From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"Woodhouse, David" <dwmw@amazon.co.uk>,
"pavel@ucw.cz" <pavel@ucw.cz>,
"tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"andi@firstfloor.org" <andi@firstfloor.org>,
"dave.hansen@intel.com" <dave.hansen@intel.com>,
"gregkh@linux-foundation.org" <gregkh@linux-foundation.org>
Subject: Re: Avoid speculative indirect calls in kernel
Date: Thu, 4 Jan 2018 17:04:42 +0000 [thread overview]
Message-ID: <20180104170442.710aa4c4@alans-desktop> (raw)
In-Reply-To: <20180104162541.GD13348@redhat.com>
> If you run lots of syscalls ibrs 1 ibpb 1 is much faster. If you do
> infrequent syscalls computing a lot in kernel like I/O with large
> buffers getting copied, ibrs 0 ibpb 2 is much faster than ibrs 1 ibpb
> 1 (on those microcodes where ibrs 1 reduces performance a lot, not all
> microcodes implementing SPEC_CTRL are inefficient like that).
Have you looked at whether you can measure activity and switch
automatically between the two (or by task). It seems silly to leave
something the machine can accurately assess toa human ?
Alan
next prev parent reply other threads:[~2018-01-04 17:05 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-03 23:09 Avoid speculative indirect calls in kernel Andi Kleen
2018-01-03 23:09 ` [PATCH 01/11] x86/retpoline: Define retpoline indirect thunk and macros Andi Kleen
2018-01-03 23:09 ` [PATCH 02/11] x86/retpoline/crypto: Convert crypto assembler indirect jumps Andi Kleen
2018-01-03 23:09 ` [PATCH 03/11] x86/retpoline/entry: Convert entry " Andi Kleen
2018-01-03 23:09 ` [PATCH 04/11] x86/retpoline/ftrace: Convert ftrace " Andi Kleen
2018-01-03 23:09 ` [PATCH 05/11] x86/retpoline/hyperv: Convert " Andi Kleen
2018-01-03 23:09 ` [PATCH 06/11] x86/retpoline/crypto: Convert xen " Andi Kleen
2018-01-03 23:09 ` [PATCH 07/11] x86/retpoline/checksum32: Convert " Andi Kleen
2018-01-03 23:09 ` [PATCH 08/11] x86/retpoline/irq32: " Andi Kleen
2018-01-03 23:09 ` [PATCH 09/11] x86/retpoline: Finally enable retpoline for C code Andi Kleen
2018-01-04 8:28 ` Greg KH
2018-01-04 8:30 ` Dave Hansen
2018-01-03 23:09 ` [PATCH 10/11] retpoline/taint: Taint kernel for missing retpoline in compiler Andi Kleen
2018-01-04 0:29 ` Thomas Gleixner
2018-01-04 0:35 ` Randy Dunlap
2018-01-03 23:09 ` [PATCH 11/11] retpoline/objtool: Disable some objtool warnings Andi Kleen
2018-01-03 23:51 ` Avoid speculative indirect calls in kernel Linus Torvalds
2018-01-04 0:00 ` Alan Cox
2018-01-04 0:09 ` Andi Kleen
2018-01-04 0:12 ` Thomas Gleixner
2018-01-04 0:15 ` Andi Kleen
2018-01-04 0:19 ` Jiri Kosina
2018-01-05 2:01 ` james harvey
2018-01-05 10:40 ` Woodhouse, David
2018-01-05 12:29 ` james harvey
2018-01-05 12:06 ` Alan Cox
2018-01-04 0:29 ` Alan Cox
2018-01-04 0:31 ` Thomas Gleixner
2018-01-04 0:38 ` Alan Cox
2018-01-04 0:40 ` Andi Kleen
