From: Dave Hansen <dave.hansen@intel.com>
To: 84a6f2f2-d5fe-6b42-0590-33723c1b4960@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 10:00:30 -0800 [thread overview]
Message-ID: <2cd1624f-7e1b-6bdd-a793-d97b8e280ed7@intel.com> (raw)
In-Reply-To: <20180105122727.GD2491@work-vm>
On 01/05/2018 04:27 AM, Dr. David Alan Gilbert wrote:
>>> 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.
Theoretically, I believe it's possible. The SMEP-based mitigations are
effective when crossing rings, but do not help with
guest-ring0->host-ring0 or presumably guest-ring3->host-ring3.
For the same-ring things, we have the indirect branch predictor flush
operation MSR (IBPB). Expect those to be posted once we have the IBRS
and retpoline approaches settled.
next prev parent reply other threads:[~2018-01-05 18:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-05 12:27 Dr. David Alan Gilbert
2018-01-05 18:00 ` Dave Hansen [this message]
-- 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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