[libvirt] [PATCH] qemu_driver: fix setting vcpus for offline domain

[Pavel Hrdina]

On 01/14/2015 10:23 AM, Peter Krempa wrote:
> On Tue, Jan 13, 2015 at 02:46:03PM +0100, Pavel Hrdina wrote:
>> Commit e3435caf fixed hot-plugging of vcpus with strict memory pinning
>> on NUMA hosts, but unfortunately it also broke updating number of vcpus
>> for offline guests using our API.
>>
>> The issue is that we try to create a cpu cgroup for non-running guest
>> which fails as there are no cgroups for that domain. We should create
>> cgroups and update cpuset.mems only if we are hot-plugging.
>>
>> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
>> ---
>>   src/qemu/qemu_driver.c | 26 ++++++++++++++------------
>>   1 file changed, 14 insertions(+), 12 deletions(-)
>>
>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>> index cdf4173..3a343d0 100644
>> --- a/src/qemu/qemu_driver.c
>> +++ b/src/qemu/qemu_driver.c
>> @@ -4576,21 +4576,23 @@ 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;
>> +    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
>
> As we are also doing the guest agent cpu config stuff in this function
> and the cgroup stuff isn't required for that operation please add
>
> && !(flags & VIR_DOMAIN_VCPU_GUEST)
>
> to the condition.
>
>> +        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 (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;
>
>
> ACK with the addition.
>
> Peter
>

Thanks, I'll push it shortly.

Pavel