[PATCH V4 12/13] hv_netvsc: Add Isolation VM support for netvsc driver

[Tianyu Lan <ltykernel@xxxxxxxxx>]

From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>

In Isolation VM, all shared memory with host needs to mark visible
to host via hvcall. vmbus_establish_gpadl() has already done it for
netvsc rx/tx ring buffer. The page buffer used by vmbus_sendpacket_
pagebuffer() stills need to be handled. Use DMA API to map/umap
these memory during sending/receiving packet and Hyper-V swiotlb
bounce buffer dma adress will be returned. The swiotlb bounce buffer
has been masked to be visible to host during boot up.

Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
---
Change since v3:
        * Add comment to explain why not to use dma_map_sg()
        * Fix some error handle.
---
 arch/x86/hyperv/ivm.c             |   1 +
 drivers/net/hyperv/hyperv_net.h   |   5 ++
 drivers/net/hyperv/netvsc.c       | 135 +++++++++++++++++++++++++++++-
 drivers/net/hyperv/rndis_filter.c |   2 +
 include/linux/hyperv.h            |   5 ++
 5 files changed, 145 insertions(+), 3 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 84563b3c9f3a..08d8e01de017 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -317,6 +317,7 @@ void *hv_map_memory(void *addr, unsigned long size)
 
        return vaddr;
 }
+EXPORT_SYMBOL_GPL(hv_map_memory);
 
 void hv_unmap_memory(void *addr)
 {
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index aa7c9962dbd8..862419912bfb 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -164,6 +164,7 @@ struct hv_netvsc_packet {
        u32 total_bytes;
        u32 send_buf_index;
        u32 total_data_buflen;
+       struct hv_dma_range *dma_range;
 };
 
 #define NETVSC_HASH_KEYLEN 40
@@ -1074,6 +1075,7 @@ struct netvsc_device {
 
        /* Receive buffer allocated by us but manages by NetVSP */
        void *recv_buf;
+       void *recv_original_buf;
        u32 recv_buf_size; /* allocated bytes */
        u32 recv_buf_gpadl_handle;
        u32 recv_section_cnt;
@@ -1082,6 +1084,7 @@ struct netvsc_device {
 
        /* Send buffer allocated by us */
        void *send_buf;
+       void *send_original_buf;
        u32 send_buf_size;
        u32 send_buf_gpadl_handle;
        u32 send_section_cnt;
@@ -1731,4 +1734,6 @@ struct rndis_message {
 #define RETRY_US_HI    10000
 #define RETRY_MAX      2000    /* >10 sec */
 
+void netvsc_dma_unmap(struct hv_device *hv_dev,
+                     struct hv_netvsc_packet *packet);
 #endif /* _HYPERV_NET_H */
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index f19bffff6a63..edd336b08c2c 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -153,8 +153,21 @@ static void free_netvsc_device(struct rcu_head *head)
        int i;
 
        kfree(nvdev->extension);
-       vfree(nvdev->recv_buf);
-       vfree(nvdev->send_buf);
+
+       if (nvdev->recv_original_buf) {
+               vunmap(nvdev->recv_buf);
+               vfree(nvdev->recv_original_buf);
+       } else {
+               vfree(nvdev->recv_buf);
+       }
+
+       if (nvdev->send_original_buf) {
+               vunmap(nvdev->send_buf);
+               vfree(nvdev->send_original_buf);
+       } else {
+               vfree(nvdev->send_buf);
+       }
+
        kfree(nvdev->send_section_map);
 
        for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
@@ -347,6 +360,7 @@ static int netvsc_init_buf(struct hv_device *device,
        unsigned int buf_size;
        size_t map_words;
        int i, ret = 0;
+       void *vaddr;
 
        /* Get receive buffer area. */
        buf_size = device_info->recv_sections * device_info->recv_section_size;
@@ -382,6 +396,17 @@ static int netvsc_init_buf(struct hv_device *device,
                goto cleanup;
        }
 
+       if (hv_isolation_type_snp()) {
+               vaddr = hv_map_memory(net_device->recv_buf, buf_size);
+               if (!vaddr) {
+                       ret = -ENOMEM;
+                       goto cleanup;
+               }
+
+               net_device->recv_original_buf = net_device->recv_buf;
+               net_device->recv_buf = vaddr;
+       }
+
        /* Notify the NetVsp of the gpadl handle */
        init_packet = &net_device->channel_init_pkt;
        memset(init_packet, 0, sizeof(struct nvsp_message));
@@ -485,6 +510,17 @@ static int netvsc_init_buf(struct hv_device *device,
                goto cleanup;
        }
 
+       if (hv_isolation_type_snp()) {
+               vaddr = hv_map_memory(net_device->send_buf, buf_size);
+               if (!vaddr) {
+                       ret = -ENOMEM;
+                       goto cleanup;
+               }
+
+               net_device->send_original_buf = net_device->send_buf;
+               net_device->send_buf = vaddr;
+       }
+
        /* Notify the NetVsp of the gpadl handle */
        init_packet = &net_device->channel_init_pkt;
        memset(init_packet, 0, sizeof(struct nvsp_message));
@@ -775,7 +811,7 @@ static void netvsc_send_tx_complete(struct net_device *ndev,
 
        /* Notify the layer above us */
        if (likely(skb)) {
-               const struct hv_netvsc_packet *packet
+               struct hv_netvsc_packet *packet
                        = (struct hv_netvsc_packet *)skb->cb;
                u32 send_index = packet->send_buf_index;
                struct netvsc_stats *tx_stats;
@@ -791,6 +827,7 @@ static void netvsc_send_tx_complete(struct net_device *ndev,
                tx_stats->bytes += packet->total_bytes;
                u64_stats_update_end(&tx_stats->syncp);
 
