From a77ab5ead5c1fef2c6c5a9b3cf3765e52643a2aa Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@redhat.com>
Date: Mon, 5 Jan 2009 13:27:34 +0200
Subject: [PATCH] KVM: x86 emulator: implement 'ret far' instruction (opcode
0xcb)
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/x86_emulate.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 94459f313f12..ca91749d2083 100644
--- 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 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
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);