Re: [PATCH v4 4/6] vdpa: Add asid parameter to vhost_vdpa_dma_map/unmap

[Jason Wang]

On Sat, Aug 6, 2022 at 12:39 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> So the caller can choose which ASID is destined.
>
> No need to update the batch functions as they will always be called from
> memory listener updates at the moment. Memory listener updates will
> always update ASID 0, as it's the passthrough ASID.
>
> All vhost devices's ASID are 0 at this moment.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
> v4: Add comment specifying behavior if device does not support _F_ASID
>
> v3: Deleted unneeded space
> ---
>  include/hw/virtio/vhost-vdpa.h |  8 +++++---
>  hw/virtio/vhost-vdpa.c         | 25 +++++++++++++++----------
>  net/vhost-vdpa.c               |  6 +++---
>  hw/virtio/trace-events         |  4 ++--
>  4 files changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> index 1111d85643..6560bb9d78 100644
> --- a/include/hw/virtio/vhost-vdpa.h
> +++ b/include/hw/virtio/vhost-vdpa.h
> @@ -29,6 +29,7 @@ typedef struct vhost_vdpa {
>      int index;
>      uint32_t msg_type;
>      bool iotlb_batch_begin_sent;
> +    uint32_t address_space_id;
>      MemoryListener listener;
>      struct vhost_vdpa_iova_range iova_range;
>      uint64_t acked_features;
> @@ -42,8 +43,9 @@ typedef struct vhost_vdpa {
>      VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
>  } VhostVDPA;
>
> -int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr iova, hwaddr size,
> -                       void *vaddr, bool readonly);
> -int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova, hwaddr size);
> +int vhost_vdpa_dma_map(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> +                       hwaddr size, void *vaddr, bool readonly);
> +int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> +                         hwaddr size);
>
>  #endif
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 34922ec20d..3eb67b27b7 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -72,22 +72,24 @@ static bool 
> vhost_vdpa_listener_skipped_section(MemoryRegionSection *section,
>      return false;
>  }
>
> -int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr iova, hwaddr size,
> -                       void *vaddr, bool readonly)
> +int vhost_vdpa_dma_map(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> +                       hwaddr size, void *vaddr, bool readonly)
>  {
>      struct vhost_msg_v2 msg = {};
>      int fd = v->device_fd;
>      int ret = 0;
>
>      msg.type = v->msg_type;
> +    msg.asid = asid; /* 0 if vdpa device does not support asid */

So this comment is still kind of confusing.

Does it mean the caller can guarantee that asid is 0 when ASID is not
supported? Even if this is true, does it silently depend on the
behaviour that the asid field is extended from the reserved field of
the ABI?

(I still wonder if it's better to avoid using msg.asid if the kernel
doesn't support that).

