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virtio-devices: fix vhost-user GPU feature negotiation

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The GPU frontend only offered transport-level features
(DEFAULT_VIRTIO_FEATURES) during vhost-user negotiation, causing all
GPU device feature bits (VIRGL, EDID, RESOURCE_BLOB, etc.) to be
zeroed out when intersected with the backend's features. The guest
driver never saw any GPU capabilities.

Add the virtio-gpu feature bit constants and include them in
avail_features, matching the pattern used by the blk and net frontends.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Davíð Steinn Geirsson 2026-03-21 18:26:18 +00:00
parent 7e071e5c68
commit 04311414b6
1 changed files with 17 additions and 1 deletions
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18
virtio-devices/src/vhost_user/gpu.rs
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@ -34,6 +34,15 @@ use crate::{
const DEFAULT_QUEUE_NUMBER: usize = 2;
const DEFAULT_QUEUE_SIZE: u16 = 256;
// Virtio GPU feature bits (virtio spec 5.7.4)
const VIRTIO_GPU_F_VIRGL: u32 = 0;
const VIRTIO_GPU_F_EDID: u32 = 1;
const VIRTIO_GPU_F_RESOURCE_UUID: u32 = 2;
const VIRTIO_GPU_F_RESOURCE_BLOB: u32 = 3;
const VIRTIO_GPU_F_CONTEXT_INIT: u32 = 4;
const VIRTIO_GPU_F_FENCE_PASSING: u32 = 5;
const VIRTIO_GPU_F_CREATE_GUEST_HANDLE: u32 = 6;
struct BackendReqHandler {
mapping: Arc<MmapRegion>,
}
@ -163,7 +172,14 @@ impl Gpu {
VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false)?;
// Filling device and vring features VMM supports.
let avail_features = DEFAULT_VIRTIO_FEATURES;
let avail_features = DEFAULT_VIRTIO_FEATURES
| (1u64 << VIRTIO_GPU_F_VIRGL)
| (1u64 << VIRTIO_GPU_F_EDID)
| (1u64 << VIRTIO_GPU_F_RESOURCE_UUID)
| (1u64 << VIRTIO_GPU_F_RESOURCE_BLOB)
| (1u64 << VIRTIO_GPU_F_CONTEXT_INIT)
| (1u64 << VIRTIO_GPU_F_FENCE_PASSING)
| (1u64 << VIRTIO_GPU_F_CREATE_GUEST_HANDLE);
let avail_protocol_features = VhostUserProtocolFeatures::CONFIG
| VhostUserProtocolFeatures::BACKEND_REQ