xenbus_scanf(XBT_NIL, xd->otherend, buf, "%u",
+ &grefs[i]);
+ if (err != 1) {
+ if (err < 0) {
+ xenbus_dev_fatal(xd,
+ err,
+ "reading gref %d from %s/%s",
+ i,
+ xd->otherend,
+ buf);
+ } else {
+ xenbus_dev_fatal(xd,
+ -EINVAL,
+ "expected an integer at %s/%s",
+ xd->otherend,
+ buf);
+ err = -EINVAL;
+ }
+ return err;
+ }
+ }
+
+ err = nc2_map_grants(gm, grefs, nr_pages, xd->otherend_id);
+ if (err < 0)
+ xenbus_dev_fatal(xd, err, "mapping ring %s from %s",
+ prefix, xd->otherend);
+ return err;
+}
+
+/* Undo the effects of attach_to_frontend */
+static void detach_from_frontend(struct netback2 *nb)
+{
+ if (!nb->attached)
+ return;
+ nc2_detach_rings(nb->chan);
+ nc2_unmap_grants(&nb->b2f_mapping);
+ nc2_unmap_grants(&nb->f2b_mapping);
+ nc2_unmap_grants(&nb->control_mapping);
+ nb->attached = 0;
+}
+
+static int attach_to_frontend(struct netback2 *nd)
+{
+ int err;
+ int evtchn;
+ struct xenbus_device *xd = nd->xenbus_device;
+ struct netchannel2 *nc = nd->chan;
+ struct netchannel2_backend_shared *nbs;
+
+ if (nd->attached)
+ return 0;
+
+ /* Attach the shared memory bits */
+ err = map_grants(nd, "b2f-ring", &nd->b2f_mapping);
+ if (err)
+ return err;
+ err = map_grants(nd, "f2b-ring", &nd->f2b_mapping);
+ if (err)
+ return err;
+ err = map_grants(nd, "control", &nd->control_mapping);
+ if (err)
+ return err;
+ nbs = nd->control_mapping.mapping->addr;
+ err = nc2_attach_rings(nc,
+ &nbs->cons,
+ nd->f2b_mapping.mapping->addr,
+ nd->f2b_mapping.nr_pages * PAGE_SIZE,
+ &nbs->prod,
+ nd->b2f_mapping.mapping->addr,
+ nd->b2f_mapping.nr_pages * PAGE_SIZE,
+ xd->otherend_id);
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err, "attaching to rings");
+ return err;
+ }
+
+ /* Connect the event channel. */
+ err = xenbus_scanf(XBT_NIL, xd->otherend, "event-channel", "%u",
+ &evtchn);
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err,
+ "reading %s/event-channel or {t,r}x-sring-pages",
+ xd->otherend);
+ return err;
+ }
+ err = nc2_connect_evtchn(nd->chan, xd->otherend_id, evtchn);
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err, "binding to event channel");
+ return err;
+ }
+
+ /* All done */
+ nd->attached = 1;
+
+ return 0;
+}
+
+static void frontend_changed(struct xenbus_device *xd,
+ enum xenbus_state frontend_state)
+{
+ struct netback2 *nb = xenbus_device_to_nb2(xd);
+ int err;
+
+ switch (frontend_state) {
+ case XenbusStateInitialising:
+ /* If the frontend does a kexec following a crash, we
+ can end up bounced back here even though we're
+ attached. Try to recover by detaching from the old
+ rings. */
+ /* (A normal shutdown, and even a normal kexec, would
+ * have gone through Closed first, so we'll already be
+ * detached, and this is pointless but harmless.) */
+ detach_from_frontend(nb);
+
+ /* Tell the frontend what sort of rings we're willing
+ to accept. */
+ xenbus_printf(XBT_NIL, nb->xenbus_device->nodename,
+ "max-sring-pages", "%d", MAX_GRANT_MAP_PAGES);
+
+ /* Start the device bring-up bit of the state
+ * machine. */
+ xenbus_switch_state(nb->xenbus_device, XenbusStateInitWait);
+ break;
+
+ case XenbusStateInitWait:
+ /* Frontend doesn't use this state */
+ xenbus_dev_fatal(xd, EINVAL,
+ "unexpected frontend state InitWait");
+ break;
+
+ case XenbusStateInitialised:
+ case XenbusStateConnected:
+ /* Frontend has advertised its rings to us */
+ err = attach_to_frontend(nb);
+ if (err >= 0)
+ xenbus_switch_state(xd, XenbusStateConnected);
+ break;
+
+ case XenbusStateClosing:
+ detach_from_frontend(nb);
+ xenbus_switch_state(xd, XenbusStateClosed);
+ break;
+
+ case XenbusStateClosed:
+ detach_from_frontend(nb);
+ xenbus_switch_state(xd, XenbusStateClosed);
+ if (!xenbus_dev_is_online(xd))
+ device_unregister(&xd->dev);
+ break;
+
+ case XenbusStateUnknown:
+ detach_from_frontend(nb);
+ xenbus_switch_state(xd, XenbusStateClosed);
+ device_unregister(&xd->dev);
+ break;
+
+ default:
+ /* Ignore transitions to unknown states */
+ break;
+ }
+}
+
+static int netback2_uevent(struct xenbus_device *xd,
+ struct kobj_uevent_env *env)
+{
+ struct netback2 *nb = xenbus_device_to_nb2(xd);
+
+ add_uevent_var(env, "vif=%s", nb->chan->net_device->name);
+
+ return 0;
+}
+
+static void netback2_shutdown(struct xenbus_device *xd)
+{
+ xenbus_switch_state(xd, XenbusStateClosing);
+}
+
+static void shutdown_watch_callback(struct xenbus_watch *watch,
+ const char **vec,
+ unsigned int len)
+{
+ struct netback2 *nb =
+ container_of(watch, struct netback2, shutdown_watch);
+ char *type;
+
+ type = xenbus_read(XBT_NIL, nb->xenbus_device->nodename,
+ "shutdown-request", NULL);
+ if (IS_ERR(type)) {
+ if (PTR_ERR(type) != -ENOENT)
+ printk(KERN_WARNING "Cannot read %s/%s: %ld\n",
+ nb->xenbus_device->nodename, "shutdown-request",
+ PTR_ERR(type));
+ return;
+ }
+ if (strcmp(type, "force") == 0) {
+ detach_from_frontend(nb);
+ xenbus_switch_state(nb->xenbus_device, XenbusStateClosed);
+ } else if (strcmp(type, "normal") == 0) {
+ netback2_shutdown(nb->xenbus_device);
+ } else {
+ printk(KERN_WARNING "Unrecognised shutdown request %s from
tools\n",
+ type);
+ }
+ xenbus_rm(XBT_NIL, nb->xenbus_device->nodename, "shutdown-request");
+ kfree(type);
+}
+
+static int netback2_probe(struct xenbus_device *xd,
+ const struct xenbus_device_id *id)
+{
+ struct netback2 *nb;
+
+ nb = kzalloc(sizeof(*nb), GFP_KERNEL);
+ if (nb == NULL)
+ goto err;
+ nb->magic = NETBACK2_MAGIC;
+ nb->xenbus_device = xd;
+
+ nb->shutdown_watch.node = kasprintf(GFP_KERNEL, "%s/shutdown-request",
+ xd->nodename);
+ if (nb->shutdown_watch.node == NULL)
+ goto err;
+ nb->shutdown_watch.callback = shutdown_watch_callback;
+ if (register_xenbus_watch(&nb->shutdown_watch))
+ goto err;
+ nb->have_shutdown_watch = 1;
+
+ nb->chan = nc2_new(xd);
+ if (!nb->chan)
+ goto err;
+
+ xd->dev.driver_data = nb;
+
+ kobject_uevent(&xd->dev.kobj, KOBJ_ONLINE);
+
+ return 0;
+
+err:
+ if (nb != NULL) {
+ if (nb->have_shutdown_watch)
+ unregister_xenbus_watch(&nb->shutdown_watch);
+ kfree(nb->shutdown_watch.node);
+ kfree(nb);
+ }
+ xenbus_dev_fatal(xd, ENOMEM, "probing netdev");
+ return -ENOMEM;
+}
+
+static int netback2_remove(struct xenbus_device *xd)
+{
+ struct netback2 *nb = xenbus_device_to_nb2(xd);
+ kobject_uevent(&xd->dev.kobj, KOBJ_OFFLINE);
+ if (nb->chan != NULL)
+ nc2_release(nb->chan);
+ if (nb->have_shutdown_watch)
+ unregister_xenbus_watch(&nb->shutdown_watch);
+ kfree(nb->shutdown_watch.node);
+ nc2_unmap_grants(&nb->b2f_mapping);
+ nc2_unmap_grants(&nb->f2b_mapping);
+ nc2_unmap_grants(&nb->control_mapping);
+ kfree(nb);
+ return 0;
+}
+
+static const struct xenbus_device_id netback2_ids[] = {
+ { "vif2" },
+ { "" }
+};
+
+static struct xenbus_driver netback2 = {
+ .name = "vif2",
+ .ids = netback2_ids,
+ .probe = netback2_probe,
+ .remove = netback2_remove,
+ .otherend_changed = frontend_changed,
+ .uevent = netback2_uevent,
+};
+
+int __init netback2_init(void)
+{
+ int r;
+
+ r = xenbus_register_backend(&netback2);
+ if (r < 0) {
+ printk(KERN_ERR "error %d registering backend driver.\n",
+ r);
+ }
+ return r;
+}
diff --git a/drivers/xen/netchannel2/netchan2.c
b/drivers/xen/netchannel2/netchan2.c
new file mode 100644
index 0000000..b23b7e4
--- /dev/null
+++ b/drivers/xen/netchannel2/netchan2.c
@@ -0,0 +1,32 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "netchannel2_endpoint.h"
+
+static int __init netchan2_init(void)
+{
+ int r;
+
+ r = nc2_init();
+ if (r < 0)
+ return r;
+ r = netfront2_init();
+ if (r < 0)
+ return r;
+ r = netback2_init();
+ if (r < 0)
+ netfront2_exit();
+ return r;
+}
+module_init(netchan2_init);
+
+/* We can't unload if we're acting as a backend. */
+#ifndef CONFIG_XEN_NETDEV2_BACKEND
+static void __exit netchan2_exit(void)
+{
+ netfront2_exit();
+ nc2_exit();
+}
+module_exit(netchan2_exit);
+#endif
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/xen/netchannel2/netchannel2_core.h
b/drivers/xen/netchannel2/netchannel2_core.h
new file mode 100644
index 0000000..6ae273d
--- /dev/null
+++ b/drivers/xen/netchannel2/netchannel2_core.h
@@ -0,0 +1,351 @@
+#ifndef NETCHANNEL2_CORE_H__
+#define NETCHANNEL2_CORE_H__
+
+#include <xen/interface/xen.h>
+#include <xen/gnttab.h>
+#include <xen/interface/io/netchannel2.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+
+/* After we send this number of frags, we request the other end to
+ * notify us when sending the corresponding finish packet message */
+#define MAX_MAX_COUNT_FRAGS_NO_EVENT 192
+
+/* Very small packets (e.g. TCP pure acks) are sent inline in the
+ * ring, to avoid the hypercall overhead. This is the largest packet
+ * which will be sent small, in bytes. It should be big enough to
+ * cover the normal headers (i.e. ethernet + IP + TCP = 66 bytes) plus
+ * a little bit of slop for options etc. */
+#define PACKET_PREFIX_SIZE 96
+
+/* How many packets can we have outstanding at any one time? This
+ * must be small enough that it won't be confused with an sk_buff
+ * pointer; see the txp_slot stuff later. */
+#define NR_TX_PACKETS 256
+
+/* A way of keeping track of a mapping of a bunch of grant references
+ into a contigous chunk of virtual address space. This is used for
+ things like multi-page rings. */
+#define MAX_GRANT_MAP_PAGES 4
+struct grant_mapping {
+ unsigned nr_pages;
+ grant_handle_t handles[MAX_GRANT_MAP_PAGES];
+ struct vm_struct *mapping;
+};
+
+enum transmit_policy {
+ transmit_policy_unknown = 0,
+ transmit_policy_first = 0xf001,
+ transmit_policy_grant = transmit_policy_first,
+ transmit_policy_small,
+ transmit_policy_last = transmit_policy_small
+};
+
+/* When we send a packet message, we need to tag it with an ID. That
+ ID is an index into the TXP slot array. Each slot contains either
+ a pointer to an sk_buff (if it's in use), or the index of the next
+ free slot (if it isn't). A slot is in use if the contents is >
+ NR_TX_PACKETS, and free otherwise. */
+struct txp_slot {
+ unsigned long __contents;
+};
+
+typedef uint32_t nc2_txp_index_t;
+
+#define INVALID_TXP_INDEX ((nc2_txp_index_t)NR_TX_PACKETS)
+
+static inline int txp_slot_in_use(struct txp_slot *slot)
+{
+ if (slot->__contents <= NR_TX_PACKETS)
+ return 0;
+ else
+ return 1;
+}
+
+static inline void txp_set_skb(struct txp_slot *slot, struct sk_buff *skb)
+{
+ slot->__contents = (unsigned long)skb;
+}
+
+static inline struct sk_buff *txp_get_skb(struct txp_slot *slot)
+{
+ if (txp_slot_in_use(slot))
+ return (struct sk_buff *)slot->__contents;
+ else
+ return NULL;
+}
+
+static inline void txp_set_next_free(struct txp_slot *slot,
+ nc2_txp_index_t idx)
+{
+ slot->__contents = idx;
+}
+
+static inline nc2_txp_index_t txp_get_next_free(struct txp_slot *slot)
+{
+ return (nc2_txp_index_t)slot->__contents;
+}
+
+/* This goes in struct sk_buff::cb */
+struct skb_cb_overlay {
+ struct txp_slot *tp;
+ unsigned nr_fragments;
+ grant_ref_t gref_pool;
+ enum transmit_policy policy;
+ uint8_t failed;
+ uint8_t expecting_finish;
+ uint8_t type;
+ uint16_t inline_prefix_size;
+};
+
+#define CASSERT(x) typedef unsigned __cassert_ ## __LINE__ [(x)-1]
+CASSERT(sizeof(struct skb_cb_overlay) <= sizeof(((struct sk_buff *)0)->cb));
+
+static inline struct skb_cb_overlay *get_skb_overlay(struct sk_buff *skb)
+{
+ return (struct skb_cb_overlay *)skb->cb;
+}
+
+
+/* Packets for which we need to send FINISH_PACKET messages for as
+ soon as possible. */
+struct pending_finish_packets {
+#define MAX_PENDING_FINISH_PACKETS 256
+ uint32_t ids[MAX_PENDING_FINISH_PACKETS];
+ RING_IDX prod;
+ RING_IDX cons;
+};
+
+#define RX_GRANT_COPY_BATCH 32
+struct hypercall_batcher {
+ unsigned nr_pending_gops;
+ gnttab_copy_t gops[RX_GRANT_COPY_BATCH];
+ void *ctxt[RX_GRANT_COPY_BATCH];
