From 43c846034c4316cf53d193f52c59f4f9df484fe5 Mon Sep 17 00:00:00 2001
Message-Id: <43c846034c4316cf53d193f52c59f4f9df484fe5@dist-git>
From: Martin Kletzander <mkletzan@redhat.com>
Date: Thu, 15 Jan 2015 15:03:49 +0100
Subject: [PATCH] qemu: Fix hotplugging cpus with strict memory pinning

When hot-plugging a VCPU into the guest, kvm needs to allocate some data
from the DMA zone, which might be in a memory node that's not allowed in
cpuset.mems.  Basically the same problem as there was with starting the
domain and due to which commit 7e72ac787848b7434c9359a57c1e2789d92350f8
exists.  This patch just extends it to hotplugging as well.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1161540

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
(cherry picked from commit e3435caf6af41748204e542dee13ede8441d88c0)
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_driver.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ea9368d..afcf326 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -97,6 +97,7 @@
 #include "virhostdev.h"
 #include "domain_capabilities.h"
 #include "vircgroup.h"
+#include "virnuma.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
@@ -4641,6 +4642,11 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
     int ncpuinfo;
     qemuDomainObjPrivatePtr priv;
     size_t i;
+    virCgroupPtr cgroup_temp = NULL;
+    char *mem_mask = NULL;
+    char *all_nodes_str = NULL;
+    virBitmapPtr all_nodes = NULL;
+    virErrorPtr err = NULL;
 
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG |
@@ -4666,9 +4672,22 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
 
     priv = vm->privateData;
 
+    if (virCgroupNewEmulator(priv->cgroup, false, &cgroup_temp) < 0)
+        goto cleanup;
+
+    if (!(all_nodes = virNumaGetHostNodeset()))
+        goto cleanup;
+
+    if (!(all_nodes_str = virBitmapFormat(all_nodes)))
+        goto cleanup;
+
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;
 
+    if (virCgroupGetCpusetMems(cgroup_temp, &mem_mask) < 0 ||
+        virCgroupSetCpusetMems(cgroup_temp, all_nodes_str) < 0)
+        goto endjob;
+
     maximum = (flags & VIR_DOMAIN_VCPU_MAXIMUM) != 0;
     flags &= ~VIR_DOMAIN_VCPU_MAXIMUM;
 
@@ -4778,6 +4797,12 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
     ret = 0;
 
  endjob:
+    if (mem_mask) {
+        err = virSaveLastError();
+        virCgroupSetCpusetMems(cgroup_temp, mem_mask);
+        virSetError(err);
+    }
+
     if (!qemuDomainObjEndJob(driver, vm))
         vm = NULL;
 
@@ -4786,6 +4811,10 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     VIR_FREE(cpuinfo);
+    VIR_FREE(mem_mask);
+    VIR_FREE(all_nodes_str);
+    virBitmapFree(all_nodes);
+    virCgroupFree(&cgroup_temp);
     virObjectUnref(cfg);
     return ret;
 }
-- 
2.2.1