RE: [PATCH V2 5/6] net: netvsc: Add Isolation VM support for netvsc driver
> -Original Message- > From: Michael Kelley (LINUX) > Sent: Wednesday, November 24, 2021 12:03 PM > To: Tianyu Lan ; t...@linutronix.de; mi...@redhat.com; > b...@alien8.de; > dave.han...@linux.intel.com; x...@kernel.org; h...@zytor.com; l...@kernel.org; > pet...@infradead.org; jgr...@suse.com; sstabell...@kernel.org; > boris.ostrov...@oracle.com; > KY Srinivasan ; Haiyang Zhang ; > Stephen > Hemminger ; wei@kernel.org; Dexuan Cui > ; > j...@8bytes.org; w...@kernel.org; da...@davemloft.net; k...@kernel.org; > j...@linux.ibm.com; > martin.peter...@oracle.com; h...@lst.de; m.szyprow...@samsung.com; > robin.mur...@arm.com; > Tianyu Lan ; thomas.lenda...@amd.com; xen- > de...@lists.xenproject.org > Cc: iommu@lists.linux-foundation.org; linux-hyp...@vger.kernel.org; linux- > ker...@vger.kernel.org; linux-s...@vger.kernel.org; net...@vger.kernel.org; > vkuznets > ; brijesh.si...@amd.com; konrad.w...@oracle.com; > parri.and...@gmail.com; dave.han...@intel.com > Subject: RE: [PATCH V2 5/6] net: netvsc: Add Isolation VM support for netvsc > driver > > From: Tianyu Lan Sent: Tuesday, November 23, 2021 6:31 > AM > > > > 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. > > > > Allocate rx/tx ring buffer via dma_alloc_noncontiguous() in Isolation > > VM. After calling vmbus_establish_gpadl() which marks these pages > > visible to host, map these pages unencrypted addes space via > > dma_vmap_noncontiguous(). > > > > The big unresolved topic is how best to do the allocation and mapping of the > big netvsc > send and receive buffers. Let me summarize and make a recommendation. > > Background > == > 1. Each Hyper-V synthetic network device requires a large pre-allocated > receive > buffer (defaults to 16 Mbytes) and a similar send buffer (defaults to 1 > Mbyte). > 2. The buffers are allocated in guest memory and shared with the Hyper-V > host. > As such, in the Hyper-V SNP environment, the memory must be unencrypted > and accessed in the Hyper-V guest with shared_gpa_boundary (i.e., VTOM) > added to the physical memory address. > 3. The buffers need *not* be contiguous in guest physical memory, but must be > contiguously mapped in guest kernel virtual space. > 4. Network devices may come and go during the life of the VM, so allocation > of > these buffers and their mappings may be done after Linux has been > running for > a long time. > 5. Performance of the allocation and mapping process is not an issue since > it is > done only on synthetic network device add/remove. > 6. So the primary goals are an appropriate logical abstraction, code that is > simple and straightforward, and efficient memory usage. > > Approaches > == > During the development of these patches, four approaches have been > implemented: > > 1. Two virtual mappings: One from vmalloc() to allocate the guest memory, > and > the second from vmap_pfns() after adding the shared_gpa_boundary. This > is > implemented in Hyper-V or netvsc specific code, with no use of DMA APIs. > No separate list of physical pages is maintained, so for creating the > second > mapping, the PFN list is assembled temporarily by doing virt-to-phys() > page-by-page on the vmalloc mapping, and then discarded because it is no > longer needed. [v4 of the original patch series.] > > 2. Two virtual mappings as in (1) above, but implemented via new DMA calls > dma_map_decrypted() and dma_unmap_encrypted(). [v3 of the original > patch series.] > > 3. Two virtual mappings as in (1) above, but implemented via DMA > noncontiguous > allocation and mapping calls, as enhanced to allow for custom map/unmap > implementations. A list of physical pages is maintained in the > dma_sgt_handle > as expected by the DMA noncontiguous API. [New split-off patch series > v1 & v2] > > 4. Single virtual mapping from vmap_pfns(). The netvsc driver allocates > physical > memory via alloc_pages() with as much contiguity as possible, and > maintains a > list of physical pages and ranges. Single virtual map is setup with > vmap_pfns() &g
RE: [PATCH V2 5/6] net: netvsc: Add Isolation VM support for netvsc driver
From: Tianyu Lan Sent: Tuesday, November 23, 2021 6:31 AM > > 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. > > Allocate rx/tx ring buffer via dma_alloc_noncontiguous() in Isolation > VM. After calling vmbus_establish_gpadl() which marks these pages visible > to host, map these pages unencrypted addes space via dma_vmap_noncontiguous(). > The big unresolved topic is how best to do the allocation and mapping of the big netvsc send and receive buffers. Let me summarize and make a recommendation. Background == 1. Each Hyper-V synthetic network device requires a large pre-allocated receive buffer (defaults to 16 Mbytes) and a similar send buffer (defaults to 1 Mbyte). 2. The buffers are allocated in guest memory and shared with the Hyper-V host. As such, in the Hyper-V SNP environment, the memory must be unencrypted and accessed in the Hyper-V guest with shared_gpa_boundary (i.e., VTOM) added to the physical memory address. 3. The buffers need *not* be contiguous in guest physical memory, but must be contiguously mapped in guest kernel virtual space. 4. Network devices may come and go during the life of the VM, so allocation of these buffers and their mappings may be done after Linux has been running for a long time. 5. Performance of the allocation and mapping process is not an issue since it is done only on synthetic network device add/remove. 