+};
+
+struct netchannel2_ring_pair {
+ struct netchannel2 *interface;
+ /* Main ring lock. Acquired from bottom halves. */
+ spinlock_t lock;
+
+ struct napi_struct napi;
+
+ /* Protected by the lock. Initialised at attach_ring() time
+ and de-initialised at detach_ring() time. */
+ struct netchannel2_prod_ring prod_ring;
+ struct netchannel2_cons_ring cons_ring;
+ uint8_t is_attached; /* True if the rings are currently safe to
+ access. */
+
+ unsigned max_count_frags_no_event;
+ unsigned expected_finish_messages;
+
+ domid_t otherend_id;
+
+ grant_ref_t gref_pool;
+
+ /* The IRQ corresponding to the event channel which is
+ connected to the other end. This only changes from the
+ xenbus state change handler. It is notified from lots of
+ other places. Fortunately, it's safe to notify on an irq
+ after it's been released, so the lack of synchronisation
+ doesn't matter. */
+ int irq;
+ int evtchn;
+
+ /* The MAC address of our peer. */
+ unsigned char remote_mac[ETH_ALEN];
+
+ /* Set if we need to check the source MAC address on incoming
+ packets. */
+ int filter_mac;
+
+ /* A pool of free transmitted_packet structures, threaded on
+ the list member. Protected by the lock. */
+ nc2_txp_index_t head_free_tx_packet;
+
+ /* Total number of packets on the allocated list. Protected
+ by the lock. */
+ unsigned nr_tx_packets_outstanding;
+ /* Maximum number of packets which the other end will allow us
+ to keep outstanding at one time. Valid whenever
+ is_attached is set. */
+ unsigned max_tx_packets_outstanding;
+
+ /* Count number of frags that we have sent to the other side
+ When we reach a max value we request that the other end
+ send an event when sending the corresponding finish message */
+ unsigned count_frags_no_event;
+
+ /* Set if we need to send a SET_MAX_PACKETS message.
+ Protected by the lock. */
+ uint8_t need_advertise_max_packets;
+
+ /* Set if there are messages on the ring which are considered
+ time-sensitive, so that it's necessary to notify the remote
+ endpoint as soon as possible. */
+ uint8_t pending_time_sensitive_messages;
+
+ /* Set if we've previously suppressed a remote notification
+ because none of the messages pending at the time of the
+ flush were time-sensitive. The remote should be notified
+ as soon as the ring is flushed, even if the normal
+ filtering rules would suppress the event. */
+ uint8_t delayed_kick;
+
+ /* A list of packet IDs which we need to return to the other
+ end as soon as there is space on the ring. Protected by
+ the lock. */
+ struct pending_finish_packets pending_finish;
+
+ /* transmitted_packet structures which are to be transmitted
+ next time the TX tasklet looks at this interface.
+ Protected by the lock. */
+ struct sk_buff_head pending_tx_queue;
+
+ /* Packets which we'll have finished transmitting as soon as
+ we flush the hypercall batcher. Protected by the lock. */
+ struct sk_buff_head release_on_flush_batcher;
+
+ struct hypercall_batcher pending_rx_hypercalls;
+
+ /* A pre-allocated pool of TX packets. The
+ allocated_tx_packets and free_tx_packets linked lists
+ contain elements of this array, and it can also be directly
+ indexed by packet ID. Protected by the lock. */
+ struct txp_slot tx_packets[NR_TX_PACKETS];
+};
+
+struct netchannel2 {
+#define NETCHANNEL2_MAGIC 0x57c68c1d
+ unsigned magic;
+
+ /* Set when the structure is created and never changed */
+ struct net_device *net_device;
+ struct xenbus_device *xenbus_device;
+
+ /* Set if we trust the remote endpoint. */
+ int remote_trusted;
+ /* Set if the remote endpoint is expected to trust us.
+ There's no guarantee that this is actually correct, but
+ it's useful for optimisation. */
+ int local_trusted;
+
+ struct netchannel2_ring_pair rings;
+
+ /* Packets which we need to transmit soon */
+ struct sk_buff_head pending_skbs;
+
+ /* Flag to indicate that the interface is stopped
+ When the interface is stopped we need to run the tasklet
+ after we receive an interrupt so that we can wake it up */
+ uint8_t is_stopped;
+
+ /* Updates are protected by the lock. This can be read at any
+ * time without holding any locks, and the rest of Linux is
+ * expected to cope. */
+ struct net_device_stats stats;
+};
+
+static inline void flush_prepared_grant_copies(struct hypercall_batcher *hb,
+ void (*on_fail)(void *ctxt,
+ gnttab_copy_t
*gop))
+{
+ unsigned x;
+
+ if (hb->nr_pending_gops == 0)
+ return;
+ if (HYPERVISOR_grant_table_op(GNTTABOP_copy, hb->gops,
+ hb->nr_pending_gops))
+ BUG();
+ for (x = 0; x < hb->nr_pending_gops; x++)
+ if (hb->gops[x].status != GNTST_okay)
+ on_fail(hb->ctxt[x], &hb->gops[x]);
+ hb->nr_pending_gops = 0;
+}
+
+static inline gnttab_copy_t *hypercall_batcher_grant_copy(struct
hypercall_batcher *hb,
+ void *ctxt,
+ void (*on_fail)(void
*,
+
gnttab_copy_t *gop))
+{
+ if (hb->nr_pending_gops == ARRAY_SIZE(hb->gops))
+ flush_prepared_grant_copies(hb, on_fail);
+ hb->ctxt[hb->nr_pending_gops] = ctxt;
+ return &hb->gops[hb->nr_pending_gops++];
+}
+
+static inline void flush_hypercall_batcher(struct hypercall_batcher *hb,
+ void (*on_fail)(void *,
+ gnttab_copy_t *gop))
+{
+ flush_prepared_grant_copies(hb, on_fail);
+}
+
+struct sk_buff *handle_receiver_copy_packet(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_packet *msg,
+ struct netchannel2_msg_hdr *hdr,
+ unsigned nr_frags,
+ unsigned frags_off);
+
+int prepare_xmit_allocate_small(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+int prepare_xmit_allocate_grant(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+void xmit_grant(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb,
+ volatile void *msg);
+
+void queue_finish_packet_message(struct netchannel2_ring_pair *ncrp,
+ uint32_t id, uint8_t flags);
+
+int allocate_txp_slot(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+void release_txp_slot(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+/* Releases the txp slot, the grant pool, and the skb */
+void release_tx_packet(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+
+void fetch_fragment(struct netchannel2_ring_pair *ncrp,
+ unsigned idx,
+ struct netchannel2_fragment *frag,
+ unsigned off);
+
+void nc2_kick(struct netchannel2_ring_pair *ncrp);
+
+int nc2_map_grants(struct grant_mapping *gm,
+ const grant_ref_t *grefs,
+ unsigned nr_grefs,
+ domid_t remote_domain);
+void nc2_unmap_grants(struct grant_mapping *gm);
+
+void queue_packet_to_interface(struct sk_buff *skb,
+ struct netchannel2_ring_pair *ncrp);
+
+void nc2_rscb_on_gntcopy_fail(void *ctxt, gnttab_copy_t *gop);
+
+int nc2_start_xmit(struct sk_buff *skb, struct net_device *dev);
+int nc2_really_start_xmit(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb);
+int prepare_xmit_allocate_resources(struct netchannel2 *nc,
+ struct sk_buff *skb);
+void nc2_handle_finish_packet_msg(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr);
+void nc2_handle_set_max_packets_msg(struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr);
+void drop_pending_tx_packets(struct netchannel2_ring_pair *ncrp);
+
+void send_finish_packet_messages(struct netchannel2_ring_pair *ncrp);
+void nc2_handle_packet_msg(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr,
+ struct sk_buff_head *pending_rx_queue);
+void advertise_max_packets(struct netchannel2_ring_pair *ncrp);
+void receive_pending_skbs(struct sk_buff_head *rx_queue);
+void nc2_queue_purge(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff_head *queue);
+
+#endif /* !NETCHANNEL2_CORE_H__ */
diff --git a/drivers/xen/netchannel2/netchannel2_endpoint.h
b/drivers/xen/netchannel2/netchannel2_endpoint.h
new file mode 100644
index 0000000..2525f23
--- /dev/null
+++ b/drivers/xen/netchannel2/netchannel2_endpoint.h
@@ -0,0 +1,63 @@
+/* Interface between the endpoint implementations (netfront2.c,
+ netback2.c) and the netchannel2 core (chan.c and the various
+ transmission modes). */
+#ifndef NETCHANNEL2_ENDPOINT_H__
+#define NETCHANNEL2_ENDPOINT_H__
+
+#include <linux/init.h>
+#include <xen/interface/xen.h>
+
+struct netchannel2_sring_prod;
+struct netchannel2_sring_cons;
+struct netchannel2;
+struct xenbus_device;
+
+struct netchannel2 *nc2_new(struct xenbus_device *xd);
+void nc2_release(struct netchannel2 *nc);
+
+int nc2_attach_rings(struct netchannel2 *nc,
+ struct netchannel2_sring_cons *cons_sring,
+ const volatile void *cons_payload,
+ size_t cons_size,
+ struct netchannel2_sring_prod *prod_sring,
+ void *prod_payload,
+ size_t prod_size,
+ domid_t otherend_id);
+void nc2_detach_rings(struct netchannel2 *nc);
+#if defined(CONFIG_XEN_NETDEV2_FRONTEND)
+int nc2_listen_evtchn(struct netchannel2 *nc, domid_t dom);
+#endif
+#if defined(CONFIG_XEN_NETDEV2_BACKEND)
+int nc2_connect_evtchn(struct netchannel2 *nc, domid_t domid,
+ int evtchn);
+#endif
+int nc2_get_evtchn_port(struct netchannel2 *nc);
+void nc2_suspend(struct netchannel2 *nc);
+
+void nc2_set_nr_tx_buffers(struct netchannel2 *nc, unsigned nr_buffers);
+
+/* Interface which the endpoints provide to the core. */
+#ifdef CONFIG_XEN_NETDEV2_FRONTEND
+int __init netfront2_init(void);
+void __exit netfront2_exit(void);
+#else
+static inline int netfront2_init(void)
+{
+ return 0;
+}
+static inline void netfront2_exit(void)
+{
+}
+#endif
+#ifdef CONFIG_XEN_NETDEV2_BACKEND
+int __init netback2_init(void);
+#else
+static inline int netback2_init(void)
+{
+ return 0;
+}
+#endif
+int __init nc2_init(void);
+void __exit nc2_exit(void);
+
+#endif /* NETCHANNEL2_ENDPOINT_H__ */
diff --git a/drivers/xen/netchannel2/netfront2.c
b/drivers/xen/netchannel2/netfront2.c
new file mode 100644
index 0000000..fb5d426
--- /dev/null
+++ b/drivers/xen/netchannel2/netfront2.c
@@ -0,0 +1,488 @@
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/version.h>
+#include <xen/gnttab.h>
+#include <xen/xenbus.h>
+
+#include "netchannel2_core.h"
+#include "netchannel2_endpoint.h"
+
+#define MAX_SRING_PAGES 4
+
+struct netfront2 {
+#define NETFRONT2_MAGIC 0x9268e704
+ unsigned magic;
+ struct xenbus_device *xenbus_device;
+
+ void *f2b_sring;
+ grant_ref_t f2b_grefs[MAX_SRING_PAGES];
+ void *b2f_sring;
+ grant_ref_t b2f_grefs[MAX_SRING_PAGES];
+
+ struct netchannel2_frontend_shared *control_shared;
+ grant_ref_t control_shared_gref;
+
+ int nr_sring_pages;
+ int sring_order;
+
+ grant_ref_t rings_gref_pool; /* Some pre-allocated grant
+ references to cover the shared
+ rings. */
+
+ struct netchannel2 *chan;
+
+ int attached; /* True if the shared rings are ready to go. */
+};
+
+static struct netfront2 *xenbus_device_to_nf2(struct xenbus_device *xd)
+{
+ struct netfront2 *work = xd->dev.driver_data;
+ BUG_ON(work->magic != NETFRONT2_MAGIC);
+ return work;
+}
+
+/* Try to revoke a bunch of grant references and return the grefs to
+ the rings grefs pool. Any cleared grefs are set to 0. Returns 0
+ on success or <0 on error. Ignores zero entries in the @grefs
+ list, and zeroes any entries which are successfully ended. */
+static int ungrant_access_to_ring(struct netfront2 *nf,
+ grant_ref_t *grefs,
+ int nr_pages)
+{
+ int i;
+ int succ;
+ int failed;
+
+ failed = 0;
+
+ for (i = 0; i < nr_pages; i++) {
+ if (grefs[i]) {
+ succ = gnttab_end_foreign_access_ref(grefs[i]);
+ if (!succ) {
+ /* XXX we can't recover when this
+ * happens. Try to do something
+ * vaguely plausible, but the device
+ * is pretty much doomed. */
+ printk(KERN_WARNING "Failed to end access to
gref %d\n",
+ i);
+ failed = 1;
+ continue;
+ }
+ gnttab_release_grant_reference(&nf->rings_gref_pool,
+ grefs[i]);
+ grefs[i] = 0;
+ }
+ }
+
+ if (failed)
+ return -EBUSY;
+ else
+ return 0;
+}
+
+/* Allocate and initialise grant references to cover a bunch of pages.
