Jiang Feng
fe9333f7b5
Currently, res->maybe_busy is false by default. If wait immediately
after the resource is created, virgl_drm_resource_wait() will return
directly without checking the actual state of the kernel, which will
cause synchronization problems, such as:
On Guest:
pipe_buffer_create [mesa]
virgl_drm_winsys_resource_create
virtio_gpu_resource_create_ioctl [kernel]
virtio_gpu_fence_alloc
virtio_gpu_object_create
virtio_gpu_cmd_resource_create_3d
VIRTIO_GPU_CMD_RESOURCE_CREATE_3D
virtio_gpu_object_attach
virtio_gpu_cmd_resource_attach_backing
VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING
resource_wait [mesa]
virgl_drm_resource_wait /* return directly without fence waiting */
pipe_buffer_map [mesa]
virgl_drm_resource_map
virtio_gpu_map_ioctl [kernel]
os_mmap
memcpy /* <== here */
On Host (with QEMU):
VIRTIO_GPU_CMD_RESOURCE_CREATE_3D
virgl_cmd_create_resource_3d [qemu]
virgl_renderer_resource_create [virglrenderer]
VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING
virgl_resource_attach_backing [qemu]
virtio_gpu_create_mapping_iov
virgl_renderer_resource_attach_iov [virglrenderer]
virgl_resource_attach_iov
vrend_pipe_resource_attach_iov
vrend_write_to_iovec /* <== here */
virtio_gpu_cleanup_mapping_iov [qemu]
In the example above, there is a race condition between memcpy and
vrend_write_to_iovec.
Signed-off-by: Jiang Feng <jiangfeng@kylinos.cn>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17592>
`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library ====================================================== Source ------ This repository lives at https://gitlab.freedesktop.org/mesa/mesa. Other repositories are likely forks, and code found there is not supported. Build & install --------------- You can find more information in our documentation (`docs/install.rst <https://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://mesa3d.org/meson.html>`_): .. code-block:: sh $ mkdir build $ cd build $ meson .. $ sudo ninja install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `OFTC's #dri-devel <irc://irc.oftc.net/dri-devel>`_, someone will redirect you if necessary. Remember that not everyone is in the same timezone as you, so it might take a while before someone qualified sees your question. To figure out who you're talking to, or which nick to ping for your question, check out `Who's Who on IRC <https://dri.freedesktop.org/wiki/WhosWho/>`_. The next best option is to ask your question in an email to the mailing lists: `mesa-dev\@lists.freedesktop.org <https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_ Bug reports ----------- If you think something isn't working properly, please file a bug report (`docs/bugs.rst <https://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.