linux-kernel - Re: [Xen-devel] [PATCH 1/2] x86/xen: don't write ptes directly in 32-bit PV guests

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Message-Id: <5B7A7E0402000078001DFD01@prv1-mh.provo.novell.com>
Date:   Mon, 20 Aug 2018 02:38:28 -0600
From:   "Jan Beulich" <JBeulich@...e.com>
To:     "Juergen Gross" <jgross@...e.com>
Cc:     "the arch/x86 maintainers" <x86@...nel.org>, <tglx@...utronix.de>,
        "xen-devel" <xen-devel@...ts.xenproject.org>,
        "Boris Ostrovsky" <boris.ostrovsky@...cle.com>, <mingo@...hat.com>,
        <linux-kernel@...r.kernel.org>, <hpa@...or.com>
Subject: Re: [Xen-devel] [PATCH 1/2] x86/xen: don't write ptes directly
 in 32-bit PV guests

>>> On 20.08.18 at 07:14, <jgross@...e.com> wrote:
> In some cases 32-bit PAE PV guests still write PTEs directly instead of
> using hypercalls. This is especially bad when clearing a PTE as this is
> done via 32-bit writes which will produce intermediate L1TF attackable
> PTEs.
> 
> Change the code to use hypercalls instead.
> 
> Signed-off-by: Juergen Gross <jgross@...e.com>

Reviewed-by: Jan Beulich <jbeulich@...e.com>