+ @ring should be in the direct-mapped region. The rings_gref_pool
+ on nf should contain at least @nr_pages references.
+ Already-populated slots in the @grefs list are left unchanged. */
+static void grant_access_to_ring(struct netfront2 *nf,
+ domid_t otherend,
+ void *ring,
+ int *grefs,
+ int nr_pages)
+{
+ void *p;
+ int i;
+ grant_ref_t ref;
+
+ for (i = 0; i < nr_pages; i++) {
+
+ if (grefs[i] != 0)
+ continue;
+
+ p = (void *)((unsigned long)ring + PAGE_SIZE * i);
+
+ ref = gnttab_claim_grant_reference(&nf->rings_gref_pool);
+ /* There should be enough grefs in the pool to handle
+ the rings. */
+ BUG_ON(ref < 0);
+ gnttab_grant_foreign_access_ref(ref,
+ otherend,
+ virt_to_mfn(p),
+ 0);
+ grefs[i] = ref;
+ }
+}
+
+/* Push an already-granted ring into xenstore. */
+static int publish_ring(struct xenbus_transaction xbt,
+ struct netfront2 *nf,
+ const char *prefix,
+ const int *grefs,
+ int nr_grefs)
+{
+ int i;
+ char buf[32];
+ int err;
+
+ sprintf(buf, "%s-nr-pages", prefix);
+ err = xenbus_printf(xbt, nf->xenbus_device->nodename, buf,
+ "%u", nr_grefs);
+ if (err)
+ return err;
+
+ for (i = 0; i < nr_grefs; i++) {
+ BUG_ON(grefs[i] == 0);
+ sprintf(buf, "%s-ref-%u", prefix, i);
+ err = xenbus_printf(xbt, nf->xenbus_device->nodename,
+ buf, "%u", grefs[i]);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+static int publish_rings(struct netfront2 *nf)
+{
+ int err;
+ struct xenbus_transaction xbt;
+ const char *msg;
+
+again:
+ err = xenbus_transaction_start(&xbt);
+ if (err) {
+ xenbus_dev_fatal(nf->xenbus_device, err,
+ "starting transaction");
+ return err;
+ }
+
+ err = publish_ring(xbt, nf, "f2b-ring", nf->f2b_grefs,
+ nf->nr_sring_pages);
+ if (err) {
+ msg = "publishing f2b-ring";
+ goto abort;
+ }
+ err = publish_ring(xbt, nf, "b2f-ring", nf->b2f_grefs,
+ nf->nr_sring_pages);
+ if (err) {
+ msg = "publishing b2f-ring";
+ goto abort;
+ }
+ err = publish_ring(xbt, nf, "control", &nf->control_shared_gref, 1);
+ if (err) {
+ msg = "publishing control";
+ goto abort;
+ }
+ err = xenbus_printf(xbt, nf->xenbus_device->nodename,
+ "event-channel", "%u",
+ nc2_get_evtchn_port(nf->chan));
+ if (err) {
+ msg = "publishing event channel";
+ goto abort;
+ }
+
+ err = xenbus_transaction_end(xbt, 0);
+ if (err) {
+ if (err == -EAGAIN)
+ goto again;
+ xenbus_dev_fatal(nf->xenbus_device, err,
+ "completing transaction");
+ }
+
+ return err;
+
+abort:
+ xenbus_transaction_end(xbt, 1);
+ xenbus_dev_fatal(nf->xenbus_device, err, msg);
+ return err;
+}
+
+/* Release the rings. WARNING: This will leak memory if the other end
+ still has the rings mapped. There isn't really anything we can do
+ about that; the alternative (giving the other end access to
+ whatever Linux puts in the memory after we released it) is probably
+ worse. */
+static void release_rings(struct netfront2 *nf)
+{
+ int have_outstanding_grants;
+
+ have_outstanding_grants = 0;
+
+ if (nf->f2b_sring) {
+ if (ungrant_access_to_ring(nf, nf->f2b_grefs,
+ nf->nr_sring_pages) >= 0) {
+ free_pages((unsigned long)nf->f2b_sring,
+ nf->sring_order);
+ } else {
+ have_outstanding_grants = 1;
+ }
+ nf->f2b_sring = NULL;
+ }
+
+ if (nf->b2f_sring) {
+ if (ungrant_access_to_ring(nf, nf->b2f_grefs,
+ nf->nr_sring_pages) >= 0) {
+ free_pages((unsigned long)nf->b2f_sring,
+ nf->sring_order);
+ } else {
+ have_outstanding_grants = 1;
+ }
+ nf->b2f_sring = NULL;
+ }
+
+ if (nf->control_shared) {
+ if (ungrant_access_to_ring(nf, &nf->control_shared_gref,
+ 1) >= 0) {
+ free_page((unsigned long)nf->control_shared);
+ } else {
+ have_outstanding_grants = 1;
+ }
+ nf->control_shared = NULL;
+ }
+
+ if (have_outstanding_grants != 0) {
+ printk(KERN_WARNING
+ "Released shared rings while the backend still had them
mapped; leaking memory\n");
+ }
+
+ /* We can't release the gref pool if there are still
+ references outstanding against it. */
+ if (!have_outstanding_grants) {
+ if (nf->rings_gref_pool)
+ gnttab_free_grant_references(nf->rings_gref_pool);
+ nf->rings_gref_pool = 0;
+ }
+
+ nf->attached = 0;
+}
+
+static int allocate_rings(struct netfront2 *nf, domid_t otherend)
+{
+ int err;
+ int max_sring_pages;
+ int sring_order;
+ int nr_sring_pages;
+ size_t sring_size;
+
+ /* Figure out how big our shared rings are going to be. */
+ err = xenbus_scanf(XBT_NIL, nf->xenbus_device->otherend,
+ "max-sring-pages", "%d", &max_sring_pages);
+ if (err < 0) {
+ xenbus_dev_fatal(nf->xenbus_device, err,
+ "reading %s/max-sring-pages",
+ nf->xenbus_device->otherend);
+ return err;
+ }
+ if (max_sring_pages > MAX_SRING_PAGES)
+ max_sring_pages = MAX_SRING_PAGES;
+ sring_order = order_base_2(max_sring_pages);
+ nr_sring_pages = 1 << sring_order;
+ sring_size = nr_sring_pages * PAGE_SIZE;
+
+ release_rings(nf);
+
+ nf->nr_sring_pages = nr_sring_pages;
+ nf->sring_order = sring_order;
+
+ nf->f2b_sring = (void *)__get_free_pages(GFP_KERNEL, sring_order);
+ if (!nf->f2b_sring)
+ return -ENOMEM;
+ memset(nf->f2b_sring, 0, sring_size);
+
+ nf->b2f_sring = (void *)__get_free_pages(GFP_KERNEL, sring_order);
+ if (!nf->b2f_sring)
+ return -ENOMEM;
+ memset(nf->b2f_sring, 0, sring_size);
+
+ nf->control_shared = (void *)get_zeroed_page(GFP_KERNEL);
+ if (!nf->control_shared)
+ return -ENOMEM;
+
+ /* Pre-allocate enough grant references to be sure that we can
+ grant access to both rings without an error. */
+ err = gnttab_alloc_grant_references(nr_sring_pages * 2 + 1,
+ &nf->rings_gref_pool);
+ if (err < 0)
+ return err;
+
+ grant_access_to_ring(nf,
+ otherend,
+ nf->b2f_sring,
+ nf->b2f_grefs,
+ nr_sring_pages);
+ grant_access_to_ring(nf,
+ otherend,
+ nf->f2b_sring,
+ nf->f2b_grefs,
+ nr_sring_pages);
+ grant_access_to_ring(nf,
+ otherend,
+ nf->control_shared,
+ &nf->control_shared_gref,
+ 1);
+ err = nc2_listen_evtchn(nf->chan, otherend);
+ if (err < 0)
+ return err;
+
+ nf->attached = 1;
+
+ return 0;
+}
+
+static void backend_changed(struct xenbus_device *xd,
+ enum xenbus_state backend_state)
+{
+ struct netfront2 *nf = xenbus_device_to_nf2(xd);
+ int err;
+
+ switch (backend_state) {
+ case XenbusStateInitialising:
+ /* Backend isn't ready yet, don't do anything. */
+ break;
+
+ case XenbusStateInitWait:
+ /* Backend has advertised the ring protocol. Allocate
+ the rings, and tell the backend about them. */
+
+ err = 0;
+ if (!nf->attached)
+ err = allocate_rings(nf, xd->otherend_id);
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err, "allocating shared rings");
+ break;
+ }
+ err = publish_rings(nf);
+ if (err >= 0)
+ xenbus_switch_state(xd, XenbusStateInitialised);
+ break;
+
+ case XenbusStateInitialised:
+ /* Backend isn't supposed to use this state. */
+ xenbus_dev_fatal(xd, EINVAL,
+ "unexpected backend state Initialised");
+ break;
+
+ case XenbusStateConnected:
+ /* All ready */
+ err = nc2_attach_rings(nf->chan,
+ &nf->control_shared->cons,
+ nf->b2f_sring,
+ nf->nr_sring_pages * PAGE_SIZE,
+ &nf->control_shared->prod,
+ nf->f2b_sring,
+ nf->nr_sring_pages * PAGE_SIZE,
+ nf->xenbus_device->otherend_id);
+ if (err < 0) {
+ xenbus_dev_fatal(xd, err,
+ "failed to attach to rings");
+ } else {
+ xenbus_switch_state(xd, XenbusStateConnected);
+ }
+ break;
+
+ case XenbusStateClosing:
+ xenbus_switch_state(xd, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ /* Tell the tools that it's safe to remove the device
+ from the bus. */
+ xenbus_frontend_closed(xd);
+ /* Note that we don't release the rings here. This
+ means that if the backend moves to a different
+ domain, we won't be able to reconnect, but it also
+ limits the amount of memory which can be wasted in
+ the release_rings() leak if the backend is faulty
+ or malicious. It's not obvious which is more
+ useful, and so I choose the safer but less
+ featureful approach. */
+ /* This is only a problem if you're using driver
+ domains and trying to recover from a driver error
+ by rebooting the backend domain. The rest of the
+ tools don't support that, so it's a bit
+ theoretical. The memory leaks aren't, though. */
+ break;
+
+ case XenbusStateUnknown:
+ /* The tools have removed the device area from the
+ store. Do nothing and rely on xenbus core to call
+ our remove method. */
+ break;
+
+ default:
+ /* Ignore transitions to unknown states */
+ break;
+ }
+}
+
+static int __devinit netfront_probe(struct xenbus_device *xd,
+ const struct xenbus_device_id *id)
+{
+ struct netfront2 *nf;
+
+ nf = kzalloc(sizeof(*nf), GFP_KERNEL);
+ if (nf == NULL)
+ goto err;
+ nf->magic = NETFRONT2_MAGIC;
+ nf->xenbus_device = xd;
+ nf->chan = nc2_new(xd);
+ if (nf->chan == NULL)
+ goto err;
+
+ xd->dev.driver_data = nf;
+
+ return 0;
+
+err:
+ kfree(nf);
+ xenbus_dev_fatal(xd, ENOMEM, "probing netdev");
+ return -ENOMEM;
+}
+
+static int netfront_resume(struct xenbus_device *xd)
+{
+ /* We've been suspended and come back. The rings are
+ therefore dead. Tear them down. */
+ /* We rely on the normal xenbus state machine to bring them
+ back to life. */
+ struct netfront2 *nf = xenbus_device_to_nf2(xd);
+
+ nc2_detach_rings(nf->chan);
+ release_rings(nf);
+
+ return 0;
+}
+
+static int __devexit netfront_remove(struct xenbus_device *xd)
+{
