conf: Introduce virtio-pmem <memory/> model

The virtio-pmem is a virtio variant of NVDIMM and just like
NVDIMM virtio-pmem also allows accessing host pages bypassing
guest page cache. The difference is that if a regular file is
used to back guest's NVDIMM (model='nvdimm') the persistence of
guest writes might not be guaranteed while with virtio-pmem it
is.

To express this new model at domain XML level, I've chosen the
following:

  <memory model='virtio-pmem' access='shared'>
    <source>
      <path>/tmp/virtio_pmem</path>
    </source>
    <target>
      <size unit='KiB'>524288</size>
    </target>
    <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
  </memory>

Another difference between NVDIMM and virtio-pmem is that while
the former supports NUMA node locality the latter doesn't. And
also, the latter goes onto PCI bus and not into a DIMM module.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

docs/formatdomain.rst

@@ -7257,20 +7257,30 @@ Example: usage of the memory devices
          </label>
        </target>
      </memory>
+     <memory model='virtio-pmem' access='shared'>
+       <source>
+         <path>/tmp/virtio_pmem</path>
+       </source>
+       <target>
+         <size unit='KiB'>524288</size>
+       </target>
+     </memory>
    </devices>
    ...
 
 ``model``
    Provide ``dimm`` to add a virtual DIMM module to the guest. :since:`Since
-   1.2.14` Provide ``nvdimm`` model adds a Non-Volatile DIMM module.
+   1.2.14` Provide ``nvdimm`` model that adds a Non-Volatile DIMM module.
-   :since:`Since 3.2.0`
+   :since:`Since 3.2.0` Provide ``virtio-pmem`` model to add a paravirtualized
+   persistent memory device. :since:`Since 7.1.0`
 
 ``access``
    An optional attribute ``access`` ( :since:`since 3.2.0` ) that provides
    capability to fine tune mapping of the memory on per module basis. Values are
    the same as `Memory Backing <#elementsMemoryBacking>`__: ``shared`` and
    ``private``. For ``nvdimm`` model, if using real NVDIMM DAX device as
-   backend, ``shared`` is required.
+   backend, ``shared`` is required. For ``virtio-pmem`` model ``shared`` is
+   required.
 
 ``discard``
    An optional attribute ``discard`` ( :since:`since 4.4.0` ) that provides
@@ -7299,9 +7309,9 @@ Example: usage of the memory devices
       This element can be used to override the default set of NUMA nodes where
       the memory would be allocated.
 
-   For model ``nvdimm`` this element is mandatory. The mandatory child element
+   For model ``nvdimm`` the ``source`` element is mandatory. The mandatory
-   ``path`` represents a path in the host that backs the nvdimm module in the
+   child element ``path`` represents a path in the host that backs the nvdimm
-   guest. The following optional elements may be used:
+   module in the guest. The following optional elements may be used:
 
    ``alignsize``
       The ``alignsize`` element defines the page size alignment used to mmap the
@@ -7315,6 +7325,13 @@ Example: usage of the memory devices
       to guarantee the persistence of writes to the vNVDIMM backend, then use
       the ``pmem`` element in order to utilize the feature. :since:`Since 5.0.0`
 
+   For model ``virtio-pmem`` the ``source`` element is mandatory. The following
+   optional elements may be used:
+
+   ``path``
+     Represents a path in the host that backs the virtio memory module in the
+     guest. It is mandatory.
+
 ``target``
    The mandatory ``target`` element configures the placement and sizing of the
    added memory from the perspective of the guest.

docs/schemas/domaincommon.rng

@@ -6019,6 +6019,7 @@
         <choice>
           <value>dimm</value>
           <value>nvdimm</value>
+          <value>virtio-pmem</value>
         </choice>
       </attribute>
       <optional>

src/conf/domain_conf.c

@@ -1309,6 +1309,7 @@ VIR_ENUM_IMPL(virDomainMemoryModel,
               "",
               "dimm",
               "nvdimm",
+              "virtio-pmem",
 );
 
 VIR_ENUM_IMPL(virDomainShmemModel,
@@ -5331,6 +5332,28 @@ virDomainVsockDefPostParse(virDomainVsockDefPtr vsock)
 }
 
