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From: David Woodhouse <dwmw2@infradead.org>
To: "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Hansen, Dave" <dave.hansen@intel.com>,
	"Liran Alon" <liran.alon@oracle.com>,
	"Laura Abbott" <labbott@redhat.com>,
	"Andrew Lutomirski" <luto@kernel.org>,
	"Janakarajan Natarajan" <Janakarajan.Natarajan@amd.com>,
	"Borislav Petkov" <bp@suse.de>,
	"Mallick, Asit K" <asit.k.mallick@intel.com>,
	"Radim Krcmár" <rkrcmar@redhat.com>,
	"KarimAllah Ahmed" <karahmed@amazon.de>,
	"Peter Anvin" <hpa@zytor.com>,
	"Nakajima, Jun" <jun.nakajima@intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	"Williams, Dan J" <dan.j.williams@intel.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	"Andrea Arcangeli" <aarcange@redhat.com>,
	"KVM list" <kvm@vger.kernel.org>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation
Date: Fri, 26 Jan 2018 18:53:13 +0000	[thread overview]
Message-ID: <1516992793.30244.280.camel@infradead.org> (raw)
In-Reply-To: <0575AF4FD06DD142AD198903C74E1CC87A601040@ORSMSX103.amr.corp.intel.com>

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On Fri, 2018-01-26 at 18:44 +0000, Van De Ven, Arjan wrote:
> your question was specific to RSB not BTB. But please show the empirical evidence for RSB ?

We were hypothesising, which should have been clear from:

On Fri, 2018-01-26 at 09:11 +0000, David Woodhouse wrote:
> Likewise if the RSB only stores the low 31 bits of the target, SMEP
> isn't much help there either.
> 
> Do we need to look again at the fact that we've disabled the RSB-
> stuffing for SMEP?

... and later... 

On Fri, 2018-01-26 at 17:31 +0000, David Woodhouse wrote:
> Note, we've switched from talking about BTB to RSB here, so this is a
> valid concern if the *RSB* only has the low bits of the target.

I'm glad to hear that it *isn't* a valid concern for the RSB and the
code in Linus' tree is correct.

Thank you for clearing that up.

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WARNING: multiple messages have this Message-ID (diff)
From: David Woodhouse <dwmw2@infradead.org>
To: "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Hansen, Dave" <dave.hansen@intel.com>,
	"Liran Alon" <liran.alon@oracle.com>,
	"Laura Abbott" <labbott@redhat.com>,
	"Andrew Lutomirski" <luto@kernel.org>,
	"Janakarajan Natarajan" <Janakarajan.Natarajan@amd.com>,
	"Borislav Petkov" <bp@suse.de>,
	"Mallick, Asit K" <asit.k.mallick@intel.com>,
	"Radim Krcmár" <rkrcmar@redhat.com>,
	"KarimAllah Ahmed" <karahmed@amazon.de>,
	"Peter Anvin" <hpa@zytor.com>,
	"Nakajima, Jun" <jun.nakajima@intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@lin>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation
Date: Fri, 26 Jan 2018 18:53:13 +0000	[thread overview]
Message-ID: <1516992793.30244.280.camel@infradead.org> (raw)
In-Reply-To: <0575AF4FD06DD142AD198903C74E1CC87A601040@ORSMSX103.amr.corp.intel.com>

[-- Attachment #1: Type: text/plain, Size: 841 bytes --]

On Fri, 2018-01-26 at 18:44 +0000, Van De Ven, Arjan wrote:
> your question was specific to RSB not BTB. But please show the empirical evidence for RSB ?

We were hypothesising, which should have been clear from:

On Fri, 2018-01-26 at 09:11 +0000, David Woodhouse wrote:
> Likewise if the RSB only stores the low 31 bits of the target, SMEP
> isn't much help there either.
> 
> Do we need to look again at the fact that we've disabled the RSB-
> stuffing for SMEP?

... and later... 

On Fri, 2018-01-26 at 17:31 +0000, David Woodhouse wrote:
> Note, we've switched from talking about BTB to RSB here, so this is a
> valid concern if the *RSB* only has the low bits of the target.

I'm glad to hear that it *isn't* a valid concern for the RSB and the
code in Linus' tree is correct.

Thank you for clearing that up.

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  reply	other threads:[~2018-01-26 18:53 UTC|newest]

