5:29 p.m.
On 9/23/20 5:01 PM, Jiri Denemark wrote:
On Wed, Sep 23, 2020 at 16:17:04 -0400, Collin Walling wrote:
> On 9/23/20 2:52 PM, Collin Walling wrote:
>> On 9/23/20 10:18 AM, Jiri Denemark wrote:
>>> On Wed, Sep 23, 2020 at 09:26:58 +0200, Tim Wiederhake wrote:
>>>> From: Collin Walling <walling(a)linux.ibm.com>
>>>>
>>>> Before:
>>>> $ uname -m
>>>> s390x
>>>> $ cat passthrough-cpu.xml
>>>> <cpu check="none" mode="host-passthrough" />
>>>> $ virsh hypervisor-cpu-compare passthrough-cpu.xml
>>>> error: Failed to compare hypervisor CPU with passthrough-cpu.xml
>>>> error: internal error: unable to execute QEMU command
'query-cpu-model-comp
>>>> arison': Invalid parameter type for 'modelb.name',
expected: string
>>>>
>>>> After:
>>>> $ virsh hypervisor-cpu-compare passthrough-cpu.xml
>>>> CPU described in passthrough-cpu.xml is identical to the CPU provided
by hy
>>>> pervisor on the host
>>>>
>>>> Signed-off-by: Tim Wiederhake <twiederh(a)redhat.com>
>>>> ---
>>>> src/qemu/qemu_driver.c | 9 +++++++++
>>>> 1 file changed, 9 insertions(+)
>>>>
>>>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>>>> index ae715c01d7..1cecef01f7 100644
>>>> --- a/src/qemu/qemu_driver.c
>>>> +++ b/src/qemu/qemu_driver.c
>>>> @@ -12336,6 +12336,15 @@ qemuConnectCompareHypervisorCPU(virConnectPtr
conn,
>>>> if (virCPUDefParseXMLString(xmlCPU, VIR_CPU_TYPE_AUTO, &cpu)
< 0)
>>>> goto cleanup;
>>>>
>>>> + if (!cpu->model) {
>>>> + if (cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH) {
>>>> + cpu->model = g_strdup("host");
>>>> + } else {
>>>> + virReportError(VIR_ERR_INVALID_ARG, "%s",
>>>> + _("cpu parameter is missing a model
name"));
>>>> + goto cleanup;
>>>> + }
>>>> + }
>>>> ret = qemuConnectCPUModelComparison(qemuCaps, cfg->libDir,
>>>> cfg->user,
cfg->group,
>>>> hvCPU, cpu,
failIncompatible);
>>>
>>> Reviewed-by: Jiri Denemark <jdenemar(a)redhat.com>
>>>
>>> I'll wait some time for Collin to add Signed-of-by tag before pushing
>>> this.
>>>
>>
>> Signed-off-by: Collin Walling <walling(a)linux.ibm.com>
>>
>> Thanks!
>>
>
> Actually, it might help to extend this functionality for baseline as
> well. If anything to at least catch the case when a CPU definition in
> the XML file is missing a <model> tag. Right now, virsh will either
> report "an unknown error occurred" when the XML file contains a _single_
> <cpu> element without a <model> tag, or it will report the same
"Invalid
> parameter type for 'modela.name', expected: string" mentioned above
when
> there are multiple definitions in the file, and at least one of them is
> missing a <model> tag.
Hmm, I would expect libvirt to complain about missing CPU model. If
that's not the case, we need to fix it. But we should not fix it the
same way. This change in the Compare API is hidden inside libvirt, we
just tell QEMU we're comparing "host" when the cpu->mode is
host-passthrough and get the result, which is basically yes/no.
But with baseline we get the result and make a guest CPU definition out
of it. By setting cpu->model to "host" we would could end up with
<model>host</model> in the result or even random result depending on the
host performing the baseline API. This API should just reject any CPU
definition without <model> as invalid argument.
Jirka
On s390x, QMP will internally convert the model "host" to a proper CPU
model.
How about when baselining and if there is only a single CPU definition
and the model is "host" (either provided verbatim by the file, or
converted when the mode is host-passthrough), then perform a CPU model
expansion on the single CPU definition? No baselining would technically
be performed in this case.
I think this would support the behavior reported by the virsh man page:
"""
When FILE contains only a single CPU definition, the command will print
the same CPU with restrictions imposed by the capabilities of
the hypervisor. Specifically, running th virsh
hypervisor-cpu-baseline command with no additional options on the
result of virsh domcapabili‐ ties will transform the host CPU
model from domain capabilities XML to a form directly usable in
domain XML.
"""
Essentially 2 patches:
- set model name to "host" when mode is "host-passthrough" for
baseline
- use CPU model expansion when baseline is executed with only a single CPU
I can propose the patches tonight and we can look them over whenever.
--
Regards,
Collin
Stay safe and stay healthy