 
+static int
+virDomainMemoryDefPostParse(virDomainMemoryDefPtr mem)
+{
+    switch (mem->model) {
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        /* Virtio-pmem mandates shared access so that guest writes get
+         * reflected in the underlying file. */
+        if (mem->access == VIR_DOMAIN_MEMORY_ACCESS_DEFAULT)
+            mem->access = VIR_DOMAIN_MEMORY_ACCESS_SHARED;
+        break;
+
+    case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
+    case VIR_DOMAIN_MEMORY_MODEL_DIMM:
+    case VIR_DOMAIN_MEMORY_MODEL_NONE:
+    case VIR_DOMAIN_MEMORY_MODEL_LAST:
+        break;
+    }
+
+    return 0;
+}
+
+
 static int
 virDomainDeviceDefPostParseCommon(virDomainDeviceDefPtr dev,
                                   const virDomainDef *def,
@@ -5376,6 +5399,10 @@ virDomainDeviceDefPostParseCommon(virDomainDeviceDefPtr dev,
         ret = 0;
         break;
 
+    case VIR_DOMAIN_DEVICE_MEMORY:
+        ret = virDomainMemoryDefPostParse(dev->data.memory);
+        break;
+
     case VIR_DOMAIN_DEVICE_LEASE:
     case VIR_DOMAIN_DEVICE_FS:
     case VIR_DOMAIN_DEVICE_INPUT:
@@ -5390,7 +5417,6 @@ virDomainDeviceDefPostParseCommon(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_SHMEM:
     case VIR_DOMAIN_DEVICE_TPM:
     case VIR_DOMAIN_DEVICE_PANIC:
-    case VIR_DOMAIN_DEVICE_MEMORY:
     case VIR_DOMAIN_DEVICE_IOMMU:
     case VIR_DOMAIN_DEVICE_AUDIO:
         ret = 0;
@@ -15310,6 +15336,10 @@ virDomainMemorySourceDefParseXML(xmlNodePtr node,
 
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        def->nvdimmPath = virXPathString("string(./path)", ctxt);
+        break;
+
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
         break;
@@ -17194,6 +17224,11 @@ virDomainMemoryFindByDefInternal(virDomainDefPtr def,
                 continue;
             break;
 
+        case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+            if (STRNEQ(tmp->nvdimmPath, mem->nvdimmPath))
+                continue;
+            break;
+
         case VIR_DOMAIN_MEMORY_MODEL_NONE:
         case VIR_DOMAIN_MEMORY_MODEL_LAST:
             break;
@@ -26486,6 +26521,10 @@ virDomainMemorySourceDefFormat(virBufferPtr buf,
             virBufferAddLit(&childBuf, "<pmem/>\n");
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        virBufferEscapeString(&childBuf, "<path>%s</path>\n", def->nvdimmPath);
+        break;
+
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
         break;

src/conf/domain_conf.h

@@ -2307,6 +2307,7 @@ typedef enum {
     VIR_DOMAIN_MEMORY_MODEL_NONE,
     VIR_DOMAIN_MEMORY_MODEL_DIMM, /* dimm hotpluggable memory device */
     VIR_DOMAIN_MEMORY_MODEL_NVDIMM, /* nvdimm memory device */
+    VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM, /* virtio-pmem memory device */
 
     VIR_DOMAIN_MEMORY_MODEL_LAST
 } virDomainMemoryModel;
@@ -2318,7 +2319,7 @@ struct _virDomainMemoryDef {
     /* source */
     virBitmapPtr sourceNodes;
     unsigned long long pagesize; /* kibibytes */
-    char *nvdimmPath;
+    char *nvdimmPath; /* valid for NVDIMM an VIRTIO_PMEM */
     unsigned long long alignsize; /* kibibytes; valid only for NVDIMM */
     bool nvdimmPmem; /* valid only for NVDIMM */
 

