From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: 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>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts
Date: Fri, 5 Jan 2018 12:27:28 +0000 [thread overview]
Message-ID: <20180105122727.GD2491@work-vm> (raw)
> 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.
>>
>> Patches for 1-3 are out there and 4 is pretty straightforward. Doing a
>> arch_prctl() is still straightforward, but will be a much more niche
>> thing than any of the other choices. Plus, with a user interface, we
>> have to argue over the ABI for at least a month or two. ;)
I was chatting to Andrea about this, and we came to the conclusion one
use might be for qemu; I was worried about (theoretically) whether
userspace in a guest could read privileged data from the guest kernel by
attacking the qemu process rather than by attacking the kernels.
Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next reply other threads:[~2018-01-05 12:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-05 12:27 Dr. David Alan Gilbert [this message]
2018-01-05 18:00 ` [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts Dave Hansen
-- strict thread matches above, loose matches on Subject: below --
2018-01-04 17:56 [PATCH 0/7] IBRS patch series Tim Chen
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
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