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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] drivers/tpm-xen: Change vTPM shared page ABI
This changes the vTPM shared page ABI from a copy of the Xen network
interface to a single-page interface that better reflects the expected
behavior of a TPM: only a single request packet can be sent at any given
time, and every packet sent generates a single response packet. This
protocol change should also increase efficiency as it avoids mapping and
unmapping grants when possible.
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
drivers/char/tpm/xen-tpmfront_if.c | 195 +++++++------------------------------
include/xen/interface/io/tpmif.h | 42 ++------
2 files changed, 42 insertions(+), 195 deletions(-)
diff --git a/drivers/char/tpm/xen-tpmfront_if.c
b/drivers/char/tpm/xen-tpmfront_if.c
index ba7fad8..374ad1b 100644
--- a/drivers/char/tpm/xen-tpmfront_if.c
+++ b/drivers/char/tpm/xen-tpmfront_if.c
@@ -53,7 +53,7 @@
struct tpm_private {
struct tpm_chip *chip;
- struct tpmif_tx_interface *tx;
+ struct vtpm_shared_page *page;
atomic_t refcnt;
unsigned int evtchn;
u8 is_connected;
@@ -61,8 +61,6 @@ struct tpm_private {
spinlock_t tx_lock;
- struct tx_buffer *tx_buffers[TPMIF_TX_RING_SIZE];
-
atomic_t tx_busy;
void *tx_remember;
@@ -73,15 +71,7 @@ struct tpm_private {
int ring_ref;
};
-struct tx_buffer {
- unsigned int size; /* available space in data */
- unsigned int len; /* used space in data */
- unsigned char *data; /* pointer to a page */
-};
-
-
/* locally visible variables */
-static grant_ref_t gref_head;
static struct tpm_private *my_priv;
/* local function prototypes */
@@ -92,8 +82,6 @@ static int tpmif_connect(struct xenbus_device *dev,
struct tpm_private *tp,
domid_t domid);
static DECLARE_TASKLET(tpmif_rx_tasklet, tpmif_rx_action, 0);
-static int tpmif_allocate_tx_buffers(struct tpm_private *tp);
-static void tpmif_free_tx_buffers(struct tpm_private *tp);
static void tpmif_set_connected_state(struct tpm_private *tp,
u8 newstate);
static int tpm_xmit(struct tpm_private *tp,
@@ -101,52 +89,6 @@ static int tpm_xmit(struct tpm_private *tp,
void *remember);
static void destroy_tpmring(struct tpm_private *tp);
-static inline int
-tx_buffer_copy(struct tx_buffer *txb, const u8 *src, int len,
- int isuserbuffer)
-{
- int copied = len;
-
- if (len > txb->size)
- copied = txb->size;
- if (isuserbuffer) {
- if (copy_from_user(txb->data, src, copied))
- return -EFAULT;
- } else {
- memcpy(txb->data, src, copied);
- }
- txb->len = len;
- return copied;
-}
-
-static inline struct tx_buffer *tx_buffer_alloc(void)
-{
- struct tx_buffer *txb;
-
- txb = kzalloc(sizeof(struct tx_buffer), GFP_KERNEL);
- if (!txb)
- return NULL;
-
- txb->len = 0;
- txb->size = PAGE_SIZE;
- txb->data = (unsigned char *)__get_free_page(GFP_KERNEL);
- if (txb->data == NULL) {
- kfree(txb);
- txb = NULL;
- }
-
- return txb;
-}
-
-
-static inline void tx_buffer_free(struct tx_buffer *txb)
-{
- if (txb) {
- free_page((long)txb->data);
- kfree(txb);
- }
-}
-
/**************************************************************
Utility function for the tpm_private structure
**************************************************************/
@@ -162,15 +104,12 @@ static void tpm_private_put(void)
if (!atomic_dec_and_test(&my_priv->refcnt))
return;
- tpmif_free_tx_buffers(my_priv);
kfree(my_priv);
my_priv = NULL;
}
static struct tpm_private *tpm_private_get(void)
{
- int err;
-
if (my_priv) {
atomic_inc(&my_priv->refcnt);
return my_priv;
@@ -181,9 +120,6 @@ static struct tpm_private *tpm_private_get(void)
