Emil Velikov
2018-Nov-02 13:34 UTC
[PATCH 2/5] drm/virtio: add uapi for in and out explicit fences
On Thu, 1 Nov 2018 at 12:56, Robert Foss <robert.foss at collabora.com> wrote:> On 2018-10-31 10:38, Emil Velikov wrote: > > Hi Rob, > > > > On Thu, 25 Oct 2018 at 19:38, Robert Foss <robert.foss at collabora.com> wrote: > >> > >> Add a new field called fence_fd that will be used by userspace to send > >> in-fences to the kernel and receive out-fences created by the kernel. > >> > >> This uapi enables virtio to take advantage of explicit synchronization of > >> dma-bufs. > >> > >> There are two new flags: > >> > >> * VIRTGPU_EXECBUF_FENCE_FD_IN to be used when passing an in-fence fd. > >> * VIRTGPU_EXECBUF_FENCE_FD_OUT to be used when requesting an out-fence fd > >> > >> The execbuffer IOCTL is now read-write to allow the userspace to read the > >> out-fence. > >> > >> On error -1 should be returned in the fence_fd field. > >> > >> Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.com> > >> Signed-off-by: Robert Foss <robert.foss at collabora.com> > >> --- > >> Changes since v2: > >> - Since exbuf-flags is a new flag, check that unsupported > >> flags aren't set. > >> > >> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 5 +++++ > >> include/uapi/drm/virtgpu_drm.h | 13 ++++++++++--- > >> 2 files changed, 15 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c > >> index d01a9ed100d1..1af289b28fc4 100644 > >> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c > >> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c > >> @@ -116,9 +116,14 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data, > >> struct ww_acquire_ctx ticket; > >> void *buf; > >> > >> + exbuf->fence_fd = -1; > >> + > > Move this after the sanity checking. > > Agreed. Fixed in v4 > > > > >> if (vgdev->has_virgl_3d == false) > >> return -ENOSYS; > >> > >> + if ((exbuf->flags & ~VIRTGPU_EXECBUF_FLAGS)) > >> + return -EINVAL; > >> + > > I assume this did this trigger when using old userspace? > > No, not as far as I'm aware. This check is there to prevent userspace from > polluting the bitspace of flag, so that all free bits can be used for new flags. > > As far as I understand this is pointed out by a drm driver development document > written by danvet, which I unfortunately can't seem to find the link for at the > moment. >Yes that is correct. What I was asking is: Does a kernel with this patch, work with mesa lacking the corresponding updates? I'd imagine things work just fine. -Emil