linux-kernel - Re: [PATCH v2] KVM: x86: Prevent exposing TSC deadline timer feature in the absence of in-kernel APIC

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Date:	Wed, 21 Dec 2011 12:35:41 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Jan Kiszka <jan.kiszka@...mens.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alexey Zaytsev <alexey.zaytsev@...il.com>,
	"Liu, Jinsong" <jinsong.liu@...el.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	"Garrett D'Amore" <garrett@...enta.com>, kvm <kvm@...r.kernel.org>
Subject: Re: [PATCH v2] KVM: x86: Prevent exposing TSC deadline timer feature
 in the absence of in-kernel APIC

On 12/21/2011 12:25 PM, Jan Kiszka wrote:
> We must not report the TSC deadline timer feature on our own when user
> space provides the APIC as we have no clue about its features.

We must not report the TSC deadline timer feature on our own, period. 
We should just update the timer mode mask there.  Don't know how this
slipped through review.

I think your original idea was correct.  Add a new KVM_CAP for the tsc
deadline timer.  Userspace can add the bit to cpuid if either it
implements the feature in a userspace apic, or if it finds the new
capability and uses the kernel apic.

-- 
error compiling committee.c: too many arguments to function

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