2018-01-04 8:15 ` Woodhouse, David
2018-01-04 15:53 ` Andi Kleen
2018-01-04 15:55 ` Woodhouse, David
2018-01-04 0:20 ` Linus Torvalds
2018-01-04 0:26 ` Thomas Gleixner
2018-01-04 0:18 ` David Lang
2018-01-04 1:00 ` Paul Turner
2018-01-04 1:41 ` Paolo Bonzini
2018-01-04 1:59 ` Alan Cox
2018-01-04 2:11 ` Paolo Bonzini
2018-01-04 8:20 ` Woodhouse, David
2018-01-04 11:42 ` Pavel Machek
2018-01-04 11:47 ` Woodhouse, David
2018-01-04 14:20 ` Paolo Bonzini
2018-01-04 14:51 ` Andrew Cooper
2018-01-04 15:29 ` Woodhouse, David
2018-01-04 15:32 ` Paolo Bonzini
2018-01-04 15:37 ` Andrew Cooper
2018-01-04 16:15 ` David Woodhouse
2018-01-04 20:00 ` Tom Lendacky
2018-01-04 20:05 ` David Woodhouse
2018-01-04 23:47 ` Tom Lendacky
2018-01-05 0:06 ` Andrew Cooper
2018-01-05 0:26 ` Tom Lendacky
2018-01-04 16:52 ` Andrea Arcangeli
2018-01-04 15:32 ` Paolo Bonzini
2018-01-04 16:25 ` Andrea Arcangeli
2018-01-04 17:04 ` Alan Cox [this message]
2018-01-04 17:40 ` Andrea Arcangeli
2018-01-04 17:13 ` Dave Hansen
2018-01-04 17:15 ` Paolo Bonzini
2018-01-04 18:05 ` Andrea Arcangeli
2018-01-04 14:55 ` Woodhouse, David
2018-01-04 18:24 ` Pavel Machek
2018-01-04 19:57 ` Jon Masters
2018-01-05 0:41 ` Jon Masters
2018-01-05 0:54 ` Thomas Gleixner
2018-01-05 4:11 ` Jon Masters
2018-01-05 9:59 ` Thomas Gleixner
2018-01-08 10:28 ` Andrea Arcangeli
2018-01-08 20:42 ` [tip:x86/pti] x86/tboot: Unbreak tboot with PTI enabled tip-bot for Dave Hansen
2018-01-08 20:53 ` Avoid speculative indirect calls in kernel Thomas Gleixner
2018-01-08 21:32 ` Andrea Arcangeli
2018-01-10 0:45 ` Thomas Gleixner
2018-01-10 1:11 ` Dave Hansen
2018-01-10 16:02 ` Thomas Gleixner
2018-01-05 6:49 ` Willy Tarreau
2018-01-05 6:57 ` Dave Hansen
2018-01-05 7:13 ` Willy Tarreau
2018-01-07 14:14 ` Borislav Petkov
2018-01-07 17:21 ` David Lang
2018-01-07 18:49 ` Borislav Petkov
2018-01-07 17:44 ` Willy Tarreau
2018-01-07 18:55 ` Borislav Petkov
2018-01-07 22:10 ` Willy Tarreau
2018-01-08 9:18 ` Thomas Gleixner
2018-01-08 9:29 ` Willy Tarreau
2018-01-08 16:22 ` Borislav Petkov
2018-01-08 16:53 ` Willy Tarreau
2018-01-05 12:12 ` Alan Cox
2018-01-09 1:44 ` Samir Bellabes
[not found] ` <CAL9bgJ8XNJgCtxR6+M+Vm9eDBVZ4Dyi_-Lt-Q1ei9N=TE2c6cg@mail.gmail.com>
2018-01-07 5:04 ` Fwd: " Kiernan Hager
2018-01-07 6:39 ` Willy Tarreau
2018-01-07 14:01 ` Alan Cox
2018-01-07 17:47 ` Willy Tarreau
2018-01-07 18:01 ` Ivan Ivanov
2018-01-07 18:16 ` Woodhouse, David
2018-01-04 11:26 ` Pavel Machek
2018-01-04 11:54 ` Alan Cox
2018-01-04 18:33 ` Linus Torvalds
2018-01-04 20:08 ` Jon Masters
-- strict thread matches above, loose matches on Subject: below --
2018-01-04 2:00 Andi Kleen
2018-01-04 11:49 ` Pavel Machek
2018-01-04 12:09 ` Alan Cox
2018-01-04 13:32 ` Pavel Machek
2018-01-12 8:20 Dr. Greg Wettstein
2018-02-23 21:10 Ywe Cærlyn
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