Re: [Xen-devel] [PATCH 2/3 v2] XSAVE/XRSTOR: fix frozen states

[Weidong Han <weidong.han@xxxxxxxxx>]

Jan Beulich wrote:
> > > > On 31.08.10 at 16:52, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
> > > >         
> > --- a/xen/include/asm-x86/i387.h        Tue Aug 31 18:12:03 2010 -0400
> > +++ b/xen/include/asm-x86/i387.h        Tue Aug 31 18:20:46 2010 -0400
> > @@ -113,9 +113,9 @@ static inline void setup_fpu(struct vcpu
> >             if ( !v->fpu_initialised )
> >                 v->fpu_initialised = 1;
> >
> > -            set_xcr0(v->arch.hvm_vcpu.xcr0 | XSTATE_FP_SSE);
> > +            /* Restore all supported feature states */
> > +            set_xcr0(xfeature_mask);
> >             xrstor(v);
> > -            set_xcr0(v->arch.hvm_vcpu.xcr0);
> >         }
> >         else
> >         {
> >     
> Aren't you taking away control from the guest OS of what part of the
> state it wants/needs to save?
>
>   
To fix 'frozen states', it needs to saves/restores all supported states.

I find an issue here. It should set_xcr0 to hvm_vcpu.xcr0 after xsave() 
and xrstor(), because applications in guest may read xcr0. I will fix it 
in next version.
Regards,
Weidong



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel