qemu: fix hot unplug of PCI devices with VFIO

Currently, on hot unplug of PCI devices with VFIO driver for QEMU, libvirt is
trying to restore the host devices to it's previous value (basically a chown
on the previous user/group).

However for devices with VFIO driver, when the device is unbinded it is
removed from the /dev/vfio file system causing the restore label to fail.

The fix is to not restore the label for those PCI devices since they are going
to be teared down anyway.

Signed-off-by: Ludovic Beliveau <ludovic.beliveau@windriver.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 87717804bf27db8143804d57d8a842e27ac10191..afa99f125d5f4806cc00b7cf55ae502deb97d317 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1278,7 +1278,8 @@ qemuDomainAttachHostPCIDevice(virQEMUDriverPtr driver,
     if (virSecurityManagerSetHostdevLabel(driver->securityManager,
                                           vm->def, hostdev, NULL) < 0)
         goto error;
-    teardownlabel = true;
+    if (backend != VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO)
+        teardownlabel = true;
 
     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE)) {
         if (qemuAssignDeviceHostdevAlias(vm->def, hostdev, -1) < 0)
@@ -2985,6 +2986,8 @@ qemuDomainRemoveHostDevice(virQEMUDriverPtr driver,
     int ret = -1;
     qemuDomainObjPrivatePtr priv = vm->privateData;
     char *drivestr = NULL;
+    int backend;
+    bool is_vfio = false;
 
     VIR_DEBUG("Removing host device %s from domain %p %s",
               hostdev->info->alias, vm, vm->def->name);
@@ -3028,6 +3031,8 @@ qemuDomainRemoveHostDevice(virQEMUDriverPtr driver,
 
     switch ((virDomainHostdevSubsysType) hostdev->source.subsys.type) {
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI:
+        backend = hostdev->source.subsys.u.pci.backend;
+        is_vfio = backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO;
         qemuDomainRemovePCIHostDevice(driver, vm, hostdev);
         /* QEMU might no longer need to lock as much memory, eg. we just
          * detached the last VFIO device, so adjust the limit here */
@@ -3047,7 +3052,8 @@ qemuDomainRemoveHostDevice(virQEMUDriverPtr driver,
     if (qemuTeardownHostdevCgroup(vm, hostdev) < 0)
         VIR_WARN("Failed to remove host device cgroup ACL");
 
-    if (virSecurityManagerRestoreHostdevLabel(driver->securityManager,
+    if (!is_vfio &&
+        virSecurityManagerRestoreHostdevLabel(driver->securityManager,
                                               vm->def, hostdev, NULL) < 0) {
         VIR_WARN("Failed to restore host device labelling");
     }