From 5b24d250629ab4ead365878933156586983770e3 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Wed, 7 Jun 2017 14:47:37 +0200
Subject: [PATCH] qemuDomainAttachMemory: Crate hugepage dir if needed

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@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
---
 src/qemu/qemu_hotplug.c |  3 +++
 src/qemu/qemu_process.c | 25 +++++++++++++++++++------
 src/qemu/qemu_process.h |  5 +++++
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 96f3f4579d..0b8d3d80f1 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2258,6 +2258,9 @@ 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 59cca2736d..85b800da3d 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3284,7 +3284,8 @@ qemuProcessReconnectCheckMemAliasOrderMismatch(virDomainObjPtr vm)
 
 
 static bool
-qemuProcessNeedHugepagesPath(virDomainDefPtr def)
+qemuProcessNeedHugepagesPath(virDomainDefPtr def,
+                             virDomainMemoryDefPtr mem)
 {
     const long system_pagesize = virGetSystemPageSizeKB();
     size_t i;
@@ -3304,13 +3305,20 @@ qemuProcessNeedHugepagesPath(virDomainDefPtr def)
             return true;
     }
 
+    if (mem &&
+        mem->model == VIR_DOMAIN_MEMORY_MODEL_DIMM &&
+        mem->pagesize &&
+        mem->pagesize != system_pagesize)
+        return true;
+
     return false;
 }
 
 
-static int
+int
 qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
                                      virDomainObjPtr vm,
+                                     virDomainMemoryDefPtr mem,
                                      bool build)
 {
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
@@ -3320,7 +3328,7 @@ qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
     int ret = -1;
 
     if (build)
-        shouldBuild = qemuProcessNeedHugepagesPath(vm->def);
+        shouldBuild = qemuProcessNeedHugepagesPath(vm->def, mem);
 
     if (!build || shouldBuild) {
         for (i = 0; i < cfg->nhugetlbfs; i++) {
@@ -3331,6 +3339,11 @@ 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"),
@@ -3504,7 +3517,7 @@ 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,
@@ -5572,7 +5585,7 @@ 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
@@ -6259,7 +6272,7 @@ 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 c38310b47a..667d5c53d5 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -38,6 +38,11 @@ int qemuProcessStopCPUs(virQEMUDriverPtr driver,
                         virDomainPausedReason reason,
                         qemuDomainAsyncJob asyncJob);
 
+int qemuProcessBuildDestroyHugepagesPath(virQEMUDriverPtr driver,
+                                         virDomainObjPtr vm,
+                                         virDomainMemoryDefPtr mem,
+                                         bool build);
+
 void qemuProcessAutostartAll(virQEMUDriverPtr driver);
 void qemuProcessReconnectAll(virConnectPtr conn, virQEMUDriverPtr driver);
 
-- 
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