Re: [Xen-devel] [PATCH] xen: fix initialization of wallclock time for PVHVM on migration

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.06.13 at 14:17, Roger Pau MonnÃ<roger.pau@xxxxxxxxxx> wrote:
> On 11/06/13 13:59, Jan Beulich wrote:
>>>>> On 11.06.13 at 12:46, Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
>>> The initial values of the wallclock time in the shared info page are
>>> set for PVHVM guests when the hypercall page is initialized, since the
>>> hypercall page is not reinitialized on resume, the hypervisor
>>> wallclock time is not properly set on resume.
>>>
>>> Fix it by forcing an update of the wallclock values when the shared
>>> info page is mapped.
>> 
>> NACK - this is a guest side bug. After migration, a guest _has_ to
>> re-init the hypercall page, as it may have got migrated between
>> a VMX and an SVM machine, and the hypercall instructions are
>> different between them.
> 
> AFAICS Linux doesn't seem to re-init the hypercall page, see
> xen_arch_hvm_post_suspend at arch/x86/xen/suspend.c, but maybe I'm
> missing something.

I just looked at the unmodified_drivers/ tree, and there this re-init
is being done.

Jan

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