[libvirt] [PATCH 2/2] qemuDomainAttachMemory: Crate hugepage dir if needed

[Michal Privoznik]

https://bugzilla.redhat.com/show_bug.cgi?id=1455819

It may happen that a domain is started without any huge pages.
However, user might try to attach a DIMM module later. DIMM
backed by huge pages (why would somebody want to mix regular and
huge pages is beyond me). Therefore we have to create the dir if
we haven't done so far.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_hotplug.c |  3 +++
 src/qemu/qemu_process.c | 20 ++++++++++++++++----
 src/qemu/qemu_process.h |  5 +++++
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 4a7d99725..62472aef8 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2254,6 +2254,9 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
                                   priv->qemuCaps, vm->def, mem, NULL, true) < 0)
         goto cleanup;
 
+    if (qemuProcessBuildDestroyHugepagesPath(driver, vm, mem, true) < 0)
+        goto cleanup;
+
     if (qemuDomainNamespaceSetupMemory(driver, vm, mem) < 0)
         goto cleanup;
     teardowndevice = true;
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index a219a8080..823a1385f 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3283,9 +3283,10 @@ qemuProcessReconnectCheckMemAliasOrderMismatch(virDomainObjPtr vm)
 }
 
 
-static int
+int
 qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
                                      virDomainObjPtr vm,
+                                     virDomainMemoryDefPtr mem,
                                      bool build)
 {
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
@@ -3314,6 +3315,12 @@ qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
         }
     }
 
+    if (mem &&
+        mem->model == VIR_DOMAIN_MEMORY_MODEL_DIMM &&
+        mem->pagesize &&
+        mem->pagesize != system_pagesize)
+        shouldBuild = true;
+
     if (!build ||
         (build && shouldBuild)) {
         for (i = 0; i < cfg->nhugetlbfs; i++) {
@@ -3324,6 +3331,11 @@ qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
                 goto cleanup;
 
             if (build) {
+                if (virFileExists(hugepagePath)) {
+                    ret = 0;
+                    goto cleanup;
+                }
+
                 if (virFileMakePathWithMode(hugepagePath, 0700) < 0) {
                     virReportSystemError(errno,
                                          _("Unable to create %s"),
@@ -3497,7 +3509,7 @@ qemuProcessReconnect(void *opaque)
         goto cleanup;
     }
 
-    if (qemuProcessBuildDestroyHugepagesPath(driver, obj, true) < 0)
+    if (qemuProcessBuildDestroyHugepagesPath(driver, obj, NULL, true) < 0)
         goto error;
 
     if ((qemuDomainAssignAddresses(obj->def, priv->qemuCaps,
@@ -5541,7 +5553,7 @@ qemuProcessPrepareHost(virQEMUDriverPtr driver,
                                NULL) < 0)
         goto cleanup;
 
-    if (qemuProcessBuildDestroyHugepagesPath(driver, vm, true) < 0)
+    if (qemuProcessBuildDestroyHugepagesPath(driver, vm, NULL, true) < 0)
         goto cleanup;
 
     /* Ensure no historical cgroup for this VM is lying around bogus
@@ -6225,7 +6237,7 @@ void qemuProcessStop(virQEMUDriverPtr driver,
         goto endjob;
     }
 
-    qemuProcessBuildDestroyHugepagesPath(driver, vm, false);
+    qemuProcessBuildDestroyHugepagesPath(driver, vm, NULL, false);
 
     vm->def->id = -1;
 
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index 830d8cef8..b63784152 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -192,4 +192,9 @@ int qemuProcessRefreshDisks(virQEMUDriverPtr driver,
                             virDomainObjPtr vm,
                             qemuDomainAsyncJob asyncJob);
 
+int qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
+                                         virDomainObjPtr vm,
+                                         virDomainMemoryDefPtr mem,
+                                         bool build);
+
 #endif /* __QEMU_PROCESS_H__ */
-- 
2.13.0