Re: [PATCH RESEND 1/1] X86: Handle Hyper-V vmbus interrupts asspecial hypervisor interrupts

From: Jan Beulich
Date: Fri Jan 25 2013 - 02:34:52 EST


>>> On 24.01.13 at 19:59, Olaf Hering <olaf@xxxxxxxxx> wrote:
> On Thu, Jan 24, KY Srinivasan wrote:
>
>
>> > Question is - considering you stated that this is supported
>> > starting in Win8, doesn't Hyper-V itself announce that
>> > capability in some explicit way?
>>
>> Thanks Jan. Unfortunately I don't think tis interrupt delivery model
>> is specified via a "feature" bit (I will check with the Windows guys).
>> Perhaps, we can have a Hyper-V specific compilation switch to address
>> the Xen emulation issue.
>
> Would that really help if both pvops XEN_PVHVM and HYPERV are enabled in
> the config? I assume at this point the access to the DMI data is not yet
> possible.

As just said in another reply - with XEN_PVHVM, there's no problem,
since Xen gets checked for first. There's only a problem when
!XEN_PVHVM, because in that case Hyper-V will be probed for.
And the problem can only get bigger when on top of that the
out-of-tree PV drivers are intended to be used.

Jan

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