src/conf/domain_validate.c

@@ -1389,7 +1389,8 @@ static int
 virDomainMemoryDefValidate(const virDomainMemoryDef *mem,
                            const virDomainDef *def)
 {
-    if (mem->model == VIR_DOMAIN_MEMORY_MODEL_NVDIMM) {
+    switch (mem->model) {
+    case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
         if (!mem->nvdimmPath) {
             virReportError(VIR_ERR_XML_DETAIL, "%s",
                            _("path is required for model 'nvdimm'"));
@@ -1407,6 +1408,43 @@ virDomainMemoryDefValidate(const virDomainMemoryDef *mem,
                            _("label size is required for NVDIMM device"));
             return -1;
         }
+        break;
+
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        if (!mem->nvdimmPath) {
+            virReportError(VIR_ERR_XML_DETAIL,
+                           _("path is required for model '%s'"),
+                           virDomainMemoryModelTypeToString(mem->model));
+            return -1;
+        }
+
+        if (mem->discard == VIR_TRISTATE_BOOL_YES) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("discard is not supported for model '%s'"),
+                           virDomainMemoryModelTypeToString(mem->model));
+            return -1;
+        }
+
+        if (mem->access != VIR_DOMAIN_MEMORY_ACCESS_SHARED) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("shared access mode required for virtio-pmem device"));
+            return -1;
+        }
+
+        if (mem->targetNode != -1) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("virtio-pmem does not support NUMA nodes"));
+            return -1;
+        }
+
+    case VIR_DOMAIN_MEMORY_MODEL_DIMM:
+        break;
+
+    case VIR_DOMAIN_MEMORY_MODEL_NONE:
+    case VIR_DOMAIN_MEMORY_MODEL_LAST:
+    default:
+        virReportEnumRangeError(virDomainMemoryModel, mem->model);
+        return -1;
     }
 
     return 0;

src/qemu/qemu_command.c

@@ -3325,6 +3325,7 @@ qemuBuildMemoryDeviceStr(const virDomainDef *def,
             return NULL;
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
         break;

src/qemu/qemu_domain.c

@@ -8605,6 +8605,8 @@ static int
 qemuDomainDefValidateMemoryHotplugDevice(const virDomainMemoryDef *mem,
                                          const virDomainDef *def)
 {
+    bool needsNuma = true;
+
     switch (mem->model) {
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
@@ -8640,11 +8642,34 @@ qemuDomainDefValidateMemoryHotplugDevice(const virDomainMemoryDef *mem,
         }
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        if (mem->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI &&
+            mem->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("only 'pci' addresses are supported for the "
+                             "virtio-pmem device"));
+            return -1;
+        }
+
+        /* virtio-pmem doesn't have .node attribute. */
+        needsNuma = false;
+        break;
+
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
         return -1;
     }
 
+    if (needsNuma &&
+        virDomainNumaGetNodeCount(def->numa) != 0) {
+        if (mem->targetNode == -1) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("target NUMA node needs to be specified for "
+                             "memory device"));
+            return -1;
+        }
+    }
+
     return 0;
 }
 

src/qemu/qemu_domain_address.c

@@ -313,11 +313,11 @@ qemuDomainPrimeVirtioDeviceAddresses(virDomainDefPtr def,
                                      virDomainDeviceAddressType type)
 {
     /*
-       declare address-less virtio devices to be of address type 'type'
+       Declare address-less virtio devices to be of address type 'type'
-       disks, networks, videos, consoles, controllers, memballoon and rng
+       disks, networks, videos, consoles, controllers, hostdevs, memballoon,
-       in this order
+       rngs and memories in this order.
-       if type is ccw filesystem and vsock devices are declared to be of
+       If type is ccw filesystem and vsock devices are declared to be of
-       address type ccw
+       address type ccw.
     */
     size_t i;
 
@@ -379,6 +379,12 @@ qemuDomainPrimeVirtioDeviceAddresses(virDomainDefPtr def,
             def->rngs[i]->info.type = type;
     }
 
+    for (i = 0; i < def->nmems; i++) {
+        if (def->mems[i]->model == VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM &&
+            def->mems[i]->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE)
+            def->mems[i]->info.type = type;
+    }
+
     if (type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_CCW) {
         for (i = 0; i < def->nfss; i++) {
             if (def->fss[i]->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE)
@@ -1005,11 +1011,23 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
         }
         break;
 
