[Mesa-dev] [PATCH v2] virgl: disable virgl when no 3D for virtio gpu.

[Lepton Wu]

If users are running mesa under old version of qemu or have turned off
GL at runtime, virtio gpu driver actually doesn't work. Adds a detection
here so mesa can fall back to software rendering.

v2:
 - move detection from loader to virgl (Ilia, Emil)

Signed-off-by: Lepton Wu <lepton at chromium.org>
---
 src/gallium/winsys/virgl/drm/virgl_drm_winsys.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c b/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
index cf3c3bac4b..4198ed7feb 100644
--- a/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
+++ b/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
@@ -800,8 +800,15 @@ virgl_drm_winsys_create(int drmFD)
 {
    struct virgl_drm_winsys *qdws;
    int ret;
+   int gl = 0;
    struct drm_virtgpu_getparam getparam = {0};
 
+   getparam.param = VIRTGPU_PARAM_3D_FEATURES;
+   getparam.value = (uint64_t)(uintptr_t)≷
+   ret = drmIoctl(drmFD, DRM_IOCTL_VIRTGPU_GETPARAM, &getparam);
+   if (ret < 0 || !gl)
+      return NULL;
+
    qdws = CALLOC_STRUCT(virgl_drm_winsys);
    if (!qdws)
       return NULL;
@@ -914,6 +921,10 @@ virgl_drm_screen_create(int fd)
       int dup_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
 
       vws = virgl_drm_winsys_create(dup_fd);
+      if (!vws) {
+         close(dup_fd);
+         goto unlock;
+      }
 
       pscreen = virgl_create_screen(vws);
       if (pscreen) {
-- 
2.17.0.484.g0c8726318c-goog