Re: [PATCH 1/5] x86/ibrs: Introduce native_rdmsrl, and native_wrmsrl

From: Andy Lutomirski
Date: Sat Jan 13 2018 - 01:20:37 EST


On Thu, Jan 11, 2018 at 7:01 PM, Raj, Ashok <ashok.raj@xxxxxxxxx> wrote:
> On Thu, Jan 11, 2018 at 06:20:13PM -0800, Andy Lutomirski wrote:
>> On Thu, Jan 11, 2018 at 5:52 PM, Raj, Ashok <ashok.raj@xxxxxxxxx> wrote:
>> >>
>> >> What's wrong with native_read_msr()?
>> >
>> > Yes, i think i should have added to msr.h. The names didn't read as a
>> > pair, one was native_read_msr, wrmsrl could be taken over when paravirt is
>> > defined?
>>
>> Why do you need to override paravirt?
>
> The idea was since these MSR's are passed through we shouldn't need to
> handle them any differently. Also its best to do this as soon as possible
> and avoid longer paths to get this barrier to hardware.
>

It should end up with essentially the same instructions at runtime.
I'm generally in favor of using the less weird code when it will work.