+    case VIR_DOMAIN_DEVICE_MEMORY:
+        switch (dev->data.memory->model) {
+        case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+            return virtioFlags;
+
+        case VIR_DOMAIN_MEMORY_MODEL_NONE:
+        case VIR_DOMAIN_MEMORY_MODEL_DIMM:
+        case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
+        case VIR_DOMAIN_MEMORY_MODEL_LAST:
+            return 0;
+        }
+        break;
+
         /* These devices don't ever connect with PCI */
     case VIR_DOMAIN_DEVICE_NVRAM:
     case VIR_DOMAIN_DEVICE_TPM:
     case VIR_DOMAIN_DEVICE_PANIC:
-    case VIR_DOMAIN_DEVICE_MEMORY:
     case VIR_DOMAIN_DEVICE_HUB:
     case VIR_DOMAIN_DEVICE_REDIRDEV:
     case VIR_DOMAIN_DEVICE_SMARTCARD:
@@ -2420,6 +2438,17 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
             return -1;
     }
 
+    for (i = 0; i < def->nmems; i++) {
+        virDomainMemoryDefPtr mem = def->mems[i];
+
+        if (mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM ||
+            !virDeviceInfoPCIAddressIsWanted(&mem->info))
+            continue;
+
+        if (qemuDomainPCIAddressReserveNextAddr(addrs, &mem->info) < 0)
+            return -1;
+    }
+
     return 0;
 }
 
@@ -3067,19 +3096,32 @@ qemuAssignMemoryDeviceSlot(virDomainMemoryDefPtr mem,
 
 
 int
-qemuDomainAssignMemoryDeviceSlot(virDomainDefPtr def,
+qemuDomainAssignMemoryDeviceSlot(virQEMUDriverPtr driver,
+                                 virDomainObjPtr vm,
                                  virDomainMemoryDefPtr mem)
 {
-    virBitmapPtr slotmap = NULL;
+    g_autoptr(virBitmap) slotmap = NULL;
-    int ret;
+    virDomainDeviceDef dev = {.type = VIR_DOMAIN_DEVICE_MEMORY, .data.memory = mem};
 
-    if (!(slotmap = qemuDomainGetMemorySlotMap(def)))
+    switch (mem->model) {
-        return -1;
+    case VIR_DOMAIN_MEMORY_MODEL_DIMM:
+    case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
+        if (!(slotmap = qemuDomainGetMemorySlotMap(vm->def)))
+            return -1;
 
-    ret = qemuAssignMemoryDeviceSlot(mem, slotmap);
+        return qemuAssignMemoryDeviceSlot(mem, slotmap);
+        break;
 
-    virBitmapFree(slotmap);
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
-    return ret;
+        return qemuDomainEnsurePCIAddress(vm, &dev, driver);
+        break;
+
+    case VIR_DOMAIN_MEMORY_MODEL_NONE:
+    case VIR_DOMAIN_MEMORY_MODEL_LAST:
+        break;
+    }
+
+    return 0;
 }
 
 
@@ -3097,8 +3139,22 @@ qemuDomainAssignMemorySlots(virDomainDefPtr def)
         return -1;
 
     for (i = 0; i < def->nmems; i++) {
-        if (qemuAssignMemoryDeviceSlot(def->mems[i], slotmap) < 0)
+        virDomainMemoryDefPtr mem = def->mems[i];
-            goto cleanup;
+
+        switch (mem->model) {
+        case VIR_DOMAIN_MEMORY_MODEL_DIMM:
+        case VIR_DOMAIN_MEMORY_MODEL_NVDIMM:
+            if (qemuAssignMemoryDeviceSlot(def->mems[i], slotmap) < 0)
+                goto cleanup;
+            break;
+
+        case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+            /* handled in qemuDomainAssignPCIAddresses() */
+            break;
+        case VIR_DOMAIN_MEMORY_MODEL_NONE:
+        case VIR_DOMAIN_MEMORY_MODEL_LAST:
+            break;
+        }
     }
 
     ret = 0;

src/qemu/qemu_domain_address.h

@@ -56,7 +56,8 @@ void qemuDomainFillDeviceIsolationGroup(virDomainDefPtr def,
 void qemuDomainReleaseDeviceAddress(virDomainObjPtr vm,
                                     virDomainDeviceInfoPtr info);
 
