[PATCH 2/2] drm/virtio: add VIRTGPU_PARAM_HOST_PAGE_SIZE to params

[Sergio Lopez <slp@redhat.com>]

Add VIRTGPU_PARAM_HOST_PAGE_SIZE as a param that can be read with
VIRTGPU_GETPARAM by userspace applications running in the guest to
obtain the host's page size and find out the right alignment to be used
in shared memory allocations.

Signed-off-by: Sergio Lopez <slp@redhat.com>
---
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 5 +++++
 include/uapi/drm/virtgpu_drm.h         | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index e4f76f315550..c16cdf2d64b4 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -117,6 +117,11 @@ static int virtio_gpu_getparam_ioctl(struct drm_device *dev, void *data,
 	case VIRTGPU_PARAM_EXPLICIT_DEBUG_NAME:
 		value = vgdev->has_context_init ? 1 : 0;
 		break;
+	case VIRTGPU_PARAM_HOST_PAGE_SIZE:
+		if (!vgdev->has_host_page_size)
+			return -EINVAL;
+		value = vgdev->host_page_size;
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
index c2ce71987e9b..505f87263a15 100644
--- a/include/uapi/drm/virtgpu_drm.h
+++ b/include/uapi/drm/virtgpu_drm.h
@@ -98,6 +98,7 @@ struct drm_virtgpu_execbuffer {
 #define VIRTGPU_PARAM_CONTEXT_INIT 6 /* DRM_VIRTGPU_CONTEXT_INIT */
 #define VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs 7 /* Bitmask of supported capability set ids */
 #define VIRTGPU_PARAM_EXPLICIT_DEBUG_NAME 8 /* Ability to set debug name from userspace */
+#define VIRTGPU_PARAM_HOST_PAGE_SIZE 9 /* Host's page size */
 
 struct drm_virtgpu_getparam {
 	__u64 param;
-- 
2.45.2