[PATCH 17/20] KVM: x86 emulator: Add LOCK prefix validity checking

Avi Kivity
2010-02-17T13:45:27Z

From: Gleb Natapov <gleb@redhat.com>

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>
---
arch/x86/kvm/emulate.c | 97 +++++++++++++++++++++++++++--------------------
1 files changed, 56 insertions(+), 41 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d632111..c2de9f0 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);
--
1.6.5.3