linux-kernel - Re: [Xen-devel] [PATCH] x86/amd: don't set X86_BUG_SYSRET_SS

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Message-ID: <20170425202712.63dauw5jtkvlm6sc@pd.tnic>
Date:   Tue, 25 Apr 2017 22:27:12 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Andrew Cooper <andrew.cooper3@...rix.com>
Cc:     Juergen Gross <jgross@...e.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
        xen-devel@...ts.xenproject.org, boris.ostrovsky@...cle.com,
        tglx@...utronix.de
Subject: Re: [Xen-devel] [PATCH] x86/amd: don't set X86_BUG_SYSRET_SS_ATTRS
 if forced to zero

On Tue, Apr 25, 2017 at 09:17:13PM +0100, Andrew Cooper wrote:
> The problem (for all ring-deprivileged virtuailsation; not just Xen PV),
> is that

I know what that that bug flag is for.

I'm asking whether the xen guest boot sets a flag early - like XENPV,
for example - which can differentiate between baremetal and virt boot in
a fairly generic manner so that we don't set that bug flag then instead
of the set and then clear dance we do currently.

-- 
Regards/Gruss,
    Boris.

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