qemu: Don't use memory-backend-memfd for NVDIMMs

If guest is configured to use memfd then the function that build
memory-backend-* part of command line will put
memory-backend-memfd, always. Even for NVDIMMs. This is not
correct, because NVDIMMs need a backing path (usually to a real
host NVDIMM device). Therefore, regardless of memfd being
requested, we have to stick with memory-backend-file.

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

src/qemu/qemu_command.c

@@ -3052,7 +3052,8 @@ qemuBuildMemoryBackendProps(virJSONValue **backendProps,
 
     props = virJSONValueNewObject();
 
-    if (def->mem.source == VIR_DOMAIN_MEMORY_SOURCE_MEMFD) {
+    if (!mem->nvdimmPath &&
+        def->mem.source == VIR_DOMAIN_MEMORY_SOURCE_MEMFD) {
         backendType = "memory-backend-memfd";
 
         if (useHugepage) {

tests/qemuxml2argvdata/memfd-memory-numa.x86_64-latest.args

@@ -10,13 +10,15 @@ XDG_CONFIG_HOME=/tmp/lib/domain--1-instance-00000092/.config \
 -name guest=instance-00000092,debug-threads=on \
 -S \
 -object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/tmp/lib/domain--1-instance-00000092/master-key.aes"}' \
--machine pc-i440fx-2.3,accel=kvm,usb=off,dump-guest-core=off \
+-machine pc-i440fx-2.3,accel=kvm,usb=off,dump-guest-core=off,nvdimm=on \
 -cpu qemu64 \
--m 14336 \
+-m size=14680064k,slots=16,maxmem=1099511627776k \
 -overcommit mem-lock=off \
 -smp 8,sockets=1,dies=1,cores=8,threads=1 \
 -object '{"qom-type":"memory-backend-memfd","id":"ram-node0","hugetlb":true,"hugetlbsize":2097152,"share":true,"prealloc":true,"size":15032385536,"host-nodes":[3],"policy":"preferred"}' \
 -numa node,nodeid=0,cpus=0-7,memdev=ram-node0 \
+-object '{"qom-type":"memory-backend-file","id":"memnvdimm0","mem-path":"/tmp/nvdimm","share":true,"prealloc":true,"size":536870912,"host-nodes":[3],"policy":"preferred"}' \
+-device nvdimm,node=0,memdev=memnvdimm0,id=nvdimm0,slot=0 \
 -uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \
 -display none \
 -no-user-config \

tests/qemuxml2argvdata/memfd-memory-numa.xml

@@ -1,6 +1,7 @@
 <domain type='kvm'>
   <name>instance-00000092</name>
   <uuid>126f2720-6f8e-45ab-a886-ec9277079a67</uuid>
+  <maxMemory slots='16' unit='KiB'>1099511627776</maxMemory>
   <memory unit='KiB'>14680064</memory>
   <currentMemory unit='KiB'>14680064</currentMemory>
   <memoryBacking>
@@ -41,5 +42,15 @@
     <memballoon model='virtio'>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </memballoon>
+    <memory model='nvdimm'>
+      <source>
+        <path>/tmp/nvdimm</path>
+      </source>
+      <target>
+        <size unit='KiB'>523264</size>
+        <node>0</node>
+      </target>
+      <address type='dimm' slot='0'/>
+    </memory>
   </devices>
 </domain>

tests/qemuxml2xmltest.c

@@ -1306,7 +1306,8 @@ mymain(void)
     DO_TEST("memfd-memory-numa",
             QEMU_CAPS_OBJECT_MEMORY_MEMFD,
             QEMU_CAPS_OBJECT_MEMORY_MEMFD_HUGETLB,
-            QEMU_CAPS_OBJECT_MEMORY_FILE);
+            QEMU_CAPS_OBJECT_MEMORY_FILE,
+            QEMU_CAPS_DEVICE_NVDIMM);
     DO_TEST("memfd-memory-default-hugepage",
             QEMU_CAPS_OBJECT_MEMORY_MEMFD,
             QEMU_CAPS_OBJECT_MEMORY_MEMFD_HUGETLB,