qemu: Allow hotplug of vhost-scsi device

Adjust the device string that is built for vhost-scsi devices so that it
can be invoked from hotplug.

From the QEMU command line, the file descriptors are expect to be numeric only.
However, for hotplug, the file descriptors are expected to begin with at least
one alphabetic character else this error occurs:

  # virsh attach-device guest_0001 ~/vhost.xml
  error: Failed to attach device from /root/vhost.xml
  error: internal error: unable to execute QEMU command 'getfd':
  Parameter 'fdname' expects a name not starting with a digit

We also close the file descriptor in this case, so that shutting down the
guest cleans up the host cgroup entries and allows future guests to use
vhost-scsi devices.  (Otherwise the guest will silently end.)

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index f751c48eb553bfe0dcb8edc37f016f7c7b61e7e8..b03e618837ec8e3bdb1364a56935bac420198fc9 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2462,6 +2462,116 @@ qemuDomainAttachHostSCSIDevice(virConnectPtr conn,
     goto cleanup;
 }
 
+static int
+qemuDomainAttachSCSIVHostDevice(virQEMUDriverPtr driver,
+                                virDomainObjPtr vm,
+                                virDomainHostdevDefPtr hostdev)
+{
+    int ret = -1;
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    virDomainDeviceDef dev = { VIR_DOMAIN_DEVICE_HOSTDEV,
+                               { .hostdev = hostdev } };
+    virDomainCCWAddressSetPtr ccwaddrs = NULL;
+    char *vhostfdName = NULL;
+    int vhostfd = -1;
+    char *devstr = NULL;
+    bool teardowncgroup = false;
+    bool teardownlabel = false;
+    bool releaseaddr = false;
+
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_SCSI_GENERIC)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("SCSI passthrough is not supported by this version of qemu"));
+        return -1;
+    }
+
+    if (qemuHostdevPrepareSCSIVHostDevices(driver, vm->def->name, &hostdev, 1) < 0) {
+        virDomainHostdevSubsysSCSIVHostPtr hostsrc = &hostdev->source.subsys.u.scsi_host;
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unable to prepare scsi_host hostdev: %s"),
+                       hostsrc->wwpn);
+        return -1;
+    }
+
+    if (qemuSetupHostdevCgroup(vm, hostdev) < 0)
+        goto cleanup;
+    teardowncgroup = true;
+
+    if (virSecurityManagerSetHostdevLabel(driver->securityManager,
+                                          vm->def, hostdev, NULL) < 0)
+        goto cleanup;
+    teardownlabel = true;
+
+    if (virSCSIVHostOpenVhostSCSI(&vhostfd) < 0)
+        goto cleanup;
+
+    if (virAsprintf(&vhostfdName, "vhostfd-%d", vhostfd) < 0)
+        goto cleanup;
+
+    if (hostdev->info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE) {
+        if (qemuDomainMachineIsS390CCW(vm->def) &&
+            virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_VIRTIO_CCW))
+            hostdev->info->type = VIR_DOMAIN_DEVICE_ADDRESS_TYPE_CCW;
+    }
+
+    if (hostdev->info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE ||
+        hostdev->info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) {
+        if (qemuDomainEnsurePCIAddress(vm, &dev) < 0)
+            goto cleanup;
+    } else if (hostdev->info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_CCW) {
+        if (!(ccwaddrs = qemuDomainCCWAddrSetCreateFromDomain(vm->def)))
+            goto cleanup;
+        if (virDomainCCWAddressAssign(hostdev->info, ccwaddrs,
+                                      !hostdev->info->addr.ccw.assigned) < 0)
+            goto cleanup;
+    }
+    releaseaddr = true;
+
+    if (qemuAssignDeviceHostdevAlias(vm->def, &hostdev->info->alias, -1) < 0)
+        goto cleanup;
+
+    if (!(devstr = qemuBuildSCSIVHostHostdevDevStr(vm->def,
+                                                   hostdev,
+                                                   priv->qemuCaps,
+                                                   vhostfdName)))
+        goto cleanup;
+
+    if (VIR_REALLOC_N(vm->def->hostdevs, vm->def->nhostdevs + 1) < 0)
+        goto cleanup;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+
+    ret = qemuMonitorAddDeviceWithFd(priv->mon, devstr, vhostfd, vhostfdName);
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0 || ret < 0)
+        goto audit;
+
+    vm->def->hostdevs[vm->def->nhostdevs++] = hostdev;
+    ret = 0;
+
+ audit:
+    virDomainAuditHostdev(vm, hostdev, "attach", (ret == 0));
+
+ cleanup:
+    if (ret < 0) {
+        if (teardowncgroup && qemuTeardownHostdevCgroup(vm, hostdev) < 0)
+            VIR_WARN("Unable to remove host device cgroup ACL on hotplug fail");
+        if (teardownlabel &&
+            virSecurityManagerRestoreHostdevLabel(driver->securityManager,
+                                                  vm->def, hostdev, NULL) < 0)
+            VIR_WARN("Unable to restore host device labelling on hotplug fail");
+        if (releaseaddr)
+            qemuDomainReleaseDeviceAddress(vm, hostdev->info, NULL);
+    }
+
+    virDomainCCWAddressSetFree(ccwaddrs);
+
+    VIR_FORCE_CLOSE(vhostfd);
+    VIR_FREE(vhostfdName);
+    VIR_FREE(devstr);
+    return ret;
+}
+
 
