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From: Greg KH <gregkh@linuxfoundation.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andi Kleen <ak@linux.intel.com>,
	Arjan Van De Ven <arjan.van.de.ven@intel.com>,
	linux-kernel@vger.kernel.org, David Woodhouse <dwmw@amazon.co.uk>
Subject: Re: [PATCH 5/7] x86: Use IBRS for firmware update path
Date: Thu, 4 Jan 2018 21:05:15 +0100	[thread overview]
Message-ID: <20180104200515.GC30228@kroah.com> (raw)
In-Reply-To: <8d3710432534b27d224283557c4629cd1aa5b0ea.1515086770.git.tim.c.chen@linux.intel.com>

On Thu, Jan 04, 2018 at 09:56:46AM -0800, Tim Chen wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> We are impervious to the indirect branch prediction attack with retpoline
> but firmware won't be, so we still need to set IBRS to protect
> firmware code execution when calling into firmware at runtime.

Wait, what?

Maybe it's just the wine from dinner talking, but if the firmware has
issues, we have bigger things to worry about here, right?  It already
handed over the "chain of trust" to us, so we have already implicitly
trusted that the firmware was correct here.  So why do we need to do
anything about firmware calls in this manner?

Or am I totally missing something else here?

thanks,

greg k-h

  parent reply	other threads:[~2018-01-04 20:05 UTC|newest]

