Re: [Xen-devel] [V8 2/4] x86/xsaves: enable xsaves/xrstors/xsavec in xen

[Shuai Ruan <shuai.ruan@xxxxxxxxxxxxxxx>]

On Mon, Oct 26, 2015 at 08:03:55AM -0600, Jan Beulich wrote:
> >>> On 23.10.15 at 11:48, <shuai.ruan@xxxxxxxxxxxxxxx> wrote:
> > This patch uses xsaves/xrstors/xsavec instead of xsaveopt/xrstor
> > to perform the xsave_area switching so that xen itself
> > can benefit from them when available.
> > 
> > For xsaves/xrstors/xsavec only use compact format. Add format conversion
> > support when perform guest os migration.
> > 
> > Also, pv guest will not support xsaves/xrstors.
> > @@ -343,11 +520,18 @@ void xstate_init(struct cpuinfo_x86 *c)
> >  
> >      /* Mask out features not currently understood by Xen. */
> >      eax &= (cpufeat_mask(X86_FEATURE_XSAVEOPT) |
> > -            cpufeat_mask(X86_FEATURE_XSAVEC));
> > +            cpufeat_mask(X86_FEATURE_XSAVEC) |
> > +            cpufeat_mask(X86_FEATURE_XGETBV1) |
> > +            cpufeat_mask(X86_FEATURE_XSAVES));
> >  
> >      c->x86_capability[X86_FEATURE_XSAVEOPT / 32] = eax;
> >  
> >      BUG_ON(eax != boot_cpu_data.x86_capability[X86_FEATURE_XSAVEOPT / 32]);
> > +
> > +    if ( setup_xstate_features(bsp) )
> > +        BUG();
> 
> BUG()? On the BSP maybe, but APs should simply fail being
> brought up instead of bringing down the whole system.
> 
For APs, setup_xsate_features will never return error. Just BSP can
return error as -ENOMEM.

> > --- a/xen/include/public/arch-x86/hvm/save.h
> > +++ b/xen/include/public/arch-x86/hvm/save.h
> > @@ -140,6 +140,7 @@ struct hvm_hw_cpu {
> >      uint64_t msr_syscall_mask;
> >      uint64_t msr_efer;
> >      uint64_t msr_tsc_aux;
> > +    uint64_t msr_xss;
> 
> You can't extend a public interface structure like this. New MSRs
> shouldn't be saved/restored this way anyway - that's what we
> have struct hvm_msr for.
Yes. I will use the exist function "hvm_save_cpu_msrs" to save this msr. I 
intend to add save msr logic before "ASSERT(ctxt->count <= msr_count_max);" in 
hvm_save_cpu_msrs. Is that Ok ?

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel