[PATCH v3 10/12] drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK

[Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>]

For the Sommelier guest Wayland proxy, it's desirable for the
DRM fd to be pollable in response to an host compositor event.
This can also be used by the 3D driver to poll events on a CPU
timeline.

This enables the DRM fd associated with a particular 3D context
to be polled independent of KMS events.  The parameter
VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK specifies the pollable
rings.

Signed-off-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
Acked-by: Nicholas Verne <nverne@xxxxxxxxxxxx>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  1 +
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 22 +++++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index cca9ab505deb..cb60d52c2bd1 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -266,6 +266,7 @@ struct virtio_gpu_fpriv {
 	bool context_created;
 	uint32_t num_rings;
 	uint64_t base_fence_ctx;
+	uint64_t ring_idx_mask;
 	struct mutex context_lock;
 };
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 262f79210283..be7b22a03884 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -694,6 +694,7 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 {
 	int ret = 0;
 	uint32_t num_params, i, param, value;
+	uint64_t valid_ring_mask;
 	size_t len;
 	struct drm_virtgpu_context_set_param *ctx_set_params = NULL;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
@@ -707,7 +708,7 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 		return -EINVAL;
 
 	/* Number of unique parameters supported at this time. */
-	if (num_params > 2)
+	if (num_params > 3)
 		return -EINVAL;
 
 	ctx_set_params = memdup_user(u64_to_user_ptr(args->ctx_set_params),
@@ -761,12 +762,31 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 			vfpriv->base_fence_ctx = dma_fence_context_alloc(value);
 			vfpriv->num_rings = value;
 			break;
+		case VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK:
+			if (vfpriv->ring_idx_mask) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			vfpriv->ring_idx_mask = value;
+			break;
 		default:
 			ret = -EINVAL;
 			goto out_unlock;
 		}
 	}
 
+	if (vfpriv->ring_idx_mask) {
+		valid_ring_mask = 0;
+		for (i = 0; i < vfpriv->num_rings; i++)
+			valid_ring_mask |= 1 << i;
+
+		if (~valid_ring_mask & vfpriv->ring_idx_mask) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+	}
+
 	virtio_gpu_create_context_locked(vgdev, vfpriv);
 	virtio_gpu_notify(vgdev);
 
-- 
2.33.0.464.g1972c5931b-goog