Re: [Xen-devel] support for more than 32 VCPUs when migrating PVHVM guest

[Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>]

Andrew Cooper <andrew.cooper3@xxxxxxxxxx> writes:

> On 02/02/15 10:47, Vitaly Kuznetsov wrote:
>> Hi Konrad,
>>
>> I just hit an issue with PVHVM guests after save/restore (or migration),
>> if a PVHVM guest has > 32 VCPUs it hangs. Turns out, you saw it almost a
>> year ago and even wrote patches to call VCPUOP_register_vcpu_info after
>> resume. Unfortunately these patches never made it to xen/kernel. Do you
>> have a plan to pick this up? What were the arguments against your
>> suggestion?
>
> 32 VCPUs is the legacy limit for HVM guests, but should not have any
> remaining artefacts these days.
>
> Do you know why the hang occurs?  I can't spot anything in the legacy
> migration code which would enforce such a limit.
>
> What is the subject of the thread you reference so I can search for it?
>

Sorry, I should have send the link:

http://lists.xen.org/archives/html/xen-devel/2014-04/msg00794.html

Konrad's patches:

http://lists.xen.org/archives/html/xen-devel/2014-04/msg01199.html

The issue is that we don't call VCPUOP_register_vcpu_info after
suspend/resume (or migration) and it is mandatory.

-- 
  Vitaly

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