KVM: x86: tag the instructions which are used to write page table

The idea is from Avi:
| tag instructions that are typically used to modify the page tables, and
| drop shadow if any other instruction is used.
| The list would include, I'd guess, and, or, bts, btc, mov, xchg, cmpxchg,
| and cmpxchg8b.

This patch is used to tag the instructions and in the later path, shadow page
is dropped if it is written by other instructions

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f1e3be1..a10950a 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -125,8 +125,9 @@
 #define Lock        (1<<26) /* lock prefix is allowed for the instruction */
 #define Priv        (1<<27) /* instruction generates #GP if current CPL != 0 */
 #define No64       (1<<28)
+#define PageTable   (1 << 29)   /* instruction used to write page table */
 /* Source 2 operand type */
-#define Src2Shift   (29)
+#define Src2Shift   (30)
 #define Src2None    (OpNone << Src2Shift)
 #define Src2CL      (OpCL << Src2Shift)
 #define Src2ImmByte (OpImmByte << Src2Shift)
@@ -3033,10 +3034,10 @@ static struct opcode group7_rm7[] = {
 
 static struct opcode group1[] = {
        I(Lock, em_add),
-       I(Lock, em_or),
+       I(Lock | PageTable, em_or),
        I(Lock, em_adc),
        I(Lock, em_sbb),
-       I(Lock, em_and),
+       I(Lock | PageTable, em_and),
        I(Lock, em_sub),
        I(Lock, em_xor),
        I(0, em_cmp),
@@ -3096,18 +3097,21 @@ static struct group_dual group7 = { {
 
 static struct opcode group8[] = {
        N, N, N, N,
-       D(DstMem | SrcImmByte | ModRM), D(DstMem | SrcImmByte | ModRM | Lock),
-       D(DstMem | SrcImmByte | ModRM | Lock), D(DstMem | SrcImmByte | ModRM | Lock),
+       D(DstMem | SrcImmByte | ModRM),
+       D(DstMem | SrcImmByte | ModRM | Lock | PageTable),
+       D(DstMem | SrcImmByte | ModRM | Lock),
+       D(DstMem | SrcImmByte | ModRM | Lock | PageTable),
 };
 
 static struct group_dual group9 = { {
-       N, D(DstMem64 | ModRM | Lock), N, N, N, N, N, N,
+       N, D(DstMem64 | ModRM | Lock | PageTable), N, N, N, N, N, N,
 }, {
        N, N, N, N, N, N, N, N,
 } };
 
 static struct opcode group11[] = {
-       I(DstMem | SrcImm | ModRM | Mov, em_mov), X7(D(Undefined)),
+       I(DstMem | SrcImm | ModRM | Mov | PageTable, em_mov),
+       X7(D(Undefined)),
 };
 
 static struct gprefix pfx_0f_6f_0f_7f = {
@@ -3120,7 +3124,7 @@ static struct opcode opcode_table[256] = {
        I(ImplicitOps | Stack | No64 | Src2ES, em_push_sreg),
        I(ImplicitOps | Stack | No64 | Src2ES, em_pop_sreg),
        /* 0x08 - 0x0F */
-       I6ALU(Lock, em_or),
+       I6ALU(Lock | PageTable, em_or),
        I(ImplicitOps | Stack | No64 | Src2CS, em_push_sreg),
        N,
        /* 0x10 - 0x17 */
@@ -3132,7 +3136,7 @@ static struct opcode opcode_table[256] = {
        I(ImplicitOps | Stack | No64 | Src2DS, em_push_sreg),
        I(ImplicitOps | Stack | No64 | Src2DS, em_pop_sreg),
        /* 0x20 - 0x27 */
-       I6ALU(Lock, em_and), N, N,
+       I6ALU(Lock | PageTable, em_and), N, N,
        /* 0x28 - 0x2F */
        I6ALU(Lock, em_sub), N, I(ByteOp | DstAcc | No64, em_das),
        /* 0x30 - 0x37 */
@@ -3165,11 +3169,11 @@ static struct opcode opcode_table[256] = {
        G(ByteOp | DstMem | SrcImm | ModRM | No64 | Group, group1),
        G(DstMem | SrcImmByte | ModRM | Group, group1),
        I2bv(DstMem | SrcReg | ModRM, em_test),
-       I2bv(DstMem | SrcReg | ModRM | Lock, em_xchg),
+       I2bv(DstMem | SrcReg | ModRM | Lock | PageTable, em_xchg),
        /* 0x88 - 0x8F */
-       I2bv(DstMem | SrcReg | ModRM | Mov, em_mov),
+       I2bv(DstMem | SrcReg | ModRM | Mov | PageTable, em_mov),
        I2bv(DstReg | SrcMem | ModRM | Mov, em_mov),
-       I(DstMem | SrcNone | ModRM | Mov, em_mov_rm_sreg),
+       I(DstMem | SrcNone | ModRM | Mov | PageTable, em_mov_rm_sreg),
        D(ModRM | SrcMem | NoAccess | DstReg),
        I(ImplicitOps | SrcMem16 | ModRM, em_mov_sreg_rm),
        G(0, group1A),
@@ -3182,7 +3186,7 @@ static struct opcode opcode_table[256] = {
        II(ImplicitOps | Stack, em_popf, popf), N, N,
        /* 0xA0 - 0xA7 */
        I2bv(DstAcc | SrcMem | Mov | MemAbs, em_mov),
-       I2bv(DstMem | SrcAcc | 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),
        /* 0xA8 - 0xAF */
@@ -3280,12 +3284,13 @@ static struct opcode twobyte_table[256] = {
        D(DstMem | SrcReg | Src2CL | ModRM), N, N,
        /* 0xA8 - 0xAF */
        I(Stack | Src2GS, em_push_sreg), I(Stack | Src2GS, em_pop_sreg),
-       DI(ImplicitOps, rsm), D(DstMem | SrcReg | ModRM | BitOp | Lock),
+       DI(ImplicitOps, rsm),
+       D(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable),
        D(DstMem | SrcReg | Src2ImmByte | ModRM),
        D(DstMem | SrcReg | Src2CL | ModRM),
        D(ModRM), I(DstReg | SrcMem | ModRM, em_imul),
        /* 0xB0 - 0xB7 */
-       D2bv(DstMem | SrcReg | ModRM | Lock),
+       D2bv(DstMem | SrcReg | ModRM | Lock | PageTable),
        I(DstReg | SrcMemFAddr | ModRM | Src2SS, em_lseg),
        D(DstMem | SrcReg | ModRM | BitOp | Lock),
        I(DstReg | SrcMemFAddr | ModRM | Src2FS, em_lseg),
@@ -3293,7 +3298,7 @@ static struct opcode twobyte_table[256] = {
        D(ByteOp | DstReg | SrcMem | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov),
        /* 0xB8 - 0xBF */
        N, N,
-       G(BitOp, group8), D(DstMem | SrcReg | ModRM | BitOp | Lock),
+       G(BitOp, group8), D(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable),
        D(DstReg | SrcMem | ModRM), D(DstReg | SrcMem | ModRM),
        D(ByteOp | DstReg | SrcMem | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov),
        /* 0xC0 - 0xCF */