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

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

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 81b0f884896047bc435cd74fa665987660942bc9..83ded7c03d124f78c3c2e8d9cd4c1295ec69095e 100644 (file)
--- 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),