From: Andi Kleen <ak@linux.intel.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: LVI
Date: Tue, 26 Nov 2019 10:28:52 -0800 [thread overview]
Message-ID: <20191126182852.GI84886@tassilo.jf.intel.com> (raw)
In-Reply-To: <e43ebda7-90fc-f44d-84e9-a0edcd4d10fd@redhat.com>
> Don't you need only half of a Spectrev1 gadget (see the Xen advisory at
> https://xenbits.xen.org/xsa/advisory-289.html and the KVM patch at
> https://marc.info/?l=kvm&m=157444806904659&w=2)?
You need the universal read gadget at least, which is the primary thing
a Spectre v1 audit is looking for. My understanding is for the kernel
cases it was all the same locations.
> Also I assume you didn't take into account using vmexits as an assist.
Yes that was missing from the write up, thanks.
For vmexit assists there are two cases:
- The CPU is not MDS_NO (e.g. pre CLX) and is vulnerable to L1TF:
In this case the L1TF mitigations (L1 cache clear and/or core scheduling)
are sufficient to avoid an attacker in a guest ever seeing any side effects
- The CPU is MDS_NO (e.g. CLX): LVI can only inject 0 values, which
are not considered a security risk for normal operation.
So no extra changes needed for vmexits.
-Andi
prev parent reply other threads:[~2019-11-26 18:28 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 17:40 [MODERATED] LVI Josh Poimboeuf
2019-11-19 17:51 ` [MODERATED] LVI Andrew Cooper
2019-11-19 18:27 ` Josh Poimboeuf
2019-11-19 19:26 ` Andrew Cooper
2019-11-20 9:52 ` Paolo Bonzini
2019-11-19 18:12 ` Greg KH
2019-11-19 18:21 ` Josh Poimboeuf
2019-11-19 18:46 ` Greg KH
2019-11-19 18:21 ` Paolo Bonzini
2019-11-19 18:22 ` Andrew Cooper
2019-11-19 18:27 ` Josh Poimboeuf
2019-11-19 18:36 ` Luck, Tony
2019-11-20 17:02 ` Greg KH
2019-11-19 18:39 ` Andrew Cooper
2019-11-19 21:00 ` Josh Poimboeuf
2019-11-19 21:03 ` Josh Poimboeuf
2019-11-20 14:11 ` Andrew Cooper
2019-11-20 8:04 ` Peter Zijlstra
2019-11-20 9:49 ` Andrew Cooper
2019-11-20 17:13 ` Josh Poimboeuf
2019-11-20 17:25 ` Greg KH
2019-11-20 17:29 ` Tyler Hicks
2019-11-20 17:30 ` Andrew Cooper
2019-11-20 17:46 ` Greg KH
2019-11-20 19:09 ` Peter Zijlstra
2019-11-20 19:19 ` Greg KH
2019-11-21 0:50 ` LVI Thomas Gleixner
2019-11-21 13:45 ` [MODERATED] LVI Greg KH
2019-11-26 0:54 ` Andi Kleen
2019-11-26 10:37 ` Greg KH
2019-11-26 18:23 ` Andi Kleen
2019-11-27 7:38 ` Greg KH
2019-11-26 10:55 ` Paolo Bonzini
2019-11-26 18:28 ` Andi Kleen [this message]
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