6. So the primary goals are an appropriate logical abstraction, code that is simple and straightforward, and efficient memory usage. Approaches == During the development of these patches, four approaches have been implemented: 1. Two virtual mappings: One from vmalloc() to allocate the guest memory, and the second from vmap_pfns() after adding the shared_gpa_boundary. This is implemented in Hyper-V or netvsc specific code, with no use of DMA APIs. No separate list of physical pages is maintained, so for creating the second mapping, the PFN list is assembled temporarily by doing virt-to-phys() page-by-page on the vmalloc mapping, and then discarded because it is no longer needed. [v4 of the original patch series.] 2. Two virtual mappings as in (1) above, but implemented via new DMA calls dma_map_decrypted() and dma_unmap_encrypted(). [v3 of the original patch series.] 3. Two virtual mappings as in (1) above, but implemented via DMA noncontiguous allocation and mapping calls, as enhanced to allow for custom map/unmap implementations. A list of physical pages is maintained in the dma_sgt_handle as expected by the DMA noncontiguous API. [New split-off patch series v1 & v2] 4. Single virtual mapping from vmap_pfns(). The netvsc driver allocates physical memory via alloc_pages() with as much contiguity as possible, and maintains a list of physical pages and ranges. Single virtual map is setup with vmap_pfns() after adding shared_gpa_boundary. [v5 of the original patch series.] Both implementations using DMA APIs use very little of the existing DMA machinery. Both require extensions to the DMA APIs, and custom ops functions. While in some sense the netvsc send and receive buffers involve DMA, they do not require any DMA actions on a per-I/O basis. It seems better to me to not try to fit these two buffers into the DMA model as a one-off. Let's just use Hyper-V specific code to allocate and map them, as is done with the Hyper-V VMbus channel ring buffers. That leaves approaches (1) and (4) above. Between those two, (1) is simpler even though there are two virtual mappings. Using alloc_pages() as in (4) is messy and there's no real benefit to using higher order allocations. (4) also requires maintaining a separate list of PFNs and ranges, which offsets some of the benefits to having only one virtual mapping active at any point in time. I don't think there's a clear "right" answer, so it's a judgment call. We've explored what other approaches would look like, and I'd say let's go with (1) as the simpler approach. Thoughts? Michael ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
RE: [PATCH V2 5/6] net: netvsc: Add Isolation VM support for netvsc driver
From: Tianyu Lan Sent: Tuesday, November 23, 2021 6:31 AM
>
> 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.
>
> Allocate rx/tx ring buffer via dma_alloc_noncontiguous() in Isolation
> VM. After calling vmbus_establish_gpadl() which marks these pages visible
> to host, map these pages unencrypted addes space via dma_vmap_noncontiguous().
>
> Signed-off-by: Tianyu Lan
> ---
> drivers/net/hyperv/hyperv_net.h | 5 +
> drivers/net/hyperv/netvsc.c | 192 +++---
> drivers/net/hyperv/rndis_filter.c | 2 +
> include/linux/hyperv.h| 6 +
> 4 files changed, 190 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index 315278a7cf88..31c77a00d01e 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;
> + struct sg_table *recv_sgt;
> 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;
> + struct sg_table *send_sgt;
> 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 1
> #define RETRY_MAX2000/* >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..9cdc71930830 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -20,6 +20,7 @@
> #include
> #include
> #include
> +#include
>
> #include
> #include
> @@ -146,15 +147,39 @@ static struct netvsc_device *alloc_net_device(void)
> return net_device;
> }
>
> +static struct hv_device *netvsc_channel_to_device(struct vmbus_channel
> *channel)
> +{
> + struct vmbus_channel *primary = channel->primary_channel;
> +
> + return primary ? primary->device_obj : channel->device_obj;
> +}
> +
> static void free_netvsc_device(struct rcu_head *head)
> {
> struct netvsc_device *nvdev
> = container_of(head, struct netvsc_device, rcu);
> + struct hv_device *dev =
> + netvsc_channel_to_device(nvdev->chan_table[0].channel);
> int i;
>
> kfree(nvdev->extension);
> - vfree(nvdev->recv_buf);
> - vfree(nvdev->send_buf);
> +
> + if (nvdev->recv_sgt) {
> + dma_vunmap_noncontiguous(>device, nvdev->recv_buf);
> + dma_free_noncontiguous(>device, nvdev->recv_buf_size,
> +nvdev->recv_sgt, DMA_FROM_DEVICE);
> + } else {
> + vfree(nvdev->recv_buf);
> + }
> +
> + if (nvdev->send_sgt) {
> + dma_vunmap_noncontiguous(>device, nvdev->send_buf);
> + dma_free_noncontiguous(>device, nvdev->send_buf_size,
> +nvdev->send_sgt, DMA_TO_DEVICE);
> + } else {
> + vfree(nvdev->send_buf);
> + }
> +
> kfree(nvdev->send_section_map);
>
> for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
> @@ -348,7 +373,21 @@ static int netvsc_init_buf(struct hv_device *device,
> buf_size = min_t(unsigned int, buf_size,
>NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
>
> - net_device->recv_buf = vzalloc(buf_size);
> + if (hv_isolation_type_snp()) {
> + net_device->recv_sgt =
> + dma_alloc_noncontiguous(>device, buf_size,
> + DMA_FROM_DEVICE, GFP_KERNEL, 0);
> + if (!net_device->recv_sgt) {
> + pr_err("Fail to allocate recv buffer buf_size %d.\n.",
> buf_size);
> + ret = -ENOMEM;
> + goto cleanup;
> + }
> +
> + net_device->recv_buf = (void
> *)net_device->recv_sgt->sgl->dma_address;
Use sg_dma_address() macro.
