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

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Message-ID: 
 <172002205406.3280081.14523962650685954182@Ubuntu-2204-jammy-amd64-base>
Date: Wed, 03 Jul 2024 15:54:14 -0000
From: "Borislav Petkov" <bp@...en8.de>
To: dave.hansen@...el.com
Cc: xin@...or.com, linux-kernel@...r.kernel.org, hpa@...or.com,
 tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
 x86@...nel.org, peterz@...radead.org, andrew.cooper3@...rix.com,
 nik.borisov@...e.com, houwenlong.hwl@...group.com
Subject: Re: [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns()

Dave Hansen <dave.hansen@...el.com> wrote:
>On 7/3/24 01:54, Xin Li (Intel) wrote:
>&gt; Do FRED MSR writes with wrmsrns() rather than wrmsrl().
>
>A longer changelog would be appreciated here.  The wrmsrns() is
>presumably to avoid the WRMSR serialization overhead and the CR4 write
>provides all of the serialization that we need.

Also, all those wrmsrns() writes better be behind a CPUID check.

Thx.