KVM: x86 emulator: Add LOCK prefix validity checking

Instructions which are not allowed to have LOCK prefix should
generate #UD if one is used.

[avi: fold opcode 82 fix from another patch]

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

1 files changed, 56 insertions, 41 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d63211169ac1..c2de9f03da84 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -76,6 +76,7 @@
 #define GroupDual   (1<<15)     /* Alternate decoding of mod == 3 */
 #define GroupMask   0xff        /* Group number stored in bits 0:7 */
 /* Misc flags */
+#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)
 /* Source 2 operand type */
@@ -94,35 +95,35 @@ enum {
 
 static u32 opcode_table[256] = {
         /* 0x00 - 0x07 */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
         ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x08 - 0x0F */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
         ImplicitOps | Stack | No64, 0,
         /* 0x10 - 0x17 */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
         ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x18 - 0x1F */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
         ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x20 - 0x27 */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         DstAcc | SrcImmByte, DstAcc | SrcImm, 0, 0,
         /* 0x28 - 0x2F */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         0, 0, 0, 0,
         /* 0x30 - 0x37 */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         0, 0, 0, 0,
         /* 0x38 - 0x3F */
@@ -158,7 +159,7 @@ static u32 opcode_table[256] = {
         Group | Group1_80, Group | Group1_81,
         Group | Group1_82, Group | Group1_83,
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
         /* 0x88 - 0x8F */
         ByteOp | DstMem | SrcReg | ModRM | Mov, DstMem | SrcReg | ModRM | Mov,
         ByteOp | DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
@@ -263,17 +264,18 @@ static u32 twobyte_table[256] = {
         DstMem | SrcReg | Src2CL | ModRM, 0, 0,
         /* 0xA8 - 0xAF */
         ImplicitOps | Stack, ImplicitOps | Stack,
-        0, DstMem | SrcReg | ModRM | BitOp,
+        0, DstMem | SrcReg | ModRM | BitOp | Lock,
         DstMem | SrcReg | Src2ImmByte | ModRM,
         DstMem | SrcReg | Src2CL | ModRM,
         ModRM, 0,
         /* 0xB0 - 0xB7 */
-        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM, 0,
-            DstMem | SrcReg | ModRM | BitOp,
+        ByteOp | DstMem | SrcReg | ModRM | Lock, DstMem | SrcReg | ModRM | Lock,
+        0, DstMem | SrcReg | ModRM | BitOp | Lock,
         0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
             DstReg | SrcMem16 | ModRM | Mov,
         /* 0xB8 - 0xBF */
-        0, 0, Group | Group8, DstMem | SrcReg | ModRM | BitOp,
+        0, 0,
+        Group | Group8, DstMem | SrcReg | ModRM | BitOp | Lock,
         0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
             DstReg | SrcMem16 | ModRM | Mov,
         /* 0xC0 - 0xCF */
@@ -290,25 +292,41 @@ static u32 twobyte_table[256] = {
 
 static u32 group_table[] = {
         [Group1_80*8] =
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM,
         [Group1_81*8] =
-        DstMem | SrcImm | ModRM, DstMem | SrcImm | ModRM,
-        DstMem | SrcImm | ModRM, DstMem | SrcImm | ModRM,
-        DstMem | SrcImm | ModRM, DstMem | SrcImm | ModRM,
-        DstMem | SrcImm | ModRM, DstMem | SrcImm | ModRM,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM | Lock,
+        DstMem | SrcImm | ModRM,
         [Group1_82*8] =
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
-        ByteOp | DstMem | SrcImm | ModRM, ByteOp | DstMem | SrcImm | ModRM,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM | Lock,
+        ByteOp | DstMem | SrcImm | ModRM,
         [Group1_83*8] =
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM,
         [Group1A*8] =
         DstMem | SrcNone | ModRM | Mov | Stack, 0, 0, 0, 0, 0, 0, 0,
         [Group3_Byte*8] =
@@ -332,10 +350,10 @@ static u32 group_table[] = {
         SrcMem16 | ModRM | Mov | Priv, SrcMem | ModRM | ByteOp | Priv,
         [Group8*8] =
         0, 0, 0, 0,
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
-        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM,
+        DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM | Lock,
+        DstMem | SrcImmByte | ModRM | Lock, DstMem | SrcImmByte | ModRM | Lock,
         [Group9*8] =
-        0, ImplicitOps | ModRM, 0, 0, 0, 0, 0, 0,
+        0, ImplicitOps | ModRM | Lock, 0, 0, 0, 0, 0, 0,
 };
 
 static u32 group2_table[] = {
@@ -1580,8 +1598,7 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt)
         u64 msr_data;
 
         /* syscall is not available in real mode */
-        if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL
-            || ctxt->mode == X86EMUL_MODE_VM86)
+        if (ctxt->mode == X86EMUL_MODE_REAL || ctxt->mode == X86EMUL_MODE_VM86)
                 return -1;
 
         setup_syscalls_segments(ctxt, &cs, &ss);
@@ -1629,10 +1646,6 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt)
         struct kvm_segment cs, ss;
         u64 msr_data;
 
-        /* inject #UD if LOCK prefix is used */
-        if (c->lock_prefix)
-                return -1;
-
         /* inject #GP if in real mode */
         if (ctxt->mode == X86EMUL_MODE_REAL) {
                 kvm_inject_gp(ctxt->vcpu, 0);
@@ -1694,10 +1707,6 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt)
         u64 msr_data;
         int usermode;
 
-        /* inject #UD if LOCK prefix is used */
-        if (c->lock_prefix)
-                return -1;
-
         /* inject #GP if in real mode or Virtual 8086 mode */
         if (ctxt->mode == X86EMUL_MODE_REAL ||
             ctxt->mode == X86EMUL_MODE_VM86) {
@@ -1819,6 +1828,12 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
         memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
         saved_eip = c->eip;
 
+        /* LOCK prefix is allowed only with some instructions */
+        if (c->lock_prefix && !(c->d & Lock)) {
+                kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                goto done;
+        }
+
         /* Privileged instruction can be executed only in CPL=0 */
         if ((c->d & Priv) && kvm_x86_ops->get_cpl(ctxt->vcpu)) {
                 kvm_inject_gp(ctxt->vcpu, 0);