linux-kernel - Re: [PATCH] x86/pti: don't report XenPV as vulnerable

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Date:   Fri, 15 Jun 2018 08:10:42 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
        Mike Latimer <mlatimer@...e.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/pti: don't report XenPV as vulnerable

On 15/06/18 08:04, Jiri Kosina wrote:
> On Fri, 15 Jun 2018, Juergen Gross wrote:
> 
>> wrong for 64-bit, too, in case the mitigation is disabled at hypervisor 
>> level.
> 
> If that is indeed possible (is it?), then the check we have in 
> pti_check_boottime_disable() is wrong as well.

No, it isn't. PTI for 32-bit kernels isn't paravirtualized, so it has to
be disabled.

> 
>> So the test should be done only for CONFIG_X86_64 
> 
> Fair enough.
> 
>> and the returned string should be e.g. "Mitigation: XEN".
> 
> Well, perhaps; it'd confuse all the scripts that are checking whether 
> system is fully secured or not by parsing sysfs files ... but that's 
> mostly their problem.

Right. And I suppose those scripts are fairly new. :-)


Juergen