From: Pavel Machek <pavel@ucw.cz>
To: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Jiri Kosina <jikos@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arch@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Greg KH <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Elena Reshetova <elena.reshetova@intel.com>
Subject: Re: [RFC PATCH] asm/generic: introduce if_nospec and nospec_barrier
Date: Thu, 4 Jan 2018 22:48:09 +0100 [thread overview]
Message-ID: <20180104214809.GB18699@amd> (raw)
In-Reply-To: <20180104212359.0b520868@alans-desktop>
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On Thu 2018-01-04 21:23:59, Alan Cox wrote:
> On Thu, 4 Jan 2018 21:39:24 +0100 (CET)
> Jiri Kosina <jikos@kernel.org> wrote:
>
> > On Thu, 4 Jan 2018, Alan Cox wrote:
> >
> > > You never go from one user process to another except via the kernel. We
> > > have no hardware scheduling going on. That means that if the kernel
> > > and/or CPU imposes the correct speculation barriers you can't attack
> > > anyone but yourself.
> >
> > So how does this work on HT with the shared BTB? There is no context
> > switch (and hence no IBPB) happening between the threads sharing it.
> >
>
> If you are paranoid in that case you either need to schedule things that
> trust each other together or disable the speculation while that situation
> occurs. However the kernel is always in the position to make that
> decision.
Actually... I'm not paranoid but would like to run flightgear on one
core (smt cpu #0), with smt cpu#1 being idle, while running
compilations on second core (smt cpus #2 and #3).
Is there easy way to do that?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-01-04 21:48 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-03 22:38 [RFC PATCH 0/4] API for inhibiting speculative arbitrary read primitives Mark Rutland
2018-01-03 22:38 ` [RFC PATCH 1/4] asm-generic/barrier: add generic nospec helpers Mark Rutland
2018-01-04 12:00 ` Mark Rutland
2018-01-05 4:21 ` Dan Williams
2018-01-05 9:15 ` Mark Rutland
2018-01-03 22:38 ` [RFC PATCH 2/4] Documentation: document " Mark Rutland
2018-01-03 22:38 ` [RFC PATCH 3/4] arm64: implement nospec_{load,ptr}() Mark Rutland
2018-01-03 22:38 ` [RFC PATCH 4/4] bpf: inhibit speculated out-of-bounds pointers Mark Rutland
2018-01-03 23:45 ` Peter Zijlstra
2018-01-04 10:59 ` Mark Rutland
2018-01-04 0:15 ` [RFC PATCH] asm/generic: introduce if_nospec and nospec_barrier Dan Williams
2018-01-04 0:39 ` Linus Torvalds
2018-01-04 1:07 ` Alan Cox
2018-01-04 1:13 ` Dan Williams
2018-01-04 6:28 ` Julia Lawall
2018-01-04 17:58 ` Dan Williams
2018-01-04 19:26 ` Pavel Machek
2018-01-04 21:43 ` Dan Williams
2018-01-04 22:20 ` Linus Torvalds
2018-01-04 22:23 ` Linus Torvalds
2018-01-04 22:55 ` Alan Cox
2018-01-04 23:06 ` Linus Torvalds
2018-01-04 23:11 ` Alan Cox
2018-01-05 0:24 ` Dan Williams
2018-01-04 22:44 ` Pavel Machek
2018-01-04 23:12 ` Dan Williams
2018-01-04 23:21 ` Alan Cox
2018-01-04 23:33 ` Pavel Machek
2018-01-05 8:11 ` Julia Lawall
2018-01-04 1:27 ` Jiri Kosina
2018-01-04 1:41 ` Alan Cox
2018-01-04 1:47 ` Jiri Kosina
2018-01-04 19:39 ` Pavel Machek
2018-01-04 20:32 ` Alan Cox
2018-01-04 20:39 ` Jiri Kosina
2018-01-04 21:23 ` Alan Cox
2018-01-04 21:48 ` Pavel Machek [this message]
2018-01-04 1:51 ` Dan Williams
2018-01-04 1:54 ` Linus Torvalds
2018-01-04 3:10 ` Williams, Dan J
2018-01-04 4:44 ` Al Viro
2018-01-04 5:44 ` Dan Williams
2018-01-04 5:49 ` Dave Hansen
2018-01-04 5:50 ` Al Viro
2018-01-04 5:55 ` Al Viro
2018-01-04 6:42 ` Dan Williams
2018-01-04 5:01 ` Eric W. Biederman
2018-01-04 5:01 ` Eric W. Biederman
2018-01-04 6:32 ` Dan Williams
2018-01-04 14:54 ` Eric W. Biederman
2018-01-04 14:54 ` Eric W. Biederman
2018-01-04 16:39 ` Mark Rutland
2018-01-04 20:56 ` Pavel Machek
2018-01-04 11:47 ` Mark Rutland
2018-01-04 11:47 ` Mark Rutland
2018-01-04 11:47 ` Mark Rutland
2018-01-04 22:09 ` Dan Williams
2018-01-05 14:40 ` Mark Rutland
2018-01-05 16:44 ` Dan Williams
2018-01-05 18:05 ` Dan Williams
2018-01-04 1:59 ` Jiri Kosina
2018-01-04 2:15 ` Alan Cox
2018-01-04 3:12 ` Alexei Starovoitov
2018-01-04 9:16 ` Reshetova, Elena
2018-01-04 20:40 ` Pavel Machek
-- strict thread matches above, loose matches on Subject: below --
2018-01-05 10:33 Alexey Dobriyan
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