From: David Woodhouse <dwmw2@infradead.org>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
KarimAllah Ahmed <karahmed@amazon.de>,
Mihai Carabas <mihai.carabas@oracle.com>
Cc: linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Asit Mallick <asit.k.mallick@intel.com>,
Borislav Petkov <bp@suse.de>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
Joerg Roedel <joro@8bytes.org>,
Jun Nakajima <jun.nakajima@intel.com>,
Laura Abbott <labbott@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Paolo Bonzini <pbonzini@redhat.co
Subject: Re: [RFC 00/10] Speculation Control feature support
Date: Mon, 22 Jan 2018 21:27:49 +0000 [thread overview]
Message-ID: <1516656469.9521.75.camel@infradead.org> (raw)
In-Reply-To: <20180121140205.GB21306@char.us.oracle.com>
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On Sun, 2018-01-21 at 09:02 -0500, Konrad Rzeszutek Wilk wrote:
>
>
> Depend on what we expose to the guest. That is if the guest is not suppose to have this exposed
> (say cpuid 27 bit is not exposed) then trap on the MSR (and give an #GP)?
I think for SPEC_CTRL we want to trap on the MSR anyway. Saving and
restoring is is *bizarrely* slow, apparently, even when it's zero.
I think we want to trap on the first access, and only then disable the
intercept and enable the save/restore. That way, sane guests that only
ever use retpoline and IBPB (which is write-only and doesn't need
saving) won't ever take the performance hit.
It's going to want this: https://patchwork.kernel.org/patch/10167667/
> Mihai (CC-ed) is working on this, when ready he can post an patch against this tree?
That'd be useful; thanks. The latest (including the bits on top that we
probably aren't going to submit, with saner bits near the beginning)
should always be at
http://git.infradead.org/linux-retpoline.git/shortlog/refs/heads/ibpb
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prev parent reply other threads:[~2018-01-22 21:27 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-20 19:22 [RFC 00/10] Speculation Control feature support KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 01/10] x86/speculation: Add basic support for IBPB KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 02/10] x86/kvm: Add IBPB support KarimAllah Ahmed
2018-01-20 20:18 ` Woodhouse, David
2018-01-22 18:56 ` Jim Mattson
2018-01-22 19:31 ` Jim Mattson
2018-01-20 19:22 ` [RFC 03/10] x86/speculation: Use Indirect Branch Prediction Barrier in context switch KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 04/10] x86/mm: Only flush indirect branches when switching into non dumpable process KarimAllah Ahmed
2018-01-20 21:06 ` Woodhouse, David
2018-01-22 18:29 ` Tim Chen
2018-01-21 11:22 ` Peter Zijlstra
2018-01-21 12:04 ` David Woodhouse
2018-01-21 14:07 ` H.J. Lu
2018-01-22 10:19 ` Peter Zijlstra
2018-01-22 10:23 ` David Woodhouse
2018-01-21 16:21 ` Ingo Molnar
2018-01-21 16:25 ` Arjan van de Ven
2018-01-21 22:20 ` Woodhouse, David
2018-01-29 6:35 ` Jon Masters
2018-01-29 14:07 ` Peter Zijlstra
2018-01-20 19:22 ` [RFC 05/10] x86/speculation: Add basic IBRS support infrastructure KarimAllah Ahmed
2018-01-21 14:31 ` Thomas Gleixner
2018-01-21 14:56 ` Borislav Petkov
2018-01-22 9:51 ` Peter Zijlstra
2018-01-22 12:06 ` Borislav Petkov
2018-01-22 13:30 ` Greg Kroah-Hartman
2018-01-22 13:36 ` Woodhouse, David
2018-01-21 15:25 ` David Woodhouse
2018-01-23 20:58 ` David Woodhouse
2018-01-24 8:47 ` Peter Zijlstra
2018-01-24 9:02 ` David Woodhouse
2018-01-24 9:10 ` Greg Kroah-Hartman
2018-01-24 15:09 ` Arjan van de Ven
2018-01-24 15:18 ` David Woodhouse
2018-01-24 9:34 ` Peter Zijlstra
2018-01-24 10:49 ` Henrique de Moraes Holschuh
2018-01-24 12:30 ` David Woodhouse