+ struct netfront2 *nf = xenbus_device_to_nf2(xd);
+ if (nf->chan != NULL)
+ nc2_release(nf->chan);
+ release_rings(nf);
+ kfree(nf);
+ return 0;
+}
+
+static const struct xenbus_device_id netfront_ids[] = {
+ { "vif2" },
+ { "" }
+};
+MODULE_ALIAS("xen:vif2");
+
+static struct xenbus_driver netfront2 = {
+ .name = "vif2",
+ .ids = netfront_ids,
+ .probe = netfront_probe,
+ .remove = __devexit_p(netfront_remove),
+ .otherend_changed = backend_changed,
+ .resume = netfront_resume,
+};
+
+int __init netfront2_init(void)
+{
+ return xenbus_register_frontend(&netfront2);
+}
+
+void __exit netfront2_exit(void)
+{
+ xenbus_unregister_driver(&netfront2);
+}
diff --git a/drivers/xen/netchannel2/recv_packet.c
b/drivers/xen/netchannel2/recv_packet.c
new file mode 100644
index 0000000..4678c28
--- /dev/null
+++ b/drivers/xen/netchannel2/recv_packet.c
@@ -0,0 +1,216 @@
+/* Support for receiving individual packets, and all the stuff which
+ * goes with that. */
+#include <linux/kernel.h>
+#include <linux/etherdevice.h>
+#include <linux/version.h>
+#include "netchannel2_core.h"
+
+/* Send as many finish packet messages as will fit on the ring. */
+void send_finish_packet_messages(struct netchannel2_ring_pair *ncrp)
+{
+ struct pending_finish_packets *pfp = &ncrp->pending_finish;
+ struct netchannel2_msg_finish_packet msg;
+ RING_IDX cons;
+
+ while (pfp->prod != pfp->cons &&
+ nc2_can_send_payload_bytes(&ncrp->prod_ring, sizeof(msg))) {
+ cons = pfp->cons;
+ msg.id = pfp->ids[pfp->cons % MAX_PENDING_FINISH_PACKETS];
+ pfp->cons++;
+ nc2_send_message(&ncrp->prod_ring,
+ NETCHANNEL2_MSG_FINISH_PACKET,
+ 0,
+ &msg,
+ sizeof(msg));
+ }
+}
+
+/* Add a packet ID to the finish packet queue. The caller should
+ arrange that send_finish_packet_messages is sent soon to flush the
+ requests out. */
+void queue_finish_packet_message(struct netchannel2_ring_pair *ncrp,
+ uint32_t id, uint8_t flags)
+{
+ struct pending_finish_packets *pfp = &ncrp->pending_finish;
+ RING_IDX prod;
+
+ prod = pfp->prod;
+ pfp->ids[prod % MAX_PENDING_FINISH_PACKETS] = id;
+ pfp->prod++;
+
+ if (flags & NC2_PACKET_FLAG_need_event)
+ ncrp->pending_time_sensitive_messages = 1;
+}
+
+/* Handle a packet message from the other end. On success, queues the
+ new skb to the pending skb list. If the packet is invalid, it is
+ discarded without generating a FINISH message. */
+/* Caution: this drops and re-acquires the ring lock. */
+void nc2_handle_packet_msg(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr,
+ struct sk_buff_head *pending_rx_queue)
+{
+ unsigned nr_frags;
+ struct netchannel2_msg_packet msg;
+ struct sk_buff *skb;
+ const unsigned frags_off = sizeof(msg);
+ unsigned frags_bytes;
+
+ if (ncrp->pending_finish.prod - ncrp->pending_finish.cons ==
+ MAX_PENDING_FINISH_PACKETS) {
+ pr_debug("Remote endpoint sent too many packets!\n");
+ nc->stats.rx_errors++;
+ return;
+ }
+
+ if (hdr->size < sizeof(msg)) {
+ pr_debug("Packet message too small (%d < %zd)\n", hdr->size,
+ sizeof(msg));
+ nc->stats.rx_errors++;
+ return;
+ }
+
+ if (hdr->size & 7) {
+ pr_debug("Packet size in ring not multiple of 8: %d\n",
+ hdr->size);
+ nc->stats.rx_errors++;
+ return;
+ }
+
+ nc2_copy_from_ring(&ncrp->cons_ring, &msg, sizeof(msg));
+
+ frags_bytes = hdr->size - sizeof(msg) - msg.prefix_size;
+ nr_frags = frags_bytes / sizeof(struct netchannel2_fragment);
+
+ switch (msg.type) {
+ case NC2_PACKET_TYPE_small:
+ if (nr_frags != 0) {
+ /* Small packets, by definition, have no
+ * fragments */
+ pr_debug("Received small packet with %d frags?\n",
+ nr_frags);
+ nc->stats.rx_errors++;
+ return;
+ }
+ /* Any of the receiver functions can handle small
+ packets as a trivial special case. Use receiver
+ copy, since that's the simplest. */
+ skb = handle_receiver_copy_packet(nc, ncrp, &msg, hdr,
+ nr_frags, frags_off);
+ /* No finish message */
+ break;
+ case NC2_PACKET_TYPE_receiver_copy:
+ skb = handle_receiver_copy_packet(nc, ncrp, &msg, hdr,
+ nr_frags, frags_off);
+ queue_finish_packet_message(ncrp, msg.id, msg.flags);
+ break;
+ default:
+ pr_debug("Unknown packet type %d\n", msg.type);
+ nc->stats.rx_errors++;
+ skb = NULL;
+ break;
+ }
+ if (skb != NULL) {
+ nc->stats.rx_bytes += skb->len;
+ nc->stats.rx_packets++;
+ skb->dev = nc->net_device;
+
+ if (ncrp->filter_mac &&
+ skb_headlen(skb) >= sizeof(struct ethhdr) &&
+ memcmp(((struct ethhdr *)skb->data)->h_source,
+ ncrp->remote_mac,
+ ETH_ALEN)) {
+ /* We're in filter MACs mode and the source
+ MAC on this packet is wrong. Drop it. */
+ /* (We know that any packet big enough to
+ contain an ethernet header at all will
+ contain it in the head space because we do
+ a pull_through at the end of the type
+ handler.) */
+ nc->stats.rx_missed_errors++;
+ goto err;
+ }
+
+ __skb_queue_tail(pending_rx_queue, skb);
+
+ if (ncrp->pending_rx_hypercalls.nr_pending_gops >=
+ RX_GRANT_COPY_BATCH) {
+
flush_prepared_grant_copies(&ncrp->pending_rx_hypercalls,
+ nc2_rscb_on_gntcopy_fail);
+ /* since receive could generate ACKs to the
+ start_xmit() function we need to release
+ the ring lock */
+ spin_unlock(&ncrp->lock);
+ /* we should receive the packet as soon as the
+ copy is complete to benefit from cache
+ locality */
+ receive_pending_skbs(pending_rx_queue);
+ spin_lock(&ncrp->lock);
+
+ }
+
+ }
+ return;
+
+err:
+ /* If the receive succeeded part-way, there may be references
+ to the skb in the hypercall batcher. Flush them out before
+ we release it. This is a slow path, so we don't care that
+ much about performance. */
+ flush_prepared_grant_copies(&ncrp->pending_rx_hypercalls,
+ nc2_rscb_on_gntcopy_fail);
+
+ /* We may need to send a FINISH message here if this was a
+ receiver-map packet. That should be handled automatically
+ by the kfree_skb(). */
+ kfree_skb(skb);
+ nc->stats.rx_errors++;
+ return;
+}
+
+/* If there is space on the ring, tell the other end how many packets
+ its allowed to send at one time and clear the
+ need_advertise_max_packets flag. */
+void advertise_max_packets(struct netchannel2_ring_pair *ncrp)
+{
+ struct netchannel2_msg_set_max_packets msg;
+
+ if (!nc2_can_send_payload_bytes(&ncrp->prod_ring, sizeof(msg)))
+ return;
+ msg.max_outstanding_packets = MAX_PENDING_FINISH_PACKETS;
+ nc2_send_message(&ncrp->prod_ring,
+ NETCHANNEL2_MSG_SET_MAX_PACKETS,
+ 0,
+ &msg,
+ sizeof(msg));
+ ncrp->need_advertise_max_packets = 0;
+ ncrp->pending_time_sensitive_messages = 1;
+}
+
+void receive_pending_skbs(struct sk_buff_head *pending_rx_queue)
+{
+ struct sk_buff *skb;
+ struct skb_cb_overlay *sco;
+ while (!skb_queue_empty(pending_rx_queue)) {
+ skb = __skb_dequeue(pending_rx_queue);
+ sco = get_skb_overlay(skb);
+ if (unlikely(sco->failed))
+ kfree_skb(skb);
+ else {
+ skb->protocol = eth_type_trans(skb, skb->dev);
+ netif_receive_skb(skb);
+ }
+ }
+}
+
+
+/* These don't really belong here, but it's as good a place as any. */
+int __init nc2_init(void)
+{
+ return 0;
+}
+
+void __exit nc2_exit(void)
+{
+}
diff --git a/drivers/xen/netchannel2/rscb.c b/drivers/xen/netchannel2/rscb.c
new file mode 100644
index 0000000..8984f90
--- /dev/null
+++ b/drivers/xen/netchannel2/rscb.c
@@ -0,0 +1,385 @@
+/* Receiver-side copy buffer support */
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/version.h>
+#include <xen/gnttab.h>
+#include <xen/live_maps.h>
+
+#include "netchannel2_core.h"
+
+/* -------------------------- Receive -------------------------------- */
+
+/* This is called whenever an RSCB grant copy fails. */
+void nc2_rscb_on_gntcopy_fail(void *ctxt, gnttab_copy_t *gop)
+{
+ struct sk_buff *skb = ctxt;
+ struct skb_cb_overlay *sco = get_skb_overlay(skb);
+ if (!sco->failed && net_ratelimit())
+ printk(KERN_WARNING "Dropping RX packet because of copy
error\n");
+ sco->failed = 1;
+}
+
+
+/* Copy @size bytes from @offset in grant ref @gref against domain
+ @domid and shove them on the end of @skb. Fails if it the head
+ does not have enough space or if the copy would span multiple
+ pages. */
+static int nc2_grant_copy(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb,
+ unsigned offset,
+ unsigned size,
+ grant_ref_t gref,
+ domid_t domid)
+{
+ gnttab_copy_t *gop;
+ void *tail;
+ void *end;
+
+ if (size > PAGE_SIZE)
+ return 0;
+
+ tail = skb_tail_pointer(skb);
+ end = skb_end_pointer(skb);
+
+ if (unlikely(size > (end-tail)))
+ return 0;
+
+ if (unlikely(offset_in_page(tail) + size > PAGE_SIZE)) {
+ unsigned f1 = PAGE_SIZE - offset_in_page(tail);
+ /* Recursive, but only ever to depth 1, so okay */
+ if (!nc2_grant_copy(ncrp, skb, offset, f1, gref, domid))
+ return 0;
+ offset += f1;
+ size -= f1;
+ tail += f1;
+ }
+
+ /* Copy this fragment into the header. */
+ gop = hypercall_batcher_grant_copy(&ncrp->pending_rx_hypercalls,
+ skb,
+ nc2_rscb_on_gntcopy_fail);
+ gop->flags = GNTCOPY_source_gref;
+ gop->source.domid = domid;
+ gop->source.offset = offset;
+ gop->source.u.ref = gref;
+ gop->dest.domid = DOMID_SELF;
+ gop->dest.offset = offset_in_page(tail);
+ gop->dest.u.gmfn = virt_to_mfn(tail);
+ gop->len = size;
+
+ skb_put(skb, size);
+
+ return 1;
+}
+
+/* We've received a receiver-copy packet message from the remote.
