[libvirt] [PATCH 05/10] qemu: domain: Add common function to perform memory hotplug checks

[Peter Krempa]

Add a function that will aggregate various checks related to memory
hotplug so that they aren't scattered accross various parts of the
code.
---
 src/qemu/qemu_command.c | 26 ++---------------
 src/qemu/qemu_domain.c  | 77 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_domain.h  |  4 +++
 src/qemu/qemu_hotplug.c |  9 ++----
 4 files changed, 87 insertions(+), 29 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 43e81c7..4a709db 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -9414,26 +9414,12 @@ qemuBuildCommandLine(virConnectPtr conn,
         qemuDomainAlignMemorySizes(def) < 0)
         goto error;

+    if (qemuDomainDefValidateMemoryHotplug(def, qemuCaps, NULL) < 0)
+        goto error;
+
     virCommandAddArg(cmd, "-m");

     if (virDomainDefHasMemoryHotplug(def)) {
-        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_PC_DIMM)) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                           _("memory hotplug isn't supported by this QEMU binary"));
-            goto error;
-        }
-
-        /* due to guest support, qemu would silently enable NUMA with one node
-         * once the memory hotplug backend is enabled. To avoid possible
-         * confusion we will enforce user originated numa configuration along
-         * with memory hotplug. */
-        if (virDomainNumaGetNodeCount(def->numa) == 0) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                           _("At least one numa node has to be configured when "
-                             "enabling memory hotplug"));
-            goto error;
-        }
-
         /* Use the 'k' suffix to let qemu handle the units */
         virCommandAddArgFormat(cmd, "size=%lluk,slots=%u,maxmem=%lluk",
                                virDomainDefGetMemoryInitial(def),
@@ -9491,12 +9477,6 @@ qemuBuildCommandLine(virConnectPtr conn,
     /* memory hotplug requires NUMA to be enabled - we already checked
      * that memory devices are present only when NUMA is */

-    if (def->nmems > def->mem.memory_slots) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("memory device count '%zu' exceeds slots count '%u'"),
-                       def->nmems, def->mem.memory_slots);
-        goto error;
-    }

     for (i = 0; i < def->nmems; i++) {
         char *backStr;
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index bdc0e67..cb50754 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3553,6 +3553,83 @@ qemuDomainMachineIsS390CCW(const virDomainDef *def)


 /**
+ * qemuDomainDefValidateMemoryHotplug:
+ * @def: domain definition
+ * @qemuCaps: qemu capabilities object
+ * @mem: definition of memory device that is to be added to @def with hotplug
+ *
+ * Validates that the domain definition and memory modules have valid
+ * configuration and are possibly able to accept @mem via hotplug if it's
+ * passed.
+ *
+ * Returns 0 on success; -1 and a libvirt error on error.
+ */
+int
+qemuDomainDefValidateMemoryHotplug(const virDomainDef *def,
+                                   virQEMUCapsPtr qemuCaps,
+                                   const virDomainMemoryDef *mem)
+{
+    unsigned int nmems = def->nmems;
+    unsigned long long hotplugSpace;
+    unsigned long long hotplugMemory = 0;
+    size_t i;
+
+    hotplugSpace = def->mem.max_memory - virDomainDefGetMemoryInitial(def);
+
+    if (mem) {
+        nmems++;
+        hotplugMemory = mem->size;
+    }
+
+    if (!virDomainDefHasMemoryHotplug(def)) {
+        if (nmems) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("maxMemory has to be specified when using memory "
+                             "devices "));
+            return -1;
+        }
+
+        return 0;
+    }
+
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_PC_DIMM)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("memory hotplug isn't supported by this QEMU binary"));
+        return -1;
+    }
+
+    /* due to guest support, qemu would silently enable NUMA with one node
+     * once the memory hotplug backend is enabled. To avoid possible
+     * confusion we will enforce user originated numa configuration along
+     * with memory hotplug. */
+    if (virDomainNumaGetNodeCount(def->numa) == 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("At least one numa node has to be configured when "
+                         "enabling memory hotplug"));
+        return -1;
+    }
+
+    if (nmems > def->mem.memory_slots) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("memory device count '%u' exceeds slots count '%u'"),
+                       nmems, def->mem.memory_slots);
+        return -1;
+    }
+
+    for (i = 0; i < def->nmems; i++)
+        hotplugMemory += def->mems[i]->size;
+
+    if (hotplugMemory > hotplugSpace) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("memory device total size exceeds hotplug space"));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/**
  * qemuDomainUpdateCurrentMemorySize:
  *
  * Updates the current balloon size from the monitor if necessary. In case when
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 64cd7e1..23f5b1f 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -482,4 +482,8 @@ bool qemuDomainMachineIsS390CCW(const virDomainDef *def);
 int qemuDomainUpdateCurrentMemorySize(virQEMUDriverPtr driver,
                                       virDomainObjPtr vm);

+int qemuDomainDefValidateMemoryHotplug(const virDomainDef *def,
+                                       virQEMUCapsPtr qemuCaps,
+                                       const virDomainMemoryDef *mem);
+
 #endif /* __QEMU_DOMAIN_H__ */
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index afc5408..2c7f165 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1784,18 +1784,15 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     int id;
     int ret = -1;

-    if (vm->def->nmems == vm->def->mem.memory_slots) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                       _("no free memory device slot available"));
-        goto cleanup;
-    }
-
     if (virAsprintf(&mem->info.alias, "dimm%zu", vm->def->nmems) < 0)
         goto cleanup;

     if (virAsprintf(&objalias, "mem%s", mem->info.alias) < 0)
         goto cleanup;

+    if (qemuDomainDefValidateMemoryHotplug(vm->def, priv->qemuCaps, mem) < 0)
+        goto cleanup;
+
     if (vm->def->mem.cur_balloon == virDomainDefGetMemoryActual(vm->def))
         fix_balloon = true;

-- 
2.4.5