 int
 qemuDomainAttachHostDevice(virConnectPtr conn,
@@ -2495,6 +2605,11 @@ qemuDomainAttachHostDevice(virConnectPtr conn,
             goto error;
         break;
 
+    case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST:
+        if (qemuDomainAttachSCSIVHostDevice(driver, vm, hostdev) < 0)
+            goto error;
+        break;
+
     default:
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("hostdev subsys type '%s' not supported"),
@@ -3587,6 +3702,14 @@ qemuDomainRemoveSCSIHostDevice(virQEMUDriverPtr driver,
     qemuHostdevReAttachSCSIDevices(driver, vm->def->name, &hostdev, 1);
 }
 
+static void
+qemuDomainRemoveSCSIVHostDevice(virQEMUDriverPtr driver,
+                                virDomainObjPtr vm,
+                                virDomainHostdevDefPtr hostdev)
+{
+    qemuHostdevReAttachSCSIVHostDevices(driver, vm->def->name, &hostdev, 1);
+}
+
 static int
 qemuDomainRemoveHostDevice(virQEMUDriverPtr driver,
                            virDomainObjPtr vm,
@@ -3665,6 +3788,7 @@ qemuDomainRemoveHostDevice(virQEMUDriverPtr driver,
         qemuDomainRemoveSCSIHostDevice(driver, vm, hostdev);
         break;
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST:
+        qemuDomainRemoveSCSIVHostDevice(driver, vm, hostdev);
         break;
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_LAST:
         break;
@@ -4520,6 +4644,31 @@ qemuDomainDetachHostSCSIDevice(virQEMUDriverPtr driver,
     return ret;
 }
 
+static int
+qemuDomainDetachSCSIVHostDevice(virQEMUDriverPtr driver,
+                                virDomainObjPtr vm,
+                                virDomainHostdevDefPtr detach)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    int ret = -1;
+
+    if (!detach->info->alias) {
+        virReportError(VIR_ERR_OPERATION_FAILED,
+                       "%s", _("device cannot be detached without a device alias"));
+        return -1;
+    }
+
+    qemuDomainMarkDeviceForRemoval(vm, detach->info);
+
+    qemuDomainObjEnterMonitor(driver, vm);
+    ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        return -1;
+
+    return ret;
+}
+
 static int
 qemuDomainDetachThisHostDevice(virQEMUDriverPtr driver,
                                virDomainObjPtr vm,
@@ -4542,6 +4691,9 @@ qemuDomainDetachThisHostDevice(virQEMUDriverPtr driver,
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI:
         ret = qemuDomainDetachHostSCSIDevice(driver, vm, detach);
         break;
+    case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST:
+        ret = qemuDomainDetachSCSIVHostDevice(driver, vm, detach);
+        break;
     default:
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("hostdev subsys type '%s' not supported"),
@@ -4619,6 +4771,8 @@ int qemuDomainDetachHostDevice(virQEMUDriverPtr driver,
             }
             break;
         }
+        case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST:
+            break;
         default:
             virReportError(VIR_ERR_INTERNAL_ERROR,
                            _("unexpected hostdev type %d"), subsys->type);