+ Parse it up, build an sk_buff, and return it. Returns NULL on
+ error. */
+struct sk_buff *handle_receiver_copy_packet(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_packet *msg,
+ struct netchannel2_msg_hdr *hdr,
+ unsigned nr_frags,
+ unsigned frags_off)
+{
+ struct netchannel2_fragment frag;
+ unsigned nr_bytes;
+ unsigned x;
+ struct sk_buff *skb;
+ unsigned skb_headsize;
+ int first_frag, first_frag_size;
+ gnttab_copy_t *gop;
+ struct skb_shared_info *shinfo;
+ struct page *new_page;
+
+ if (msg->prefix_size > NETCHANNEL2_MAX_INLINE_BYTES) {
+ pr_debug("Inline prefix too big! (%d > %d)\n",
+ msg->prefix_size, NETCHANNEL2_MAX_INLINE_BYTES);
+ return NULL;
+ }
+
+ /* Count the number of bytes in the packet. Be careful: the
+ other end can still access the packet on the ring, so the
+ size could change later. */
+ nr_bytes = msg->prefix_size;
+ for (x = 0; x < nr_frags; x++) {
+ fetch_fragment(ncrp, x, &frag, frags_off);
+ nr_bytes += frag.size;
+ }
+ if (nr_bytes > NETCHANNEL2_MAX_PACKET_BYTES) {
+ pr_debug("Packet too big! (%d > %d)\n", nr_bytes,
+ NETCHANNEL2_MAX_PACKET_BYTES);
+ return NULL;
+ }
+ if (nr_bytes < 64) {
+ /* Linux sometimes has problems with very small SKBs.
+ Impose a minimum size of 64 bytes. */
+ nr_bytes = 64;
+ }
+
+ first_frag = 0;
+ if (nr_frags > 0) {
+ fetch_fragment(ncrp, 0, &frag, frags_off);
+ first_frag_size = frag.size;
+ first_frag = 1;
+ } else {
+ first_frag_size = 0;
+ first_frag = 0;
+ }
+
+ /* We try to have both prefix and the first frag in the skb head
+ if they do not exceed the page size */
+ skb_headsize = msg->prefix_size + first_frag_size + NET_IP_ALIGN;
+ if (skb_headsize >
+ ((PAGE_SIZE - sizeof(struct skb_shared_info) - NET_SKB_PAD) &
+ ~(SMP_CACHE_BYTES - 1))) {
+ skb_headsize = msg->prefix_size + NET_IP_ALIGN;
+ first_frag = 0;
+ }
+
+ skb = dev_alloc_skb(skb_headsize);
+ if (!skb) {
+ /* Drop the packet. */
+ pr_debug("Couldn't allocate a %d byte skb.\n", nr_bytes);
+ nc->stats.rx_dropped++;
+ return NULL;
+ }
+
+ /* Arrange that the IP header is nicely aligned in memory. */
+ skb_reserve(skb, NET_IP_ALIGN);
+
+ /* The inline prefix should always fit in the SKB head. */
+ nc2_copy_from_ring_off(&ncrp->cons_ring,
+ skb_put(skb, msg->prefix_size),
+ msg->prefix_size,
+ frags_off + nr_frags * sizeof(frag));
+
+ /* copy first frag into skb head if it does not cross a
+ page boundary */
+ if (first_frag == 1) {
+ fetch_fragment(ncrp, 0, &frag, frags_off);
+ if (!nc2_grant_copy(ncrp, skb, frag.off, frag.size,
+ frag.receiver_copy.gref,
+ ncrp->otherend_id)) {
+ get_skb_overlay(skb)->failed = 1;
+ return skb;
+ }
+ }
+
+ shinfo = skb_shinfo(skb);
+ for (x = first_frag; x < nr_frags; x++) {
+ fetch_fragment(ncrp, x, &frag, frags_off);
+
+ /* Allocate a new page for the fragment */
+ new_page = alloc_page(GFP_ATOMIC);
+ if (!new_page) {
+ get_skb_overlay(skb)->failed = 1;
+ return skb;
+ }
+
+ gop = hypercall_batcher_grant_copy(&ncrp->pending_rx_hypercalls,
+ skb,
+ nc2_rscb_on_gntcopy_fail);
+ gop->flags = GNTCOPY_source_gref;
+ gop->source.domid = ncrp->otherend_id;
+ gop->source.offset = frag.off;
+ gop->source.u.ref = frag.receiver_copy.gref;
+ gop->dest.domid = DOMID_SELF;
+ gop->dest.offset = 0;
+ gop->dest.u.gmfn = pfn_to_mfn(page_to_pfn(new_page));
+ gop->len = frag.size;
+
+ shinfo->frags[x-first_frag].page = new_page;
+ shinfo->frags[x-first_frag].page_offset = 0;
+ shinfo->frags[x-first_frag].size = frag.size;
+ shinfo->nr_frags++;
+
+ skb->truesize += frag.size;
+ skb->data_len += frag.size;
+ skb->len += frag.size;
+ }
+ return skb;
+}
+
+
+
+/* ------------------------------- Transmit ---------------------------- */
+
+struct grant_packet_plan {
+ volatile struct netchannel2_fragment *out_fragment;
+ grant_ref_t gref_pool;
+ unsigned prefix_avail;
+};
+
+static inline int nfrags_skb(struct sk_buff *skb, int prefix_size)
+{
+ unsigned long start_grant;
+ unsigned long end_grant;
+
+ if (skb_headlen(skb) <= prefix_size)
+ return skb_shinfo(skb)->nr_frags;
+
+ start_grant = ((unsigned long)skb->data + prefix_size) &
+ ~(PAGE_SIZE-1);
+ end_grant = ((unsigned long)skb->data +
+ skb_headlen(skb) + PAGE_SIZE - 1) &
+ ~(PAGE_SIZE-1);
+ return ((end_grant - start_grant) >> PAGE_SHIFT)
+ + skb_shinfo(skb)->nr_frags;
+}
+
+int prepare_xmit_allocate_grant(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ unsigned nr_fragments;
+ grant_ref_t gref_pool;
+ int err;
+ unsigned inline_prefix_size;
+
+ if (allocate_txp_slot(ncrp, skb) < 0)
+ return -1;
+
+ /* We're going to have to get the remote to issue a grant copy
+ hypercall anyway, so there's no real benefit to shoving the
+ headers inline. */
+ /* (very small packets won't go through here, so there's no
+ chance that we could completely eliminate the grant
+ copy.) */
+ inline_prefix_size = sizeof(struct ethhdr);
+
+ if (skb_co->nr_fragments == 0) {
+ nr_fragments = nfrags_skb(skb, inline_prefix_size);
+
+ /* No-fragments packets should be policy small, not
+ * policy grant. */
+ BUG_ON(nr_fragments == 0);
+
+ skb_co->nr_fragments = nr_fragments;
+ }
+
+ /* Grab the grant references. */
+ err = gnttab_suballoc_grant_references(skb_co->nr_fragments,
+ &ncrp->gref_pool,
+ &gref_pool);
+ if (err < 0) {
+ release_txp_slot(ncrp, skb);
+ /* Leave skb_co->nr_fragments set, so that we don't
+ have to recompute it next time around. */
+ return -1;
+ }
+ skb_co->gref_pool = gref_pool;
+ skb_co->inline_prefix_size = inline_prefix_size;
+
+ skb_co->type = NC2_PACKET_TYPE_receiver_copy;
+
+ return 0;
+}
+
+static void prepare_subpage_grant(struct netchannel2_ring_pair *ncrp,
+ struct page *page,
+ unsigned off_in_page,
+ unsigned size,
+ struct grant_packet_plan *plan)
+{
+ volatile struct netchannel2_fragment *frag;
+ domid_t trans_domid;
+ grant_ref_t trans_gref;
+ grant_ref_t gref;
+
+ if (size <= plan->prefix_avail) {
+ /* This fragment is going to be inline -> nothing to
+ * do. */
+ plan->prefix_avail -= size;
+ return;
+ }
+ if (plan->prefix_avail > 0) {
+ /* Part inline, part in payload. */
+ size -= plan->prefix_avail;
+ off_in_page += plan->prefix_avail;
+ plan->prefix_avail = 0;
+ }
+ frag = plan->out_fragment;
+ gref = gnttab_claim_grant_reference(&plan->gref_pool);
+ frag->receiver_copy.gref = gref;
+ if (page_is_tracked(page)) {
+ lookup_tracker_page(page, &trans_domid, &trans_gref);
+ gnttab_grant_foreign_access_ref_trans(gref,
+ ncrp->otherend_id,
+ GTF_readonly,
+ trans_domid,
+ trans_gref);
+ } else {
+ gnttab_grant_foreign_access_ref_subpage(gref,
+ ncrp->otherend_id,
+
virt_to_mfn(page_address(page)),
+ GTF_readonly,
+ off_in_page,
+ size);
+ }
+
+ frag->off = off_in_page;
+ frag->size = size;
+ plan->out_fragment++;
+}
+
+static int grant_data_area(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb,
+ struct grant_packet_plan *plan)
+{
+ void *ptr = skb->data;
+ unsigned len = skb_headlen(skb);
+ unsigned off;
+ unsigned this_time;
+
+ for (off = 0; off < len; off += this_time) {
+ this_time = len - off;
+ if (this_time + offset_in_page(ptr + off) > PAGE_SIZE)
+ this_time = PAGE_SIZE - offset_in_page(ptr + off);
+ prepare_subpage_grant(ncrp,
+ virt_to_page(ptr + off),
+ offset_in_page(ptr + off),
+ this_time,
+ plan);
+ }
+ return 0;
+}
+
+void xmit_grant(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb,
+ volatile void *msg_buf)
+{
+ volatile struct netchannel2_msg_packet *msg = msg_buf;
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ struct grant_packet_plan plan;
+ unsigned x;
+ struct skb_shared_info *shinfo;
+ skb_frag_t *frag;
+
+ memset(&plan, 0, sizeof(plan));
+ plan.prefix_avail = skb_co->inline_prefix_size;
+ plan.out_fragment = msg->frags;
+ plan.gref_pool = skb_co->gref_pool;
+
+ ncrp->count_frags_no_event += skb_co->nr_fragments;
+ if (ncrp->count_frags_no_event >= ncrp->max_count_frags_no_event) {
+ msg->flags |= NC2_PACKET_FLAG_need_event;
+ ncrp->count_frags_no_event = 0;
+ }
+
+ grant_data_area(ncrp, skb, &plan);
+
+ shinfo = skb_shinfo(skb);
+ for (x = 0; x < shinfo->nr_frags; x++) {
+ frag = &shinfo->frags[x];
+ prepare_subpage_grant(ncrp,
+ frag->page,
+ frag->page_offset,
+ frag->size,
+ &plan);
+ }
+
+ skb_co->nr_fragments = plan.out_fragment - msg->frags;
+}
+
diff --git a/drivers/xen/netchannel2/util.c b/drivers/xen/netchannel2/util.c
new file mode 100644
index 0000000..302dfc1
--- /dev/null
+++ b/drivers/xen/netchannel2/util.c
@@ -0,0 +1,230 @@
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/version.h>
+#ifdef CONFIG_XEN_NETDEV2_BACKEND
+#include <xen/driver_util.h>
+#endif
+#include <xen/gnttab.h>
+#include "netchannel2_core.h"
+
+int allocate_txp_slot(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ struct txp_slot *tp;
+
+ BUG_ON(skb_co->tp);
+
+ if (ncrp->head_free_tx_packet == INVALID_TXP_INDEX ||
+ ncrp->nr_tx_packets_outstanding ==
+ ncrp->max_tx_packets_outstanding) {
+ return -1;
+ }
+
+ tp = &ncrp->tx_packets[ncrp->head_free_tx_packet];
+ ncrp->head_free_tx_packet = txp_get_next_free(tp);
+
+ txp_set_skb(tp, skb);
+ skb_co->tp = tp;
+ ncrp->nr_tx_packets_outstanding++;
+ return 0;
+}
+
+static void nc2_free_skb(struct netchannel2 *nc,
+ struct sk_buff *skb)
+{
+ dev_kfree_skb(skb);
+}
+
+void release_txp_slot(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ struct txp_slot *tp = skb_co->tp;
+
+ BUG_ON(txp_get_skb(tp) != skb);
+
+ /* Try to keep the free TX packet list in order as far as
+ * possible, since that gives slightly better cache behaviour.
