[PATCH 1/5] qemu.conf changes to support multiple memory backend directories

[mgalaxy@xxxxxxxxxx]

From: Michael Galaxy <mgalaxy@xxxxxxxxxx>

We start by introducing a backwards-compatible, comma-separated
specification that will not break existing installations, such
as in the following example:

$ cat qemu.conf | grep memory_backing_dir
memory_backing_dir = "/path/to/pmem/0,/path/to/pmem/1"

In our case, we almost always have two NUMA nodes, so in that
example, we have two PMEM regions which are created on the
Linux kernel command line that get mounted into those two
locations for libvirt to use.

Later patches will recognize this configuration and activate it.

Signed-off-by: Michael Galaxy <mgalaxy@xxxxxxxxxx>
---
 src/qemu/qemu_conf.c | 39 +++++++++++++++++++++++++++++++++------
 src/qemu/qemu_conf.h |  3 ++-
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 4050a82341..aae9f316d8 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -43,6 +43,7 @@
 #include "virfile.h"
 #include "virstring.h"
 #include "virutil.h"
+#include "virnuma.h"
 #include "configmake.h"
 #include "security/security_util.h"
 
@@ -137,6 +138,9 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
 
     cfg->cgroupControllers = -1; /* -1 == auto-detect */
 
+    cfg->memoryBackingDirs = g_new0(char *, 1);
+    cfg->nb_memoryBackingDirs = 1;
+
     if (root != NULL) {
         cfg->logDir = g_strdup_printf("%s/log/qemu", root);
         cfg->swtpmLogDir = g_strdup_printf("%s/log/swtpm", root);
@@ -153,7 +157,7 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
         cfg->checkpointDir = g_strdup_printf("%s/checkpoint", cfg->libDir);
         cfg->autoDumpPath = g_strdup_printf("%s/dump", cfg->libDir);
         cfg->nvramDir = g_strdup_printf("%s/nvram", cfg->libDir);
-        cfg->memoryBackingDir = g_strdup_printf("%s/ram", cfg->libDir);
+        cfg->memoryBackingDirs[0] = g_strdup_printf("%s/ram", cfg->libDir);
     } else if (privileged) {
         cfg->logDir = g_strdup_printf("%s/log/libvirt/qemu", LOCALSTATEDIR);
 
@@ -174,7 +178,8 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
         cfg->checkpointDir = g_strdup_printf("%s/checkpoint", cfg->libDir);
         cfg->autoDumpPath = g_strdup_printf("%s/dump", cfg->libDir);
         cfg->nvramDir = g_strdup_printf("%s/nvram", cfg->libDir);
-        cfg->memoryBackingDir = g_strdup_printf("%s/ram", cfg->libDir);
+
+        cfg->memoryBackingDirs[0] = g_strdup_printf("%s/ram", cfg->libDir);
         cfg->swtpmStorageDir = g_strdup_printf("%s/lib/libvirt/swtpm",
                                                LOCALSTATEDIR);
     } else {
@@ -201,7 +206,7 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
                                              cfg->configBaseDir);
         cfg->autoDumpPath = g_strdup_printf("%s/qemu/dump", cfg->configBaseDir);
         cfg->nvramDir = g_strdup_printf("%s/qemu/nvram", cfg->configBaseDir);
-        cfg->memoryBackingDir = g_strdup_printf("%s/qemu/ram", cfg->configBaseDir);
+        cfg->memoryBackingDirs[0] = g_strdup_printf("%s/qemu/ram", cfg->configBaseDir);
         cfg->swtpmStorageDir = g_strdup_printf("%s/qemu/swtpm",
                                                cfg->configBaseDir);
     }
@@ -369,7 +374,12 @@ static void virQEMUDriverConfigDispose(void *obj)
 
     virFirmwareFreeList(cfg->firmwares, cfg->nfirmwares);
 
-    g_free(cfg->memoryBackingDir);
+    for (size_t i = 0; i < cfg->nb_memoryBackingDirs; i++) {
+	    g_free(cfg->memoryBackingDirs[i]);
+    }
+
+    g_free(cfg->memoryBackingDirs);
+
     g_free(cfg->swtpmStorageDir);
 
     g_strfreev(cfg->capabilityfilters);
@@ -1019,14 +1029,31 @@ virQEMUDriverConfigLoadMemoryEntry(virQEMUDriverConfig *cfg,
                                    virConf *conf)
 {
     g_autofree char *dir = NULL;
+    g_auto(GStrv) params = NULL;
+    GStrv next;
     int rc;
 
     if ((rc = virConfGetValueString(conf, "memory_backing_dir", &dir)) < 0)
         return -1;
 
     if (rc > 0) {
-        VIR_FREE(cfg->memoryBackingDir);
-        cfg->memoryBackingDir = g_strdup_printf("%s/libvirt/qemu", dir);
+        size_t i;
+        for (i = 0; i < cfg->nb_memoryBackingDirs; i++)
+            VIR_FREE(cfg->memoryBackingDirs[i]);
+
+        if (!(params = g_strsplit(dir, ",", 0))) {
+            return -1;
+        }
+
+        cfg->nb_memoryBackingDirs = 0;
+        for (next = params; *next; next++) {
+            cfg->nb_memoryBackingDirs++;
+        }
+
+        cfg->memoryBackingDirs = g_new0(char *, cfg->nb_memoryBackingDirs);
+        for (i = 0, next = params; *next; next++, i++) {
+            cfg->memoryBackingDirs[i] = g_strdup_printf("%s/libvirt/qemu", *next);
+        }
     }
 
     return 0;
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index 36049b4bfa..2b8d540df0 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -221,7 +221,8 @@ struct _virQEMUDriverConfig {
     unsigned int glusterDebugLevel;
     bool virtiofsdDebug;
 
-    char *memoryBackingDir;
+    char **memoryBackingDirs;
+    size_t nb_memoryBackingDirs;
 
     uid_t swtpm_user;
     gid_t swtpm_group;
-- 
2.25.1
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