+               netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
                napi_consume_skb(skb, budget);
        }
 
@@ -955,6 +992,87 @@ static void netvsc_copy_to_send_buf(struct netvsc_device 
*net_device,
                memset(dest, 0, padding);
 }
 
+void netvsc_dma_unmap(struct hv_device *hv_dev,
+                     struct hv_netvsc_packet *packet)
+{
+       u32 page_count = packet->cp_partial ?
+               packet->page_buf_cnt - packet->rmsg_pgcnt :
+               packet->page_buf_cnt;
+       int i;
+
+       if (!hv_is_isolation_supported())
+               return;
+
+       if (!packet->dma_range)
+               return;
+
+       for (i = 0; i < page_count; i++)
+               dma_unmap_single(&hv_dev->device, packet->dma_range[i].dma,
+                                packet->dma_range[i].mapping_size,
+                                DMA_TO_DEVICE);
+
+       kfree(packet->dma_range);
+}
+
+/* netvsc_dma_map - Map swiotlb bounce buffer with data page of
+ * packet sent by vmbus_sendpacket_pagebuffer() in the Isolation
+ * VM.
+ *
+ * In isolation VM, netvsc send buffer has been marked visible to
+ * host and so the data copied to send buffer doesn't need to use
+ * bounce buffer. The data pages handled by vmbus_sendpacket_pagebuffer()
+ * may not be copied to send buffer and so these pages need to be
+ * mapped with swiotlb bounce buffer. netvsc_dma_map() is to do
+ * that. The pfns in the struct hv_page_buffer need to be converted
+ * to bounce buffer's pfn. The loop here is necessary becuase the
+ * entries in the page buffer array are not necessarily full
+ * pages of data.  Each entry in the array has a separate offset and
+ * len that may be non-zero, even for entries in the middle of the
+ * array.  And the entries are not physically contiguous.  So each
+ * entry must be individually mapped rather than as a contiguous unit.
+ * So not use dma_map_sg() here.
+ */
+int netvsc_dma_map(struct hv_device *hv_dev,
+                  struct hv_netvsc_packet *packet,
+                  struct hv_page_buffer *pb)
+{
+       u32 page_count =  packet->cp_partial ?
+               packet->page_buf_cnt - packet->rmsg_pgcnt :
+               packet->page_buf_cnt;
+       dma_addr_t dma;
+       int i;
+
+       if (!hv_is_isolation_supported())
+               return 0;
+
+       packet->dma_range = kcalloc(page_count,
+                                   sizeof(*packet->dma_range),
+                                   GFP_KERNEL);
+       if (!packet->dma_range)
+               return -ENOMEM;
+
+       for (i = 0; i < page_count; i++) {
+               char *src = phys_to_virt((pb[i].pfn << HV_HYP_PAGE_SHIFT)
+                                        + pb[i].offset);
+               u32 len = pb[i].len;
+
+               dma = dma_map_single(&hv_dev->device, src, len,
+                                    DMA_TO_DEVICE);
+               if (dma_mapping_error(&hv_dev->device, dma)) {
+                       kfree(packet->dma_range);
+                       return -ENOMEM;
+               }
+
+               packet->dma_range[i].dma = dma;
+               packet->dma_range[i].mapping_size = len;
+               pb[i].pfn = dma >> HV_HYP_PAGE_SHIFT;
+               pb[i].offset = offset_in_hvpage(dma);
+               pb[i].len = len;
+       }
+
+       return 0;
+}
+
 static inline int netvsc_send_pkt(
        struct hv_device *device,
        struct hv_netvsc_packet *packet,
@@ -995,14 +1113,24 @@ static inline int netvsc_send_pkt(
 
        trace_nvsp_send_pkt(ndev, out_channel, rpkt);
 
+       packet->dma_range = NULL;
        if (packet->page_buf_cnt) {
                if (packet->cp_partial)
                        pb += packet->rmsg_pgcnt;
 
+               ret = netvsc_dma_map(ndev_ctx->device_ctx, packet, pb);
+               if (ret) {
+                       ret = -EAGAIN;
+                       goto exit; 
+               }
+
                ret = vmbus_sendpacket_pagebuffer(out_channel,
                                                  pb, packet->page_buf_cnt,
                                                  &nvmsg, sizeof(nvmsg),
                                                  req_id);
+
+               if (ret)
+                       netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
        } else {
                ret = vmbus_sendpacket(out_channel,
                                       &nvmsg, sizeof(nvmsg),
@@ -1010,6 +1138,7 @@ static inline int netvsc_send_pkt(
                                       
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        }
 
+exit:
        if (ret == 0) {
                atomic_inc_return(&nvchan->queue_sends);
 
diff --git a/drivers/net/hyperv/rndis_filter.c 
b/drivers/net/hyperv/rndis_filter.c
index f6c9c2a670f9..448fcc325ed7 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -361,6 +361,8 @@ static void rndis_filter_receive_response(struct net_device 
*ndev,
                        }
                }
 
+               netvsc_dma_unmap(((struct net_device_context *)
+                       netdev_priv(ndev))->device_ctx, &request->pkt);
                complete(&request->wait_event);
        } else {
                netdev_err(ndev,
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 724a735d722a..139a43ad65a1 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1596,6 +1596,11 @@ struct hyperv_service_callback {
        void (*callback)(void *context);
 };
 
+struct hv_dma_range {
+       dma_addr_t dma;
+       u32 mapping_size;
+};
+
 #define MAX_SRV_VER    0x7ffffff
 extern bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, u8 *buf, 
u32 buflen,
                                const int *fw_version, int fw_vercnt,
-- 
2.25.1