+ * It's not worth spending a lot of effort getting this right,
+ * though, so just use a simple heuristic: if we're freeing a
+ * packet, and the previous packet is already free, chain this
+ * packet directly after it, rather than putting it at the
+ * head of the list. This isn't perfect by any means, but
+ * it's enough that you get nice long runs of contiguous
+ * packets in the free list, and that's all we really need.
+ * Runs much bigger than a cache line aren't really very
+ * useful, anyway. */
+ if (tp != ncrp->tx_packets && !txp_slot_in_use(tp - 1)) {
+ txp_set_next_free(tp, txp_get_next_free(tp - 1));
+ txp_set_next_free(tp - 1, tp - ncrp->tx_packets);
+ } else {
+ txp_set_next_free(tp, ncrp->head_free_tx_packet);
+ ncrp->head_free_tx_packet = tp - ncrp->tx_packets;
+ }
+ skb_co->tp = NULL;
+ ncrp->nr_tx_packets_outstanding--;
+}
+
+void release_tx_packet(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ struct txp_slot *tp = skb_co->tp;
+ grant_ref_t gref;
+ int r;
+ unsigned cntr;
+
+ if (skb_co->type == NC2_PACKET_TYPE_receiver_copy) {
+ while (1) {
+ r = gnttab_claim_grant_reference(&skb_co->gref_pool);
+ if (r == -ENOSPC)
+ break;
+ gref = (grant_ref_t)r;
+ /* It's a subpage grant reference, so Xen
+ guarantees to release it quickly. Sit and
+ wait for it to do so. */
+ cntr = 0;
+ while (!gnttab_end_foreign_access_ref(gref)) {
+ cpu_relax();
+ if (++cntr % 65536 == 0)
+ printk(KERN_WARNING "Having trouble
ending gref %d for receiver copy.\n",
+ gref);
+ }
+ gnttab_release_grant_reference(&ncrp->gref_pool, gref);
+ }
+ } else if (skb_co->gref_pool != 0) {
+ gnttab_subfree_grant_references(skb_co->gref_pool,
+ &ncrp->gref_pool);
+ }
+
+ if (tp != NULL)
+ release_txp_slot(ncrp, skb);
+
+ nc2_free_skb(ncrp->interface, skb);
+}
+
+void fetch_fragment(struct netchannel2_ring_pair *ncrp,
+ unsigned idx,
+ struct netchannel2_fragment *frag,
+ unsigned off)
+{
+ nc2_copy_from_ring_off(&ncrp->cons_ring,
+ frag,
+ sizeof(*frag),
+ off + idx * sizeof(*frag));
+}
+
+/* Copy @count bytes from the skb's data area into its head, updating
+ * the pointers as appropriate. The caller should ensure that there
+ * is actually enough space in the head. */
+void pull_through(struct sk_buff *skb, unsigned count)
+{
+ unsigned frag = 0;
+ unsigned this_frag;
+ void *buf;
+ void *va;
+
+ while (count != 0 && frag < skb_shinfo(skb)->nr_frags) {
+ this_frag = skb_shinfo(skb)->frags[frag].size;
+ if (this_frag > count)
+ this_frag = count;
+ va = page_address(skb_shinfo(skb)->frags[frag].page);
+ buf = skb->tail;
+ memcpy(buf, va + skb_shinfo(skb)->frags[frag].page_offset,
+ this_frag);
+ skb->tail += this_frag;
+ BUG_ON(skb->tail > skb->end);
+ skb_shinfo(skb)->frags[frag].size -= this_frag;
+ skb_shinfo(skb)->frags[frag].page_offset += this_frag;
+ skb->data_len -= this_frag;
+ count -= this_frag;
+ frag++;
+ }
+ for (frag = 0;
+ frag < skb_shinfo(skb)->nr_frags &&
+ skb_shinfo(skb)->frags[frag].size == 0;
+ frag++) {
+ put_page(skb_shinfo(skb)->frags[frag].page);
+ }
+ skb_shinfo(skb)->nr_frags -= frag;
+ memmove(skb_shinfo(skb)->frags,
+ skb_shinfo(skb)->frags+frag,
+ sizeof(skb_shinfo(skb)->frags[0]) *
+ skb_shinfo(skb)->nr_frags);
+}
+
+#ifdef CONFIG_XEN_NETDEV2_BACKEND
+
+/* Zap a grant_mapping structure, releasing all mappings and the
+ reserved virtual address space. Prepare the grant_mapping for
+ re-use. */
+void nc2_unmap_grants(struct grant_mapping *gm)
+{
+ struct gnttab_unmap_grant_ref op[MAX_GRANT_MAP_PAGES];
+ int i;
+
+ if (gm->mapping == NULL)
+ return;
+ for (i = 0; i < gm->nr_pages; i++) {
+ gnttab_set_unmap_op(&op[i],
+ (unsigned long)gm->mapping->addr +
+ i * PAGE_SIZE,
+ GNTMAP_host_map,
+ gm->handles[i]);
+ }
+ if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, op, i))
+ BUG();
+ free_vm_area(gm->mapping);
+ memset(gm, 0, sizeof(*gm));
+}
+
+int nc2_map_grants(struct grant_mapping *gm,
+ const grant_ref_t *grefs,
+ unsigned nr_grefs,
+ domid_t remote_domain)
+{
+ struct grant_mapping work;
+ struct gnttab_map_grant_ref op[MAX_GRANT_MAP_PAGES];
+ int i;
+
+ memset(&work, 0, sizeof(work));
+
+ if (nr_grefs > MAX_GRANT_MAP_PAGES || nr_grefs == 0)
+ return -EINVAL;
+
+ if (nr_grefs & (nr_grefs-1)) {
+ /* Must map a power-of-two number of pages. */
+ return -EINVAL;
+ }
+
+ work.nr_pages = nr_grefs;
+ work.mapping = alloc_vm_area(PAGE_SIZE * work.nr_pages);
+ if (!work.mapping)
+ return -ENOMEM;
+ for (i = 0; i < nr_grefs; i++)
+ gnttab_set_map_op(&op[i],
+ (unsigned long)work.mapping->addr +
+ i * PAGE_SIZE,
+ GNTMAP_host_map,
+ grefs[i],
+ remote_domain);
+
+ if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, op, nr_grefs))
+ BUG();
+
+ for (i = 0; i < nr_grefs; i++) {
+ if (op[i].status) {
+ work.nr_pages = i;
+ nc2_unmap_grants(&work);
+ return -EFAULT;
+ }
+ work.handles[i] = op[i].handle;
+ }
+
+ nc2_unmap_grants(gm);
+ *gm = work;
+ return 0;
+}
+#endif
diff --git a/drivers/xen/netchannel2/xmit_packet.c
b/drivers/xen/netchannel2/xmit_packet.c
new file mode 100644
index 0000000..92fbabf
--- /dev/null
+++ b/drivers/xen/netchannel2/xmit_packet.c
@@ -0,0 +1,318 @@
+/* Things related to actually sending packet messages, and which is
+ shared across all transmit modes. */
+#include <linux/kernel.h>
+#include <linux/version.h>
+#include "netchannel2_core.h"
+
+/* We limit the number of transmitted packets which can be in flight
+ at any one time, as a somewhat paranoid safety catch. */
+#define MAX_TX_PACKETS MAX_PENDING_FINISH_PACKETS
+
+static enum transmit_policy transmit_policy(struct netchannel2 *nc,
+ struct sk_buff *skb)
+{
+ if (skb->len <= PACKET_PREFIX_SIZE && !skb_is_nonlinear(skb))
+ return transmit_policy_small;
+ else
+ return transmit_policy_grant;
+}
+
+/* Allocate resources for a small packet. The entire thing will be
+ transmitted in the ring. This is only called for small, linear
+ SKBs. It always succeeds, but has an int return type for symmetry
+ with the other prepare_xmit_*() functions. */
+int prepare_xmit_allocate_small(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+
+ BUG_ON(skb_is_nonlinear(skb));
+ BUG_ON(skb->len > NETCHANNEL2_MAX_INLINE_BYTES);
+
+ skb_co->type = NC2_PACKET_TYPE_small;
+ skb_co->gref_pool = 0;
+ skb_co->inline_prefix_size = skb->len;
+
+ return 0;
+}
+
+/* Figure out how much space @tp will take up on the ring. */
+static unsigned get_transmitted_packet_msg_size(struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ return (sizeof(struct netchannel2_msg_packet) +
+ sizeof(struct netchannel2_fragment) * skb_co->nr_fragments +
+ skb_co->inline_prefix_size + 7) & ~7;
+}
+
+/* Do the minimum amount of work to be certain that when we come to
+ transmit this packet we won't run out of resources. This includes
+ figuring out how we're going to fragment the packet for
+ transmission, which buffers we're going to use, etc. Return <0 if
+ insufficient resources are available right now, or 0 if we
+ succeed. */
+/* Careful: this may allocate e.g. a TXP slot and then discover that
+ it can't reserve ring space. In that case, the TXP remains
+ allocated. The expected case is that the caller will arrange for
+ us to retry the allocation later, in which case we'll pick up the
+ already-allocated buffers. */
+int prepare_xmit_allocate_resources(struct netchannel2 *nc,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ enum transmit_policy policy;
+ unsigned msg_size;
+ int r;
+
+ if (skb_co->policy == transmit_policy_unknown) {
+ policy = transmit_policy(nc, skb);
+ switch (policy) {
+ case transmit_policy_small:
+ r = prepare_xmit_allocate_small(&nc->rings, skb);
+ break;
+ case transmit_policy_grant:
+ r = prepare_xmit_allocate_grant(&nc->rings, skb);
+ break;
+ default:
+ BUG();
+ /* Shut the compiler up. */
+ r = -1;
+ }
+ if (r < 0)
+ return r;
+ skb_co->policy = policy;
+ }
+
+ msg_size = get_transmitted_packet_msg_size(skb);
+ if (nc2_reserve_payload_bytes(&nc->rings.prod_ring, msg_size))
+ return 0;
+
+ return -1;
+}
+
+/* Transmit a packet which has previously been prepared with
+ prepare_xmit_allocate_resources(). */
+/* Once this has been called, the ring must not be flushed until the
+ TX hypercall batcher is (assuming this ring has a hypercall
+ batcher). */
+int nc2_really_start_xmit(struct netchannel2_ring_pair *ncrp,
+ struct sk_buff *skb)
+{
+ struct skb_cb_overlay *skb_co = get_skb_overlay(skb);
+ struct netchannel2 *nc = ncrp->interface;
+ unsigned msg_size;
+ volatile struct netchannel2_msg_packet *msg;
+
+ msg_size = get_transmitted_packet_msg_size(skb);
+ /* Un-reserve the space we reserved for the packet. */
+ BUG_ON(ncrp->prod_ring.reserve < msg_size);
+ ncrp->prod_ring.reserve -= msg_size;
+ if (!nc2_can_send_payload_bytes(&ncrp->prod_ring, msg_size)) {
+ /* Aw, crud. We had to transmit a PAD message at just
+ the wrong time, and our attempt to reserve ring
+ space failed. Delay transmiting this packet
+ Make sure we redo the space reserve */
+ ncrp->prod_ring.reserve += msg_size;
+ return 0;
+ }
+ __nc2_avoid_ring_wrap(&ncrp->prod_ring, msg_size);
+
+ /* Set up part of the message. We do the message header
+ itself and the inline prefix. The individual xmit_*
+ methods are responsible for the fragments. They may also
+ set some more msg flags. */
+ msg = __nc2_get_message_ptr(&ncrp->prod_ring);
+ msg->hdr.type = NETCHANNEL2_MSG_PACKET;
+ msg->hdr.flags = 0;
+ msg->id = skb_co->tp - ncrp->tx_packets;
+ msg->type = skb_co->type;
+ msg->flags = 0;
+ msg->prefix_size = skb_co->inline_prefix_size;
+
+ /* We cast away the volatile to avoid compiler warnings, and
+ then use barrier()s to discourage gcc from using msg->frags
+ in CSE or somesuch. It's kind of unlikely that it would,
+ but better to make sure. */
+ barrier();
+ memcpy((void *)(msg->frags + skb_co->nr_fragments),
+ skb->data,
+ skb_co->inline_prefix_size);
+ barrier();
+
+ switch (skb_co->policy) {
+ case transmit_policy_small:
+ /* Nothing to do */
+ break;
+ case transmit_policy_grant:
+ xmit_grant(ncrp, skb, msg);
+ break;
+ default:
+ BUG();
+ }
+
+ /* The transmission method may have decided not to use all the
+ fragments it reserved, which changes the message size. */
+ msg_size = get_transmitted_packet_msg_size(skb);
+ msg->hdr.size = msg_size;
+
+ ncrp->prod_ring.prod_pvt += msg_size;
+
+ BUG_ON(ncrp->prod_ring.bytes_available < msg_size);
+
+ ncrp->prod_ring.bytes_available -= msg_size;
+
+ ncrp->pending_time_sensitive_messages = 1;
+
+ if (skb_co->tp) {
+ ncrp->expected_finish_messages++;
+ /* We're now ready to accept a FINISH message for this
+ packet. */
+ skb_co->expecting_finish = 1;
+ } else {
+ /* This packet doesn't need a FINISH message. Queue
+ it up to be released as soon as we flush the
+ hypercall batcher and the ring. */
+ nc->stats.tx_bytes += skb->len;