2018-01-24 12:14 ` David Woodhouse
2018-01-24 12:29 ` Peter Zijlstra
2018-01-24 12:58 ` David Woodhouse
2018-01-29 20:14 ` [RFC,05/10] " Eduardo Habkost
2018-01-29 20:17 ` David Woodhouse
2018-01-29 20:42 ` Eduardo Habkost
2018-01-29 20:44 ` Arjan van de Ven
2018-01-29 21:02 ` David Woodhouse
2018-01-29 21:37 ` Jim Mattson
2018-01-29 21:50 ` Eduardo Habkost
2018-01-29 22:12 ` Jim Mattson
2018-01-30 1:22 ` Eduardo Habkost
2018-01-29 22:25 ` Andi Kleen
2018-01-30 1:37 ` Eduardo Habkost
2018-01-29 21:37 ` Andi Kleen
2018-01-29 21:44 ` Eduardo Habkost
2018-01-29 22:10 ` Konrad Rzeszutek Wilk
2018-01-30 1:12 ` Eduardo Habkost
2018-01-30 0:23 ` Linus Torvalds
2018-01-30 1:03 ` Jim Mattson
2018-01-30 3:13 ` Andi Kleen
2018-01-31 15:03 ` Paolo Bonzini
2018-01-31 15:07 ` Dr. David Alan Gilbert
2018-01-30 1:32 ` Arjan van de Ven
2018-01-30 3:32 ` Linus Torvalds
2018-01-30 12:04 ` Eduardo Habkost
2018-01-30 13:54 ` Arjan van de Ven
2018-01-30 8:22 ` David Woodhouse
2018-01-30 11:35 ` David Woodhouse
2018-01-30 11:56 ` Dr. David Alan Gilbert
2018-01-30 12:11 ` Christian Borntraeger
2018-01-30 14:46 ` Christophe de Dinechin
2018-01-30 14:52 ` Christian Borntraeger
2018-01-30 14:56 ` Christophe de Dinechin
2018-01-30 15:33 ` Christian Borntraeger
2018-01-30 20:46 ` Alan Cox
2018-01-31 10:05 ` Christophe de Dinechin
2018-01-31 10:15 ` Thomas Gleixner
2018-01-31 11:04 ` Dr. David Alan Gilbert
2018-01-31 11:52 ` Borislav Petkov
2018-01-31 12:30 ` Dr. David Alan Gilbert
2018-01-31 13:18 ` Borislav Petkov
2018-01-31 14:04 ` Dr. David Alan Gilbert
2018-01-31 14:44 ` Eduardo Habkost
2018-01-31 16:28 ` Borislav Petkov
2018-01-31 11:07 ` Christophe de Dinechin
2018-01-31 15:00 ` Eduardo Habkost
2018-01-31 15:11 ` Arjan van de Ven
2018-01-31 10:03 ` [RFC 05/10] " Christophe de Dinechin
2018-01-20 19:22 ` [RFC 06/10] x86/speculation: Add inlines to control Indirect Branch Speculation KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 07/10] x86: Simplify spectre_v2 command line parsing KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 08/10] x86/idle: Control Indirect Branch Speculation in idle KarimAllah Ahmed
2018-01-20 19:23 ` [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation KarimAllah Ahmed
2018-01-21 19:14 ` Andy Lutomirski
2018-01-23 16:12 ` Tom Lendacky
2018-01-23 16:20 ` Woodhouse, David
2018-01-23 22:37 ` Tom Lendacky
2018-01-23 22:49 ` Andi Kleen
2018-01-23 23:14 ` Woodhouse, David
2018-01-23 23:22 ` Andi Kleen
2018-01-24 0:47 ` Tim Chen
2018-01-24 1:00 ` Andy Lutomirski
2018-01-24 1:22 ` David Woodhouse
2018-01-24 1:59 ` Van De Ven, Arjan
2018-01-24 3:25 ` Andy Lutomirski
[not found] ` <CA+55aFxUEPHc7JRQG3zmxEsfmfJOiJa1QqFBKCBNb5Tt5vfiSg@mail.gmail.com>
2018-01-21 20:28 ` David Woodhouse
2018-01-21 21:35 ` Linus Torvalds
2018-01-21 22:00 ` David Woodhouse
2018-01-21 22:27 ` Linus Torvalds
2018-01-22 16:27 ` David Woodhouse
2018-01-23 7:29 ` Ingo Molnar
2018-01-23 7:53 ` Ingo Molnar
2018-01-23 9:27 ` Ingo Molnar
2018-01-23 9:37 ` David Woodhouse
2018-01-23 15:01 ` Dave Hansen
2018-01-23 9:30 ` David Woodhouse
2018-01-23 10:15 ` Ingo Molnar
2018-01-23 10:27 ` David Woodhouse
2018-01-23 10:44 ` Ingo Molnar
2018-01-23 10:23 ` Ingo Molnar
2018-02-04 18:43 ` Thomas Gleixner
2018-02-04 20:22 ` David Woodhouse
2018-02-06 9:14 ` David Woodhouse
2018-01-23 20:16 ` Pavel Machek
2018-01-20 19:23 ` [RFC 10/10] x86/enter: Use IBRS on syscall and interrupts KarimAllah Ahmed
2018-01-21 13:50 ` Konrad Rzeszutek Wilk
2018-01-21 14:40 ` KarimAllah Ahmed
2018-01-21 17:22 ` Dave Hansen
2018-01-21 14:02 ` [RFC 00/10] Speculation Control feature support Konrad Rzeszutek Wilk
2018-01-22 21:27 ` David Woodhouse [this message]
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