KVM: x86 emulator: mark CMP, CMPS, SCAS, TEST as NoWrite

Acked-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi.kivity@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 8 insertions, 12 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index fe113fbb3737..2af0c4475605 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3069,16 +3069,12 @@ static int em_xor(struct x86_emulate_ctxt *ctxt)
 static int em_cmp(struct x86_emulate_ctxt *ctxt)
 {
         emulate_2op_SrcV(ctxt, "cmp");
-        /* Disable writeback. */
-        ctxt->dst.type = OP_NONE;
         return X86EMUL_CONTINUE;
 }
 
 static int em_test(struct x86_emulate_ctxt *ctxt)
 {
         emulate_2op_SrcV(ctxt, "test");
-        /* Disable writeback. */
-        ctxt->dst.type = OP_NONE;
         return X86EMUL_CONTINUE;
 }
 
@@ -3747,7 +3743,7 @@ static const struct opcode group1[] = {
         I(Lock | PageTable, em_and),
         I(Lock, em_sub),
         I(Lock, em_xor),
-        I(0, em_cmp),
+        I(NoWrite, em_cmp),
 };
 
 static const struct opcode group1A[] = {
@@ -3755,8 +3751,8 @@ static const struct opcode group1A[] = {
 };
 
 static const struct opcode group3[] = {
-        I(DstMem | SrcImm, em_test),
-        I(DstMem | SrcImm, em_test),
+        I(DstMem | SrcImm | NoWrite, em_test),
+        I(DstMem | SrcImm | NoWrite, em_test),
         I(DstMem | SrcNone | Lock, em_not),
         I(DstMem | SrcNone | Lock, em_neg),
         I(SrcMem, em_mul_ex),
@@ -3920,7 +3916,7 @@ static const struct opcode opcode_table[256] = {
         /* 0x30 - 0x37 */
         I6ALU(Lock, em_xor), N, N,
         /* 0x38 - 0x3F */
-        I6ALU(0, em_cmp), N, N,
+        I6ALU(NoWrite, em_cmp), N, N,
         /* 0x40 - 0x4F */
         X16(D(DstReg)),
         /* 0x50 - 0x57 */
@@ -3946,7 +3942,7 @@ static const struct opcode opcode_table[256] = {
         G(DstMem | SrcImm, group1),
         G(ByteOp | DstMem | SrcImm | No64, group1),
         G(DstMem | SrcImmByte, group1),
-        I2bv(DstMem | SrcReg | ModRM, em_test),
+        I2bv(DstMem | SrcReg | ModRM | NoWrite, em_test),
         I2bv(DstMem | SrcReg | ModRM | Lock | PageTable, em_xchg),
         /* 0x88 - 0x8F */
         I2bv(DstMem | SrcReg | ModRM | Mov | PageTable, em_mov),
@@ -3966,12 +3962,12 @@ static const struct opcode opcode_table[256] = {
         I2bv(DstAcc | SrcMem | Mov | MemAbs, em_mov),
         I2bv(DstMem | SrcAcc | Mov | MemAbs | PageTable, em_mov),
         I2bv(SrcSI | DstDI | Mov | String, em_mov),
-        I2bv(SrcSI | DstDI | String, em_cmp),
+        I2bv(SrcSI | DstDI | String | NoWrite, em_cmp),
         /* 0xA8 - 0xAF */
-        I2bv(DstAcc | SrcImm, em_test),
+        I2bv(DstAcc | SrcImm | NoWrite, em_test),
         I2bv(SrcAcc | DstDI | Mov | String, em_mov),
         I2bv(SrcSI | DstAcc | Mov | String, em_mov),
-        I2bv(SrcAcc | DstDI | String, em_cmp),
+        I2bv(SrcAcc | DstDI | String | NoWrite, em_cmp),
         /* 0xB0 - 0xB7 */
         X8(I(ByteOp | DstReg | SrcImm | Mov, em_mov)),
         /* 0xB8 - 0xBF */