This driver open codes the cap chain manipulations. Instead use
vfio_info_add_capability() and the get_region_info_caps() op.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 samples/vfio-mdev/mbochs.c | 75 ++++++++++++--------------------------
 1 file changed, 23 insertions(+), 52 deletions(-)

diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 7f889b31fa2ce2..a4228a67014c2a 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -143,11 +143,6 @@ static struct mdev_parent mbochs_parent;
 static atomic_t mbochs_avail_mbytes;
 static const struct vfio_device_ops mbochs_dev_ops;
 
-struct vfio_region_info_ext {
-	struct vfio_region_info          base;
-	struct vfio_region_info_cap_type type;
-};
-
 struct mbochs_mode {
 	u32 drm_format;
 	u32 bytepp;
@@ -1033,10 +1028,12 @@ static int mbochs_dmabuf_export(struct mbochs_dmabuf *dmabuf)
 	return 0;
 }
 
-static int mbochs_get_region_info(struct mdev_state *mdev_state,
-				  struct vfio_region_info_ext *ext)
+static int mbochs_get_region_info(struct vfio_device *vdev,
+				  struct vfio_region_info *region_info,
+				  struct vfio_info_cap *caps)
 {
-	struct vfio_region_info *region_info = &ext->base;
+	struct mdev_state *mdev_state =
+		container_of(vdev, struct mdev_state, vdev);
 
 	if (region_info->index >= MBOCHS_NUM_REGIONS)
 		return -EINVAL;
@@ -1061,20 +1058,23 @@ static int mbochs_get_region_info(struct mdev_state *mdev_state,
 		region_info->flags  = (VFIO_REGION_INFO_FLAG_READ  |
 				       VFIO_REGION_INFO_FLAG_WRITE);
 		break;
-	case MBOCHS_EDID_REGION_INDEX:
-		ext->base.argsz = sizeof(*ext);
-		ext->base.offset = MBOCHS_EDID_OFFSET;
-		ext->base.size = MBOCHS_EDID_SIZE;
-		ext->base.flags = (VFIO_REGION_INFO_FLAG_READ  |
-				   VFIO_REGION_INFO_FLAG_WRITE |
-				   VFIO_REGION_INFO_FLAG_CAPS);
-		ext->base.cap_offset = offsetof(typeof(*ext), type);
-		ext->type.header.id = VFIO_REGION_INFO_CAP_TYPE;
-		ext->type.header.version = 1;
-		ext->type.header.next = 0;
-		ext->type.type = VFIO_REGION_TYPE_GFX;
-		ext->type.subtype = VFIO_REGION_SUBTYPE_GFX_EDID;
-		break;
+	case MBOCHS_EDID_REGION_INDEX: {
+		struct vfio_region_info_cap_type cap_type = {
+			.header.id = VFIO_REGION_INFO_CAP_TYPE,
+			.header.version = 1,
+			.type = VFIO_REGION_TYPE_GFX,
+			.subtype = VFIO_REGION_SUBTYPE_GFX_EDID,
+		};
+
+		region_info->offset = MBOCHS_EDID_OFFSET;
+		region_info->size = MBOCHS_EDID_SIZE;
+		region_info->flags = (VFIO_REGION_INFO_FLAG_READ |
+				      VFIO_REGION_INFO_FLAG_WRITE |
+				      VFIO_REGION_INFO_FLAG_CAPS);
+
+		return vfio_info_add_capability(caps, &cap_type.header,
+						sizeof(cap_type));
+	}
 	default:
 		region_info->size   = 0;
 		region_info->offset = 0;
@@ -1185,35 +1185,6 @@ static int mbochs_get_gfx_dmabuf(struct mdev_state *mdev_state, u32 id)
 	return dma_buf_fd(dmabuf->buf, 0);
 }
 
-static int mbochs_ioctl_get_region_info(struct vfio_device *vdev,
-					struct vfio_region_info __user *arg)
-{
-	struct mdev_state *mdev_state =
-		container_of(vdev, struct mdev_state, vdev);
-	struct vfio_region_info_ext info;
-	unsigned long minsz, outsz;
-	int ret;
-
-	minsz = offsetofend(typeof(info), base.offset);
-
-	if (copy_from_user(&info, arg, minsz))
-		return -EFAULT;
-
-	outsz = info.base.argsz;
-	if (outsz < minsz)
-		return -EINVAL;
-	if (outsz > sizeof(info))
-		return -EINVAL;
-
-	ret = mbochs_get_region_info(mdev_state, &info);
-	if (ret)
-		return ret;
-
-	if (copy_to_user(arg, &info, outsz))
-		return -EFAULT;
-	return 0;
-}
-
 static long mbochs_ioctl(struct vfio_device *vdev, unsigned int cmd,
 			 unsigned long arg)
 {
@@ -1381,7 +1352,7 @@ static const struct vfio_device_ops mbochs_dev_ops = {
 	.read = mbochs_read,
 	.write = mbochs_write,
 	.ioctl = mbochs_ioctl,
-	.get_region_info = mbochs_ioctl_get_region_info,
+	.get_region_info_caps = mbochs_get_region_info,
 	.mmap = mbochs_mmap,
 	.bind_iommufd	= vfio_iommufd_emulated_bind,
 	.unbind_iommufd	= vfio_iommufd_emulated_unbind,
-- 
2.43.0