[PATCH v3 4/7] KVM: x86 emulator: mark CMP, CMPS, SCAS, TEST as NoWrite

[Avi Kivity]

Signed-off-by: Avi Kivity <avi.kiv...@gmail.com>
---
 arch/x86/kvm/emulate.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index fe113fb..2af0c44 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 */
-- 
1.8.0.1

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