linux-kernel - Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

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Message-ID: <20170907185002.g5r5oaeyghtx2fgl@docker>
Date:   Thu, 7 Sep 2017 12:50:02 -0600
From:   Tycho Andersen <tycho@...ker.com>
To:     Ralph Campbell <rcampbell@...dia.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        Marco Benatto <marco.antonio.780@...il.com>,
        Juerg Haefliger <juerg.haefliger@...onical.com>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame
 Ownership (XPFO)

On Thu, Sep 07, 2017 at 06:33:09PM +0000, Ralph Campbell wrote:
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2736,6 +2736,8 @@
> > 
> >  	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
> > 
> > +	noxpfo		[X86-64] Disable XPFO when CONFIG_XPFO is on.
> > +
> >  	cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
> >  			CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
> >  			Some features depend on CPU0. Known dependencies
> <... snip>
> 
> A bit more description for system administrators would be very useful.
> Perhaps something like:
> 
> noxpfo		[XPFO,X86-64] Disable eXclusive Page Frame Ownership (XPFO)
>                              Physical pages mapped into user applications will also be mapped
>                              in the kernel's address space as if CONFIG_XPFO was not enabled.
> 
> Patch 05 should also update kernel-parameters.txt and add "ARM64" to the config option list for noxpfo.

Nice catch, thanks. I'll fix both.

Cheers,

Tycho