Re: [PATCH V6 5/5] net: netvsc: Add Isolation VM support for netvsc driver

Tianyu Lan
2021-12-09T08:08:45Z

On 12/9/2021 4:14 AM, Haiyang Zhang wrote:
>> From: Tianyu Lan <ltykernel@gmail.com>
>> Sent: Tuesday, December 7, 2021 2:56 AM
>> To: KY Srinivasan <kys@microsoft.com>; Haiyang Zhang <haiyangz@microsoft.com>; Stephen
>> Hemminger <sthemmin@microsoft.com>; wei.liu@kernel.org; Dexuan Cui <decui@microsoft.com>;
>> tglx@linutronix.de; mingo@redhat.com; bp@alien8.de; dave.hansen@linux.intel.com;
>> x86@kernel.org; hpa@zytor.com; davem@davemloft.net; kuba@kernel.org; jejb@linux.ibm.com;
>> martin.petersen@oracle.com; arnd@arndb.de; hch@infradead.org; m.szyprowski@samsung.com;
>> robin.murphy@arm.com; Tianyu Lan <Tianyu.Lan@microsoft.com>; thomas.lendacky@amd.com;
>> Michael Kelley (LINUX) <mikelley@microsoft.com>
>> Cc: iommu@lists.linux-foundation.org; linux-arch@vger.kernel.org; linux-
>> hyperv@vger.kernel.org; linux-kernel@vger.kernel.org; linux-scsi@vger.kernel.org;
>> netdev@vger.kernel.org; vkuznets <vkuznets@redhat.com>; brijesh.singh@amd.com;
>> konrad.wilk@oracle.com; hch@lst.de; joro@8bytes.org; parri.andrea@gmail.com;
>> dave.hansen@intel.com
>> Subject: [PATCH V6 5/5] net: netvsc: Add Isolation VM support for netvsc driver
>>
>> From: Tianyu Lan <Tianyu.Lan@microsoft.com>
>>
>> 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 address will be returned. The swiotlb bounce buffer
>> has been masked to be visible to host during boot up.
>>
>> rx/tx ring buffer is allocated via vzalloc() and they need to be
>> mapped into unencrypted address space(above vTOM) before sharing
>> with host and accessing. Add hv_map/unmap_memory() to map/umap rx
>> /tx ring buffer.
>>
>> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
>> ---
>> Change since v3:
>> * Replace HV_HYP_PAGE_SIZE with PAGE_SIZE and virt_to_hvpfn()
>> with vmalloc_to_pfn() in the hv_map_memory()
>>
>> Change since v2:
>> * Add hv_map/unmap_memory() to map/umap rx/tx ring buffer.
>> ---
>> arch/x86/hyperv/ivm.c | 28 ++++++
>> drivers/hv/hv_common.c | 11 +++
>> drivers/net/hyperv/hyperv_net.h | 5 ++
>> drivers/net/hyperv/netvsc.c | 136 +++++++++++++++++++++++++++++-
>> drivers/net/hyperv/netvsc_drv.c | 1 +
>> drivers/net/hyperv/rndis_filter.c | 2 +
>> include/asm-generic/mshyperv.h | 2 +
>> include/linux/hyperv.h | 5 ++
>> 8 files changed, 187 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
>> index 69c7a57f3307..2b994117581e 100644
>> --- a/arch/x86/hyperv/ivm.c
>> +++ b/arch/x86/hyperv/ivm.c
>> @@ -287,3 +287,31 @@ int hv_set_mem_host_visibility(unsigned long kbuffer, int pagecount,
>> bool visibl
>> kfree(pfn_array);
>> return ret;
>> }
>> +
>> +/*
>> + * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
>> + */
>> +void *hv_map_memory(void *addr, unsigned long size)
>> +{
>> + unsigned long *pfns = kcalloc(size / PAGE_SIZE,
>> + sizeof(unsigned long), GFP_KERNEL);
>> + void *vaddr;
>> + int i;
>> +
>> + if (!pfns)
>> + return NULL;
>> +
>> + for (i = 0; i < size / PAGE_SIZE; i++)
>> + pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
>> + (ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
>> +
>> + vaddr = vmap_pfn(pfns, size / PAGE_SIZE, PAGE_KERNEL_IO);
>> + kfree(pfns);
>> +
>> + return vaddr;
>> +}
>> +
>> +void hv_unmap_memory(void *addr)
>> +{
>> + vunmap(addr);
>> +}
>> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
>> index 7be173a99f27..3c5cb1f70319 100644
>> --- a/drivers/hv/hv_common.c
>> +++ b/drivers/hv/hv_common.c
>> @@ -295,3 +295,14 @@ u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output,
>> u32 input_s
>> return HV_STATUS_INVALID_PARAMETER;
>> }
>> EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
>> +
>> +void __weak *hv_map_memory(void *addr, unsigned long size)
>> +{
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(hv_map_memory);
>> +
>> +void __weak hv_unmap_memory(void *addr)
>> +{
>> +}
>> +EXPORT_SYMBOL_GPL(hv_unmap_memory);
>> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
>> index 315278a7cf88..cf69da0e296c 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 */
>> struct vmbus_gpadl 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;
>> struct vmbus_gpadl 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 396bc1c204e6..b7ade735a806 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) {
>> + hv_unmap_memory(nvdev->recv_buf);
>> + vfree(nvdev->recv_original_buf);
>> + } else {
>> + vfree(nvdev->recv_buf);
>> + }
>> +
>> + if (nvdev->send_original_buf) {
>> + hv_unmap_memory(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++) {
>> @@ -338,6 +351,7 @@ 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;
>> @@ -373,6 +387,17 @@ 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));
>> @@ -476,6 +501,17 @@ 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));
>> @@ -766,7 +802,7 @@ 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;
>> @@ -782,6 +818,7 @@ 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);
>> }
>>
>> @@ -946,6 +983,88 @@ 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 because 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;
>> + }
>> +
>> + /* pb[].offset and pb[].len are not changed during dma mapping
>> + * and so not reassign.
>> + */
>> + packet->dma_range[i].dma = dma;
>> + packet->dma_range[i].mapping_size = len;
>> + pb[i].pfn = dma >> HV_HYP_PAGE_SHIFT;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static inline int netvsc_send_pkt(
>> struct hv_device *device,
>> struct hv_netvsc_packet *packet,
>> @@ -986,14 +1105,24 @@ 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;
>> + }
>
> Returning EAGAIN will let the upper network layer busy retry,
> which may make things worse.
> I suggest to return ENOSPC here like another place in this
> function, which will just drop the packet, and let the network
> protocol/app layer decide how to recover.
>

Yes, agree. Will update in the next version. Thanks.