KVM: x86 emulator: implement 'ret far' instruction (opcode 0xcb)

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 94459f313f12d259ceceb249f8256d06782847f9..ca91749d2083ff71a44b66f4253bda00dff7f4b3 100644 (file)
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -178,7 +178,7 @@ static u32 opcode_table[256] = {
        0, ImplicitOps | Stack, 0, 0,
        ByteOp | DstMem | SrcImm | ModRM | Mov, DstMem | SrcImm | ModRM | Mov,
        /* 0xC8 - 0xCF */
-       0, 0, 0, 0, 0, 0, 0, 0,
+       0, 0, 0, ImplicitOps | Stack, 0, 0, 0, 0,
        /* 0xD0 - 0xD7 */
        ByteOp | DstMem | SrcImplicit | ModRM, DstMem | SrcImplicit | ModRM,
        ByteOp | DstMem | SrcImplicit | ModRM, DstMem | SrcImplicit | ModRM,
@@ -1278,6 +1278,25 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
        return 0;
 }
 
+static int emulate_ret_far(struct x86_emulate_ctxt *ctxt,
+                          struct x86_emulate_ops *ops)
+{
+       struct decode_cache *c = &ctxt->decode;
+       int rc;
+       unsigned long cs;
+
+       rc = emulate_pop(ctxt, ops, &c->eip, c->op_bytes);
+       if (rc)
+               return rc;
+       if (c->op_bytes == 4)
+               c->eip = (u32)c->eip;
+       rc = emulate_pop(ctxt, ops, &cs, c->op_bytes);
+       if (rc)
+               return rc;
+       rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)cs, 1, VCPU_SREG_CS);
+       return rc;
+}
+
 static inline int writeback(struct x86_emulate_ctxt *ctxt,
                            struct x86_emulate_ops *ops)
 {
@@ -1735,6 +1754,11 @@ special_insn:
        mov:
                c->dst.val = c->src.val;
                break;
+       case 0xcb:              /* ret far */
+               rc = emulate_ret_far(ctxt, ops);
+               if (rc)
+                       goto done;
+               break;
        case 0xd0 ... 0xd1:     /* Grp2 */
                c->src.val = 1;
                emulate_grp2(ctxt);