On Thu, Sep 12, 2024 at 04:53:33PM +0200, Albert Esteve wrote:
> The frontend can use this command to retrieve
> VIRTIO Shared Memory Regions configuration from
> the backend. The response contains the number of
> shared memory regions, their size, and shmid.
>
> This is useful when the frontend is unaware of
> specific backend type and configuration,
> for example, in the `vhost-user-device` case.
>
> Signed-off-by: Albert Esteve <aest...@redhat.com>
> ---
> hw/virtio/vhost-user.c | 45 +++++++++++++++++++++++++++++++
> include/hw/virtio/vhost-backend.h | 6 +++++
> include/hw/virtio/vhost-user.h | 1 +
> 3 files changed, 52 insertions(+)
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index de0bb35257..83f5c02bea 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -57,6 +57,8 @@
> */
> #define VHOST_USER_MAX_CONFIG_SIZE 256
>
> +#define VHOST_USER_MAX_SHMEM_REGIONS 256
> +
> #define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) -
> 1)
>
> typedef enum VhostUserRequest {
> @@ -104,6 +106,7 @@ typedef enum VhostUserRequest {
> VHOST_USER_GET_SHARED_OBJECT = 41,
> VHOST_USER_SET_DEVICE_STATE_FD = 42,
> VHOST_USER_CHECK_DEVICE_STATE = 43,
> + VHOST_USER_GET_SHMEM_CONFIG = 44,
> VHOST_USER_MAX
> } VhostUserRequest;
>
> @@ -138,6 +141,12 @@ typedef struct VhostUserMemRegMsg {
> VhostUserMemoryRegion region;
> } VhostUserMemRegMsg;
>
> +typedef struct VhostUserShMemConfig {
> + uint32_t nregions;
> + uint32_t padding;
> + uint64_t memory_sizes[VHOST_MEMORY_BASELINE_NREGIONS];
> +} VhostUserShMemConfig;
> +
> typedef struct VhostUserLog {
> uint64_t mmap_size;
> uint64_t mmap_offset;
> @@ -245,6 +254,7 @@ typedef union {
> VhostUserShared object;
> VhostUserTransferDeviceState transfer_state;
> VhostUserMMap mmap;
> + VhostUserShMemConfig shmem;
> } VhostUserPayload;
>
> typedef struct VhostUserMsg {
> @@ -3134,6 +3144,40 @@ static int vhost_user_check_device_state(struct
> vhost_dev *dev, Error **errp)
> return 0;
> }
>
> +static int vhost_user_get_shmem_config(struct vhost_dev *dev,
> + int *nregions,
> + uint64_t *memory_sizes,
> + Error **errp)
> +{
> + int ret;
> + VhostUserMsg msg = {
> + .hdr.request = VHOST_USER_GET_SHMEM_CONFIG,
> + .hdr.flags = VHOST_USER_VERSION,
> + };
> +
> + if (!virtio_has_feature(dev->protocol_features,
> + VHOST_USER_PROTOCOL_F_SHMEM)) {
> + return 0;
> + }
> +
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + assert(msg.payload.shmem.nregions <= VHOST_USER_MAX_SHMEM_REGIONS);
> + *nregions = msg.payload.shmem.nregions;
> + memcpy(memory_sizes,
> + &msg.payload.shmem.memory_sizes,
> + sizeof(uint64_t) * VHOST_MEMORY_BASELINE_NREGIONS);
> + return 0;
> +}
> +
> const VhostOps user_ops = {
> .backend_type = VHOST_BACKEND_TYPE_USER,
> .vhost_backend_init = vhost_user_backend_init,
> @@ -3172,4 +3216,5 @@ const VhostOps user_ops = {
> .vhost_supports_device_state = vhost_user_supports_device_state,
> .vhost_set_device_state_fd = vhost_user_set_device_state_fd,
> .vhost_check_device_state = vhost_user_check_device_state,
> + .vhost_get_shmem_config = vhost_user_get_shmem_config,
> };
> diff --git a/include/hw/virtio/vhost-backend.h
> b/include/hw/virtio/vhost-backend.h
> index 70c2e8ffee..f9c2955420 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -159,6 +159,11 @@ typedef int (*vhost_set_device_state_fd_op)(struct
> vhost_dev *dev,
> int *reply_fd,
> Error **errp);
> typedef int (*vhost_check_device_state_op)(struct vhost_dev *dev, Error
> **errp);
> +typedef int (*vhost_get_shmem_config_op)(struct vhost_dev *dev,
> + int *nregions,
> + uint64_t *memory_sizes,
VHOST_USER_MAX_SHMEM_REGIONS is defined inside vhost-user.c and not
visible here. However, vhost_get_shmem_config_op() assumes the caller
knows the maximum number of memory_sizes[] array elements.
I think a constant should be declared in the VIRTIO header files and a
doc comment is needed here stating that memory_sizes[] must be at least
VIRTIO_MAX_SHMEM_REGIONS.
> + Error **errp);
> +
>
> typedef struct VhostOps {
> VhostBackendType backend_type;
> @@ -214,6 +219,7 @@ typedef struct VhostOps {
> vhost_supports_device_state_op vhost_supports_device_state;
> vhost_set_device_state_fd_op vhost_set_device_state_fd;
> vhost_check_device_state_op vhost_check_device_state;
> + vhost_get_shmem_config_op vhost_get_shmem_config;
> } VhostOps;
>
> int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
> diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
> index 324cd8663a..d4bb2c3958 100644
> --- a/include/hw/virtio/vhost-user.h
> +++ b/include/hw/virtio/vhost-user.h
> @@ -32,6 +32,7 @@ enum VhostUserProtocolFeature {
> /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
> VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
> VHOST_USER_PROTOCOL_F_DEVICE_STATE = 19,
> + VHOST_USER_PROTOCOL_F_SHMEM = 20,
> VHOST_USER_PROTOCOL_F_MAX
> };
>
> --
> 2.45.2
>
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