Thanks

>      msg.iotlb.iova = iova;
>      msg.iotlb.size = size;
>      msg.iotlb.uaddr = (uint64_t)(uintptr_t)vaddr;
>      msg.iotlb.perm = readonly ? VHOST_ACCESS_RO : VHOST_ACCESS_RW;
>      msg.iotlb.type = VHOST_IOTLB_UPDATE;
>
> -   trace_vhost_vdpa_dma_map(v, fd, msg.type, msg.iotlb.iova, msg.iotlb.size,
> -                            msg.iotlb.uaddr, msg.iotlb.perm, msg.iotlb.type);
> +    trace_vhost_vdpa_dma_map(v, fd, msg.type, msg.asid, msg.iotlb.iova,
> +                             msg.iotlb.size, msg.iotlb.uaddr, msg.iotlb.perm,
> +                             msg.iotlb.type);
>
>      if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) {
>          error_report("failed to write, fd=%d, errno=%d (%s)",
> @@ -98,18 +100,20 @@ int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr 
> iova, hwaddr size,
>      return ret;
>  }
>
> -int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova, hwaddr size)
> +int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> +                         hwaddr size)
>  {
>      struct vhost_msg_v2 msg = {};
>      int fd = v->device_fd;
>      int ret = 0;
>
>      msg.type = v->msg_type;
> +    msg.asid = asid; /* 0 if vdpa device does not support asid */
>      msg.iotlb.iova = iova;
>      msg.iotlb.size = size;
>      msg.iotlb.type = VHOST_IOTLB_INVALIDATE;
>
> -    trace_vhost_vdpa_dma_unmap(v, fd, msg.type, msg.iotlb.iova,
> +    trace_vhost_vdpa_dma_unmap(v, fd, msg.type, msg.asid, msg.iotlb.iova,
>                                 msg.iotlb.size, msg.iotlb.type);
>
>      if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) {
> @@ -229,7 +233,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener 
> *listener,
>      }
>
>      vhost_vdpa_iotlb_batch_begin_once(v);
> -    ret = vhost_vdpa_dma_map(v, iova, int128_get64(llsize),
> +    ret = vhost_vdpa_dma_map(v, 0, iova, int128_get64(llsize),
>                               vaddr, section->readonly);
>      if (ret) {
>          error_report("vhost vdpa map fail!");
> @@ -303,7 +307,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener 
> *listener,
>          vhost_iova_tree_remove(v->iova_tree, result);
>      }
>      vhost_vdpa_iotlb_batch_begin_once(v);
> -    ret = vhost_vdpa_dma_unmap(v, iova, int128_get64(llsize));
> +    ret = vhost_vdpa_dma_unmap(v, 0, iova, int128_get64(llsize));
>      if (ret) {
>          error_report("vhost_vdpa dma unmap error!");
>      }
> @@ -894,7 +898,7 @@ static bool vhost_vdpa_svq_unmap_ring(struct vhost_vdpa 
> *v,
>      }
>
>      size = ROUND_UP(result->size, qemu_real_host_page_size());
> -    r = vhost_vdpa_dma_unmap(v, result->iova, size);
> +    r = vhost_vdpa_dma_unmap(v, v->address_space_id, result->iova, size);
>      return r == 0;
>  }
>
> @@ -936,7 +940,8 @@ static bool vhost_vdpa_svq_map_ring(struct vhost_vdpa *v, 
> DMAMap *needle,
>          return false;
>      }
>
> -    r = vhost_vdpa_dma_map(v, needle->iova, needle->size + 1,
> +    r = vhost_vdpa_dma_map(v, v->address_space_id, needle->iova,
> +                           needle->size + 1,
>                             (void *)(uintptr_t)needle->translated_addr,
>                             needle->perm == IOMMU_RO);
>      if (unlikely(r != 0)) {
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 7c0d600aea..9b932442f0 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -239,7 +239,7 @@ static void vhost_vdpa_cvq_unmap_buf(struct vhost_vdpa 
> *v, void *addr)
>          return;
>      }
>
> -    r = vhost_vdpa_dma_unmap(v, map->iova, map->size + 1);
> +    r = vhost_vdpa_dma_unmap(v, v->address_space_id, map->iova, map->size + 
> 1);
>      if (unlikely(r != 0)) {
>          error_report("Device cannot unmap: %s(%d)", g_strerror(r), r);
>      }
> @@ -279,8 +279,8 @@ static int vhost_vdpa_cvq_map_buf(struct vhost_vdpa *v, 
> void *buf, size_t size,
>          return r;
>      }
>
> -    r = vhost_vdpa_dma_map(v, map.iova, vhost_vdpa_net_cvq_cmd_page_len(), 
> buf,
> -                           !write);
> +    r = vhost_vdpa_dma_map(v, v->address_space_id, map.iova,
> +                           vhost_vdpa_net_cvq_cmd_page_len(), buf, !write);
>      if (unlikely(r < 0)) {
>          goto dma_map_err;
>      }
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 20af2e7ebd..36e5ae75f6 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -26,8 +26,8 @@ vhost_user_write(uint32_t req, uint32_t flags) "req:%d 
> flags:0x%"PRIx32""
>  vhost_user_create_notifier(int idx, void *n) "idx:%d n:%p"
>
>  # vhost-vdpa.c
> -vhost_vdpa_dma_map(void *vdpa, int fd, uint32_t msg_type, uint64_t iova, 
> uint64_t size, uint64_t uaddr, uint8_t perm, uint8_t type) "vdpa:%p fd: %d 
> msg_type: %"PRIu32" iova: 0x%"PRIx64" size: 0x%"PRIx64" uaddr: 0x%"PRIx64" 
> perm: 0x%"PRIx8" type: %"PRIu8
> -vhost_vdpa_dma_unmap(void *vdpa, int fd, uint32_t msg_type, uint64_t iova, 
> uint64_t size, uint8_t type) "vdpa:%p fd: %d msg_type: %"PRIu32" iova: 
> 0x%"PRIx64" size: 0x%"PRIx64" type: %"PRIu8
> +vhost_vdpa_dma_map(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
> uint64_t iova, uint64_t size, uint64_t uaddr, uint8_t perm, uint8_t type) 
> "vdpa:%p fd: %d msg_type: %"PRIu32" asid: %"PRIu32" iova: 0x%"PRIx64" size: 
> 0x%"PRIx64" uaddr: 0x%"PRIx64" perm: 0x%"PRIx8" type: %"PRIu8
> +vhost_vdpa_dma_unmap(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
> uint64_t iova, uint64_t size, uint8_t type) "vdpa:%p fd: %d msg_type: 
> %"PRIu32" asid: %"PRIu32" iova: 0x%"PRIx64" size: 0x%"PRIx64" type: %"PRIu8
>  vhost_vdpa_listener_begin_batch(void *v, int fd, uint32_t msg_type, uint8_t 
> type)  "vdpa:%p fd: %d msg_type: %"PRIu32" type: %"PRIu8
>  vhost_vdpa_listener_commit(void *v, int fd, uint32_t msg_type, uint8_t type) 
>  "vdpa:%p fd: %d msg_type: %"PRIu32" type: %"PRIu8
>  vhost_vdpa_listener_region_add(void *vdpa, uint64_t iova, uint64_t llend, 
> void *vaddr, bool readonly) "vdpa: %p iova 0x%"PRIx64" llend 0x%"PRIx64" 
> vaddr: %p read-only: %d"
> --
> 2.31.1
>