From 7be804cd87131dbb2a0861e07980826a15dce376 Mon Sep 17 00:00:00 2001
Message-Id: <7be804cd87131dbb2a0861e07980826a15dce376@dist-git>
From: Andrea Bolognani <abologna@redhat.com>
Date: Tue, 4 Jun 2019 16:22:06 +0200
Subject: [PATCH] qemu: Fix qemuProcessInitCpuAffinity()
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Ever since the feature was introduced with commit 0f8e7ae33ace,
it has contained a logic error in that it attempted to use a NUMA
node map where a CPU map was expected.

Because of that, guests using <numatune> might fail to start:

  # virsh start guest
  error: Failed to start domain guest
  error: cannot set CPU affinity on process 40055: Invalid argument

This was particularly easy to trigger on POWER 8 machines, where
secondary threads always show up as offline in the host: having

  <numatune>
    <memory mode='strict' placement='static' nodeset='1'/>
  </numatune>

in the guest configuration, for example, would result in libvirt
trying to set the process affinity so that it would prefer
running on CPU 1, but since that's a secondary thread and thus
shows up as offline, the operation would fail, and so would
starting the guest.

Use the newly introduced virNumaNodesetToCPUset() to convert the
NUMA node map to a CPU map, which in the example above would be
48,56,64,72,80,88 - a valid input for virProcessSetAffinity().

https://bugzilla.redhat.com/show_bug.cgi?id=1703661

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
(cherry picked from commit 5f2212c062c720716b7701fa0a5511311dc6e906)
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Message-Id: <20190604142207.2036-6-abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_process.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 7f70d79566..4c28f250f6 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -2382,11 +2382,16 @@ qemuProcessInitCpuAffinity(virDomainObjPtr vm)
     if (virDomainNumaGetNodeCount(vm->def->numa) <= 1 &&
         virDomainNumatuneGetMode(vm->def->numa, -1, &mem_mode) == 0 &&
         mem_mode == VIR_DOMAIN_NUMATUNE_MEM_STRICT) {
+        virBitmapPtr nodeset = NULL;
+
         if (virDomainNumatuneMaybeGetNodeset(vm->def->numa,
                                              priv->autoNodeset,
-                                             &cpumapToSet,
+                                             &nodeset,
                                              -1) < 0)
             goto cleanup;
+
+        if (virNumaNodesetToCPUset(nodeset, &cpumapToSet) < 0)
+            goto cleanup;
     } else if (vm->def->cputune.emulatorpin) {
         cpumapToSet = vm->def->cputune.emulatorpin;
     } else {
-- 
2.21.0