> + } else {
> + net_device->recv_buf = vzalloc(buf_size);
> + }
> +
> if
[PATCH V2 5/6] net: netvsc: Add Isolation VM support for netvsc driver
From: Tianyu Lan
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.
Allocate rx/tx ring buffer via dma_alloc_noncontiguous() in Isolation
VM. After calling vmbus_establish_gpadl() which marks these pages visible
to host, map these pages unencrypted addes space via dma_vmap_noncontiguous().
Signed-off-by: Tianyu Lan
---
drivers/net/hyperv/hyperv_net.h | 5 +
drivers/net/hyperv/netvsc.c | 192 +++---
drivers/net/hyperv/rndis_filter.c | 2 +
include/linux/hyperv.h| 6 +
4 files changed, 190 insertions(+), 15 deletions(-)
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 315278a7cf88..31c77a00d01e 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;
+ struct sg_table *recv_sgt;
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;
+ struct sg_table *send_sgt;
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_HI1
#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..9cdc71930830 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -20,6 +20,7 @@
#include
#include
#include
+#include
#include
#include
@@ -146,15 +147,39 @@ static struct netvsc_device *alloc_net_device(void)
return net_device;
}
+static struct hv_device *netvsc_channel_to_device(struct vmbus_channel
*channel)
+{
+ struct vmbus_channel *primary = channel->primary_channel;
+
+ return primary ? primary->device_obj : channel->device_obj;
+}
+
static void free_netvsc_device(struct rcu_head *head)
{
struct netvsc_device *nvdev
= container_of(head, struct netvsc_device, rcu);
+ struct hv_device *dev =
+ netvsc_channel_to_device(nvdev->chan_table[0].channel);
int i;
kfree(nvdev->extension);
- vfree(nvdev->recv_buf);
- vfree(nvdev->send_buf);
+
+ if (nvdev->recv_sgt) {
+ dma_vunmap_noncontiguous(>device, nvdev->recv_buf);
+ dma_free_noncontiguous(>device, nvdev->recv_buf_size,
+ nvdev->recv_sgt, DMA_FROM_DEVICE);
+ } else {
+ vfree(nvdev->recv_buf);
+ }
+
+ if (nvdev->send_sgt) {
+ dma_vunmap_noncontiguous(>device, nvdev->send_buf);
+ dma_free_noncontiguous(>device, nvdev->send_buf_size,
+ nvdev->send_sgt, DMA_TO_DEVICE);
+ } else {
+ vfree(nvdev->send_buf);
+ }
+
kfree(nvdev->send_section_map);
for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
@@ -348,7 +373,21 @@ static int netvsc_init_buf(struct hv_device *device,
buf_size = min_t(unsigned int, buf_size,
NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
- net_device->recv_buf = vzalloc(buf_size);
+ if (hv_isolation_type_snp()) {
+ net_device->recv_sgt =
+ dma_alloc_noncontiguous(>device, buf_size,
+ DMA_FROM_DEVICE, GFP_KERNEL, 0);
+ if (!net_device->recv_sgt) {
+ pr_err("Fail to allocate recv buffer buf_size %d.\n.",
buf_size);
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+
+ net_device->recv_buf = (void
*)net_device->recv_sgt->sgl->dma_address;
+ } else {
+ net_device->recv_buf = vzalloc(buf_size);
+ }
+
if (!net_device->recv_buf) {
netdev_err(ndev,
"unable to allocate receive buffer of size %u\n",
@@ -357,8 +396,6 @@ static int netvsc_init_buf(struct hv_device *device,
