Re: [PATCH 5/5] KVM: x86: Fix wrong masking on relative jump/call

[Nadav Amit]

On 5/7/14, 5:43 PM, Bandan Das wrote:
> Nadav Amit <namit@xxxxxxxxxxxxxxxxx> writes:
>
> > Relative jumps and calls do the masking according to the operand size, and not
> > according to the address size as the KVM emulator does today.  In 64-bit mode,
> > the resulting RIP is always 64-bit. Otherwise it is masked according to the
> > instruction operand-size. Note that when 16-bit address size is used, bits
> > 63:32 are unmodified.
> >
> > Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/emulate.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> > index 6833b41..e406705 100644
> > --- a/arch/x86/kvm/emulate.c
> > +++ b/arch/x86/kvm/emulate.c
> > @@ -506,7 +506,9 @@ static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc)
> >
> >   static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel)
> >   {
> > -	register_address_increment(ctxt, &ctxt->_eip, rel);
> > +	/* 64-bit mode relative jumps are always 64-bit; otherwise mask */
> > +	int op_bytes = ctxt->mode == X86EMUL_MODE_PROT64 ? 8 : ctxt->op_bytes;
>
> Just a nit, probably break this up for readability ?
I will make it more readable on the next version.

Thanks,
Nadav
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