+ nc->stats.tx_packets++;
+ __skb_queue_tail(&ncrp->release_on_flush_batcher, skb);
+ }
+
+ return 1;
+}
+
+/* Arrange that @skb will be sent on ring @ncrp soon. Assumes that
+ prepare_xmit_allocate_resources() has been successfully called on
+ @skb already. */
+void queue_packet_to_interface(struct sk_buff *skb,
+ struct netchannel2_ring_pair *ncrp)
+{
+ __skb_queue_tail(&ncrp->pending_tx_queue, skb);
+ if (ncrp->pending_tx_queue.qlen == 1)
+ nc2_kick(ncrp);
+}
+
+int nc2_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct netchannel2 *nc = netdev_priv(dev);
+ struct skb_cb_overlay *sco = get_skb_overlay(skb);
+ int r;
+
+ memset(sco, 0, sizeof(*sco));
+
+ spin_lock_bh(&nc->rings.lock);
+
+ if (!nc->rings.is_attached) {
+ spin_unlock_bh(&nc->rings.lock);
+ dev_kfree_skb(skb);
+ nc->stats.tx_dropped++;
+ return NETDEV_TX_OK;
+ }
+
+ r = prepare_xmit_allocate_resources(nc, skb);
+ if (r < 0)
+ goto out_busy;
+ queue_packet_to_interface(skb, &nc->rings);
+ spin_unlock_bh(&nc->rings.lock);
+
+ return NETDEV_TX_OK;
+
+out_busy:
+ /* Some more buffers may have arrived, so kick the worker
+ * thread to go and have a look. */
+ nc2_kick(&nc->rings);
+
+ __skb_queue_tail(&nc->pending_skbs, skb);
+ nc->is_stopped = 1;
+ netif_stop_queue(dev);
+ spin_unlock_bh(&nc->rings.lock);
+ return NETDEV_TX_OK;
+}
+
+
+void nc2_handle_finish_packet_msg(struct netchannel2 *nc,
+ struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr)
+{
+ struct skb_cb_overlay *sco;
+ struct netchannel2_msg_finish_packet msg;
+ struct txp_slot *tp;
+ struct sk_buff *skb;
+
+ if (hdr->size < sizeof(msg)) {
+ pr_debug("Packet finish message had strange size %d\n",
+ hdr->size);
+ return;
+ }
+ nc2_copy_from_ring(&ncrp->cons_ring, &msg, sizeof(msg));
+ if (msg.id > NR_TX_PACKETS) {
+ pr_debug("Other end tried to end bad packet id %d\n",
+ msg.id);
+ return;
+ }
+ tp = &ncrp->tx_packets[msg.id];
+ skb = txp_get_skb(tp);
+ if (!skb) {
+ pr_debug("Other end tried to end packet id %d which wasn't in
use\n",
+ msg.id);
+ return;
+ }
+ sco = get_skb_overlay(skb);
+ /* Careful: if the remote is malicious, they may try to end a
+ packet after we allocate it but before we send it (e.g. if
+ we've had to back out because we didn't have enough ring
+ space). */
+ if (!sco->expecting_finish) {
+ pr_debug("Other end finished packet before we sent it?\n");
+ return;
+ }
+ nc->stats.tx_bytes += skb->len;
+ nc->stats.tx_packets++;
+ release_tx_packet(ncrp, skb);
+ ncrp->expected_finish_messages--;
+}
+
+
+/* ------------------------ Control-path operations ---------------------- */
+void nc2_handle_set_max_packets_msg(struct netchannel2_ring_pair *ncrp,
+ struct netchannel2_msg_hdr *hdr)
+{
+ struct netchannel2_msg_set_max_packets msg;
+
+ if (hdr->size != sizeof(msg)) {
+ pr_debug("Set max packets message had strange size %d\n",
+ hdr->size);
+ return;
+ }
+ if (ncrp->max_tx_packets_outstanding != 0) {
+ pr_debug("Other end tried to change number of outstanding
packets from %d.\n",
+ ncrp->max_tx_packets_outstanding);
+ return;
+ }
+ nc2_copy_from_ring(&ncrp->cons_ring, &msg, sizeof(msg));
+ /* Limit the number of outstanding packets to something sane.
+ This is a little bit paranoid (it should be safe to set
+ this arbitrarily high), but limiting it avoids nasty
+ surprises in untested configurations. */
+ if (msg.max_outstanding_packets > MAX_TX_PACKETS) {
+ pr_debug("Other end tried to set max outstanding to %d,
limiting to %d.\n",
+ msg.max_outstanding_packets, MAX_TX_PACKETS);
+ ncrp->max_tx_packets_outstanding = MAX_TX_PACKETS;
+ } else {
+ ncrp->max_tx_packets_outstanding = msg.max_outstanding_packets;
+ }
+}
+
+/* Release all packets on the transmitted and pending_tx lists. */
+void drop_pending_tx_packets(struct netchannel2_ring_pair *ncrp)
+{
+ struct sk_buff *skb;
+ unsigned x;
+
+ nc2_queue_purge(ncrp, &ncrp->pending_tx_queue);
+ for (x = 0; x < NR_TX_PACKETS; x++) {
+ skb = txp_get_skb(&ncrp->tx_packets[x]);
+ if (skb)
+ release_tx_packet(ncrp, skb);
+ }
+}
+
diff --git a/include/xen/interface/io/netchannel2.h
b/include/xen/interface/io/netchannel2.h
new file mode 100644
index 0000000..c45963e
--- /dev/null
+++ b/include/xen/interface/io/netchannel2.h
@@ -0,0 +1,106 @@
+#ifndef __NETCHANNEL2_H__
+#define __NETCHANNEL2_H__
+
+#include <xen/interface/io/uring.h>
+
+/* Tell the other end how many packets its allowed to have
+ * simultaneously outstanding for transmission. An endpoint must not
+ * send PACKET messages which would take it over this limit.
+ *
+ * The SET_MAX_PACKETS message must be sent before any PACKET
+ * messages. It should only be sent once, unless the ring is
+ * disconnected and reconnected.
+ */
+#define NETCHANNEL2_MSG_SET_MAX_PACKETS 1
+struct netchannel2_msg_set_max_packets {
+ struct netchannel2_msg_hdr hdr;
+ uint32_t max_outstanding_packets;
+};
+
+/* Pass a packet to the other end. The packet consists of a header,
+ * followed by a bunch of fragment descriptors, followed by an inline
+ * packet prefix. Every fragment descriptor in a packet must be the
+ * same type, and the type is determined by the header. The receiving
+ * endpoint should respond with a finished_packet message as soon as
+ * possible. The prefix may be no more than
+ * NETCHANNEL2_MAX_INLINE_BYTES. Packets may contain no more than
+ * NETCHANNEL2_MAX_PACKET_BYTES bytes of data, including all fragments
+ * and the prefix.
+ */
+#define NETCHANNEL2_MSG_PACKET 2
+#define NETCHANNEL2_MAX_PACKET_BYTES 65536
+#define NETCHANNEL2_MAX_INLINE_BYTES 256
+struct netchannel2_fragment {
+ uint16_t size;
+ /* The offset is always relative to the start of the page.
+ For pre_posted packet types, it is not relative to the
+ start of the buffer (although the fragment range will
+ obviously be within the buffer range). */
+ uint16_t off;
+ union {
+ struct {
+ grant_ref_t gref;
+ } receiver_copy;
+ };
+};
+struct netchannel2_msg_packet {
+ struct netchannel2_msg_hdr hdr;
+ uint32_t id; /* Opaque ID which is echoed into the finished
+ packet message. */
+ uint8_t type;
+ uint8_t flags;
+ uint8_t pad0;
+ uint8_t pad1;
+ uint16_t prefix_size;
+ uint16_t pad2;
+ uint16_t pad3;
+ uint16_t pad4;
+ /* Variable-size array. The number of elements is determined
+ by the size of the message. */
+ /* Until we support scatter-gather, this will be either 0 or 1
+ element. */
+ struct netchannel2_fragment frags[0];
+};
+
+/* If set, the transmitting domain requires an event urgently when
+ * this packet's finish message is sent. Otherwise, the event can be
+ * delayed. */
+#define NC2_PACKET_FLAG_need_event 8
+
+/* The mechanism which should be used to receive the data part of
+ * a packet:
+ *
+ * receiver_copy -- The transmitting domain has granted the receiving
+ * domain access to the original RX buffers using
+ * copy-only grant references. The receiving domain
+ * should copy the data out of the buffers and issue
+ * a FINISH message.
+ *
+ * Due to backend bugs, it is in not safe to use this
+ * packet type except on bypass rings.
+ *
+ * small -- The packet does not have any fragment descriptors
+ * (i.e. the entire thing is inline in the ring). The receiving
+ * domain should simply the copy the packet out of the ring
+ * into a locally allocated buffer. No FINISH message is required
+ * or allowed.
+ *
+ * This packet type may be used on any ring.
+ *
+ * All endpoints must be able to receive all packet types, but note
+ * that it is correct to treat receiver_map and small packets as
+ * receiver_copy ones. */
+#define NC2_PACKET_TYPE_receiver_copy 1
+#define NC2_PACKET_TYPE_small 4
+
+/* Tell the other end that we're finished with a message it sent us,
+ and it can release the transmit buffers etc. This must be sent in
+ response to receiver_copy and receiver_map packets. It must not be
+ sent in response to pre_posted or small packets. */
+#define NETCHANNEL2_MSG_FINISH_PACKET 3
+struct netchannel2_msg_finish_packet {
+ struct netchannel2_msg_hdr hdr;
+ uint32_t id;
+};
+
+#endif /* !__NETCHANNEL2_H__ */
diff --git a/include/xen/interface/io/uring.h b/include/xen/interface/io/uring.h
new file mode 100644
index 0000000..663c3d7
--- /dev/null
+++ b/include/xen/interface/io/uring.h
@@ -0,0 +1,426 @@
+#ifndef __XEN_PUBLIC_IO_URING_H__
+#define __XEN_PUBLIC_IO_URING_H__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/system.h>
+
+typedef unsigned RING_IDX;
+
+#define NETCHANNEL2_MSG_PAD 255
+
+/* The sring structures themselves. The _cons and _prod variants are
+ different views of the same bit of shared memory, and are supposed
+ to provide better checking of the expected use patterns. Fields in
+ the shared ring are owned by either the producer end or the
+ consumer end. If a field is owned by your end, the other end will
+ never modify it. If it's owned by the other end, the other end is
+ allowed to modify it whenever it likes, and you can never do so.
+
+ Fields owned by the other end are always const (because you can't
+ change them). They're also volatile, because there are a bunch
+ of places where we go:
+
+ local_x = sring->x;
+ validate(local_x);
+ use(local_x);
+
+ and it would be very bad if the compiler turned that into:
+
+ local_x = sring->x;
+ validate(sring->x);
+ use(local_x);
+
+ because that contains a potential TOCTOU race (hard to exploit, but
+ still present). The compiler is only allowed to do that
+ optimisation because it knows that local_x == sring->x at the start
+ of the call to validate(), and it only knows that if it can reorder
+ the read of sring->x over the sequence point at the end of the
+ first statement. In other words, it can only do the bad
+ optimisation if it knows that reads of sring->x are side-effect
+ free. volatile stops it from making that assumption.
+
+ We don't need a full memory barrier here, because it's sufficient
+ to copy the volatile data into stable guest-local storage, and
+ volatile achieves that. i.e. we don't need local_x to be precisely
+ sring->x, but we do need it to be a stable snapshot of some
+ previous valud of sring->x.
+
+ Note that there are still plenty of other places where we *do* need
+ full barriers. volatile just deals with this one, specific, case.
+
+ We could also deal with it by putting compiler barriers in all over
+ the place. The downside of that approach is that you need to put
+ the barrier()s in lots of different places (basically, everywhere
+ which needs to access these fields), and it's easy to forget one.
+ barrier()s also have somewhat heavier semantics than volatile
+ (because they prevent all reordering, rather than just reordering
+ on this one field), although that's pretty much irrelevant because
+ gcc usually treats pretty much any volatile access as a call to
+ barrier().
