Re: [Xen-devel] [PATCH 08/14] Nested Virtualization: efer

[Christoph Egger <Christoph.Egger@xxxxxxx>]

On Thursday 19 August 2010 10:41:03 Tim Deegan wrote:
> At 04:33 +0100 on 19 Aug (1282192384), Dong, Eddie wrote:
> > > # HG changeset patch
> > > # User cegger
> > > # Date 1281003856 -7200
> > > Allow guest to enable SVM in EFER
> > >
> > > diff -r 7789f1d7d7e7 -r 8c7c597735c6 xen/arch/x86/hvm/hvm.c
> > > --- a/xen/arch/x86/hvm/hvm.c
> > > +++ b/xen/arch/x86/hvm/hvm.c
> > > @@ -616,6 +616,7 @@ static bool_t hvm_efer_valid(uint64_t va
> > >  {
> > >      return !((value & ~efer_validbits) ||
> > >               ((sizeof(long) != 8) && (value & EFER_LME)) ||
> > > +             (!cpu_has_svm && (value & EFER_SVME)) ||
> > >               (!cpu_has_nx && (value & EFER_NX)) ||
> > >               (!cpu_has_syscall && (value & EFER_SCE)) ||
> > >               (!cpu_has_lmsl && (value & EFER_LMSLE)) ||
> > > @@ -630,6 +631,7 @@ static int hvm_load_cpu_ctxt(struct doma
> > >      struct hvm_hw_cpu ctxt;
> > >      struct segment_register seg;
> > >      struct vcpu_guest_context *vc;
> > > +    uint64_t efer_validbits;
> > >
> > >      /* Which vcpu is this? */
> > >      vcpuid = hvm_load_instance(h);
> > > @@ -669,9 +671,12 @@ static int hvm_load_cpu_ctxt(struct doma
> > >          return -EINVAL;
> > >      }
> > >
> > > -    if ( !hvm_efer_valid(
> > > -        ctxt.msr_efer,
> > > -        EFER_FFXSE | EFER_LMSLE | EFER_LME | EFER_LMA | EFER_NX |
> > > EFER_SCE) ) +    efer_validbits = EFER_FFXSE | EFER_LMSLE | EFER_LME
> > >
> > > | EFER_LMA +                   | EFER_NX | EFER_SCE;
> > >
> > > +    if ( nestedhvm_enabled(v->domain) )
> > > +        efer_validbits |= EFER_SVME;
> >
> > Check it is running on SVM first.
>
> This check is made in hvm_efer_valid().  But it might be less confusing
> to have hvm_efer_valid() check nestedhvm_enabled() as well rather than
> do half the check in the caller and half in the function.

Good point. Fixed in local tree.

Christoph


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