[PATCH] KVM: x86 emulator: simplify BSF/BSR instruction emulation

[PATCH] KVM: x86 emulator: simplify BSF/BSR instruction emulation

[Wei Yongjun]

Since ____emulate_2op() changed to use register for
destination, we can now simplify BSF/BSR instruction
to use it.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
---
 arch/x86/kvm/emulate.c |   30 ++++++++----------------------
 1 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7d99cbe..77da7b6 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3727,30 +3727,16 @@ twobyte_insn:
 	      btc:		/* btc */
 		emulate_2op_SrcV_nobyte("btc", c->src, c->dst, ctxt->eflags);
 		break;
-	case 0xbc: {		/* bsf */
-		u8 zf;
-		__asm__ ("bsf %2, %0; setz %1"
-			 : "=r"(c->dst.val), "=q"(zf)
-			 : "r"(c->src.val));
-		ctxt->eflags &= ~X86_EFLAGS_ZF;
-		if (zf) {
-			ctxt->eflags |= X86_EFLAGS_ZF;
-			c->dst.type = OP_NONE;	/* Disable writeback. */
-		}
+	case 0xbc:		/* bsf */
+		emulate_2op_SrcV_nobyte("bsf", c->src, c->dst, ctxt->eflags);
+		if (ctxt->eflags & X86_EFLAGS_ZF)
+			c->dst.type = OP_NONE;  /* Disable writeback. */
 		break;
-	}
-	case 0xbd: {		/* bsr */
-		u8 zf;
-		__asm__ ("bsr %2, %0; setz %1"
-			 : "=r"(c->dst.val), "=q"(zf)
-			 : "r"(c->src.val));
-		ctxt->eflags &= ~X86_EFLAGS_ZF;
-		if (zf) {
-			ctxt->eflags |= X86_EFLAGS_ZF;
-			c->dst.type = OP_NONE;	/* Disable writeback. */
-		}
+	case 0xbd:		/* bsr */
+		emulate_2op_SrcV_nobyte("bsr", c->src, c->dst, ctxt->eflags);
+		if (ctxt->eflags & X86_EFLAGS_ZF)
+			c->dst.type = OP_NONE;  /* Disable writeback. */
 		break;
-	}
 	case 0xbe ... 0xbf:	/* movsx */
 		c->dst.bytes = c->op_bytes;
 		c->dst.val = (c->d & ByteOp) ? (s8) c->src.val :
-- 
1.7.0.4