return NULL;
tpm_private_init(my_priv);
- err = tpmif_allocate_tx_buffers(my_priv);
- if (err < 0)
- tpm_private_put();
return my_priv;
}
@@ -218,22 +154,22 @@ int vtpm_vd_send(struct tpm_private *tp,
static int setup_tpmring(struct xenbus_device *dev,
struct tpm_private *tp)
{
- struct tpmif_tx_interface *sring;
+ struct vtpm_shared_page *sring;
int err;
tp->ring_ref = GRANT_INVALID_REF;
- sring = (void *)__get_free_page(GFP_KERNEL);
+ sring = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
if (!sring) {
xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
return -ENOMEM;
}
- tp->tx = sring;
+ tp->page = sring;
- err = xenbus_grant_ring(dev, virt_to_mfn(tp->tx));
+ err = xenbus_grant_ring(dev, virt_to_mfn(tp->page));
if (err < 0) {
free_page((unsigned long)sring);
- tp->tx = NULL;
+ tp->page = NULL;
xenbus_dev_fatal(dev, err, "allocating grant reference");
goto fail;
}
@@ -256,9 +192,9 @@ static void destroy_tpmring(struct tpm_private *tp)
if (tp->ring_ref != GRANT_INVALID_REF) {
gnttab_end_foreign_access(tp->ring_ref,
- 0, (unsigned long)tp->tx);
+ 0, (unsigned long)tp->page);
tp->ring_ref = GRANT_INVALID_REF;
- tp->tx = NULL;
+ tp->page = NULL;
}
if (tp->evtchn)
@@ -457,10 +393,10 @@ static int tpmif_connect(struct xenbus_device *dev,
}
static const struct xenbus_device_id tpmfront_ids[] = {
- { "vtpm" },
+ { "vtpm2" },
{ "" }
};
-MODULE_ALIAS("xen:vtpm");
+MODULE_ALIAS("xen:vtpm2");
static DEFINE_XENBUS_DRIVER(tpmfront, ,
.probe = tpmfront_probe,
@@ -470,62 +406,30 @@ static DEFINE_XENBUS_DRIVER(tpmfront, ,
.suspend = tpmfront_suspend,
);
-static int tpmif_allocate_tx_buffers(struct tpm_private *tp)
-{
- unsigned int i;
-
- for (i = 0; i < TPMIF_TX_RING_SIZE; i++) {
- tp->tx_buffers[i] = tx_buffer_alloc();
- if (!tp->tx_buffers[i]) {
- tpmif_free_tx_buffers(tp);
- return -ENOMEM;
- }
- }
- return 0;
-}
-
-static void tpmif_free_tx_buffers(struct tpm_private *tp)
-{
- unsigned int i;
-
- for (i = 0; i < TPMIF_TX_RING_SIZE; i++)
- tx_buffer_free(tp->tx_buffers[i]);
-}
-
static void tpmif_rx_action(unsigned long priv)
{
struct tpm_private *tp = (struct tpm_private *)priv;
- int i = 0;
unsigned int received;
unsigned int offset = 0;
u8 *buffer;
- struct tpmif_tx_request *tx = &tp->tx->ring[i].req;
+ struct vtpm_shared_page *shr = tp->page;
atomic_set(&tp->tx_busy, 0);
wake_up_interruptible(&tp->wait_q);
- received = tx->size;
+ offset = sizeof(*shr) + 4*shr->nr_extra_pages;
+ received = shr->length;
+
+ if (offset > PAGE_SIZE || offset + received > PAGE_SIZE) {
+ printk(KERN_WARNING "tpmif_rx_action packet too large\n");
+ return;
+ }
buffer = kmalloc(received, GFP_ATOMIC);
if (!buffer)
return;
- for (i = 0; i < TPMIF_TX_RING_SIZE && offset < received; i++) {
- struct tx_buffer *txb = tp->tx_buffers[i];
- struct tpmif_tx_request *tx;
- unsigned int tocopy;
-
- tx = &tp->tx->ring[i].req;
- tocopy = tx->size;
- if (tocopy > PAGE_SIZE)
- tocopy = PAGE_SIZE;
-
- memcpy(&buffer[offset], txb->data, tocopy);
-
- gnttab_release_grant_reference(&gref_head, tx->ref);
-
- offset += tocopy;
- }
+ memcpy(buffer, offset + (u8*)shr, received);
vtpm_vd_recv(tp->chip, buffer, received, tp->tx_remember);
kfree(buffer);
@@ -550,8 +454,7 @@ static int tpm_xmit(struct tpm_private *tp,
const u8 *buf, size_t count, int isuserbuffer,
void *remember)
{
- struct tpmif_tx_request *tx;
- int i;
+ struct vtpm_shared_page *shr;
unsigned int offset = 0;
spin_lock_irq(&tp->tx_lock);
@@ -566,48 +469,23 @@ static int tpm_xmit(struct tpm_private *tp,
return -EIO;
}
- for (i = 0; count > 0 && i < TPMIF_TX_RING_SIZE; i++) {
- struct tx_buffer *txb = tp->tx_buffers[i];
