[PATCH 2/2] qemu: allow configuring mem-path for ivshmem-plain device

[Wang Xin]

The shared memory path is generated by shmem name as default,
however, we may need to change it to avoid filename conflict
when VM migrate to other host.

Signed-off-by: Yang Hang <yanghang44 at huawei.com>
Signed-off-by: Wang Xin <wangxinxin.wang at huawei.com>

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 09d4ad3e96..27fa6306df 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -4442,6 +4442,13 @@
             <ref name="scaledInteger"/>
           </element>
         </optional>
+        <optional>
+          <element name="mem">
+            <attribute name="path">
+              <ref name="absFilePath"/>
+            </attribute>
+          </element>
+        </optional>
         <optional>
           <element name="server">
             <optional>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 83a005a479..641f712877 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -2906,6 +2906,7 @@ void virDomainShmemDefFree(virDomainShmemDefPtr def)
 
     virDomainDeviceInfoClear(&def->info);
     virDomainChrSourceDefClear(&def->server.chr);
+    VIR_FREE(def->memPath);
     VIR_FREE(def->name);
     VIR_FREE(def);
 }
@@ -15365,6 +15366,12 @@ virDomainShmemDefParseXML(virDomainXMLOptionPtr xmlopt,
                             &def->size, 1, ULLONG_MAX, false) < 0)
         goto cleanup;
 
+    tmp = virXPathString("string(./mem/@path)", ctxt);
+    if (tmp) {
+        def->memPath = virFileSanitizePath(tmp);
+        VIR_FREE(tmp);
+    }
+
     if ((server = virXPathNode("./server[1]", ctxt))) {
         def->server.enabled = true;
 
@@ -27383,6 +27390,12 @@ virDomainShmemDefFormat(virBufferPtr buf,
     virBufferAsprintf(buf, "<model type='%s'/>\n",
                       virDomainShmemModelTypeToString(def->model));
 
+    if (def->memPath) {
+        virBufferAddLit(buf, "<mem");
+        virBufferEscapeString(buf, " path='%s'", def->memPath);
+        virBufferAddLit(buf, "/>\n");
+    }
+
     if (def->size)
         virBufferAsprintf(buf, "<size unit='M'>%llu</size>\n", def->size >> 20);
 
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 855c144ddb..58fd4f2122 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1782,6 +1782,7 @@ typedef enum {
 struct _virDomainShmemDef {
     char *name;
     unsigned long long size;
+    char *memPath;
     int model; /* enum virDomainShmemModel */
     int role; /* enum virDomainShmemRole */
     struct {
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 5ad7964b90..dc40e62186 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -8513,7 +8513,10 @@ qemuBuildShmemBackendMemProps(virDomainShmemDefPtr shmem)
     g_autofree char *mem_path = NULL;
     virJSONValuePtr ret = NULL;
 
-    mem_path = g_strdup_printf("/dev/shm/%s", shmem->name);
+    if (!shmem->memPath)
+        mem_path = g_strdup_printf("/dev/shm/%s", shmem->name);
+    else
+        mem_path = g_strdup_printf("%s", shmem->memPath);
 
     mem_alias = g_strdup_printf("shmmem-%s", shmem->info.alias);
 
diff --git a/tests/qemuxml2argvdata/shmem-plain-doorbell.xml b/tests/qemuxml2argvdata/shmem-plain-doorbell.xml
index 7c76e0fbba..ccad19efe2 100644
--- a/tests/qemuxml2argvdata/shmem-plain-doorbell.xml
+++ b/tests/qemuxml2argvdata/shmem-plain-doorbell.xml
@@ -28,6 +28,7 @@
     </shmem>
     <shmem name='shmem2' role='master'>
       <model type='ivshmem-plain'/>
+      <mem path='/dev/shm/shmem2'/>
       <size unit='M'>256</size>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
     </shmem>
diff --git a/tests/qemuxml2xmloutdata/shmem-plain-doorbell.xml b/tests/qemuxml2xmloutdata/shmem-plain-doorbell.xml
index 64c0a7d753..aa1b59a50b 100644
--- a/tests/qemuxml2xmloutdata/shmem-plain-doorbell.xml
+++ b/tests/qemuxml2xmloutdata/shmem-plain-doorbell.xml
@@ -33,6 +33,7 @@
     </shmem>
     <shmem name='shmem2' role='master'>
       <model type='ivshmem-plain'/>
+      <mem path='/dev/shm/shmem2'/>
       <size unit='M'>256</size>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
     </shmem>
-- 
2.26.0.windows.1