linux-kernel - Re: rom 3540f985652f41041e54ee82aa53e7dbd55739ae Mon Sep 17 00:00:00 2001

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Message-ID: <ZQ1mdoMBJd4PCvZa@gmail.com>
Date:   Fri, 22 Sep 2023 12:03:34 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Sandipan Das <sandipan.das@....com>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        x86@...nel.org, peterz@...radead.org, leitao@...ian.org,
        mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
        tglx@...utronix.de, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, leit@...com, dcostantino@...a.com,
        jhladky@...hat.com, eranian@...gle.com, ananth.narayan@....com,
        ravi.bangoria@....com, santosh.shukla@....com
Subject: Re: rom 3540f985652f41041e54ee82aa53e7dbd55739ae Mon Sep 17 00:00:00
 2001


* Sandipan Das <sandipan.das@....com> wrote:

> Zen 4 systems running buggy microcode can hit a WARN_ON() in the PMI
> handler, as shown below, several times while perf runs. A simple
> `perf top` run is enough to render the system unusable.
> 
> WARNING: CPU: 18 PID: 20608 at arch/x86/events/amd/core.c:944 amd_pmu_v2_handle_irq+0x1be/0x2b0
> 
> This happens because the Performance Counter Global Status Register
> (PerfCntGlobalStatus) has one or more bits set which are considered
> reserved according to the "AMD64 Architecture Programmer???s Manual,
> Volume 2: System Programming, 24593". The document can be found at
> https://www.amd.com/system/files/TechDocs/24593.pdf
> 
> To make this less intrusive, warn just once if any reserved bit is set
> and prompt the user to update the microcode. Also sanitize the value to
> what the code is handling, so that the overflow events continue to be
> handled for the number of counters that are known to be sane.
> 
> Going forward, the following microcode patch levels are recommended
> for Zen 4 processors in order to avoid such issues with reserved bits.
> 
>   Family=0x19 Model=0x11 Stepping=0x01: Patch=0x0a10113e
>   Family=0x19 Model=0x11 Stepping=0x02: Patch=0x0a10123e
>   Family=0x19 Model=0xa0 Stepping=0x01: Patch=0x0aa00116
>   Family=0x19 Model=0xa0 Stepping=0x02: Patch=0x0aa00212
> 
> Commit f2eb058afc57 ("linux-firmware: Update AMD cpu microcode") from
> the linux-firmware tree has binaries that meet the minimum required
> patch levels.
> 
> Fixes: 7685665c390d ("perf/x86/amd/core: Add PerfMonV2 overflow handling")
> Reported-by: Jirka Hladky <jhladky@...hat.com>
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> [sandipan: add message to prompt users to update microcode]
> [sandipan: rework commit message and call out required microcode levels]
> Signed-off-by: Sandipan Das <sandipan.das@....com>

> v2:
>  - Use pr_warn_once() instead of WARN_ON_ONCE() to prompt users to
>    update microcode
>  - Rework commit message and add details of minimum required microcode
>    patch levels.

1)

I don't think you ever re-sent this patch with the correct subject line.
( Or at least it's not in my mbox. )

2)

So if the fix is from Breno Leitao originally, then there should be a:

   From: Breno Leitao <leitao@...ian.org>

at the beginning of the patch to make authorship clear.

You might also want to add:

  Co-developed-by: Sandipan Das <sandipan.das@....com>

to make your contributions clear.

Thanks,

	Ingo