Please send kvm patches to [email protected] too. On Thu, Jul 04, 2013 at 01:27:00PM +0200, Denys Vlasenko wrote: > We do not need to check for reg == RAX for opcodes 0x91...0x97. > The is no reason to optimize here. This is not performance sensitive path, far from it. If not for "clear high bits" behaviour of em_xchg() we would just call it to emulate nop.
> Signed-off-by: Denys Vlasenko <[email protected]> > CC: Paolo Bonzini <[email protected]> > CC: Avi Kivity <[email protected]> > > Signed-off-by: Denys Vlasenko <[email protected]> > CC: Paolo Bonzini <[email protected]> > CC: Avi Kivity <[email protected]> > --- > arch/x86/kvm/emulate.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 2bc1e81..2dc48a1 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -4544,9 +4544,14 @@ special_insn: > case 0x8d: /* lea r16/r32, m */ > ctxt->dst.val = ctxt->src.addr.mem.ea; > break; > - case 0x90 ... 0x97: /* nop / xchg reg, rax */ > + case 0x90: /* nop / xchg reg, rax */ > + /* Not all opcodes 90 are NOPs, only ones which refer to RAX */ > + /* For example, 49 90 is xchg %rax,%r8 */ > + /* Bare 90 and 40 90 (redundant REX prefix) are nop */ > if (ctxt->dst.addr.reg == reg_rmw(ctxt, VCPU_REGS_RAX)) > break; > + /* Fall through */ > + case 0x91 ... 0x97: /* xchg reg, rax */ > rc = em_xchg(ctxt); > break; > case 0x98: /* cbw/cwde/cdqe */ > -- > 1.8.1.4 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
