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From: Andi Kleen <ak@linux.intel.com>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Tony Battersby <tonyb@cybernetics.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Mario Limonciello <mario.limonciello@amd.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC] x86/cpu: fix intermittent lockup on poweroff
Date: Wed, 26 Apr 2023 15:02:10 -0700	[thread overview]
Message-ID: <ZEmfYpOyyul4BaKP@tassilo> (raw)
In-Reply-To: <469754ab-d8ec-168a-15c7-61045a880792@amd.com>

> > > This is probably going to pull in a cache line and cause the problem the
> > > native_wbinvd() is trying to avoid.
> > 
> > Is one _more_ cacheline really the problem?
> 
> The answer is it depends. If the cacheline ends up modified/dirty, then it
> can be a problem.

I haven't followed this all in detail, but if any dirty cache line a
problem you probably would need to be sure that any possible NMI user
(like perf or watchdogs) is disabled at this point, otherwise you could
still get NMIs here. 

I don't think perf currently has a mechanism to do that other
than to offline the CPU.

Also there are of course machine checks and SMIs that could still happen, 
but I guess there's nothing you could do about them.

-Andi

  reply	other threads:[~2023-04-26 22:02 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-25 19:26 [PATCH RFC] x86/cpu: fix intermittent lockup on poweroff Tony Battersby
2023-04-25 19:39 ` Borislav Petkov
2023-04-25 19:58   ` Tony Battersby
2023-04-25 20:03 ` Dave Hansen
2023-04-25 20:34   ` Dave Hansen
2023-04-25 21:06     ` Borislav Petkov
2023-04-25 21:05   ` Thomas Gleixner
2023-04-25 22:29     ` Dave Hansen
2023-04-25 23:00       ` Thomas Gleixner
2023-04-26  0:10       ` H. Peter Anvin
2023-04-26 14:45     ` Tony Battersby
2023-04-26 16:37       ` Thomas Gleixner
2023-04-26 17:37         ` Tony Battersby
2023-04-26 17:41           ` [PATCH v2] x86/cpu: fix SME test in stop_this_cpu() Tony Battersby
2023-05-22 14:07             ` [PATCH v2 RESEND] " Tony Battersby
2023-04-26 17:51           ` [PATCH RFC] x86/cpu: fix intermittent lockup on poweroff Tom Lendacky
2023-04-26 18:15             ` Dave Hansen
2023-04-26 19:18               ` Tom Lendacky
2023-04-26 22:02                 ` Andi Kleen [this message]
2023-04-26 23:20                   ` Thomas Gleixner
2023-04-26 20:00             ` Thomas Gleixner
2023-06-20 13:00 ` [tip: x86/core] x86/smp: Make stop_other_cpus() more robust tip-bot2 for Thomas Gleixner
2023-06-20 13:00 ` [tip: x86/core] x86/smp: Dont access non-existing CPUID leaf tip-bot2 for Tony Battersby

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