KVM: x86 emulator: implement DAS (opcode 2F)

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

1 files changed, 41 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 81b0f8848960..83ded7c03d12 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2175,6 +2175,45 @@ static int em_push(struct x86_emulate_ctxt *ctxt)
         return X86EMUL_CONTINUE;
 }
 
+static int em_das(struct x86_emulate_ctxt *ctxt)
+{
+        struct decode_cache *c = &ctxt->decode;
+        u8 al, old_al;
+        bool af, cf, old_cf;
+
+        cf = ctxt->eflags & X86_EFLAGS_CF;
+        al = c->dst.val;
+
+        old_al = al;
+        old_cf = cf;
+        cf = false;
+        af = ctxt->eflags & X86_EFLAGS_AF;
+        if ((al & 0x0f) > 9 || af) {
+                al -= 6;
+                cf = old_cf | (al >= 250);
+                af = true;
+        } else {
+                af = false;
+        }
+        if (old_al > 0x99 || old_cf) {
+                al -= 0x60;
+                cf = true;
+        }
+
+        c->dst.val = al;
+        /* Set PF, ZF, SF */
+        c->src.type = OP_IMM;
+        c->src.val = 0;
+        c->src.bytes = 1;
+        emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
+        ctxt->eflags &= ~(X86_EFLAGS_AF | X86_EFLAGS_CF);
+        if (cf)
+                ctxt->eflags |= X86_EFLAGS_CF;
+        if (af)
+                ctxt->eflags |= X86_EFLAGS_AF;
+        return X86EMUL_CONTINUE;
+}
+
 #define D(_y) { .flags = (_y) }
 #define N    D(0)
 #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
@@ -2258,7 +2297,8 @@ static struct opcode opcode_table[256] = {
         /* 0x28 - 0x2F */
         D(ByteOp | DstMem | SrcReg | ModRM | Lock), D(DstMem | SrcReg | ModRM | Lock),
         D(ByteOp | DstReg | SrcMem | ModRM), D(DstReg | SrcMem | ModRM),
-        D(ByteOp | DstAcc | SrcImmByte), D(DstAcc | SrcImm), N, N,
+        D(ByteOp | DstAcc | SrcImmByte), D(DstAcc | SrcImm),
+        N, I(ByteOp | DstAcc | No64, em_das),
         /* 0x30 - 0x37 */
         D(ByteOp | DstMem | SrcReg | ModRM | Lock), D(DstMem | SrcReg | ModRM | Lock),
         D(ByteOp | DstReg | SrcMem | ModRM), D(DstReg | SrcMem | ModRM),