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-26  2:11 [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation Liran Alon
2018-01-26  2:23 ` Dave Hansen
2018-01-26  9:11   ` David Woodhouse
2018-01-26  9:11     ` David Woodhouse
2018-01-26 17:19     ` Linus Torvalds
2018-01-26 17:19       ` Linus Torvalds
2018-01-26 17:27       ` Borislav Petkov
2018-01-26 17:27         ` Borislav Petkov
2018-01-26 17:29       ` David Woodhouse
2018-01-26 17:29         ` David Woodhouse
2018-01-26 17:31         ` David Woodhouse
2018-01-26 17:31           ` David Woodhouse
2018-01-26 17:59       ` Andi Kleen
2018-01-26 17:59         ` Andi Kleen
2018-01-26 18:11         ` David Woodhouse
2018-01-26 18:11           ` David Woodhouse
2018-01-26 18:12           ` Arjan van de Ven
2018-01-26 18:12             ` Arjan van de Ven
2018-01-26 18:26             ` David Woodhouse
2018-01-26 18:26               ` David Woodhouse
2018-01-26 18:28               ` Van De Ven, Arjan
2018-01-26 18:28                 ` Van De Ven, Arjan
2018-01-26 18:43                 ` David Woodhouse
2018-01-26 18:43                   ` David Woodhouse
2018-01-26 18:44                   ` Van De Ven, Arjan
2018-01-26 18:44                     ` Van De Ven, Arjan
2018-01-26 18:53                     ` David Woodhouse [this message]
2018-01-26 18:53                       ` David Woodhouse
2018-01-26 19:02         ` Konrad Rzeszutek Wilk
2018-01-26 19:02           ` Konrad Rzeszutek Wilk
2018-01-26 19:11           ` Hansen, Dave
2018-01-26 19:11             ` Hansen, Dave
2018-01-27 13:42             ` Konrad Rzeszutek Wilk
2018-01-27 13:42               ` Konrad Rzeszutek Wilk
2018-01-27 15:55               ` Dave Hansen
2018-01-27 15:55                 ` Dave Hansen
2018-01-26 19:11           ` David Woodhouse
2018-01-26 19:11             ` David Woodhouse
2018-01-26  8:46 ` David Woodhouse
2018-01-26  8:46   ` David Woodhouse
  -- strict thread matches above, loose matches on Subject: below --
2018-01-26  2:50 Liran Alon
2018-01-26  2:55 ` Van De Ven, Arjan
2018-01-26  2:55   ` Van De Ven, Arjan
2018-01-23 11:13 Liran Alon
2018-01-25 22:20 ` Dave Hansen
2018-01-22 22:15 Luke Kenneth Casson Leighton
2018-01-20 19:22 [RFC 00/10] Speculation Control feature support KarimAllah Ahmed
2018-01-20 19:23 ` [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation KarimAllah Ahmed
2018-01-20 19:23   ` KarimAllah Ahmed
2018-01-21 19:14   ` Andy Lutomirski
2018-01-21 19:14     ` Andy Lutomirski
2018-01-23 16:12     ` Tom Lendacky
2018-01-23 16:12       ` Tom Lendacky
2018-01-23 16:20       ` Woodhouse, David
2018-01-23 16:20         ` Woodhouse, David
2018-01-23 22:37         ` Tom Lendacky
2018-01-23 22:37           ` Tom Lendacky
2018-01-23 22:49           ` Andi Kleen
2018-01-23 22:49             ` Andi Kleen
2018-01-23 23:14             ` Woodhouse, David
2018-01-23 23:14               ` Woodhouse, David
2018-01-23 23:22               ` Andi Kleen
2018-01-23 23:22                 ` Andi Kleen
2018-01-24  0:47               ` Tim Chen
2018-01-24  0:47                 ` Tim Chen
2018-01-24  1:00                 ` Andy Lutomirski
2018-01-24  1:00                   ` Andy Lutomirski
2018-01-24  1:22                   ` David Woodhouse
2018-01-24  1:22                     ` David Woodhouse
2018-01-24  1:59                   ` Van De Ven, Arjan
2018-01-24  1:59                     ` Van De Ven, Arjan
2018-01-24  3:25                     ` Andy Lutomirski
2018-01-24  3:25                       ` Andy Lutomirski
2018-01-21 19:34   ` Linus Torvalds
2018-01-21 20:28     ` David Woodhouse
2018-01-21 20:28       ` David Woodhouse
2018-01-21 21:35       ` Linus Torvalds
2018-01-21 21:35         ` Linus Torvalds
2018-01-21 22:00         ` David Woodhouse
2018-01-21 22:00           ` David Woodhouse
2018-01-21 22:27           ` Linus Torvalds
2018-01-21 22:27             ` Linus Torvalds
2018-01-22 16:27             ` David Woodhouse
2018-01-22 16:27               ` David Woodhouse
2018-01-23  7:29               ` Ingo Molnar
2018-01-23  7:29                 ` Ingo Molnar
2018-01-23  7:53                 ` Ingo Molnar
2018-01-23  7:53                   ` Ingo Molnar
2018-01-23  9:27                   ` Ingo Molnar
2018-01-23  9:27                     ` Ingo Molnar
2018-01-23  9:37                     ` David Woodhouse
2018-01-23  9:37                       ` David Woodhouse
2018-01-23 15:01                     ` Dave Hansen
2018-01-23 15:01                       ` Dave Hansen
2018-01-23  9:30                   ` David Woodhouse
2018-01-23  9:30                     ` David Woodhouse
2018-01-23 10:15                     ` Ingo Molnar
2018-01-23 10:15                       ` Ingo Molnar
2018-01-23 10:27                       ` David Woodhouse
2018-01-23 10:27                         ` David Woodhouse
2018-01-23 10:44                         ` Ingo Molnar
2018-01-23 10:44                           ` Ingo Molnar
2018-01-23 10:57                           ` David Woodhouse
2018-01-23 10:23                     ` Ingo Molnar
2018-01-23 10:23                       ` Ingo Molnar
2018-01-23 10:35                       ` David Woodhouse
2018-02-04 18:43                       ` Thomas Gleixner
2018-02-04 18:43                         ` Thomas Gleixner
2018-02-04 20:22                         ` David Woodhouse
2018-02-04 20:22                           ` David Woodhouse
2018-02-06  9:14                         ` David Woodhouse
2018-02-06  9:14                           ` David Woodhouse
2018-01-25 16:19                     ` Mason
2018-01-25 16:19                       ` Mason
2018-01-25 17:16                       ` Greg Kroah-Hartman
2018-01-25 17:16                         ` Greg Kroah-Hartman
2018-01-29 11:59                         ` Mason
2018-01-29 11:59                           ` Mason
2018-01-24  0:05                 ` Andi Kleen
2018-01-23 20:16       ` Pavel Machek
2018-01-23 20:16         ` Pavel Machek

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