[libvirt PATCH v2] qemu: substitute missing model name for host-passthrough

[Collin Walling]

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 at 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 at 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 at redhat.com>
>>
>> I'll wait some time for Collin to add Signed-of-by tag before pushing
>> this.
>>
> 
> Signed-off-by: Collin Walling <walling at 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.

I can propose something to wrap the above in a helper function and
extend its use for baseline as well.

-- 
Regards,
Collin

Stay safe and stay healthy