linux.git/include/uapi/drm/virtgpu_drm.h, branch v7.2-rc1

drm/virtio: add VIRTGPU_PARAM_BLOB_ALIGNMENT to params

2026-05-20T14:59:21+00:00

Add VIRTGPU_PARAM_BLOB_ALIGNMENT as a param that can be read with
VIRTGPU_GETPARAM by userspace applications running in the guest to
obtain the host's page size and find out the right alignment to be used
in shared memory allocations.

Signed-off-by: Sergio Lopez 
Signed-off-by: Dmitry Osipenko 
Link: https://patch.msgid.link/20260428194450.518296-4-slp@redhat.com

drm/virtio: Extend blob UAPI with deferred-mapping hinting

2026-05-13T21:57:34+00:00

If userspace never maps GEM object, then BO wastes hostmem space
because VirtIO-GPU driver maps VRAM BO at the BO's creating time.

Make mappings on-demand by adding new RESOURCE_CREATE_BLOB IOCTL/UAPI
hinting flag telling that host mapping should be deferred until first
mapping is made when the flag is set by userspace.

Signed-off-by: Dmitry Osipenko 
Reviewed-by: Rob Clark 
Link: https://patch.msgid.link/20260501000043.2483678-1-dmitry.osipenko@collabora.com

drm/virtio: Add capset definitions to UAPI

2025-03-28T01:53:51+00:00

Since the context-type additions to the virtio-gpu spec, these have been
defined locally in guest user-space, and virtio-gpu backend library code.

Now, these capsets have been stabilized, and should be defined in a
common space, in both the virtio_gpu header, and alongside the virtgpu_drm
interface that they apply to.

Reviewed-by: Gurchetan Singh 
Signed-off-by: Aaron Ruby 
Signed-off-by: Dmitry Osipenko 
[dmitry.osipenko@collabora.com: edit commit title]
Link: https://patchwork.freedesktop.org/patch/msgid/YT3PR01MB5857E808EDF6949F2DF517FDAFA12@YT3PR01MB5857.CANPRD01.PROD.OUTLOOK.COM

drm/uapi: add explicit virtgpu context debug name

2023-11-11T18:31:00+00:00

There are two problems with the current method of determining the
virtio-gpu debug name.

1) TASK_COMM_LEN is defined to be 16 bytes only, and this is a
   Linux kernel idiom (see PR_SET_NAME + PR_GET_NAME). Though,
   Android/FreeBSD get around this via setprogname(..)/getprogname(..)
   in libc.

   On Android, names longer than 16 bytes are common.  For example,
   one often encounters a program like "com.android.systemui".

   The virtio-gpu spec allows the debug name to be up to 64 bytes, so
   ideally userspace should be able to set debug names up to 64 bytes.

2) The current implementation determines the debug name using whatever
   task initiated virtgpu.  This is could be a "RenderThread" of a
   larger program, when we actually want to propagate the debug name
   of the program.

To fix these issues, add a new CONTEXT_INIT param that allows userspace
to set the debug name when creating a context.

It takes a null-terminated C-string as the param value. The length of the
string (excluding the terminator) **should** be <= 64 bytes.  Otherwise,
the debug_name will be truncated to 64 bytes.

Link to open-source userspace:
https://android-review.googlesource.com/c/platform/hardware/google/gfxstream/+/2787176

Signed-off-by: Gurchetan Singh 
Reviewed-by: Josh Simonot 
Reviewed-by: Dmitry Osipenko 
Signed-off-by: Dmitry Osipenko 
Link: https://patchwork.freedesktop.org/patch/msgid/20231018181727.772-2-gurchetansingh@chromium.org

drm/virtio: Support sync objects

2023-07-31T22:41:04+00:00

Add sync object DRM UAPI support to VirtIO-GPU driver. Sync objects
support is needed by native context VirtIO-GPU Mesa drivers, it also will
be used by Venus and Virgl contexts.

Reviewed-by; Emil Velikov 
Signed-off-by: Dmitry Osipenko 
Tested-by: Pierre-Eric Pelloux-Prayer  # amdgpu nctx
Tested-by: Rob Clark  # freedreno nctx
Reviewed-by: Rob Clark 
Acked-by: Gurchetan Singh 
Acked-by: Gerd Hoffmann 
Link: https://patchwork.freedesktop.org/patch/msgid/20230416115237.798604-4-dmitry.osipenko@collabora.com

drm/virtio: exbuf->fence_fd unmodified on interrupted wait

2023-02-06T17:10:56+00:00

An interrupted dma_fence_wait() becomes an -ERESTARTSYS returned
to userspace ioctl(DRM_IOCTL_VIRTGPU_EXECBUFFER) calls, prompting to
retry the ioctl(), but the passed exbuf->fence_fd has been reset to -1,
making the retry attempt fail at sync_file_get_fence().

