KVM: x86 emulator: add LOOP/LOOPcc instruction emulation

Add LOOP/LOOPcc instruction emulation (opcode 0xe0~0xe2).

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 312dda57f93b..2f816edfe31e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2330,7 +2330,7 @@ static struct opcode opcode_table[256] = {
         /* 0xD8 - 0xDF */
         N, N, N, N, N, N, N, N,
         /* 0xE0 - 0xE7 */
-        N, N, N, N,
+        X3(D(SrcImmByte)), N,
         D(ByteOp | SrcImmUByte | DstAcc), D(SrcImmUByte | DstAcc),
         D(ByteOp | SrcAcc | DstImmUByte), D(SrcAcc | DstImmUByte),
         /* 0xE8 - 0xEF */
@@ -3084,6 +3084,12 @@ special_insn:
                 c->src.val = c->regs[VCPU_REGS_RCX];
                 emulate_grp2(ctxt);
                 break;
+        case 0xe0 ... 0xe2:     /* loop/loopz/loopnz */
+                register_address_increment(c, &c->regs[VCPU_REGS_RCX], -1);
+                if (address_mask(c, c->regs[VCPU_REGS_RCX]) != 0 &&
+                    (c->b == 0xe2 || test_cc(c->b ^ 0x5, ctxt->eflags)))
+                        jmp_rel(c, c->src.val);
+                break;
         case 0xe4:      /* inb */
         case 0xe5:      /* in */
                 goto do_io_in;