From: Ingo Molnar <mingo@kernel.org>
To: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
Borislav Petkov <bpetkov@suse.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 1/2] x86/mm: Reinitialize TLB state on hotplug and resume
Date: Thu, 7 Sep 2017 09:48:34 +0200 [thread overview]
Message-ID: <20170907074834.tmwo6vsvody2qrlg@gmail.com> (raw)
In-Reply-To: <alpine.LRH.2.00.1709070930530.16356@gjva.wvxbf.pm>
* Jiri Kosina <jikos@kernel.org> wrote:
> On Wed, 6 Sep 2017, Andy Lutomirski wrote:
>
> > When Linux brings a CPU down and back up, it switches to init_mm and then
> > loads swapper_pg_dir into CR3. With PCID enabled, this has the side effect
> > of masking off the ASID bits in CR3.
> >
> > This can result in some confusion in the TLB handling code. If we
> > bring a CPU down and back up with any ASID other than 0, we end up
> > with the wrong ASID active on the CPU after resume. This could
> > cause our internal state to become corrupt, although major
> > corruption is unlikely because init_mm doesn't have any user pages.
> > More obviously, if CONFIG_DEBUG_VM=y, we'll trip over an assertion
> > in the next context switch. The result of *that* is a failure to
> > resume from suspend with probability 1 - 1/6^(cpus-1).
> >
> > Fix it by reinitializing cpu_tlbstate on resume and CPU bringup.
> >
> > Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> > Reported-by: Jiri Kosina <jikos@kernel.org>
> > Fixes: 10af6235e0d3 ("x86/mm: Implement PCID based optimization: try to preserve old TLB entries using PCID")
> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
>
> Tested-by: Jiri Kosina <jkosina@suse.cz>
The fix should be upstream already, as of 1c9fe4409ce3 and later.
Thanks,
Ingo
next prev parent reply other threads:[~2017-09-07 7:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 2:54 [PATCH 0/2] Fix resume failure due to PCID Andy Lutomirski
2017-09-07 2:54 ` [PATCH 1/2] x86/mm: Reinitialize TLB state on hotplug and resume Andy Lutomirski
2017-09-07 7:01 ` [PATCH] mm/debug: Change BUG_ON() crashes to survivable WARN_ON() warnings Ingo Molnar
2017-09-07 20:50 ` Linus Torvalds
2017-09-07 7:31 ` [PATCH 1/2] x86/mm: Reinitialize TLB state on hotplug and resume Jiri Kosina
2017-09-07 7:48 ` Ingo Molnar [this message]
2017-09-07 19:55 ` Jiri Kosina
2017-09-08 1:23 ` Andy Lutomirski
2017-09-07 9:54 ` Borislav Petkov
2017-09-07 9:59 ` Ingo Molnar
2017-09-07 10:10 ` Borislav Petkov
2017-09-07 2:54 ` [PATCH 2/2] x86/mm: Document how CR4.PCIDE restore works Andy Lutomirski
2017-09-07 3:25 ` [PATCH 0/2] Fix resume failure due to PCID Linus Torvalds
2017-09-07 4:15 ` Andy Lutomirski
2017-09-15 6:59 ` x60: warnings on boot and resume, arch/x86/mm/tlb.c:257 initialize_ ... was " Pavel Machek
2017-09-15 8:39 ` Ingo Molnar
2017-09-15 9:16 ` Pavel Machek
2017-09-15 9:35 ` Ingo Molnar
2017-09-15 10:22 ` [4.14-rc0 regression] " Pavel Machek
2017-09-15 18:47 ` Linus Torvalds
2017-09-15 19:29 ` Andy Lutomirski
2017-09-15 21:06 ` Andy Lutomirski
2017-09-07 8:59 ` Borislav Petkov
2017-09-15 11:01 ` Pavel Machek
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