+*/
+
+/* Messages are sent over sring pairs. Each sring in a pair provides
+ * a unidirectional byte stream which can generate events when either
+ * the producer or consumer pointers cross a particular threshold.
+ *
+ * We define both sring_prod and sring_cons structures. The two
+ * structures will always map onto the same physical bytes in memory,
+ * but they provide different views of that memory which are
+ * appropriate to either producers or consumers.
+ *
+ * Obviously, the endpoints need to agree on which end produces
+ * messages on which ring. The endpoint which provided the memory
+ * backing the ring always produces on the first sring, and the one
+ * which just mapped the ring produces on the second. By convention,
+ * these are known as the frontend and backend, respectively.
+ */
+
+/* For both rings, the producer (consumer) pointers point at the
+ * *next* byte which is going to be produced (consumed). An endpoint
+ * must generate an event on the event channel port if it moves the
+ * producer pointer (consumer pointer) across prod_event (cons_event).
+ *
+ * i.e if an endpoint ever updates a pointer so that the old pointer
+ * is strictly less than the event, and the new pointer is greater
+ * than or equal to the event then the remote must be notified. If
+ * the pointer overflows the ring, treat the new value as if it were
+ * (actual new value) + (1 << 32).
+ */
+struct netchannel2_sring_prod {
+ RING_IDX prod;
+ volatile const RING_IDX cons;
+ volatile const RING_IDX prod_event;
+ RING_IDX cons_event;
+ unsigned char pad[48];
+};
+
+struct netchannel2_sring_cons {
+ volatile const RING_IDX prod;
+ RING_IDX cons;
+ RING_IDX prod_event;
+ volatile const RING_IDX cons_event;
+ unsigned char pad[48];
+};
+
+struct netchannel2_frontend_shared {
+ struct netchannel2_sring_prod prod;
+ struct netchannel2_sring_cons cons;
+};
+
+struct netchannel2_backend_shared {
+ struct netchannel2_sring_cons cons;
+ struct netchannel2_sring_prod prod;
+};
+
+struct netchannel2_prod_ring {
+ struct netchannel2_sring_prod *sring;
+ void *payload;
+ RING_IDX prod_pvt;
+ /* This is the number of bytes available after prod_pvt last
+ time we checked, minus the number of bytes which we've
+ consumed since then. It's used to a avoid a bunch of
+ memory barriers when checking for ring space. */
+ unsigned bytes_available;
+ /* Number of bytes reserved by nc2_reserve_payload_bytes() */
+ unsigned reserve;
+ size_t payload_bytes;
+};
+
+struct netchannel2_cons_ring {
+ struct netchannel2_sring_cons *sring;
+ const volatile void *payload;
+ RING_IDX cons_pvt;
+ size_t payload_bytes;
+};
+
+/* A message header. There is one of these at the start of every
+ * message. @type is one of the #define's below, and @size is the
+ * size of the message, including the header and any padding.
+ * size should be a multiple of 8 so we avoid unaligned memory copies.
+ * structs defining message formats should have sizes multiple of 8
+ * bytes and should use paddding fields if needed.
+ */
+struct netchannel2_msg_hdr {
+ uint8_t type;
+ uint8_t flags;
+ uint16_t size;
+};
+
+/* Copy some bytes from the shared ring to a stable local buffer,
+ * starting at the private consumer pointer. Does not update the
+ * private consumer pointer.
+ */
+static inline void nc2_copy_from_ring_off(struct netchannel2_cons_ring *ring,
+ void *buf,
+ size_t nbytes,
+ unsigned off)
+{
+ unsigned start, end;
+
+ start = (ring->cons_pvt + off) & (ring->payload_bytes-1);
+ end = (ring->cons_pvt + nbytes + off) & (ring->payload_bytes-1);
+ /* We cast away the volatile modifier to get rid of an
+ irritating compiler warning, and compensate with a
+ barrier() at the end. */
+ memcpy(buf, (const void *)ring->payload + start, nbytes);
+ barrier();
+}
+
+static inline void nc2_copy_from_ring(struct netchannel2_cons_ring *ring,
+ void *buf,
+ size_t nbytes)
+{
+ nc2_copy_from_ring_off(ring, buf, nbytes, 0);
+}
+
+
+/* Copy some bytes to the shared ring, starting at the private
+ * producer pointer. Does not update the private pointer.
+ */
+static inline void nc2_copy_to_ring_off(struct netchannel2_prod_ring *ring,
+ const void *src,
+ unsigned nr_bytes,
+ unsigned off)
+{
+ unsigned start, end;
+
+ start = (ring->prod_pvt + off) & (ring->payload_bytes-1);
+ end = (ring->prod_pvt + nr_bytes + off) & (ring->payload_bytes-1);
+ memcpy(ring->payload + start, src, nr_bytes);
+}
+
+static inline void nc2_copy_to_ring(struct netchannel2_prod_ring *ring,
+ const void *src,
+ unsigned nr_bytes)
+{
+ nc2_copy_to_ring_off(ring, src, nr_bytes, 0);
+}
+
+static inline void __nc2_send_pad(struct netchannel2_prod_ring *ring,
+ unsigned nr_bytes)
+{
+ struct netchannel2_msg_hdr msg;
+ msg.type = NETCHANNEL2_MSG_PAD;
+ msg.flags = 0;
+ msg.size = nr_bytes;
+ nc2_copy_to_ring(ring, &msg, sizeof(msg));
+ ring->prod_pvt += nr_bytes;
+ ring->bytes_available -= nr_bytes;
+}
+
+static inline int __nc2_ring_would_wrap(struct netchannel2_prod_ring *ring,
+ unsigned nr_bytes)
+{
+ RING_IDX mask;
+ mask = ~(ring->payload_bytes - 1);
+ return (ring->prod_pvt & mask) != ((ring->prod_pvt + nr_bytes) & mask);
+}
+
+static inline unsigned __nc2_pad_needed(struct netchannel2_prod_ring *ring)
+{
+ return ring->payload_bytes -
+ (ring->prod_pvt & (ring->payload_bytes - 1));
+}
+
+static inline void __nc2_avoid_ring_wrap(struct netchannel2_prod_ring *ring,
+ unsigned nr_bytes)
+{
+ if (!__nc2_ring_would_wrap(ring, nr_bytes))
+ return;
+ __nc2_send_pad(ring, __nc2_pad_needed(ring));
+
+}
+
+/* Prepare a message for the other end and place it on the shared
+ * ring, updating the private producer pointer. You need to call
+ * nc2_flush_messages() before the message is actually made visible to
+ * the other end. It is permissible to send several messages in a
+ * batch and only flush them once.
+ */
+static inline void nc2_send_message(struct netchannel2_prod_ring *ring,
+ unsigned type,
+ unsigned flags,
+ const void *msg,
+ size_t size)
+{
+ struct netchannel2_msg_hdr *hdr = (struct netchannel2_msg_hdr *)msg;
+
+ __nc2_avoid_ring_wrap(ring, size);
+
+ hdr->type = type;
+ hdr->flags = flags;
+ hdr->size = size;
+
+ nc2_copy_to_ring(ring, msg, size);
+ ring->prod_pvt += size;
+ BUG_ON(ring->bytes_available < size);
+ ring->bytes_available -= size;
+}
+
+static inline volatile void *__nc2_get_message_ptr(struct
netchannel2_prod_ring *ncrp)
+{
+ return (volatile void *)ncrp->payload +
+ (ncrp->prod_pvt & (ncrp->payload_bytes-1));
+}
+
+/* Copy the private producer pointer to the shared producer pointer,
+ * with a suitable memory barrier such that all messages placed on the
+ * ring are stable before we do the copy. This effectively pushes any
+ * messages which we've just sent out to the other end. Returns 1 if
+ * we need to notify the other end and 0 otherwise.
+ */
+static inline int nc2_flush_ring(struct netchannel2_prod_ring *ring)
+{
+ RING_IDX old_prod, new_prod;
+
+ old_prod = ring->sring->prod;
+ new_prod = ring->prod_pvt;
+
+ wmb();
+
+ ring->sring->prod = new_prod;
+
+ /* We need the update to prod to happen before we read
+ * event. */
+ mb();
+
+ /* We notify if the producer pointer moves across the event
+ * pointer. */
+ if ((RING_IDX)(new_prod - ring->sring->prod_event) <
+ (RING_IDX)(new_prod - old_prod))
+ return 1;
+ else
+ return 0;
+}
+
+/* Copy the private consumer pointer to the shared consumer pointer,
+ * with a memory barrier so that any previous reads from the ring
+ * complete before the pointer is updated. This tells the other end
+ * that we're finished with the messages, and that it can re-use the
+ * ring space for more messages. Returns 1 if we need to notify the
+ * other end and 0 otherwise.
+ */
+static inline int nc2_finish_messages(struct netchannel2_cons_ring *ring)
+{
+ RING_IDX old_cons, new_cons;
+
+ old_cons = ring->sring->cons;
+ new_cons = ring->cons_pvt;
+
+ /* Need to finish reading from the ring before updating
+ cons */
+ mb();
+ ring->sring->cons = ring->cons_pvt;
+
+ /* Need to publish our new consumer pointer before checking
+ event. */
+ mb();
+ if ((RING_IDX)(new_cons - ring->sring->cons_event) <
+ (RING_IDX)(new_cons - old_cons))
+ return 1;
+ else
+ return 0;
+}
+
+/* Check whether there are any unconsumed messages left on the shared
+ * ring. Returns 1 if there are, and 0 if there aren't. If there are
+ * no more messages, set the producer event so that we'll get a
+ * notification as soon as another one gets sent. It is assumed that
+ * all messages up to @prod have been processed, and none of the ones
+ * after it have been. */
+static inline int nc2_final_check_for_messages(struct netchannel2_cons_ring
*ring,
+ RING_IDX prod)
+{
+ if (prod != ring->sring->prod)
+ return 1;
+ /* Request an event when more stuff gets poked on the ring. */
+ ring->sring->prod_event = prod + 1;
+
+ /* Publish event before final check for responses. */
+ mb();
+ if (prod != ring->sring->prod)
+ return 1;
+ else
+ return 0;
+}
+
+/* Can we send a message with @nr_bytes payload bytes? Returns 1 if
+ * we can or 0 if we can't. If there isn't space right now, set the
+ * consumer event so that we'll get notified when space is
+ * available. */
+static inline int nc2_can_send_payload_bytes(struct netchannel2_prod_ring
*ring,
+ unsigned nr_bytes)
+{
+ unsigned space;
+ RING_IDX cons;
+ BUG_ON(ring->bytes_available > ring->payload_bytes);
+ /* Times 2 because we might need to send a pad message */
+ if (likely(ring->bytes_available > nr_bytes * 2 + ring->reserve))
+ return 1;
+ if (__nc2_ring_would_wrap(ring, nr_bytes))
+ nr_bytes += __nc2_pad_needed(ring);
+retry:
+ cons = ring->sring->cons;
+ space = ring->payload_bytes - (ring->prod_pvt - cons);
+ if (likely(space >= nr_bytes + ring->reserve)) {
+ /* We have enough space to send the message. */
+
+ /* Need to make sure that the read of cons happens
+ before any following memory writes. */
+ mb();
+
+ ring->bytes_available = space;
+
+ return 1;
+ } else {
+ /* Not enough space available. Set an event pointer
+ when cons changes. We need to be sure that the
+ @cons used here is the same as the cons used to
+ calculate @space above, and the volatile modifier
+ on sring->cons achieves that. */
+ ring->sring->cons_event = cons + 1;
+
+ /* Check whether more space became available while we
+ were messing about. */
+
+ /* Need the event pointer to be stable before we do
+ the check. */
+ mb();
+ if (unlikely(cons != ring->sring->cons)) {
+ /* Cons pointer changed. Try again. */
+ goto retry;
+ }
+
+ /* There definitely isn't space on the ring now, and
+ an event has been set such that we'll be notified
+ if more space becomes available. */
+ /* XXX we get a notification as soon as any more space
+ becomes available. We could maybe optimise by
+ setting the event such that we only get notified
+ when we know that enough space is available. The
+ main complication is handling the case where you
+ try to send a message of size A, fail due to lack
+ of space, and then try to send one of size B, where
+ B < A. It's not clear whether you want to set the
+ event for A bytes or B bytes. The obvious answer
+ is B, but that means moving the event pointer
+ backwards, and it's not clear that that's always
+ safe. Always setting for a single byte is safe, so
+ stick with that for now. */
+ return 0;
+ }
+}
+
+static inline int nc2_reserve_payload_bytes(struct netchannel2_prod_ring *ring,
+ unsigned nr_bytes)
+{
+ if (nc2_can_send_payload_bytes(ring, nr_bytes)) {
+ ring->reserve += nr_bytes;
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+#endif /* __XEN_PUBLIC_IO_URING_H__ */
--
1.6.3.1
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