qemu: Handle host devices not being available better

We can't retrieve the isolation group of a device that's not present
in the system. However, it's very common for VFs to be created late
in the boot, so they might not be present yet when libvirtd starts,
which would cause the guests using them to disappear.

Moreover, for other architectures and even ppc64 before isolation
groups were introduced, it's considered perfectly fine to configure a
guest to use a device that's not yet (or no longer) available to the
host, with the obvious caveat that such a guest won't be able to
start before the device is available.

In order to be consistent, when a device's isolation group can't be
determined fall back to not isolating it rather than erroring out or,
worse, making the guest disappear.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1484254

Signed-off-by: Andrea Bolognani <abologna@redhat.com>

diff --git a/src/qemu/qemu_domain_address.c b/src/qemu/qemu_domain_address.c
index 16bf0cdf91f8149723c55bfb6cdbb81698c0a5a9..f27d0ce8ee27b2c85212902a8a8d212123955c25 100644 (file)
--- a/src/qemu/qemu_domain_address.c
+++ b/src/qemu/qemu_domain_address.c
@@ -982,8 +982,6 @@ int
 qemuDomainFillDeviceIsolationGroup(virDomainDefPtr def,
                                    virDomainDeviceDefPtr dev)
 {
-    int ret = -1;
-
     /* Only host devices need their isolation group to be different from
      * the default. Interfaces of type hostdev are just host devices in
      * disguise, but we don't need to handle them separately because for
@@ -1012,12 +1010,11 @@ qemuDomainFillDeviceIsolationGroup(virDomainDefPtr def,
         tmp = virPCIDeviceAddressGetIOMMUGroupNum(hostAddr);
 
         if (tmp < 0) {
-            virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("Can't look up isolation group for host device "
-                             "%04x:%02x:%02x.%x"),
-                           hostAddr->domain, hostAddr->bus,
-                           hostAddr->slot, hostAddr->function);
-            goto cleanup;
+            VIR_WARN("Can't look up isolation group for host device "
+                     "%04x:%02x:%02x.%x, device won't be isolated",
+                     hostAddr->domain, hostAddr->bus,
+                     hostAddr->slot, hostAddr->function);
+            goto skip;
         }
 
         /* The isolation group for a host device is its IOMMU group,
@@ -1057,12 +1054,11 @@ qemuDomainFillDeviceIsolationGroup(virDomainDefPtr def,
         tmp = qemuDomainFindUnusedIsolationGroup(def);
 
         if (tmp == 0) {
-            virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("Can't obtain usable isolation group for "
-                             "interface configured to use hostdev-backed "
-                             "network '%s'"),
-                             iface->data.network.name);
-            goto cleanup;
+            VIR_WARN("Can't obtain usable isolation group for interface "
+                     "configured to use hostdev-backed network '%s', "
+                     "device won't be isolated",
+                     iface->data.network.name);
+            goto skip;
         }
 
         info->isolationGroup = tmp;
@@ -1073,10 +1069,7 @@ qemuDomainFillDeviceIsolationGroup(virDomainDefPtr def,
     }
 
  skip:
-    ret = 0;
-
- cleanup:
-    return ret;
+    return 0;
 }