Re: [PATCH v6 16/21] vfio/ccw: Allow the selection of a given iommu backend

[Cédric Le Goater]

On 11/14/23 11:09, Zhenzhong Duan wrote:

Now we support two types of iommu backends, let's add the capability
to select one of them. This depends on whether an iommufd object has
been linked with the vfio-ccw device:

If the user wants to use the legacy backend, it shall not
link the vfio-ccw device with any iommufd object:

  -device vfio-ccw,sysfsdev=/sys/bus/mdev/devices/XXX

This is called the legacy mode/backend.

If the user wants to use the iommufd backend (/dev/iommu) it
shall pass an iommufd object id in the vfio-ccw device options:

  -object iommufd,id=iommufd0
  -device vfio-ccw,sysfsdev=/sys/bus/mdev/devices/XXX,iommufd=iommufd0

Suggested-by: Alex Williamson <alex.william...@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
Reviewed-by: Matthew Rosato <mjros...@linux.ibm.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  hw/vfio/ccw.c | 6 ++++++
  1 file changed, 6 insertions(+)

diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index d857bb8d0f..d2d58bb677 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -15,12 +15,14 @@
   */

#include "qemu/osdep.h"

+#include CONFIG_DEVICES /* CONFIG_IOMMUFD */
  #include <linux/vfio.h>
  #include <linux/vfio_ccw.h>
  #include <sys/ioctl.h>

#include "qapi/error.h"

  #include "hw/vfio/vfio-common.h"
+#include "sysemu/iommufd.h"
  #include "hw/s390x/s390-ccw.h"
  #include "hw/s390x/vfio-ccw.h"
  #include "hw/qdev-properties.h"
@@ -677,6 +679,10 @@ static void vfio_ccw_unrealize(DeviceState *dev)
  static Property vfio_ccw_properties[] = {
      DEFINE_PROP_STRING("sysfsdev", VFIOCCWDevice, vdev.sysfsdev),
      DEFINE_PROP_BOOL("force-orb-pfch", VFIOCCWDevice, force_orb_pfch, false),
+#ifdef CONFIG_IOMMUFD
+    DEFINE_PROP_LINK("iommufd", VFIOCCWDevice, vdev.iommufd,
+                     TYPE_IOMMUFD_BACKEND, IOMMUFDBackend *),
+#endif
      DEFINE_PROP_END_OF_LIST(),
  };