Re: [PATCH 4/4] kvm: Emulate MOVBE

Re: [PATCH 4/4] kvm: Emulate MOVBE

[Borislav Petkov]

Fix kvm ML already.

On Tue, Jul 16, 2013 at 12:39:30AM +0200, Borislav Petkov wrote:
> On Sun, Jul 07, 2013 at 01:18:27PM +0300, Gleb Natapov wrote:
> > KVM does not enables emulation because QEMU called
> > KVM_GET_EMULATED_CPUID. KVM enables emulation because QEMU sets
> > MOVBE bit in a guest visible cpuid using KVM_SET_CPUID2. QEMU does
> > that either because host and cpu model QEMU uses both have it, or
> > because user asked for it specifically and KVM reports that it can
> > be emulated. Why emulator should care what is the reason MOVBE is
> > enabled?
> 
> Ok, I think I know what you mean:
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 6fe5a838116a..c963ff8e43dd 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -3147,10 +3147,18 @@ static int em_mov(struct x86_emulate_ctxt *ctxt)
>         return X86EMUL_CONTINUE;
>  }
>  
> +#undef F
> +#define F(x) bit(X86_FEATURE_##x)
> +
>  static int em_movbe(struct x86_emulate_ctxt *ctxt)
>  {
> +       u32 ebx, ecx, edx, eax = 1;
>         u16 tmp;
>  
> +       ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
> +       if (!(ecx & F(MOVBE)))
> +               return X86EMUL_PROPAGATE_FAULT;
> +
>         switch (ctxt->op_bytes) {
>         case 2:
>                 /*
> ---
> 
> Right?

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Re: [PATCH 4/4] kvm: Emulate MOVBE

[Gleb Natapov]

On Tue, Jul 16, 2013 at 12:41:15AM +0200, Borislav Petkov wrote:
> Fix kvm ML already.
> 
> On Tue, Jul 16, 2013 at 12:39:30AM +0200, Borislav Petkov wrote:
> > On Sun, Jul 07, 2013 at 01:18:27PM +0300, Gleb Natapov wrote:
> > > KVM does not enables emulation because QEMU called
> > > KVM_GET_EMULATED_CPUID. KVM enables emulation because QEMU sets
> > > MOVBE bit in a guest visible cpuid using KVM_SET_CPUID2. QEMU does
> > > that either because host and cpu model QEMU uses both have it, or
> > > because user asked for it specifically and KVM reports that it can
> > > be emulated. Why emulator should care what is the reason MOVBE is
> > > enabled?
> > 
> > Ok, I think I know what you mean:
> > 
> > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> > index 6fe5a838116a..c963ff8e43dd 100644
> > --- a/arch/x86/kvm/emulate.c
> > +++ b/arch/x86/kvm/emulate.c
> > @@ -3147,10 +3147,18 @@ static int em_mov(struct x86_emulate_ctxt *ctxt)
> >         return X86EMUL_CONTINUE;
> >  }
> >  
> > +#undef F
> > +#define F(x) bit(X86_FEATURE_##x)
> > +
> >  static int em_movbe(struct x86_emulate_ctxt *ctxt)
> >  {
> > +       u32 ebx, ecx, edx, eax = 1;
> >         u16 tmp;
> >  
> > +       ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
> > +       if (!(ecx & F(MOVBE)))
> > +               return X86EMUL_PROPAGATE_FAULT;
> > +
> >         switch (ctxt->op_bytes) {
> >         case 2:
> >                 /*
> > ---
> > 
> > Right?
> 
Right, just replace return X86EMUL_PROPAGATE_FAULT; with return emulate_ud(ctxt);

--
			Gleb.