linux-kernel - Re: [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns()

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Message-ID: <AC8AACE5-7A77-479A-B776-AE65BFA241FF@zytor.com>
Date: Thu, 04 Jul 2024 00:58:55 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Xin Li <xin@...or.com>, Andrew Cooper <andrew.cooper3@...rix.com>,
        Borislav Petkov <bp@...en8.de>, dave.hansen@...el.com
CC: linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        dave.hansen@...ux.intel.com, x86@...nel.org, peterz@...radead.org,
        nik.borisov@...e.com, houwenlong.hwl@...group.com
Subject: Re: [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns()

On July 3, 2024 10:57:29 PM PDT, Xin Li <xin@...or.com> wrote:
>On 7/3/2024 9:18 AM, Andrew Cooper wrote:
>> On 03/07/2024 5:06 pm, H. Peter Anvin wrote:
>>> I believe tglx declared53  to use them unconditionally since FRED depends on WRMSRNS (and the kernel enforces that.)
>> 
>> I know that Linux has chosen to have this as a software-enforced
>> requirement.
>> 
>> The dependency does not exist architecturally, and just because it
>> happens to be true on Intel processors doesn't mean it's true of other
>> implementations.
>
>Won't it be way better if we could have all x86 vendors agree on it?
>
>

It was tglx' explicit request to keep it simple unless someone objects. All it would take is for someone to come up with a countercase.