Re: [Xen-devel] [PATCH] x86/cpuid: fix dom0 crash on skylake machine

["Han, Huaitong" <huaitong.han@xxxxxxxxx>]

Y, I think it works well, and more better.

to Luwei: you can test if the problem is solved. 

On Wed, 2016-06-01 at 10:03 +0100, Andrew Cooper wrote:
> On 01/06/16 05:58, Luwei Kang wrote:
> > CPUID.0XD.0X0.EAX is from machine value for dom0, and dom0 kernel will 
> > xsetbv
> > with xfeatures_mask that is from CPUID.0XD.0X0.EAX, but handle_xsetbv has
> > ingored XSTATE_PKRU with hardware protection fault emulation, so dom0 kernel
> > will crash on skylake machine with PKRU support.
> >
> > Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> > ---
> >  xen/arch/x86/traps.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> > index 1ef8401..5e72e44 100644
> > --- a/xen/arch/x86/traps.c
> > +++ b/xen/arch/x86/traps.c
> > @@ -1100,6 +1100,9 @@ void pv_cpuid(struct cpu_user_regs *regs)
> >               */
> >              if ( !is_control_domain(currd) && !is_hardware_domain(currd) )
> >                  cpuid_count(leaf, subleaf, &tmp, &b, &tmp, &tmp);
> > +
> > +            /* PV is not supported by XSTATE_PKRU. */
> > +            a &= ~XSTATE_PKRU;
> >              break;
> >          }
> >  
> 
> While this does work, it undoes some of the work I started with my cpuid
> improvements in 4.7
> 
> Does the attached patch also resolve your issue?
> 
> ~Andrew

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