KVM: x86 emulator: add CBW/CWDE/CDQE instruction emulation

Add CBW/CWDE/CDQE instruction emulation.(opcode 0x98)
Used by FreeBSD's boot loader.

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

1 files changed, 8 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index aab62d50752e..312dda57f93b 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2300,7 +2300,7 @@ static struct opcode opcode_table[256] = {
         /* 0x90 - 0x97 */
         X8(D(SrcAcc | DstReg)),
         /* 0x98 - 0x9F */
-        N, N, D(SrcImmFAddr | No64), N,
+        D(DstAcc | SrcNone), N, D(SrcImmFAddr | No64), N,
         D(ImplicitOps | Stack), D(ImplicitOps | Stack), N, N,
         /* 0xA0 - 0xA7 */
         D(ByteOp | DstAcc | SrcMem | Mov | MemAbs), D(DstAcc | SrcMem | Mov | MemAbs),
@@ -3003,6 +3003,13 @@ special_insn:
                 if (c->dst.addr.reg == &c->regs[VCPU_REGS_RAX])
                         break;
                 goto xchg;
+        case 0x98: /* cbw/cwde/cdqe */
+                switch (c->op_bytes) {
+                case 2: c->dst.val = (s8)c->dst.val; break;
+                case 4: c->dst.val = (s16)c->dst.val; break;
+                case 8: c->dst.val = (s32)c->dst.val; break;
+                }
+                break;
         case 0x9c: /* pushf */
                 c->src.val =  (unsigned long) ctxt->eflags;
                 emulate_push(ctxt, ops);