From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock
Date: Fri, 23 Apr 2010 12:34:45 +0300
Message-ID: <4BD169B5.4000409@redhat.com>
References: <1271675100.1674.818.camel@laptop> <4BCC3A3E.9070909@redhat.com> <20100419142158.GD14158@mothafucka.localdomain> <4BCC69D5.3050209@redhat.com> <1271688411.1488.248.camel@laptop> <4BCC8246.9040202@goop.org> <4BCD748E.7080007@redhat.com> <4BCDF12C.1020702@goop.org> <4BCDF85C.3000004@redhat.com> <4BCE0399.2010708@goop.org> <20100422131113.GA3364@mothafucka.localdomain> <4BD0FB92.4060301@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Glauber Costa <glommer@redhat.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	Peter Zijlstra <peterz@infradead.org>, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>
To: Zachary Amsden <zamsden@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <4BD0FB92.4060301@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 04/23/2010 04:44 AM, Zachary Amsden wrote:
>    Or apply this patch.
> time-warp.patch
>
>
> diff -rup a/time-warp-test.c b/time-warp-test.c
> --- a/time-warp-test.c	2010-04-15 16:30:13.955981607 -1000
> +++ b/time-warp-test.c	2010-04-15 16:35:37.777982377 -1000
> @@ -91,7 +91,7 @@ static inline unsigned long long __rdtsc
>   {
>   	DECLARE_ARGS(val, low, high);
>
> -	asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high));
> +	asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high) :: "ebx", "ecx");
>
>    

Plus, replace cpuid by lfence/mfence.  cpuid will trap.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.