Re: [libvirt] [PATCH 4/4] qemu: Fix qemuProcessInitCpuAffinity()

Commit f136b83139c6 made some changes in the way we set CPU affinity for QEMU processes, and while doing so unfortunately also introduced a logic bug in that it tried to use a NUMA node map where a CPU map was expected. Because of that, guests using <numatune> would suddenly 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 8-15 with CPU 8 showing up as online in the guest. https://bugzilla.redhat.com/show_bug.cgi?id=1703661 Signed-off-by: Andrea Bolognani <abologna(a)redhat.com&gt; --- 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 fa5909e9be..295ad2e1ff 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2489,11 +2489,16 @@ 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 {