[RFC v2 15/15] vfio/as: Allow the selection of a given iommu backend

[Yi Liu]

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 depends on whether an iommufd object has
been linked with the vfio-pci device:

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

-device vfio-pci,host=0000:02:00.0

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-pci device options:

 -object iommufd,id=iommufd0
 -device vfio-pci,host=0000:02:00.0,iommufd=iommufd0

Note the /dev/iommu device may have been pre-opened by a
management tool such as libvirt. This mode is no more considered
for the legacy backend. So let's remove the "TODO" comment.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
---
 hw/vfio/as.c  |  9 ++++++---
 hw/vfio/pci.c | 19 ++++++++++++++-----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/hw/vfio/as.c b/hw/vfio/as.c
index 56485f9299..e799750104 100644
--- a/hw/vfio/as.c
+++ b/hw/vfio/as.c
@@ -1007,6 +1007,8 @@ vfio_get_container_ops(VFIOIOMMUBackendType be)
     switch (be) {
     case VFIO_IOMMU_BACKEND_TYPE_LEGACY:
         return &legacy_container_ops;
+    case VFIO_IOMMU_BACKEND_TYPE_IOMMUFD:
+        return &iommufd_container_ops;
     default:
         return NULL;
     }
@@ -1016,9 +1018,10 @@ int vfio_attach_device(VFIODevice *vbasedev, 
AddressSpace *as, Error **errp)
 {
     const VFIOContainerOps *ops;
 
-    ops = vfio_get_container_ops(VFIO_IOMMU_BACKEND_TYPE_LEGACY);
-    if (!ops) {
-        return -ENOENT;
+    if (vbasedev->iommufd) {
+        ops = vfio_get_container_ops(VFIO_IOMMU_BACKEND_TYPE_IOMMUFD);
+    } else {
+        ops = vfio_get_container_ops(VFIO_IOMMU_BACKEND_TYPE_LEGACY);
     }
     return ops->attach_device(vbasedev, as, errp);
 }
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 6d10e86331..7efd3382ca 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -42,6 +42,7 @@
 #include "qapi/error.h"
 #include "migration/blocker.h"
 #include "migration/qemu-file.h"
+#include "sysemu/iommufd.h"
 
 #define TYPE_VFIO_PCI_NOHOTPLUG "vfio-pci-nohotplug"
 
@@ -2852,6 +2853,13 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     int i, ret;
     bool is_mdev;
 
+    if (vbasedev->iommufd) {
+        iommufd_backend_connect(vbasedev->iommufd, errp);
+        if (*errp) {
+            return;
+        }
+    }
+
     if (!vbasedev->sysfsdev) {
         if (!(~vdev->host.domain || ~vdev->host.bus ||
               ~vdev->host.slot || ~vdev->host.function)) {
@@ -3134,6 +3142,7 @@ error:
 static void vfio_instance_finalize(Object *obj)
 {
     VFIOPCIDevice *vdev = VFIO_PCI(obj);
+    VFIODevice *vbasedev = &vdev->vbasedev;
 
     vfio_display_finalize(vdev);
     vfio_bars_finalize(vdev);
@@ -3146,6 +3155,9 @@ static void vfio_instance_finalize(Object *obj)
      *
      * g_free(vdev->igd_opregion);
      */
+    if (vbasedev->iommufd) {
+        iommufd_backend_disconnect(vbasedev->iommufd);
+    }
     vfio_put_device(vdev);
 }
 
@@ -3281,11 +3293,8 @@ static Property vfio_pci_dev_properties[] = {
                                    qdev_prop_nv_gpudirect_clique, uint8_t),
     DEFINE_PROP_OFF_AUTO_PCIBAR("x-msix-relocation", VFIOPCIDevice, msix_relo,
                                 OFF_AUTOPCIBAR_OFF),
-    /*
-     * TODO - support passed fds... is this necessary?
-     * DEFINE_PROP_STRING("vfiofd", VFIOPCIDevice, vfiofd_name),
-     * DEFINE_PROP_STRING("vfiogroupfd, VFIOPCIDevice, vfiogroupfd_name),
-     */
+    DEFINE_PROP_LINK("iommufd", VFIOPCIDevice, vbasedev.iommufd,
+                     TYPE_IOMMUFD_BACKEND, IOMMUFDBackend *),
     DEFINE_PROP_END_OF_LIST(),
 };
 
-- 
2.27.0