From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg KH <gregkh@linuxfoundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andi Kleen <ak@linux.intel.com>,
Arjan Van De Ven <arjan.van.de.ven@intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts
Date: Fri, 5 Jan 2018 12:01:00 +0000 [thread overview]
Message-ID: <20180105120100.73f0b4b7@alans-desktop> (raw)
In-Reply-To: <84a6f2f2-d5fe-6b42-0590-33723c1b4960@intel.com>
On Thu, 4 Jan 2018 21:11:23 -0800
Dave Hansen <dave.hansen@intel.com> wrote:
> On 01/04/2018 08:51 PM, Andy Lutomirski wrote:
> > Do we need an arch_prctl() to enable IBRS for user mode?
>
> Eventually, once the dust settles. I think there's a spectrum of
> paranoia here, that is roughly (with increasing paranoia):
>
> 1. do nothing
> 2. do retpoline
> 3. do IBRS in kernel
> 4. do IBRS always
>
> I think you're asking for ~3.5.
And we'll actually end up with cgroups needing to handle this and a prctl
because the answer is simply not a systemwide single constant. To start
with if my code has CAP_SYS_RAWIO who gives a **** about IBRS protecting
it.
Likewise on many real world systems I trust my base OS (or I might as
well turn off the power) I sort of trust my apps, and I deeply distrust
my web browser which itself probably wants to turn some of the
protections on for crap like javascript and webassembly.
If I'm running containers well my desktop is probably #2 and my container
#3 or #4
There's no point getting hung up about a single magic default number,
because that's not how it's going to end up.
Alan
next prev parent reply other threads:[~2018-01-05 12:01 UTC|newest]
Thread overview: 116+ 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 [this message]
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
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
-- strict thread matches above, loose matches on Subject: below --
2018-01-05 12:27 [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts Dr. David Alan Gilbert
2018-01-05 18:00 ` Dave Hansen
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