| Message ID | 20230304220510.964715-1-dmitry.osipenko@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] drm/virtio: Fix handling CONFIG_DRM_VIRTIO_GPU_KMS option | expand |
> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c > @@ -45,9 +45,11 @@ static void virtio_gpu_config_changed_work_func(struct work_struct *work) > if (events_read & VIRTIO_GPU_EVENT_DISPLAY) { > if (vgdev->has_edid) > virtio_gpu_cmd_get_edids(vgdev); > - virtio_gpu_cmd_get_display_info(vgdev); > - virtio_gpu_notify(vgdev); > - drm_helper_hpd_irq_event(vgdev->ddev); > + if (vgdev->num_scanouts) { > + virtio_gpu_cmd_get_display_info(vgdev); > + virtio_gpu_notify(vgdev); > + drm_helper_hpd_irq_event(vgdev->ddev); > + } I'd suggest to make the edid lines conditional too. > - if (IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) || !vgdev->num_scanouts) { > + if (!IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) || !vgdev->num_scanouts) { > DRM_INFO("KMS disabled\n"); > vgdev->num_scanouts = 0; > vgdev->has_edid = false; Doesn't make a difference because has_edid gets set to false here, but IMHO it is less confusing that way. take care, Gerd
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c index 874ad6c2621a..7522fab2b709 100644 --- a/drivers/gpu/drm/virtio/virtgpu_kms.c +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c @@ -45,9 +45,11 @@ static void virtio_gpu_config_changed_work_func(struct work_struct *work) if (events_read & VIRTIO_GPU_EVENT_DISPLAY) { if (vgdev->has_edid) virtio_gpu_cmd_get_edids(vgdev); - virtio_gpu_cmd_get_display_info(vgdev); - virtio_gpu_notify(vgdev); - drm_helper_hpd_irq_event(vgdev->ddev); + if (vgdev->num_scanouts) { + virtio_gpu_cmd_get_display_info(vgdev); + virtio_gpu_notify(vgdev); + drm_helper_hpd_irq_event(vgdev->ddev); + } events_clear |= VIRTIO_GPU_EVENT_DISPLAY; } virtio_cwrite_le(vgdev->vdev, struct virtio_gpu_config, @@ -224,7 +226,7 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev) vgdev->num_scanouts = min_t(uint32_t, num_scanouts, VIRTIO_GPU_MAX_SCANOUTS); - if (IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) || !vgdev->num_scanouts) { + if (!IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) || !vgdev->num_scanouts) { DRM_INFO("KMS disabled\n"); vgdev->num_scanouts = 0; vgdev->has_edid = false;
VirtIO-GPU got a new config option for disabling KMS. There were two problems left unnoticed during review when the new option was added: 1. The IS_ENABLED(CONFIG_DRM_VIRTIO_GPU_KMS) check in the code was inverted, hence KMS was disabled when it should be enabled and vice versa. 2. The disabled KMS crashed kernel with a NULL dereference in drm_kms_helper_hotplug_event(), which shall not be invoked with a disabled KMS. Fix the inverted config option check in the code and skip handling the VIRTIO_GPU_EVENT_DISPLAY sent by host when KMS is disabled in guest to fix the crash. Fixes: 72122c69d717 ("drm/virtio: Add option to disable KMS support") Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/virtio/virtgpu_kms.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)