Re: [PATCH 8/8] x86, cleanups: Simplify sync_core() in the case ofno CPUID

From: H. Peter Anvin
Date: Thu Nov 29 2012 - 16:20:07 EST


On 11/29/2012 01:18 PM, Borislav Petkov wrote:
> On Thu, Nov 29, 2012 at 01:06:20PM -0800, H. Peter Anvin wrote:
>> It doesn't matter in that context, as the surrounding MSR references
>> have barriers, but what I'm refering to is the "memory" barrier.
>
> Ok, but the only difference between the two versions is this line:
>
> movl %esi, %ecx # tmp144, ecx
>
> coming from the cpuid_eax() function. So the memory barrier is the same
> and in the right place in both cases.
>

In the case of that one call site, yes, because the MSR references
include the barrier. Other sites, current or future, may not have the
same property.

-hpa


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