[RFC 17/18] vfio/as: Allow the selection of a given iommu backend

Yi Liu
2022-04-14T10:47:51Z

From: Eric Auger <eric.auger@redhat.com>

Now we support two types of iommu backends, let's add the capability
to select one of them. This is based on a VFIODevice auto/on/off
iommu_be field. This field is likely to be forced to a given value or
set by a device option.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
hw/vfio/as.c | 31 ++++++++++++++++++++++++++++++-
include/hw/vfio/vfio-common.h | 1 +
2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/as.c b/hw/vfio/as.c
index 13a6653a0d..fce7a088e9 100644
--- a/hw/vfio/as.c
+++ b/hw/vfio/as.c
@@ -985,16 +985,45 @@ vfio_get_container_class(VFIOIOMMUBackendType be)
case VFIO_IOMMU_BACKEND_TYPE_LEGACY:
klass = object_class_by_name(TYPE_VFIO_LEGACY_CONTAINER);
return VFIO_CONTAINER_OBJ_CLASS(klass);
+ case VFIO_IOMMU_BACKEND_TYPE_IOMMUFD:
+ klass = object_class_by_name(TYPE_VFIO_IOMMUFD_CONTAINER);
+ return VFIO_CONTAINER_OBJ_CLASS(klass);
default:
return NULL;
}
}

+static VFIOContainerClass *
+select_iommu_backend(OnOffAuto value, Error **errp)
+{
+ VFIOContainerClass *vccs = NULL;
+
+ if (value == ON_OFF_AUTO_OFF) {
+ return vfio_get_container_class(VFIO_IOMMU_BACKEND_TYPE_LEGACY);
+ } else {
+ int iommufd = qemu_open_old("/dev/iommu", O_RDWR);
+
+ vccs = vfio_get_container_class(VFIO_IOMMU_BACKEND_TYPE_IOMMUFD);
+ if (iommufd < 0 || !vccs) {
+ if (value == ON_OFF_AUTO_AUTO) {
+ vccs = vfio_get_container_class(VFIO_IOMMU_BACKEND_TYPE_LEGACY);
+ } else { /* ON */
+ error_setg(errp, "iommufd backend is not supported by %s",
+ iommufd < 0 ? "the host" : "QEMU");
+ error_append_hint(errp, "set iommufd=off\n");
+ vccs = NULL;
+ }
+ }
+ close(iommufd);
+ }
+ return vccs;
+}
+
int vfio_attach_device(VFIODevice *vbasedev, AddressSpace *as, Error **errp)
{
VFIOContainerClass *vccs;

- vccs = vfio_get_container_class(VFIO_IOMMU_BACKEND_TYPE_LEGACY);
+ vccs = select_iommu_backend(vbasedev->iommufd_be, errp);
if (!vccs) {
return -ENOENT;
}
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index bef48ddfaf..2d941aae70 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -126,6 +126,7 @@ typedef struct VFIODevice {
VFIOMigration *migration;
Error *migration_blocker;
OnOffAuto pre_copy_dirty_page_tracking;
+ OnOffAuto iommufd_be;
} VFIODevice;

struct VFIODeviceOps {
--
2.27.0