[PATCH 1/2] drm/virtio: Create Dumb BOs as guest Blobs

[Gerd Hoffmann]

On Tue, Mar 30, 2021 at 08:04:38PM -0700, Vivek Kasireddy wrote:
> If support for Blob resources is available, then dumb BOs created
> by the driver can be considered as guest Blobs. And, for guest
> Blobs, there is no need to do any transfers or flushes

No.  VIRTGPU_BLOB_FLAG_USE_SHAREABLE means the host (aka device in
virtio terms) *can* create a shared mapping.  So, the guest sends still
needs to send transfer commands, and then the device can shortcut the
transfer commands on the host side in case a shared mapping exists.

flush commands are still needed for dirty tracking.

> but we do need to do set_scanout even if the FB has not changed as
> part of plane updates.

Sounds like you workaround host bugs.  This should not be needed with
properly implemented flush.

take care,
  Gerd