linux-kernel - [PATCH 4/6] drm/virtio: implement userptr: probe for the feature

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Message-ID: <20251112074548.3718563-5-honglei1.huang@amd.com>
Date: Wed, 12 Nov 2025 15:45:46 +0800
From: Honglei Huang <honglei1.huang@....com>
To: David Airlie <airlied@...hat.com>, Gerd Hoffmann <kraxel@...hat.com>,
	Dmitry Osipenko <dmitry.osipenko@...labora.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, Simona Vetter <simona@...ll.ch>,
	<Ray.Huang@....com>
CC: Gurchetan Singh <gurchetansingh@...omium.org>, Chia-I Wu
	<olvaffe@...il.com>, <dri-devel@...ts.freedesktop.org>,
	<virtualization@...ts.linux.dev>, <linux-kernel@...r.kernel.org>, "Honglei
 Huang" <Honglei1.Huang@....com>
Subject: [PATCH 4/6] drm/virtio: implement userptr: probe for the feature

From: Honglei Huang <Honglei1.Huang@....com>

Probe and advertise VIRTIO_GPU_F_RESOURCE_USERPTR feature:

- Add VIRTIO_GPU_F_RESOURCE_USERPTR to feature table
- Store capability in vgdev->has_resource_userptr flag
- Expose via VIRTGPU_PARAM_RESOURCE_USERPTR getparam
- Display in debugfs features file for debugging

This allows userspace to detect if the host supports userptr before
attempting to create userptr resources.

Signed-off-by: Honglei Huang <Honglei1.Huang@....com>
---
 drivers/gpu/drm/virtio/virtgpu_debugfs.c | 1 +
 drivers/gpu/drm/virtio/virtgpu_drv.c     | 1 +
 drivers/gpu/drm/virtio/virtgpu_drv.h     | 1 +
 drivers/gpu/drm/virtio/virtgpu_ioctl.c   | 3 +++
 drivers/gpu/drm/virtio/virtgpu_kms.c     | 8 ++++++--
 5 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_debugfs.c b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
index 853dd9aa397e..da9fa034db0e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_debugfs.c
+++ b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
@@ -57,6 +57,7 @@ static int virtio_gpu_features(struct seq_file *m, void *data)
 	virtio_gpu_add_bool(m, "context init", vgdev->has_context_init);
 	virtio_gpu_add_int(m, "cap sets", vgdev->num_capsets);
 	virtio_gpu_add_int(m, "scanouts", vgdev->num_scanouts);
+	virtio_gpu_add_int(m, "blob userptr", vgdev->has_resource_userptr);
 	if (vgdev->host_visible_region.len) {
 		seq_printf(m, "%-16s : 0x%lx +0x%lx\n", "host visible region",
 			   (unsigned long)vgdev->host_visible_region.addr,
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 71c6ccad4b99..902a4fb38ee4 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -162,6 +162,7 @@ static unsigned int features[] = {
 	VIRTIO_GPU_F_RESOURCE_UUID,
 	VIRTIO_GPU_F_RESOURCE_BLOB,
 	VIRTIO_GPU_F_CONTEXT_INIT,
+	VIRTIO_GPU_F_RESOURCE_USERPTR,
 };
 static struct virtio_driver virtio_gpu_driver = {
 	.feature_table = features,
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index f17660a71a3e..ab19106af105 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -257,6 +257,7 @@ struct virtio_gpu_device {
 	bool has_resource_blob;
 	bool has_host_visible;
 	bool has_context_init;
+	bool has_resource_userptr;
 	struct virtio_shm_region host_visible_region;
 	struct drm_mm host_visible_mm;
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index c33c057365f8..9081dbeaa362 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -117,6 +117,9 @@ 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_RESOURCE_USERPTR:
+		value = vgdev->has_resource_userptr ? 1 : 0;
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 7dfb2006c561..3d5158caef46 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -174,6 +174,9 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_BLOB)) {
 		vgdev->has_resource_blob = true;
 	}
+	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_USERPTR)) {
+		vgdev->has_resource_userptr = true;
+	}
 	if (virtio_get_shm_region(vgdev->vdev, &vgdev->host_visible_region,
 				  VIRTIO_GPU_SHM_ID_HOST_VISIBLE)) {
 		if (!devm_request_mem_region(&vgdev->vdev->dev,
@@ -197,11 +200,12 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 		vgdev->has_context_init = true;
 	}
 
-	DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible",
+	DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible %cresource_userptr",
 		 vgdev->has_virgl_3d    ? '+' : '-',
 		 vgdev->has_edid        ? '+' : '-',
 		 vgdev->has_resource_blob ? '+' : '-',
-		 vgdev->has_host_visible ? '+' : '-');
+		 vgdev->has_host_visible ? '+' : '-',
+		 vgdev->has_resource_userptr ? '+' : '-');
 
 	DRM_INFO("features: %ccontext_init\n",
 		 vgdev->has_context_init ? '+' : '-');
-- 
2.34.1