drm/v3d: add generic ioctl extension

Add support to attach generic extensions on job submission. This patch
is third prep work to enable multiple syncobjs on job submission. With
this work, when the job submission interface needs to be extended to
accommodate a new feature, we will use a generic extension struct where
an id determines the data type to be pointed. The first application is
to enable multiples in/out syncobj (next patch), but the base is
already done for future features. Therefore, to attach a new feature,
a specific extension struct should subclass drm_v3d_extension and
update the list of extensions in a job submission.

v2:
- remove redundant elements to subclass struct (Daniel)

v3:
- add comment for v3d_get_extensions
Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ed53b1cd7e3125b76f18fe3fb995a04393639bc6.1633016479.git.mwen@igalia.com

drivers/gpu/drm/v3d/v3d_drv.c

@@ -83,7 +83,6 @@ static int v3d_get_param_ioctl(struct drm_device *dev, void *data,
 		return 0;
 	}
 
-
 	switch (args->param) {
 	case DRM_V3D_PARAM_SUPPORTS_TFU:
 		args->value = 1;
@@ -147,7 +146,7 @@ v3d_postclose(struct drm_device *dev, struct drm_file *file)
 DEFINE_DRM_GEM_FOPS(v3d_drm_fops);
 
 /* DRM_AUTH is required on SUBMIT_CL for now, while we don't have GMP
- * protection between clients.  Note that render nodes would be be
+ * protection between clients.  Note that render nodes would be
  * able to submit CLs that could access BOs from clients authenticated
  * with the master node.  The TFU doesn't use the GMP, so it would
  * need to stay DRM_AUTH until we do buffer size/offset validation.
@@ -219,7 +218,6 @@ static int v3d_platform_drm_probe(struct platform_device *pdev)
 	u32 mmu_debug;
 	u32 ident1;
 
-
 	v3d = devm_drm_dev_alloc(dev, &v3d_drm_driver, struct v3d_dev, drm);
 	if (IS_ERR(v3d))
 		return PTR_ERR(v3d);

drivers/gpu/drm/v3d/v3d_gem.c

@@ -537,6 +537,36 @@ v3d_attach_fences_and_unlock_reservation(struct drm_file *file_priv,
 	}
 }
 
+/* Whenever userspace sets ioctl extensions, v3d_get_extensions parses data
+ * according to the extension id (name).
+ */
+static int
+v3d_get_extensions(struct drm_file *file_priv, u64 ext_handles)
+{
+	struct drm_v3d_extension __user *user_ext;
+
+	user_ext = u64_to_user_ptr(ext_handles);
+	while (user_ext) {
+		struct drm_v3d_extension ext;
+
+		if (copy_from_user(&ext, user_ext, sizeof(ext))) {
+			DRM_DEBUG("Failed to copy submit extension\n");
+			return -EFAULT;
+		}
+
+		switch (ext.id) {
+		case 0:
+		default:
+			DRM_DEBUG_DRIVER("Unknown extension id: %d\n", ext.id);
+			return -EINVAL;
+		}
+
+		user_ext = u64_to_user_ptr(ext.next);
+	}
+
+	return 0;
+}
+
 /**
  * v3d_submit_cl_ioctl() - Submits a job (frame) to the V3D.
  * @dev: DRM device
@@ -565,15 +595,24 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
 
 	trace_v3d_submit_cl_ioctl(&v3d->drm, args->rcl_start, args->rcl_end);
 
-	if (args->pad != 0)
+	if (args->pad)
 		return -EINVAL;
 
-	if (args->flags != 0 &&
-	    args->flags != DRM_V3D_SUBMIT_CL_FLUSH_CACHE) {
+	if (args->flags &&
+	    args->flags & ~(DRM_V3D_SUBMIT_CL_FLUSH_CACHE |
+			    DRM_V3D_SUBMIT_EXTENSION)) {
 		DRM_INFO("invalid flags: %d\n", args->flags);
 		return -EINVAL;
 	}
 