The uapi for DRM_IOCTL_VIRTGPU_EXECBUFFER is changed to retain the
passed value for exbuf->fence_fd when returning anything besides a
successful result from the ioctl.

Fixes: 2cd7b6f08bc4 ("drm/virtio: add in/out fence support for explicit synchronization")
Signed-off-by: Ryan Neph 
Reviewed-by: Rob Clark 
Reviewed-by: Dmitry Osipenko 
Signed-off-by: Dmitry Osipenko 
Link: https://patchwork.freedesktop.org/patch/msgid/20230203233345.2477767-1-ryanneph@chromium.org

drm/virtgpu api: define a dummy fence signaled event

2021-11-29T10:46:32+00:00

The current virtgpu implementation of poll(..) drops events
when VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK is enabled (otherwise
it's like a normal DRM driver).

This is because paravirtualized userspaces receives responses in a
buffer of type BLOB_MEM_GUEST, not by read(..).

To be in line with other DRM drivers and avoid specialized behavior,
it is possible to define a dummy event for virtgpu.  Paravirtualized
userspace will now have to call read(..) on the DRM fd to receive the
dummy event.

Fixes: b10790434cf2 ("drm/virtgpu api: create context init feature")
Reported-by: Daniel Vetter 
Signed-off-by: Gurchetan Singh 
Reviewed-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/20211122232210.602-2-gurchetansingh@google.com
Signed-off-by: Gerd Hoffmann

drm/virtgpu api: create context init feature

2021-09-29T07:22:29+00:00

This change allows creating contexts of depending on set of
context parameters. The meaning of each of the parameters
is listed below:

1) VIRTGPU_CONTEXT_PARAM_CAPSET_ID

This determines the type of a context based on the capability set
ID. For example, the current capsets:

VIRTIO_GPU_CAPSET_VIRGL
VIRTIO_GPU_CAPSET_VIRGL2

define a Gallium, TGSI based "virgl" context. We only need 1 capset
ID per context type, though virgl has two due a bug that has since
been fixed.

The use case is the "gfxstream" rendering library and "venus"
renderer.

gfxstream doesn't do Gallium/TGSI translation and mostly relies on
auto-generated API streaming. Certain users prefer gfxstream over
virgl for GLES on GLES emulation. {gfxstream vk}/{venus} are also
required for Vulkan emulation. The maximum capset ID is 63.

The goal is for guest userspace to choose the optimal context type
depending on the situation/hardware.

2) VIRTGPU_CONTEXT_PARAM_NUM_RINGS

This tells the number of independent command rings that the context
will use. This value may be zero and is inferred to be zero if
VIRTGPU_CONTEXT_PARAM_NUM_RINGS is not passed in. This is for backwards
compatibility for virgl, which has one big giant command ring for all
commands.

The maxiumum number of rings is 64. In practice, multi-queue or
multi-ring submission is used for powerful dGPUs and virtio-gpu
may not be the best option in that case (see PCI passthrough or
rendernode forwarding).

3) VIRTGPU_CONTEXT_PARAM_POLL_RING_IDX_MASK

This is a mask of ring indices for which the DRM fd is pollable.
For example, if VIRTGPU_CONTEXT_PARAM_NUM_RINGS is 2, then the mask
may be:

[ring idx] | [1 << ring_idx] | final mask
-------------------------------------------
0 1 1
1 2 3

The "Sommelier" guest Wayland proxy uses this to poll for events
from the host compositor.

Signed-off-by: Gurchetan Singh
Acked-by: Lingfeng Yang
Acked-by: Nicholas Verne
Link: http://patchwork.freedesktop.org/patch/msgid/20210921232024.817-3-gurchetansingh@chromium.org
Signed-off-by: Gerd Hoffmann

drm/virtgpu api: cross-device feature

2020-09-29T09:23:18+00:00

This feature was recently added to virtio-gpu, lets make
it userspace queryable. It's an error to use
BLOB_FLAG_USE_CROSS_DEVICE when this feature is not present.

Signed-off-by: Gurchetan Singh 
Acked-by: Tomeu Vizoso 
Link: http://patchwork.freedesktop.org/patch/msgid/20200924003214.662-7-gurchetansingh@chromium.org
Signed-off-by: Gerd Hoffmann

drm/virtgpu api: host visible feature

2020-09-29T09:23:14+00:00

This exposes the host visible feature to userspace.  Without it,
it is an error to specify BLOB_MEM_HOST3D with
BLOG_FLAG_USE_MAPPABLE.

Signed-off-by: Gurchetan Singh 
Acked-by: Tomeu Vizoso 
Acked-by: Lingfeng Yang 
Link: http://patchwork.freedesktop.org/patch/msgid/20200924003214.662-6-gurchetansingh@chromium.org
Signed-off-by: Gerd Hoffmann