qemu: Extract -mem-path building into its own function

That function is called qemuBuildMemPathStr() and will be used in
other places in the future.  The change in the test suite is proper due
to the fact that -mem-prealloc makes only sense with -mem-path (from
qemu documentation -- html/qemu-doc.html).
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_command.c

@@ -7996,6 +7996,71 @@ qemuBuildSmpArgStr(const virDomainDef *def,
     return virBufferContentAndReset(&buf);
 }
 
+static int
+qemuBuildMemPathStr(virQEMUDriverConfigPtr cfg,
+                    virDomainDefPtr def,
+                    virQEMUCapsPtr qemuCaps,
+                    virCommandPtr cmd)
+{
+    const long system_page_size = virGetSystemPageSizeKB();
+    char *mem_path = NULL;
+    size_t i = 0;
+
+    /*
+     *  No-op if hugepages were not requested.
+     */
+    if (!def->mem.nhugepages)
+        return 0;
+
+    /* There is one special case: if user specified "huge"
+     * pages of regular system pages size.
+     * And there is nothing to do in this case.
+     */
+    if (def->mem.hugepages[0].size == system_page_size)
+        return 0;
+
+    if (!cfg->nhugetlbfs) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       "%s", _("hugetlbfs filesystem is not mounted "
+                               "or disabled by administrator config"));
+        return -1;
+    }
+
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_MEM_PATH)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("hugepage backing not supported by '%s'"),
+                       def->emulator);
+        return -1;
+    }
+
+    if (!def->mem.hugepages[0].size) {
+        if (!(mem_path = qemuGetDefaultHugepath(cfg->hugetlbfs,
+                                                cfg->nhugetlbfs)))
+            return -1;
+    } else {
+        for (i = 0; i < cfg->nhugetlbfs; i++) {
+            if (cfg->hugetlbfs[i].size == def->mem.hugepages[0].size)
+                break;
+        }
+
+        if (i == cfg->nhugetlbfs) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to find any usable hugetlbfs "
+                             "mount for %llu KiB"),
+                           def->mem.hugepages[0].size);
+            return -1;
+        }
+
+        if (!(mem_path = qemuGetHugepagePath(&cfg->hugetlbfs[i])))
+            return -1;
+    }
+
+    virCommandAddArgList(cmd, "-mem-prealloc", "-mem-path", mem_path, NULL);
+    VIR_FREE(mem_path);
+
+    return 0;
+}
+
 static int
 qemuBuildNumaArgStr(virQEMUDriverConfigPtr cfg,
                     virDomainDefPtr def,
@@ -9370,54 +9435,13 @@ qemuBuildCommandLine(virConnectPtr conn,
        virCommandAddArgFormat(cmd, "%llu", virDomainDefGetMemoryInitial(def) / 1024);
     }
 
-    if (def->mem.nhugepages && !virDomainNumaGetNodeCount(def->numa)) {
-        const long system_page_size = virGetSystemPageSizeKB();
-        char *mem_path = NULL;
-
-        if (def->mem.hugepages[0].size == system_page_size) {
-            /* There is one special case: if user specified "huge"
-             * pages of regular system pages size. */
-        } else {
-            if (!cfg->nhugetlbfs) {
-                virReportError(VIR_ERR_INTERNAL_ERROR,
-                               "%s", _("hugetlbfs filesystem is not mounted "
-                                       "or disabled by administrator config"));
-                goto error;
-            }
-            if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_MEM_PATH)) {
-                virReportError(VIR_ERR_INTERNAL_ERROR,
-                               _("hugepage backing not supported by '%s'"),
-                               def->emulator);
-                goto error;
-            }
-
-            if (def->mem.hugepages[0].size) {
-                for (j = 0; j < cfg->nhugetlbfs; j++) {
-                    if (cfg->hugetlbfs[j].size == def->mem.hugepages[0].size)
-                        break;
-                }
-
-                if (j == cfg->nhugetlbfs) {
-                    virReportError(VIR_ERR_INTERNAL_ERROR,
-                                   _("Unable to find any usable hugetlbfs mount for %llu KiB"),
-                                   def->mem.hugepages[0].size);
-                    goto error;
-                }
-
-                if (!(mem_path = qemuGetHugepagePath(&cfg->hugetlbfs[j])))
-                    goto error;
-            } else {
-                if (!(mem_path = qemuGetDefaultHugepath(cfg->hugetlbfs,
-                                                        cfg->nhugetlbfs)))
-                    goto error;
-            }
-        }
-
-        virCommandAddArg(cmd, "-mem-prealloc");
-        if (mem_path)
-            virCommandAddArgList(cmd, "-mem-path", mem_path, NULL);
-        VIR_FREE(mem_path);
-    }
+    /*
+     * Add '-mem-path' (and '-mem-prealloc') parameter here only if
+     * there is no numa node specified.
+     */
+    if (!virDomainNumaGetNodeCount(def->numa) &&
+        qemuBuildMemPathStr(cfg, def, qemuCaps, cmd) < 0)
+        goto error;
 
     if (def->mem.locked && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_MLOCK)) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

tests/qemuxml2argvdata/qemuxml2argv-hugepages-pages6.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc -m 1024 -mem-prealloc -smp 2 -nographic \
+/usr/bin/qemu -S -M pc -m 1024 -smp 2 -nographic \
 -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
 -hda /dev/HostVG/QEMUGuest1 -net none -serial none -parallel none