- int copied;
-
- if (!txb) {
- spin_unlock_irq(&tp->tx_lock);
- return -EFAULT;
- }
-
- copied = tx_buffer_copy(txb, &buf[offset], count,
- isuserbuffer);
- if (copied < 0) {
- /* An error occurred */
- spin_unlock_irq(&tp->tx_lock);
- return copied;
- }
- count -= copied;
- offset += copied;
-
- tx = &tp->tx->ring[i].req;
- tx->addr = virt_to_machine(txb->data).maddr;
- tx->size = txb->len;
- tx->unused = 0;
-
- /* Get the granttable reference for this page. */
- tx->ref = gnttab_claim_grant_reference(&gref_head);
- if (tx->ref == -ENOSPC) {
- spin_unlock_irq(&tp->tx_lock);
- return -ENOSPC;
- }
- gnttab_grant_foreign_access_ref(tx->ref,
- tp->backend_id,
- virt_to_mfn(txb->data),
- 0 /*RW*/);
- wmb();
- }
+ shr = tp->page;
+ offset = sizeof(*shr) + 4*shr->nr_extra_pages;
+
+ if (offset > PAGE_SIZE)
+ return -EIO;
+
+ if (offset + count > PAGE_SIZE)
+ count = PAGE_SIZE - offset;
+
+ memcpy(offset + (u8*)shr, buf, count);
+ shr->length = count;
+ barrier();
+ shr->state = 1;
atomic_set(&tp->tx_busy, 1);
tp->tx_remember = remember;
- mb();
-
notify_remote_via_evtchn(tp->evtchn);
spin_unlock_irq(&tp->tx_lock);
@@ -667,12 +545,6 @@ static int __init tpmif_init(void)
if (!tp)
return -ENOMEM;
- if (gnttab_alloc_grant_references(TPMIF_TX_RING_SIZE,
- &gref_head) < 0) {
- tpm_private_put();
- return -EFAULT;
- }
-
return xenbus_register_frontend(&tpmfront_driver);
}
module_init(tpmif_init);
@@ -680,7 +552,6 @@ module_init(tpmif_init);
static void __exit tpmif_exit(void)
{
xenbus_unregister_driver(&tpmfront_driver);
- gnttab_free_grant_references(gref_head);
tpm_private_put();
}
module_exit(tpmif_exit);
diff --git a/include/xen/interface/io/tpmif.h b/include/xen/interface/io/tpmif.h
index c9e7294..b55ac56 100644
--- a/include/xen/interface/io/tpmif.h
+++ b/include/xen/interface/io/tpmif.h
@@ -1,7 +1,7 @@
/******************************************************************************
* tpmif.h
*
- * TPM I/O interface for Xen guest OSes.
+ * TPM I/O interface for Xen guest OSes, v2
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
@@ -21,45 +21,21 @@
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
- * Copyright (c) 2005, IBM Corporation
- *
- * Author: Stefan Berger, stefanb@xxxxxxxxxx
- * Grant table support: Mahadevan Gomathisankaran
- *
- * This code has been derived from tools/libxc/xen/io/netif.h
- *
- * Copyright (c) 2003-2004, Keir Fraser
*/
#ifndef __XEN_PUBLIC_IO_TPMIF_H__
#define __XEN_PUBLIC_IO_TPMIF_H__
-#include "../grant_table.h"
-
-struct tpmif_tx_request {
- unsigned long addr; /* Machine address of packet. */
- grant_ref_t ref; /* grant table access reference */
- uint16_t unused;
- uint16_t size; /* Packet size in bytes. */
-};
-struct tpmif_tx_request;
+struct vtpm_shared_page {
+ uint32_t length; /* request/response length in bytes */
-/*
- * The TPMIF_TX_RING_SIZE defines the number of pages the
- * front-end and backend can exchange (= size of array).
- */
-#define TPMIF_TX_RING_SIZE 1
-
-/* This structure must fit in a memory page. */
-
-struct tpmif_ring {
- struct tpmif_tx_request req;
-};
-struct tpmif_ring;
+ uint8_t state; /* 0 - response ready / idle
+ * 1 - request ready / working */
+ uint8_t locality; /* for the current request */
+ uint8_t pad;
-struct tpmif_tx_interface {
- struct tpmif_ring ring[TPMIF_TX_RING_SIZE];
+ uint8_t nr_extra_pages; /* extra pages for long packets; may be zero */
+ uint32_t extra_pages[0]; /* grant IDs; length is actually
nr_extra_pages */
};
-struct tpmif_tx_interface;
#endif
--
1.8.1
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