linux-kernel - Re: [Xen-devel] [V5 PATCH 1/1] x86/xen: Set EFER.NX and EFER.SCE in PVH guests

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Date:	Fri, 12 Sep 2014 13:46:45 -0700
From:	Mukesh Rathor <mukesh.rathor@...cle.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [V5 PATCH 1/1] x86/xen: Set EFER.NX and EFER.SCE in
 PVH guests

On Fri, 12 Sep 2014 16:42:58 -0400
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> wrote:

> On Wed, Sep 10, 2014 at 04:36:06PM -0700, Mukesh Rathor wrote:
> > This fixes two bugs in PVH guests:
> > 
> >   - Not setting EFER.NX means the NX bit in page table entries is
> >     ignored on Intel processors and causes reserved bit page faults
> > on AMD processors.
> > 
> >   - After the Xen commit 7645640d6ff1 ("x86/PVH: don't set EFER_SCE
> > for pvh guest") PVH guests are required to set EFER.SCE to enable
> > the SYSCALL instruction.
> > 
> > Secondary VCPUs are started with pagetables with the NX bit set so
> > EFER.NX must be set before using any stack or data segment.
> > xen_pvh_cpu_early_init() is the new secondary VCPU entry point that
> > sets EFER before jumping to cpu_bringup_and_idle().
> > 
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
> > Signed-off-by: David Vrabel <david.vrabel@...rix.com>
> 
> Huh? So who wrote it? Or did you mean 'Reviewed-by'?

No, meant SOB. I wrote v1, v2, then David came up with V3 and v4, 
then i took comments from v4 and came up with v5.

-Mukesh

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