On 12/10/25 1:51 PM, Dmitry Osipenko wrote:
Hi,
On 12/10/25 18:39, Val Packett wrote:
This functionality was added for using a KMS-only virtgpu with a physical
(or SR-IOV) headless GPU in passthrough, but it should not be restricted
to KMS-only mode. It can be used with cross-domain to pass guest memfds
to the host compositor with zero copies (using udmabuf on both sides).
Drop the check for the absence of virgl_3d to allow for more use cases.
Fixes: ca77f27a2665 ("drm/virtio: Import prime buffers from other devices as guest
blobs")
Signed-off-by: Val Packett <[email protected]>
---
Hi. I couldn't find any comments on that line in the reviews (on patchwork), so
I assume
there was never a specific technical reason for that check, just an abundance
of caution?
BTW, while here.. The drm_gem_prime_import "fallback" seems pretty much
equivalent to
`return (-ENODEV)`, as drm_gem_prime_import(_dev) just translates the call to
gem_prime_import_sg_table which we don't use. Should it be replaced with
`return (-ENODEV)`?
Returning -ENODEV should break dmabuf self-importing where virtio-gpu
driver export dmabuf and then imports to itself.
Hm, I don't think so because the self-import case (for when `buf->ops ==
&virtgpu_dmabuf_ops`) is handled right here, right above this check.
drm_gem_prime_import would handle the self-import for `buf->ops ==
&drm_gem_prime_dmabuf_ops` which shouldn't be the case since we have
`virtgpu_dmabuf_ops`..
---
drivers/gpu/drm/virtio/virtgpu_prime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c
b/drivers/gpu/drm/virtio/virtgpu_prime.c
index ce49282198cb..2fedd5d3bd62 100644
--- a/drivers/gpu/drm/virtio/virtgpu_prime.c
+++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
@@ -312,7 +312,7 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct
drm_device *dev,
}
}
- if (!vgdev->has_resource_blob || vgdev->has_virgl_3d)
+ if (!vgdev->has_resource_blob)
return drm_gem_prime_import(dev, buf);
bo = kzalloc(sizeof(*bo), GFP_KERNEL);
At a quick glance the change looks fine. Will take another stab after
Holidays and merge if no problems will be spotted. Thanks.
Thanks!
~val
