Re: [PATCH] x86/kvm/emulate.c: simplify NOP (opcode 0x90) check

2013-07-04 Thread Paolo Bonzini
Il 04/07/2013 13:06, Denys Vlasenko ha scritto: >>> >> -case 0x90 ... 0x97: /* nop / xchg reg, rax */ >>> >> -if (ctxt->dst.addr.reg == reg_rmw(ctxt, VCPU_REGS_RAX)) >>> >> -break; >>> >> +case 0x90: /* nop */ >>> >> +break; >>

Re: [PATCH] x86/kvm/emulate.c: simplify NOP (opcode 0x90) check

2013-07-04 Thread Gleb Natapov
On Thu, Jul 04, 2013 at 01:06:16PM +0200, Denys Vlasenko wrote: > On 07/04/2013 11:13 AM, Gleb Natapov wrote: > > On Thu, Jul 04, 2013 at 10:58:29AM +0200, Denys Vlasenko wrote: > >> The check sits in switch() statement which itself can check > >> for opcode 0x90 far more efficiently. > >> > >> On

Re: [PATCH] x86/kvm/emulate.c: simplify NOP (opcode 0x90) check

2013-07-04 Thread Denys Vlasenko
On 07/04/2013 11:13 AM, Gleb Natapov wrote: > On Thu, Jul 04, 2013 at 10:58:29AM +0200, Denys Vlasenko wrote: >> The check sits in switch() statement which itself can check >> for opcode 0x90 far more efficiently. >> >> On assembler level, this change simply eliminates the following >> bit of code:

Re: [PATCH] x86/kvm/emulate.c: simplify NOP (opcode 0x90) check

2013-07-04 Thread Gleb Natapov
On Thu, Jul 04, 2013 at 10:58:29AM +0200, Denys Vlasenko wrote: > The check sits in switch() statement which itself can check > for opcode 0x90 far more efficiently. > > On assembler level, this change simply eliminates the following > bit of code: > > 4c 8b a3 d8 00 00 00mov0xd8(%rbx),%r