virtgpu_virgl: use blobs NV12 encoder input

Use blob buffers for encoder NV12 input, even when software access is
required. This is helpful for ARCVM, since the v4l2_codec2 stack
sometimes needs to do a format conversion in the guest as the
virtio-video encoder only supports NV12/I420 input.

Supporting this requires knowing the host buffer layout before creating
the blob resource. This is done by creating a temporary resource to
query the layout. To avoid the overhead of querying the host every time
a buffer is created, the allocator process keeps a cache of the most
recently used buffer formats and their host layout.

Creating temporary resources to discover host buffer parameters is a bit
of a cludge. However, since virtgpu_virgl will eventually be deprecated
in favor of virtgpu_cross_domain, a self-contained and simple approach
like this gives some nice performance gains on low end devices.

TEST=decode-edit-encode workflows
TEST=Cts{NativeHardware,Camera,Graphics,Video}TestCases on volteer
BUG=b:203380807, b:232531771

Change-Id: Ibda500862b42680ba898ba689e1600ebe5d258bd
Auto-Submit: David Stevens <>
Reviewed-by: Lepton Wu <>
Reviewed-by: Yiwei Zhang <>
Commit-Queue: Yiwei Zhang <>
Tested-by: David Stevens <>
3 files changed