On 09/25/2014 02:59 PM, Ján Tomko wrote:
> On 09/25/2014 04:31 AM, zhang bo wrote:
>> On 2014/9/24 19:49, Ján Tomko wrote:
>>> I think the simplest fix for host-passthrough would be to apply the same
>>> filter host-model has.
>>>
>>> But since using invtsc with host-passthrough requires both +invtsc and
>>> migratable=no, so we'd need to either add a 'migratable' option to
>>> host-passthrough (this would skip the filter and add migratable=on), or
>>> allow
>>> fine-tuning the features for host-passthrough too.
>>>
>>> Jan
>>>
>>
>> Additional to the 2 suggestions, will that be OK to remove the codes in
>> qemuProcessVerifyGuestCPU that checks whether the vm->def has
>> invtsc flag while qemu doesn't?
>>
>> - if (STREQ(feature->name, "invtsc") &&
>> - !cpuHasFeature(guestcpu, feature->name)) {
>> - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> - _("host doesn't support invariant TSC"));
>> - goto cleanup;
>> - }
>
> Without this check, the feature would be quietly discarded by QEMU if the host
> kernel or host CPU does not support this feature.
>
> I think it's better to leave "invtsc" out when we're generating the cpu
> definition for host-passthrough, as we do for host-model.
>
> Jan
>
>>
>> Removing these codes, plus with the solution that "add 'migratable'
>> option to host-passthrough", it seems the problem would
>> be gone, and invtsc would not be so 'distinctive' in libvirt any more.
>>I've sent a patch that filters out the flag and also ignores the check for host-passthrough (to allow guests already saved with the flag to be restored) https://www.redhat.com/archives/libvir-list/2014-September/msg01680.html Can you please take a look at it? Thanks, Jan
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