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From: Arjan van de Ven <arjan@linux.intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David Woodhouse" <dwmw2@infradead.org>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"KarimAllah Ahmed" <karahmed@amazon.de>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Andi Kleen" <ak@linux.intel.com>,
	"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>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"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: Tue, 30 Jan 2018 05:54:15 -0800	[thread overview]
Message-ID: <012d6cd1-2dc1-4130-9ac8-9e966475d120@linux.intel.com> (raw)
In-Reply-To: <CA+55aFyrKudn2QKe4D==BZCCQDqqfDzQZ6i8PR8-AfAufTtGFQ@mail.gmail.com>

On 1/29/2018 7:32 PM, Linus Torvalds wrote:
> On Mon, Jan 29, 2018 at 5:32 PM, Arjan van de Ven <arjan@linux.intel.com> wrote:
>>
>> the most simple solution is that we set the internal feature bit in Linux
>> to turn on the "stuff the RSB" workaround is we're on a SKL *or* as a guest
>> in a VM.
> 
> That sounds reasonable.
> 
> However, wouldn't it be even better to extend on the current cpuid
> model, and actually have some real architectural bits in there.
> 
> Maybe it could be a bit in that IA32_ARCH_CAPABILITIES MSR. Say, add a
> bit #2 that says "ret falls back on BTB".
> 
> Then that bit basically becomes the "Skylake bit". Hmm?

we can try to do that, but existing systems don't have that, and then we
get in another long thread here about weird lists of stuff ;-)

  parent reply	other threads:[~2018-01-30 13:54 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
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 [this message]
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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