linux-kernel - Re: [RESEND PATCH] perf/x86/amd: Do not touch the AMD64_EVENTSEL

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Message-ID: <173cb541-fa2e-494c-f1b7-e9894bd4f25b@gmail.com>
Date:   Thu, 29 Jul 2021 21:49:40 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Kim Phillips <kim.phillips@....com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Robert Richter <rrichter@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RESEND PATCH] perf/x86/amd: Do not touch the
 AMD64_EVENTSEL_HOSTONLY bit inside the guest

On 24/7/2021 4:16 am, Kim Phillips wrote:
> +Tom L., Robert R.
> 
> On 7/20/21 6:26 AM, Like Xu wrote:
>> From: Like Xu <likexu@...cent.com>
>>
>> If we use "perf record" in an AMD Milan guest, dmesg reports a #GP
>> warning from an unchecked MSR access error on MSR_F15H_PERF_CTLx:
>>
>> [] unchecked MSR access error: WRMSR to 0xc0010200 (tried to write
>> 0x0000020000110076) at rIP: 0xffffffff8106ddb4 
>> (native_write_msr+0x4/0x20)
>> [] Call Trace:
>> []  amd_pmu_disable_event+0x22/0x90
>> []  x86_pmu_stop+0x4c/0xa0
>> []  x86_pmu_del+0x3a/0x140
>>
>> The AMD64_EVENTSEL_HOSTONLY bit is defined and used on the host,
>> while the guest perf driver should avoid such use.
>>
>> Signed-off-by: Like Xu <likexu@...cent.com>
>> ---
> 
> Tested-by: Kim Phillips <kim.phillips@....com>

Thanks Kim.

Hi Peter, should I post a new version with the fix tag ?

> 
> If we were to add a Fixes: tag, would this be the right commit?:
> 
> commit 1018faa6cf23b256bf25919ef203cd7c129f06f2
> 
> Author: Joerg Roedel <joerg.roedel@....com>
> 
> Date:   Wed Feb 29 14:57:32 2012 +0100
> 
> 
> 
>      perf/x86/kvm: Fix Host-Only/Guest-Only counting with SVM disabled
> 
> 
> Thanks,
> 
> Kim