From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kim Phillips <kim.phillips@amd.com>, Jiri Olsa <jolsa@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
x86@kernel.org, lkml <linux-kernel@vger.kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Stanislav Kozina <skozina@redhat.com>,
Michael Petlan <mpetlan@redhat.com>,
Pierre Amadio <pamadio@redhat.com>,
onatalen@redhat.com, darcari@redhat.com,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: unknown NMI on AMD Rome
Date: Wed, 17 Mar 2021 11:13:09 +0100 [thread overview]
Message-ID: <YFHWNWBAQ4rsyAMG@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210317084829.GA474581@gmail.com>
On Wed, Mar 17, 2021 at 09:48:29AM +0100, Ingo Molnar wrote:
> > https://developer.amd.com/wp-content/resources/56323-PUB_0.78.pdf
>
> So:
>
>
> 1215 IBS (Instruction Based Sampling) Counter Valid Value
> May be Incorrect After Exit From Core C6 (CC6) State
>
> Description
>
> If a core's IBS feature is enabled and configured to generate an interrupt, including NMI (Non-Maskable
> Interrupt), and the IBS counter overflows during the entry into the Core C6 (CC6) state, the interrupt may be
> issued, but an invalid value of the valid bit may be restored when the core exits CC6.
> Potential Effect on System
>
> The operating system may receive interrupts due to an IBS counter event, including NMI, and not observe an
> valid IBS register. Console messages indicating "NMI received for unknown reason" have been observed on
> Linux systems.
>
> Suggested Workaround: None
> Fix Planned: No fix planned
Should be simple enough to disable CC6 while IBS is in use. Kim, can you
please make that happen?
next prev parent reply other threads:[~2021-03-17 10:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 15:45 unknown NMI on AMD Rome Jiri Olsa
2021-03-16 16:02 ` Adam Borowski
2021-03-16 16:48 ` Alexander Monakov
2021-03-16 19:53 ` Peter Zijlstra
2021-03-16 20:02 ` Kim Phillips
2021-03-17 8:48 ` Ingo Molnar
2021-03-17 10:13 ` Peter Zijlstra [this message]
2021-03-17 13:32 ` Alexander Monakov
2021-03-17 13:37 ` Arnaldo Carvalho de Melo
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