Re: [PATCH v3 0/4] Virtio shared dma-buf

[Michael S. Tsirkin]

On Wed, May 24, 2023 at 11:13:29AM +0200, Albert Esteve wrote:
> v1 link -> https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg00598.html
> v2 link -> https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg04530.html
> v2 -> v3:
>     - Change UUID hash function strategy to djb
>     - Add qemu_uuid_is_equal wrapper

Posted some minor comments. Pls address and I'll merge.


> This patch covers the required steps to add support for virtio cross-device 
> resource sharing[1],
> which support is already available in the kernel.
> 
> The main usecase will be sharing dma buffers from virtio-gpu devices (as the 
> exporter
> -see VIRTIO_GPU_CMD_RESOURCE_ASSIGN_UUID in [2]), to virtio-video (under 
> discussion)
> devices (as the buffer-user or importer). Therefore, even though virtio specs 
> talk about
> resources or objects[3], this patch adds the infrastructure with dma-bufs in 
> mind.
> Note that virtio specs let the devices themselves define what a vitio object 
> is.
> 
> These are the main parts that are covered in the patch:
> 
> - Add hash_func and key_equal_func to uuid
> - Shared resources table, to hold all resources that can be shared in the 
> host and their assigned UUID
> - Internal shared table API for virtio devices to add, lookup and remove 
> resources
> - Unit test to verify the API.
> - New message to the vhost-user protocol to allow backend to interact with 
> the shared
>   table API through the control socket
> 
> Applies cleanly to 1c12355
> 
> [1] - https://lwn.net/Articles/828988/
> [2] - 
> https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html#x1-3730006
> [3] - 
> https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html#x1-10500011
> 
> Albert Esteve (4):
>   uuid: add hash_func and equal_func
>   virtio-dmabuf: introduce virtio-dmabuf
>   vhost-user: add shared_object msg
>   vhost-user: refactor send_resp code
> 
>  MAINTAINERS                               |   7 ++
>  docs/interop/vhost-user.rst               |  15 +++
>  hw/display/meson.build                    |   1 +
>  hw/display/virtio-dmabuf.c                |  90 +++++++++++++++++
>  hw/virtio/vhost-user.c                    |  90 ++++++++++++++---
>  include/hw/virtio/virtio-dmabuf.h         |  59 ++++++++++++
>  include/qemu/uuid.h                       |   2 +
>  subprojects/libvhost-user/libvhost-user.c |  88 +++++++++++++++++
>  subprojects/libvhost-user/libvhost-user.h |  56 +++++++++++
>  tests/unit/meson.build                    |   1 +
>  tests/unit/test-uuid.c                    |  27 ++++++
>  tests/unit/test-virtio-dmabuf.c           | 112 ++++++++++++++++++++++
>  util/uuid.c                               |  14 +++
>  13 files changed, 549 insertions(+), 13 deletions(-)
>  create mode 100644 hw/display/virtio-dmabuf.c
>  create mode 100644 include/hw/virtio/virtio-dmabuf.h
>  create mode 100644 tests/unit/test-virtio-dmabuf.c
> 
> -- 
> 2.40.0