[RFC PATCH 020/162] drm/i915: Disable userptr pread/pwrite support.

[Matthew Auld]

From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

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().

Still needs an ack from relevant userspace that it won't break,
but should be good.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 30edc5a0a54e..8c3d1eb2f96a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/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,
 };
 
-- 
2.26.2