From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: Tom Lendacky <Thomas.Lendacky@amd.com>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [RFC PATCH 4/4] x86/TSC: Use RDTSCP
Date: Wed, 12 Dec 2018 21:00:05 +0100 [thread overview]
Message-ID: <20181212200005.GF6653@zn.tnic> (raw)
In-Reply-To: <CALCETrXcBa3eUN2okedig+sECnQ8zuSWojahqWLR4vWqD8mEhg@mail.gmail.com>
On Wed, Dec 12, 2018 at 10:50:30AM -0800, Andy Lutomirski wrote:
> As far as I know, RDTSCP gets the job done, as does LFENCE, RDTSC on
> Intel.
Same on AMD when LFENCE has been made dispatch-serializing.
> There was a big discussion a few years ago where we changed it
> from LFENCE;RDTSC;LFENCE to just LFENCE;RDTSC after everyone was
> reasonably convinced that the uarch would not dispatch two RDTSCs
> backwards if the first one was immediately preceeded by LFENCE.
Yeah, the second one won't pass the LFENCE so you won't see time going
backwards, sure.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-12-12 20:00 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-11 22:23 [RFC PATCH 0/4] x86/alternative: Add ALTERNATIVE_3 Borislav Petkov
2018-12-11 22:23 ` [RFC PATCH 1/4] x86/alternatives: Add macro comments Borislav Petkov
2019-01-16 11:57 ` [tip:x86/alternatives] " tip-bot for Borislav Petkov
2018-12-11 22:23 ` [RFC PATCH 2/4] x86/alternatives: Print containing function Borislav Petkov
2019-01-16 11:58 ` [tip:x86/alternatives] " tip-bot for Borislav Petkov
2018-12-11 22:23 ` [RFC PATCH 3/4] x86/alternatives: Add an ALTERNATIVE_3() macro Borislav Petkov
2019-01-16 11:59 ` [tip:x86/alternatives] " tip-bot for Borislav Petkov
2018-12-11 22:23 ` [RFC PATCH 4/4] x86/TSC: Use RDTSCP Borislav Petkov
2018-12-11 22:59 ` Andy Lutomirski
2018-12-11 23:12 ` Lendacky, Thomas
2018-12-11 23:39 ` Borislav Petkov
2018-12-12 2:24 ` Andy Lutomirski
2018-12-12 9:59 ` Peter Zijlstra
2018-12-12 12:02 ` Andrea Parri
2018-12-12 10:08 ` Borislav Petkov
2018-12-12 18:07 ` Andy Lutomirski
2018-12-12 18:44 ` Borislav Petkov
2018-12-12 18:50 ` Andy Lutomirski
2018-12-12 20:00 ` Borislav Petkov [this message]
2018-12-12 20:09 ` Andy Lutomirski
2018-12-12 20:29 ` Borislav Petkov
2018-12-14 13:39 ` David Laight
2018-12-15 18:53 ` Andy Lutomirski
2018-12-12 14:15 ` Lendacky, Thomas
2018-12-12 14:18 ` Lendacky, Thomas
-- strict thread matches above, loose matches on Subject: below --
2018-12-11 23:37 Alexey Dobriyan
2018-12-11 23:43 ` Borislav Petkov
2018-12-12 0:06 ` Borislav Petkov
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