From: Paolo Bonzini <pbonzini@redhat.com>
To: Andi Kleen <ak@linux.intel.com>, Jim Mattson <jmattson@google.com>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
"David Woodhouse" <dwmw2@infradead.org>,
"Arjan van de Ven" <arjan@linux.intel.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"KarimAllah Ahmed" <karahmed@amazon.de>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Andy Lutomirski" <luto@kernel.org>,
"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>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Tim Chen" <tim.c.chen@linux.intel.com>,
"Tom Lendacky" <thomas.lendacky@amd.com>,
"KVM list" <kvm@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure
Date: Wed, 31 Jan 2018 10:03:51 -0500 [thread overview]
Message-ID: <68a15b64-1031-ddf1-e209-e38ac1280c59@redhat.com> (raw)
In-Reply-To: <20180130031340.GV26209@tassilo.jf.intel.com>
On 29/01/2018 22:13, Andi Kleen wrote:
>> What happens when someone introduces a
>> workaround tied to some other model numbers?
> There are already many of those in the tree for other issues and features.
> So far you managed to survive without. Likely that will be true
> in the future too.
"Guests have to live with processor fuckups" is actually a much better
answer than "Hypervisors may need to revisit their practice", since at
least it's clear where the blame lies.
Because really it's just plain luck. It just happens that most errata
are for functionality that is not available to a virtual machine (e.g.
perfmon and monitor workarounds or buggy TSC deadline timer that
hypervisors emulate anyway), that only needs a chicken bit to be set in
the host, or the bugs are there only for old hardware that doesn't have
virtualization (X86_BUG_F00F, X86_BUGS_SWAPGS_FENCE).
CPUID flags are guaranteed to never change---never come, never go away.
For anything that doesn't map nicely to a CPUID flag, you cannot really
express it. Also if something is not architectural, you can pretty much
assume that you cannot know it under virtualization. f/m/s is not
architectural; family, model and stepping mean absolutely nothing when
running in virtualization, because the host CPU model can change under
your feet at any time. We force guest vendor == host vendor just
because otherwise too much stuff breaks, but that's it.
Paolo
next prev parent reply other threads:[~2018-01-31 15:03 UTC|newest]
Thread overview: 143+ 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 13:37 ` Woodhouse, David
2018-01-21 15:25 ` David Woodhouse
2018-01-23 20:58 ` David Woodhouse
2018-01-23 22:43 ` Johannes Erdfelt
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 [this message]
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
2018-01-21 19:34 ` Linus Torvalds
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 10:57 ` David Woodhouse
2018-01-23 10:23 ` Ingo Molnar
2018-01-23 10:35 ` David Woodhouse
2018-02-04 18:43 ` Thomas Gleixner
2018-02-04 20:22 ` David Woodhouse
2018-02-06 9:14 ` David Woodhouse
2018-01-25 16:19 ` Mason
2018-01-25 17:16 ` Greg Kroah-Hartman
2018-01-29 11:59 ` Mason
2018-01-24 0:05 ` Andi Kleen
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
2018-01-29 22:29 [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure David Dunn
2018-01-29 22:41 ` Andi Kleen
2018-01-29 22:49 ` Jim Mattson
2018-01-30 1:10 ` Eduardo Habkost
2018-01-30 1:20 ` David Dunn
2018-01-30 1:30 ` Eduardo Habkost
2018-01-29 23:51 ` Fred Jacobs
2018-01-30 1:08 ` Eduardo Habkost
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