Re: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI

From: Nadav Amit
Date: Tue Jan 20 2015 - 16:04:24 EST


Radim Kr?mÃ? <rkrcmar@xxxxxxxxxx> wrote:

> 2015-01-14 01:27+0000, Wu, Feng:
>>> the new
>>>> hardware even doesn't consider the TPR for lowest priority interrupts
>>> delivery.
>>>
>>> A bold move ... what hardware was the first to do so?
>>
>> I think it was starting with Nehalem.
>
> Thanks, (Could be that QPI can't inform about TPR changes anymore ...)
>
> I played with Linux's TPR on Haswell and found that is has no effect.

Sorry for jumping into the discussion, but doesnât it depend on
IA32_MISC_ENABLE[23]? This bit disables xTPR messages. On my machine it is
set (probably by the BIOS), but since there is no IA32_MISC_ENABLE is not
locked for changes, the OS can control it.

Nadav--
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