Re: [PATCH 0/3] Infinite loops in microcode while running guests

From: Jan Kiszka
Date: Thu Nov 12 2015 - 09:08:30 EST

On 2015-11-11 14:12, Austin S Hemmelgarn wrote:
> On 2015-11-11 08:07, Paolo Bonzini wrote:
>> On 11/11/2015 13:47, Austin S Hemmelgarn wrote:
>>> I just finished running a couple of tests in a KVM instance running
>>> nested on a Xen HVM instance, and found no issues, so for the set as a
>>> whole:
>>> Tested-by: Austin S. Hemmelgarn <ahferroin7@xxxxxxxxx>
>>> Now to hope the equivalent fix for Xen gets into the Gentoo repositories
>>> soon, as the issue propagates down through nested virtualization and
>>> ties up the CPU regardless (and in turn triggers the watchdog).
>> Note that nested guests should _not_ lock up the outer (L0) hypervisor
>> if the outer hypervisor has the fix. At least this is the case for KVM:
>> a fixed outer KVM can protect any vulnerable nested (L1) hypervisor from
>> malicious nested guests. A vulnerable outer KVM is also protected if
>> the nested hypervisor has the workaround.
> I already knew this, I just hadn't remembered that I hadn't updated Xen
> since before the XSA and patch for this had been posted (and it took me
> a while to remember this when I accidentally panicked Xen :))

As I'm lazy, both to search and to write something myself: is there
already a test case for the issue(s) circling around?


Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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