Re: [PATCH v2 0/7] x86/kvm/hyperv: stable clocksorce for L2 guests when running nested KVM on Hyper-V

From: Vitaly Kuznetsov
Date: Fri Dec 15 2017 - 04:31:05 EST


Paolo Bonzini <pbonzini@xxxxxxxxxx> writes:

> On 13/12/2017 16:09, Vitaly Kuznetsov wrote:
>> Currently, KVM passes PVCLOCK_TSC_STABLE_BIT to its guests when running in
>> so called 'masterclock' mode and this is only possible when the clocksource
>> on the host is TSC. When running nested on Hyper-V we're using a different
>> clocksource in L1 (Hyper-V TSC Page) which can actually be used for
>> masterclock. This series brings the required support.
>>
>> Making KVM work with TSC page clocksource is relatively easy, it is done in
>> PATCH 5 of the series. All the rest is required to support L1 migration
> ^^^^^^^
>
> Patch 6. :)
>

Off-by-one :-)

>> when TSC frequency changes, we use a special feature from Hyper-V to do
>> the job.
>
> Patches 5-7 are
>
> Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>

Thanks!

> I would appreciate if the Hyper-V folks can provide a topic branch to be
> merged in both HV and KVM trees.
>

There's no such thing as Hyper-V tree, patches are usually getting
merged through 'tip' tree when the majority of changes go to arch/x86 or
Greg's char-misc tree when changes are drivers/hv heavy (+ net, scsi,
pci, hid, ... trees for individual drivers).

In this particular case the series is x86-heavy and I believe it should
go through x86 'tip' tree.

Thomas, Ingo, Peter, could you please take a look? Thanks!

--
Vitaly