add hostdev pci backend type for xen

Add VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN. For legacy xen, it will use "pciback" as
stub driver.

docs/schemas/domaincommon.rng

@@ -3421,6 +3421,7 @@
             <choice>
               <value>kvm</value>
               <value>vfio</value>
+              <value>xen</value>
             </choice>
           </attribute>
           <empty/>

src/conf/domain_conf.c

@@ -627,7 +627,8 @@ VIR_ENUM_IMPL(virDomainHostdevSubsysPciBackend,
               VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST,
               "default",
               "kvm",
-              "vfio")
+              "vfio",
+              "xen")
 
 VIR_ENUM_IMPL(virDomainHostdevCaps, VIR_DOMAIN_HOSTDEV_CAPS_TYPE_LAST,
               "storage",

src/conf/domain_conf.h

@@ -415,6 +415,7 @@ typedef enum {
     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT, /* detect automaticaly, prefer VFIO */
     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM,    /* force legacy kvm style */
     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO,   /* force vfio */
+    VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN,    /* force legacy xen style, use pciback */
 
     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST
 } virDomainHostdevSubsysPciBackendType;

src/libxl/libxl_domain.c

@@ -478,6 +478,15 @@ libxlDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
         STRNEQ(def->os.type, "hvm"))
         dev->data.chr->targetType = VIR_DOMAIN_CHR_CONSOLE_TARGET_TYPE_XEN;
 
+    if (dev->type == VIR_DOMAIN_DEVICE_HOSTDEV) {
+        virDomainHostdevDefPtr hostdev = dev->data.hostdev;
+
+        if (hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
+            hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI &&
+            hostdev->source.subsys.u.pci.backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT)
+            hostdev->source.subsys.u.pci.backend = VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN;
+    }
+
     return 0;
 }
 

src/qemu/qemu_command.c

@@ -5544,8 +5544,7 @@ qemuBuildPCIHostdevDevStr(virDomainDefPtr def,
         virBufferAddLit(&buf, "vfio-pci");
         break;
 
-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:
-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST:
+    default:
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("invalid PCI passthrough type '%s'"),
                        virDomainHostdevSubsysPciBackendTypeToString(backend));

src/qemu/qemu_hostdev.c

@@ -205,6 +205,7 @@ qemuPrepareHostdevPCICheckSupport(virDomainHostdevDefPtr *hostdevs,
 
             break;
 
+        case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN:
         case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST:
             break;
         }

src/qemu/qemu_hotplug.c

@@ -1199,9 +1199,7 @@ qemuDomainAttachHostPCIDevice(virQEMUDriverPtr driver,
         virProcessSetMaxMemLock(vm->pid, memKB * 1024);
         break;
 
-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:
-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM:
-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST:
+    default:
         break;
     }
 

src/util/virhostdev.c

@@ -170,6 +170,12 @@ virHostdevGetPCIHostDeviceList(virDomainHostdevDefPtr *hostdevs, int nhostdevs)
                 virObjectUnref(list);
                 return NULL;
             }
+        } else if (hostdev->source.subsys.u.pci.backend
+                   == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN) {
+            if (virPCIDeviceSetStubDriver(dev, "pciback") < 0) {
+                virObjectUnref(list);
+                return NULL;
+            }
         } else {
             if (virPCIDeviceSetStubDriver(dev, "pci-stub") < 0) {
                 virObjectUnref(list);
@@ -819,6 +825,10 @@ virHostdevUpdateActivePCIDevices(virHostdevManagerPtr mgr,
             == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) {
             if (virPCIDeviceSetStubDriver(dev, "vfio-pci") < 0)
                 goto cleanup;
+        } else if (hostdev->source.subsys.u.pci.backend
+                   == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN) {
+            if (virPCIDeviceSetStubDriver(dev, "pciback") < 0)
+                goto cleanup;
         } else {
             if (virPCIDeviceSetStubDriver(dev, "pci-stub") < 0)
                 goto cleanup;