-int qemuDomainAssignMemoryDeviceSlot(virDomainDefPtr def,
+int qemuDomainAssignMemoryDeviceSlot(virQEMUDriverPtr driver,
+                                     virDomainObjPtr vm,
                                      virDomainMemoryDefPtr mem);
 
 int qemuDomainEnsureVirtioAddress(bool *releaseAddr,

src/qemu/qemu_hotplug.c

@@ -2412,7 +2412,7 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     if (qemuDomainDefValidateMemoryHotplug(vm->def, mem) < 0)
         goto cleanup;
 
-    if (qemuDomainAssignMemoryDeviceSlot(vm->def, mem) < 0)
+    if (qemuDomainAssignMemoryDeviceSlot(driver, vm, mem) < 0)
         goto cleanup;
 
     /* in cases where we are using a VM with aliases generated according to the

src/qemu/qemu_validate.c

@@ -4624,6 +4624,14 @@ qemuValidateDomainDeviceDefMemory(virDomainMemoryDefPtr mem,
         }
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
+        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VIRTIO_PMEM_PCI)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("virtio-pmem isn't supported by this QEMU binary"));
+            return -1;
+        }
+        break;
+
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
         break;

src/security/security_apparmor.c

@@ -690,6 +690,7 @@ AppArmorSetMemoryLabel(virSecurityManagerPtr mgr,
             return -1;
         }
         return reload_profile(mgr, def, mem->nvdimmPath, true);
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:

src/security/security_dac.c

@@ -1892,6 +1892,7 @@ virSecurityDACRestoreMemoryLabel(virSecurityManagerPtr mgr,
         ret = virSecurityDACRestoreFileLabel(mgr, mem->nvdimmPath);
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
@@ -2074,6 +2075,7 @@ virSecurityDACSetMemoryLabel(virSecurityManagerPtr mgr,
                                          user, group, true);
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:

src/security/security_selinux.c

@@ -1581,6 +1581,7 @@ virSecuritySELinuxSetMemoryLabel(virSecurityManagerPtr mgr,
             return -1;
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:
@@ -1608,6 +1609,7 @@ virSecuritySELinuxRestoreMemoryLabel(virSecurityManagerPtr mgr,
         ret = virSecuritySELinuxRestoreFileLabel(mgr, mem->nvdimmPath, true);
         break;
 
+    case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM:
     case VIR_DOMAIN_MEMORY_MODEL_DIMM:
     case VIR_DOMAIN_MEMORY_MODEL_NONE:
     case VIR_DOMAIN_MEMORY_MODEL_LAST:

tests/qemuxml2argvdata/memory-hotplug-virtio-pmem.xml

@@ -0,0 +1,53 @@
+<domain type='kvm'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <maxMemory slots='16' unit='KiB'>1099511627776</maxMemory>
+  <memory unit='KiB'>2095104</memory>
+  <currentMemory unit='KiB'>2095104</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu mode='custom' match='exact' check='none'>
+    <model fallback='forbid'>qemu64</model>
+    <topology sockets='2' dies='1' cores='1' threads='1'/>
+    <numa>
+      <cell id='0' cpus='0-1' memory='2095104' unit='KiB'/>
+    </numa>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i386</emulator>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='usb' index='0' model='piix3-uhci'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </memballoon>
+    <memory model='virtio-pmem' access='shared'>
+      <source>
+        <path>/tmp/virtio_pmem</path>
+      </source>
+      <target>
+        <size unit='KiB'>524288</size>
+      </target>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </memory>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/memory-hotplug-virtio-pmem.x86_64-latest.xml

@@ -0,0 +1 @@
+../qemuxml2argvdata/memory-hotplug-virtio-pmem.xml

tests/qemuxml2xmltest.c

@@ -1261,6 +1261,7 @@ mymain(void)
                  QEMU_CAPS_OBJECT_MEMORY_FILE,
                  QEMU_CAPS_DEVICE_NVDIMM,
                  QEMU_CAPS_LAST);
+    DO_TEST_CAPS_LATEST("memory-hotplug-virtio-pmem");
 
     DO_TEST("net-udp", NONE);