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

[Albert Esteve]

Hi!

It has been a month since I sent this patch, so I'll give it a bump to get some attention back.

@mst and @Fam any comments? What would be the next steps to take to move this forward?

BR,

Albert

On Wed, May 24, 2023 at 11:13 AM Albert Esteve <aesteve@redhat.com> 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

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

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2.40.0