drm/i915: Disable userptr pread/pwrite support.

Userptr should not need the kernel for a userspace memcpy, userspace
needs to call memcpy directly.

Specifically, disable i915_gem_pwrite_ioctl() and i915_gem_pread_ioctl().
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-12-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_userptr.c

@@ -700,6 +700,24 @@ i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
 	return i915_gem_userptr_init__mmu_notifier(obj, 0);
 }
 
+static int
+i915_gem_userptr_pwrite(struct drm_i915_gem_object *obj,
+			const struct drm_i915_gem_pwrite *args)
+{
+	drm_dbg(obj->base.dev, "pwrite to userptr no longer allowed\n");
+
+	return -EINVAL;
+}
+
+static int
+i915_gem_userptr_pread(struct drm_i915_gem_object *obj,
+		       const struct drm_i915_gem_pread *args)
+{
+	drm_dbg(obj->base.dev, "pread from userptr no longer allowed\n");
+
+	return -EINVAL;
+}
+
 static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
 	.name = "i915_gem_object_userptr",
 	.flags = I915_GEM_OBJECT_IS_SHRINKABLE |
@@ -708,6 +726,8 @@ static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
 	.get_pages = i915_gem_userptr_get_pages,
 	.put_pages = i915_gem_userptr_put_pages,
 	.dmabuf_export = i915_gem_userptr_dmabuf_export,
+	.pwrite = i915_gem_userptr_pwrite,
+	.pread = i915_gem_userptr_pread,
 	.release = i915_gem_userptr_release,
 };
 

drivers/gpu/drm/i915/i915_gem.c

@@ -407,6 +407,11 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 	}
 
 	trace_i915_gem_object_pread(obj, args->offset, args->size);
+	ret = -ENODEV;
+	if (obj->ops->pread)
+		ret = obj->ops->pread(obj, args);
+	if (ret != -ENODEV)
+		goto out;
 
 	ret = -ENODEV;
 	if (obj->ops->pread)