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From: Konrad Rzeszutek Wilk <konrad@darnok.org>
To: "Hansen, Dave" <dave.hansen@intel.com>
Cc: "Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Andi Kleen" <ak@linux.intel.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"David Woodhouse" <dwmw2@infradead.org>,
	"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 Krčmář" <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>,
	"Van De Ven, Arjan" <arjan.van.de.ven@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>,
	"Arjan van de Ven" <arjan@linux.intel.com>,
	"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>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation
Date: Sat, 27 Jan 2018 08:42:43 -0500	[thread overview]
Message-ID: <20180127134239.GA25029@localhost.localdomain> (raw)
In-Reply-To: <0089A7AA75120F4087B2E7CB6BF3E53442A9AA0A@CRSMSX104.amr.corp.intel.com>

On Fri, Jan 26, 2018 at 07:11:47PM +0000, Hansen, Dave wrote:
> The need for RSB stuffing in all the various scenarios and what the heck it actually mitigates is freakishly complicated.  I've tried to write it all down in one place: https://goo.gl/pXbvBE

Thank you for sharing that.

One question on the third from the top (' RSB Stuff (16) After
irq/nmi/#PF/...').

It says that :"Return from interrupt path (more than 16 deep) can empty
RSB".

Just to clarify - you mean all the returns ('ret') that are happening after
we call do_IRQ and the stack unwinds - but before we do an 'iret' correct?

I am 99% sure that is what you mean, but just confirming as one could read
this as: 'Need to do RSB after an iret' (say you are in the kernel
and then get an interrupt and iret back to kernel).

  reply	other threads:[~2018-01-27 13:42 UTC|newest]

Thread overview: 65+ 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 17:19     ` Linus Torvalds
2018-01-26 17:27       ` Borislav Petkov
2018-01-26 17:29       ` David Woodhouse
2018-01-26 17:31         ` David Woodhouse
2018-01-26 17:59       ` Andi Kleen
2018-01-26 18:11         ` David Woodhouse
2018-01-26 18:12           ` Arjan van de Ven
2018-01-26 18:26             ` David Woodhouse
2018-01-26 18:28               ` Van De Ven, Arjan
2018-01-26 18:43                 ` David Woodhouse
2018-01-26 18:44                   ` Van De Ven, Arjan
2018-01-26 18:53                     ` David Woodhouse
2018-01-26 19:02         ` Konrad Rzeszutek Wilk
2018-01-26 19:11           ` Hansen, Dave
2018-01-27 13:42             ` Konrad Rzeszutek Wilk [this message]
2018-01-27 15:55               ` Dave Hansen
2018-01-26 19:11           ` 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
2018-01-23 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
2018-01-21 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

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