From: Borislav Petkov <bp@alien8.de>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>,
arjan@linux.intel.com, tglx@linutronix.de, karahmed@amazon.de,
x86@kernel.org, linux-kernel@vger.kernel.org,
peterz@infradead.org, pbonzini@redhat.com, ak@linux.intel.com,
torvalds@linux-foundation.org, gregkh@linux-foundation.org,
mingo@kernel.org, luto@kernel.org, linux@dominikbrodowski.net
Subject: Re: [PATCH] x86/speculation: Use Indirect Branch Prediction Barrier in context switch
Date: Wed, 31 Jan 2018 01:41:55 +0100 [thread overview]
Message-ID: <20180131004155.r2iz6vl7mmlav2yn@pd.tnic> (raw)
In-Reply-To: <74fd9c82-cd18-562b-8df6-69f629da460b@linux.intel.com>
On Tue, Jan 30, 2018 at 04:25:26PM -0800, Tim Chen wrote:
> As dumpable is a property in mm->flags, it affects all threads running
> on other cpus sharing the same mm.
It is not about sharing the same mm - it is about sharing the RSB. How
many logical CPUs share an RSB? If it is per core (which can have two
threads) then issuing the barrier should have effect on both threads.
Thus one barrier is enough.
IOW, the granularity is determined by how many logical CPUs share the
RSB not by how many logical CPUs share an mm.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-01-31 0:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 22:04 [PATCH] x86/speculation: Use Indirect Branch Prediction Barrier in context switch David Woodhouse
2018-01-30 17:48 ` Josh Poimboeuf
2018-01-30 21:23 ` Tim Chen
2018-01-30 22:00 ` Borislav Petkov
2018-01-30 22:21 ` Thomas Gleixner
2018-01-30 22:55 ` Borislav Petkov
2018-01-31 3:59 ` Josh Poimboeuf
2018-01-31 23:25 ` Tim Chen
2018-01-30 20:38 ` Borislav Petkov
2018-01-30 21:03 ` Tim Chen
2018-01-30 21:57 ` Borislav Petkov
2018-01-30 22:26 ` Tim Chen
2018-01-30 22:43 ` Borislav Petkov
2018-01-31 0:25 ` Tim Chen
2018-01-31 0:41 ` Borislav Petkov [this message]
2018-01-30 22:39 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-01-31 7:03 ` Dominik Brodowski
2018-01-31 13:24 ` Josh Poimboeuf
2018-02-01 8:25 ` Christian Brauner
2018-02-01 8:31 ` David Woodhouse
2018-02-01 15:40 ` Josh Poimboeuf
2018-02-04 19:39 ` Dominik Brodowski
2018-02-05 14:18 ` David Woodhouse
2018-02-05 19:35 ` Tim Chen
2018-02-05 19:35 ` Tim Chen
-- strict thread matches above, loose matches on Subject: below --
2018-01-29 11:33 [PATCH] " David Woodhouse
2018-01-29 12:28 ` Dominik Brodowski
2018-01-29 12:44 ` David Woodhouse
2018-01-29 13:56 ` Dominik Brodowski
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