[v6] virtio-gpu: Add userptr support and ROCm capability enhancements

[RFC v6 0/4] virtio-gpu: Add userptr support and ROCm capability enhancements
Posted by Honglei Huang 3 weeks ago
This patch series introduces enhancements to virtio-gpu to improve
memory management and GPU virtualization capabilities for ROCm (Radeon Open Compute) 
workloads.

Usage example:
  -device virtio-gpu-gl,rocm=on

The series includes:

1. Linux header updates for userptr blob flags: Synchronizes virtio-gpu headers
   with upstream kernel changes, adding VIRTIO_GPU_BLOB_FLAG_USE_USERPTR and
   VIRTIO_GPU_BLOB_FLAG_USERPTR_RDONLY blob flags. This enables user pointer
   mapping for blob resources, allowing guest applications to use user-allocated
   memory for GPU resources more efficiently.

2. Removal of nr_entries limit: Removes the artificial 16384 entry limit in
   virtio_gpu_create_mapping_iov() to align with kernel driver behavior and
   support legitimate large scatter-gather operations.

3. Linux header updates for ROCm capability: Synchronizes headers to add
   VIRTIO_GPU_CAPSET_ROCM capability set definition.

4. ROCm capability support: Adds native support for AMD's ROCm (Radeon Open
   Compute) platform through a new "rocm=on" device property and capability.
   This enables GPU compute workloads using the ROCm stack through virtio-gpu.

Changes in v6:
- Changed to RFC status
- Removed VIRTIO_GPU_F_RESOURCE_USERPTR feature flag from patch 1
- Added VIRTIO_GPU_BLOB_FLAG_USERPTR_RDONLY flag to patch 1

Changes in v5:
- Split userptr header updates into dedicated patch (patch 1/4)
- Extracted nr_entries limit removal into standalone commit (patch 2/4)
- Split ROCm header updates into dedicated patch (patch 3/4)
- Removed VIRTIO_GPU_F_RESOURCE_USERPTR feature detection
- Keep ROCm capability support with "rocm=on" device property (patch 4/4)
- Change corresponding commit messages, change corresponding cover letter content
- Remove RFC label

Changes in v4:
- Change this series to RFC
- Renamed HSAKMT-related functionality to ROCm for better clarity and
  alignment with the ROCm ecosystem terminology
- Changed device property from "hsakmt=on" to "rocm=on"
- Changed flag from VIRTIO_GPU_FLAG_HSAKMT_ENABLED to
  VIRTIO_GPU_FLAG_ROCM_ENABLED
- Changed renderer flag from VIRGL_RENDER_USE_HSAKMT to
  VIRGL_RENDERER_USE_ROCM
- Updated capset handling to use VIRTIO_GPU_CAPSET_ROCM (8) instead of
  VIRTIO_GPU_CAPSET_HSAKMT (8)
- Removed the error handling fix from patch 1 (virtio-gpu-virgl.c) into
  another thread

Changes in v3:
- Renamed HSAKMT-related functionality to ROCm for better clarity and
  alignment with the ROCm ecosystem terminology
- Changed device property from "hsakmt=on" to "rocm=on"
- Changed flag from VIRTIO_GPU_FLAG_HSAKMT_ENABLED to
  VIRTIO_GPU_FLAG_ROCM_ENABLED
- Changed renderer flag from VIRGL_RENDER_USE_HSAKMT to
  VIRGL_RENDERER_USE_ROCM
- Updated capset handling to use VIRTIO_GPU_CAPSET_ROCM (8) instead of
  VIRTIO_GPU_CAPSET_HSAKMT (8)
- Removed the error handling fix from patch 1 (virtio-gpu-virgl.c) into
  another thread

Changes in v2:
- Fixed error handling bug in virtio-gpu-virgl.c where the return
  value check was inverted (changed from "if (!ret)" to "if (ret != 0)")
- Added VIRGL_RENDER_USE_HSAKMT flag initialization in virtio_gpu_virgl_init()
  when HSAKMT support is enabled
- Simplified blob resource creation logic by removing complex conditional
  branching for userptr vs regular blob handling
- Updated commit messages to reflect bug fixes and improvements
- Added references to related patches in Linux kernel, virglrenderer, and
  ROCm Runtime components for complete feature implementation tracking

Related patches in other components:
- Linux kernel virtio-gpu support:
  https://lore.kernel.org/lkml/20251112072910.3716944-1-honglei1.huang@amd.com/
- Virglrenderer support:
  https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/1568
- ROCm Runtime support (merged):
  https://github.com/ROCm/ROCR-Runtime/commit/48d3719dba6ca91f597a8179d8b341387ce155e8

Honglei Huang (4):
  virtio-gpu: Update Linux headers to add userptr blob flags
  virtio-gpu: Remove nr_entries limit check in create_mapping_iov
  virtio-gpu: Update Linux headers to add ROCM capability set
  virtio-gpu: Add ROCm capability support

 hw/display/virtio-gpu-gl.c                  |  2 ++
 hw/display/virtio-gpu-virgl.c               | 12 ++++++++++++
 hw/display/virtio-gpu.c                     |  7 -------
 include/hw/virtio/virtio-gpu.h              |  3 +++
 include/standard-headers/linux/virtio_gpu.h |  3 +++
 5 files changed, 20 insertions(+), 7 deletions(-)

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2.34.1