From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Kees Cook <keescook@chromium.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Erik Bosman <ebn310@few.vu.nl>
Subject: Re: [RFC 2/5] x86: Store a per-cpu shadow copy of CR4
Date: Thu, 16 Oct 2014 10:26:24 +0200 [thread overview]
Message-ID: <20141016082624.GH7369@worktop.fdxtended.com> (raw)
In-Reply-To: <808fa43ef6e24d1df47c2666174d997105b9582d.1413323611.git.luto@amacapital.net>
On Tue, Oct 14, 2014 at 03:57:36PM -0700, Andy Lutomirski wrote:
> Context switches and TLB flushes can change individual bits of CR4.
> CR4 reads take several cycles, so store a shadow copy of CR4 in a
> per-cpu variable.
>
> To avoid wasting a cache line, I added the CR4 shadow to
> cpu_tlbstate, which is already touched during context switches.
I'm a little confused. We should be more specific I suppose, context
switches don't always change mm, but CR4 state is per task.
>From a quick look, only switch_mm() pokes at tlb, switch_to() does not.
next prev parent reply other threads:[~2014-10-16 8:26 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-14 22:57 [RFC 0/5] CR4 handling improvements Andy Lutomirski
2014-10-14 22:57 ` [RFC 1/5] x86: Clean up cr4 manipulation Andy Lutomirski
2014-10-16 8:16 ` Peter Zijlstra
2014-10-16 11:18 ` Borislav Petkov
2014-10-16 11:29 ` Borislav Petkov
2014-10-16 15:32 ` Andy Lutomirski
2014-10-16 15:47 ` Borislav Petkov
2014-10-14 22:57 ` [RFC 2/5] x86: Store a per-cpu shadow copy of CR4 Andy Lutomirski
2014-10-16 8:26 ` Peter Zijlstra [this message]
2014-10-16 11:49 ` Borislav Petkov
2014-10-16 15:30 ` Andy Lutomirski
2014-10-14 22:57 ` [RFC 3/5] x86: Add a comment clarifying LDT context switching Andy Lutomirski
2014-10-16 15:49 ` Borislav Petkov
2014-10-16 16:21 ` Andy Lutomirski
2014-10-21 5:41 ` Borislav Petkov
2014-10-21 5:44 ` Andy Lutomirski
2014-10-21 6:05 ` Borislav Petkov
2014-10-14 22:57 ` [RFC 4/5] perf: Add pmu callbacks to track event mapping and unmapping Andy Lutomirski
2014-10-14 22:57 ` [RFC 5/5] x86,perf: Only allow rdpmc if a perf_event is mapped Andy Lutomirski
2014-10-16 8:42 ` Peter Zijlstra
2014-10-16 15:37 ` Andy Lutomirski
2014-10-16 15:57 ` Borislav Petkov
2014-10-17 0:00 ` Andy Lutomirski
2014-10-19 20:23 ` Andy Lutomirski
2014-10-19 21:33 ` Peter Zijlstra
2014-10-19 22:05 ` Andy Lutomirski
2014-10-19 22:20 ` Peter Zijlstra
2014-10-19 22:57 ` Andy Lutomirski
2014-10-20 8:33 ` Peter Zijlstra
2014-10-20 16:49 ` Andy Lutomirski
2014-10-20 17:39 ` Andy Lutomirski
2014-10-21 8:59 ` Peter Zijlstra
2014-10-19 21:35 ` Peter Zijlstra
2014-10-20 0:08 ` Andy Lutomirski
2014-10-20 8:48 ` Peter Zijlstra
2014-10-20 9:24 ` Martin Schwidefsky
2014-10-20 10:51 ` Hendrik Brueckner
2014-10-21 9:14 ` Peter Zijlstra
2014-10-21 15:52 ` Andy Lutomirski
2014-10-21 4:06 ` [RFC 0/5] CR4 handling improvements Vince Weaver
2014-10-21 4:28 ` Andy Lutomirski
2014-10-21 15:00 ` Vince Weaver
2014-10-21 16:04 ` Peter Zijlstra
2014-10-21 17:05 ` Vince Weaver
2014-10-23 11:42 ` Peter Zijlstra
2014-10-24 12:41 ` Vince Weaver
2014-10-24 22:14 ` Andy Lutomirski
2014-10-15 7:37 [RFC 2/5] x86: Store a per-cpu shadow copy of CR4 Hillf Danton
2014-10-15 14:43 ` Andy Lutomirski
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