+	if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {
+		ret = v3d_get_extensions(file_priv, args->extensions);
+		if (ret) {
+			DRM_DEBUG("Failed to get extensions.\n");
+			return ret;
+		}
+	}
+
 	ret = v3d_job_init(v3d, file_priv, (void *)&render, sizeof(*render),
 			   v3d_render_job_free, args->in_sync_rcl, V3D_RENDER);
 	if (ret)
@@ -702,6 +741,19 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data,
 
 	trace_v3d_submit_tfu_ioctl(&v3d->drm, args->iia);
 
+	if (args->flags && !(args->flags & DRM_V3D_SUBMIT_EXTENSION)) {
+		DRM_DEBUG("invalid flags: %d\n", args->flags);
+		return -EINVAL;
+	}
+
+	if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {
+		ret = v3d_get_extensions(file_priv, args->extensions);
+		if (ret) {
+			DRM_DEBUG("Failed to get extensions.\n");
+			return ret;
+		}
+	}
+
 	ret = v3d_job_init(v3d, file_priv, (void *)&job, sizeof(*job),
 			   v3d_job_free, args->in_sync, V3D_TFU);
 	if (ret)
@@ -786,11 +838,27 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
 
 	trace_v3d_submit_csd_ioctl(&v3d->drm, args->cfg[5], args->cfg[6]);
 
+	if (args->pad)
+		return -EINVAL;
+
 	if (!v3d_has_csd(v3d)) {
 		DRM_DEBUG("Attempting CSD submit on non-CSD hardware\n");
 		return -EINVAL;
 	}
 
+	if (args->flags && !(args->flags & DRM_V3D_SUBMIT_EXTENSION)) {
+		DRM_INFO("invalid flags: %d\n", args->flags);
+		return -EINVAL;
+	}
+
+	if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {
+		ret = v3d_get_extensions(file_priv, args->extensions);
+		if (ret) {
+			DRM_DEBUG("Failed to get extensions.\n");
+			return ret;
+		}
+	}
+
 	ret = v3d_job_init(v3d, file_priv, (void *)&job, sizeof(*job),
 			   v3d_job_free, args->in_sync, V3D_CSD);
 	if (ret)

include/uapi/drm/v3d_drm.h

@@ -58,6 +58,20 @@ extern "C" {
 						   struct drm_v3d_perfmon_get_values)
 
 #define DRM_V3D_SUBMIT_CL_FLUSH_CACHE             0x01
+#define DRM_V3D_SUBMIT_EXTENSION		  0x02
+
+/* struct drm_v3d_extension - ioctl extensions
+ *
+ * Linked-list of generic extensions where the id identify which struct is
+ * pointed by ext_data. Therefore, DRM_V3D_EXT_ID_* is used on id to identify
+ * the extension type.
+ */
+struct drm_v3d_extension {
+	__u64 next;
+	__u32 id;
+#define DRM_V3D_EXT_ID_MULTI_SYNC		0x01
+	__u32 flags; /* mbz */
+};
 
 /**
  * struct drm_v3d_submit_cl - ioctl argument for submitting commands to the 3D
@@ -135,12 +149,16 @@ struct drm_v3d_submit_cl {
 	/* Number of BO handles passed in (size is that times 4). */
 	__u32 bo_handle_count;
 
+	/* DRM_V3D_SUBMIT_* properties */
 	__u32 flags;
 
 	/* ID of the perfmon to attach to this job. 0 means no perfmon. */
 	__u32 perfmon_id;
 
 	__u32 pad;
+
+	/* Pointer to an array of ioctl extensions*/
+	__u64 extensions;
 };
 
 /**
@@ -248,6 +266,12 @@ struct drm_v3d_submit_tfu {
 	__u32 in_sync;
 	/* Sync object to signal when the TFU job is done. */
 	__u32 out_sync;
+
+	__u32 flags;
+
+	/* Pointer to an array of ioctl extensions*/
+	__u64 extensions;
+
 };
 
 /* Submits a compute shader for dispatch.  This job will block on any
@@ -276,6 +300,13 @@ struct drm_v3d_submit_csd {
 
 	/* ID of the perfmon to attach to this job. 0 means no perfmon. */
 	__u32 perfmon_id;
+
+	/* Pointer to an array of ioctl extensions*/
+	__u64 extensions;
+
+	__u32 flags;
+
+	__u32 pad;
 };
 
 enum {