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Subject: Re: [PATCH v4 2/2] x86/kvm: Provide optimized version of
 vcpu_is_preempted() for x86-64
To: Peter Zijlstra <peterz@infradead.org>
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From: Waiman Long <longman@redhat.com>
Organization: Red Hat
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Date: Thu, 16 Feb 2017 16:00:10 -0500
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On 02/16/2017 11:48 AM, Peter Zijlstra wrote:
> On Wed, Feb 15, 2017 at 04:37:50PM -0500, Waiman Long wrote:
>> +/*
>> + * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
>> + * restoring to/from the stack. It is assumed that the preempted value
>> + * is at an offset of 16 from the beginning of the kvm_steal_time structure
>> + * which is verified by the BUILD_BUG_ON() macro below.
>> + */
>> +#define PREEMPTED_OFFSET	16
> As per Andrew's suggestion, the 'right' way is something like so.

Thanks for the tip. I was not aware of the asm-offsets stuff. I will
update the patch to use it.

Cheers,
Longman