Thread overview: 114+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-04 17:56 [PATCH 0/7] IBRS patch series Tim Chen
2018-01-04 17:56 ` [PATCH 1/7] x86/feature: Detect the x86 feature to control Speculation Tim Chen
2018-01-04 19:58   ` Greg KH
2018-01-04 20:47     ` Tim Chen
2018-01-05 11:14   ` David Woodhouse
2018-01-05 15:14     ` Tom Lendacky
2018-01-05 17:07       ` Tim Chen
2018-01-05 13:09   ` Thomas Gleixner
2018-01-05 13:44     ` Andrea Arcangeli
2018-01-05 13:51       ` Thomas Gleixner
2018-01-04 17:56 ` [PATCH 2/7] x86/enter: MACROS to set/clear IBRS Tim Chen
2018-01-04 22:16   ` Peter Zijlstra
2018-01-04 22:21     ` Tim Chen
2018-01-04 22:23       ` Dave Hansen
2018-01-05  4:54         ` Andy Lutomirski
2018-01-05  5:05           ` Dave Hansen
2018-01-05 13:19       ` Thomas Gleixner
2018-01-04 17:56 ` [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts Tim Chen
2018-01-04 20:00   ` Greg KH
2018-01-04 20:26     ` Tim Chen
2018-01-04 20:45   ` Dave Hansen
2018-01-04 22:33   ` Peter Zijlstra
2018-01-04 23:12     ` Andrea Arcangeli
2018-01-05  0:08     ` Dave Hansen
2018-01-05  4:51       ` Andy Lutomirski
2018-01-05  5:11         ` Dave Hansen
2018-01-05 12:01           ` Alan Cox
2018-01-05 13:35   ` Thomas Gleixner
2018-01-04 17:56 ` [PATCH 4/7] x86/idle: Disable IBRS entering idle and enable it on wakeup Tim Chen
2018-01-04 22:47   ` Peter Zijlstra
2018-01-04 23:00     ` Andrea Arcangeli
2018-01-04 23:22     ` Tim Chen
2018-01-04 23:42       ` Andrea Arcangeli
2018-01-04 23:45         ` Thomas Gleixner
2018-01-05  0:03           ` Andrea Arcangeli
2018-01-08  8:24       ` Peter Zijlstra
2018-01-04 17:56 ` [PATCH 5/7] x86: Use IBRS for firmware update path Tim Chen
2018-01-04 18:48   ` Alan Cox
2018-01-04 20:05   ` Greg KH [this message]
2018-01-04 20:08     ` Woodhouse, David
2018-01-05 16:08       ` gregkh
2018-01-05 16:37         ` Andrea Arcangeli
2018-01-04 20:21     ` Andrew Cooper
2018-01-04 20:48     ` Andrea Arcangeli
2018-01-04 20:51   ` Yves-Alexis Perez
2018-01-04 21:13     ` Tim Chen
2018-01-04 22:51   ` Peter Zijlstra
2018-01-05 13:40   ` Thomas Gleixner
2018-01-04 17:56 ` [PATCH 6/7] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature Tim Chen
2018-01-04 18:33   ` Borislav Petkov
2018-01-04 18:36     ` Dave Hansen
2018-01-04 18:52       ` Borislav Petkov
2018-01-04 18:57         ` Andrea Arcangeli
2018-01-04 18:59         ` Dave Hansen
2018-01-04 19:06           ` Borislav Petkov
2018-01-05 13:48       ` Thomas Gleixner
2018-01-04 18:38     ` Andrea Arcangeli
2018-01-04 18:54       ` Dave Hansen
2018-01-04 18:56         ` Borislav Petkov
2018-01-04 18:55       ` Borislav Petkov
2018-01-04 18:34   ` Andrea Arcangeli
2018-01-04 19:02     ` Tim Chen
2018-01-04 18:50   ` Alan Cox
2018-01-04 20:16   ` Greg KH
2018-01-04 20:58     ` Tim Chen
2018-01-04 22:54   ` Peter Zijlstra
2018-01-04 23:26     ` Tim Chen
2018-01-04 23:51       ` Andrea Arcangeli
2018-01-04 23:59         ` Borislav Petkov
2018-01-05  0:07           ` Thomas Gleixner
2018-01-05 11:16   ` David Woodhouse
2018-01-06  1:29     ` Tim Chen
2018-01-04 17:56 ` [PATCH 7/7] x86/microcode: Recheck IBRS features on microcode reload Tim Chen
2018-01-04 18:28   ` Borislav Petkov
2018-01-04 18:34     ` Andrea Arcangeli
2018-01-04 18:50       ` Borislav Petkov
2018-01-04 19:10         ` Tim Chen
2018-01-05 13:32         ` Greg KH
2018-01-05 13:37           ` Borislav Petkov
2018-01-05 13:47             ` Greg KH
2018-01-05 15:28           ` Andrea Arcangeli
2018-01-04 19:00 ` [PATCH 0/7] IBRS patch series Linus Torvalds
2018-01-04 19:19   ` David Woodhouse
2018-01-04 19:33     ` Linus Torvalds
2018-01-04 19:39       ` David Woodhouse
2018-01-04 19:40       ` Andrew Cooper
2018-01-04 19:46         ` David Woodhouse
2018-01-04 21:22       ` Van De Ven, Arjan
2018-01-05 11:32         ` Paolo Bonzini
2018-01-05 12:09           ` Paul Turner
2018-01-05 14:45           ` Van De Ven, Arjan
2018-01-05 14:43         ` Andrea Arcangeli
2018-01-05 14:52           ` Van De Ven, Arjan
2018-01-05 15:03             ` Andrea Arcangeli
2018-01-05 14:54           ` Thomas Gleixner
2018-01-05 11:52       ` Paul Turner
2018-01-05 14:28         ` David Woodhouse
2018-01-05 14:42           ` Van De Ven, Arjan
2018-01-05 15:38             ` David Woodhouse
2018-01-05 16:05               ` Andrea Arcangeli
2018-01-05 16:37                 ` David Woodhouse
2018-01-05 16:42                   ` Andrea Arcangeli
2018-01-05 16:44                     ` Van De Ven, Arjan
2018-01-05 16:46                     ` David Woodhouse
2018-01-05  5:25   ` Florian Weimer
2018-01-05 11:05     ` David Woodhouse
2018-01-04 19:05 ` Justin Forbes
2018-01-04 19:10   ` Tim Chen
2018-01-04 21:01     ` Yves-Alexis Perez
2018-01-05 13:28       ` Greg KH
2018-01-05 13:47         ` Yves-Alexis Perez
2018-01-05 14:01           ` Greg KH
2018-01-05 14:26             ` Paolo Bonzini
2018-01-05 14:54               ` Yves-Alexis Perez

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