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Subject: Re: [PATCH 1/5] x86/ibrs: Introduce native_rdmsrl, and native_wrmsrl
To: "Raj, Ashok" <ashok.raj@intel.com>,
        Andy Lutomirski <luto@kernel.org>
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From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <917cf067-c986-a459-ea87-7b7724c3c2d6@intel.com>
Date: Thu, 11 Jan 2018 21:03:56 -0800
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On 01/11/2018 07:01 PM, Raj, Ashok 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@intel.com> 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.

We were also worried about the indirect calls that are part of the
paravirt interfaces when retpolines are not in place.