KVM: x86 emulator: Introduce No64 decode option

Introduces a new decode option "No64", which is used for instructions that are
invalid in long mode.

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 14 insertions, 28 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 1cdfec5231d0..1f0ff4afa73e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -75,6 +75,8 @@
 #define Group       (1<<14)     /* Bits 3:5 of modrm byte extend opcode */
 #define GroupDual   (1<<15)     /* Alternate decoding of mod == 3 */
 #define GroupMask   0xff        /* Group number stored in bits 0:7 */
+/* Misc flags */
+#define No64        (1<<28)
 /* Source 2 operand type */
 #define Src2None    (0<<29)
 #define Src2CL      (1<<29)
@@ -93,21 +95,21 @@ static u32 opcode_table[256] = {
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
-        ImplicitOps | Stack, ImplicitOps | Stack,
+        ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x08 - 0x0F */
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-        0, 0, ImplicitOps | Stack, 0,
+        0, 0, ImplicitOps | Stack | No64, 0,
         /* 0x10 - 0x17 */
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
-        ImplicitOps | Stack, ImplicitOps | Stack,
+        ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x18 - 0x1F */
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
         ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
-        ImplicitOps | Stack, ImplicitOps | Stack,
+        ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
         /* 0x20 - 0x27 */
         ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
         ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
@@ -161,7 +163,7 @@ static u32 opcode_table[256] = {
         /* 0x90 - 0x97 */
         DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg,
         /* 0x98 - 0x9F */
-        0, 0, SrcImm | Src2Imm16, 0,
+        0, 0, SrcImm | Src2Imm16 | No64, 0,
         ImplicitOps | Stack, ImplicitOps | Stack, 0, 0,
         /* 0xA0 - 0xA7 */
         ByteOp | DstReg | SrcMem | Mov | MemAbs, DstReg | SrcMem | Mov | MemAbs,
@@ -188,7 +190,7 @@ static u32 opcode_table[256] = {
         ByteOp | DstMem | SrcImm | ModRM | Mov, DstMem | SrcImm | ModRM | Mov,
         /* 0xC8 - 0xCF */
         0, 0, 0, ImplicitOps | Stack,
-        ImplicitOps, SrcImmByte, ImplicitOps, ImplicitOps,
+        ImplicitOps, SrcImmByte, ImplicitOps | No64, ImplicitOps,
         /* 0xD0 - 0xD7 */
         ByteOp | DstMem | SrcImplicit | ModRM, DstMem | SrcImplicit | ModRM,
         ByteOp | DstMem | SrcImplicit | ModRM, DstMem | SrcImplicit | ModRM,
@@ -201,7 +203,7 @@ static u32 opcode_table[256] = {
         ByteOp | SrcImmUByte, SrcImmUByte,
         /* 0xE8 - 0xEF */
         SrcImm | Stack, SrcImm | ImplicitOps,
-        SrcImmU | Src2Imm16, SrcImmByte | ImplicitOps,
+        SrcImmU | Src2Imm16 | No64, SrcImmByte | ImplicitOps,
         SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps,
         SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps,
         /* 0xF0 - 0xF7 */
@@ -967,6 +969,11 @@ done_prefixes:
                 }
         }
 
+        if (mode == X86EMUL_MODE_PROT64 && (c->d & No64)) {
+                kvm_report_emulation_failure(ctxt->vcpu, "invalid x86/64 instruction");;
+                return -1;
+        }
+
         if (c->d & Group) {
                 group = c->d & GroupMask;
                 c->modrm = insn_fetch(u8, 1, c->eip);
@@ -1739,15 +1746,9 @@ special_insn:
                 emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
                 break;
         case 0x06:              /* push es */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 emulate_push_sreg(ctxt, VCPU_SREG_ES);
                 break;
         case 0x07:              /* pop es */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
                 if (rc != 0)
                         goto done;
@@ -1757,9 +1758,6 @@ special_insn:
                 emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
                 break;
         case 0x0e:              /* push cs */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 emulate_push_sreg(ctxt, VCPU_SREG_CS);
                 break;
         case 0x10 ... 0x15:
@@ -1767,15 +1765,9 @@ special_insn:
                 emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
                 break;
         case 0x16:              /* push ss */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 emulate_push_sreg(ctxt, VCPU_SREG_SS);
                 break;
         case 0x17:              /* pop ss */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
                 if (rc != 0)
                         goto done;
@@ -1785,15 +1777,9 @@ special_insn:
                 emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
                 break;
         case 0x1e:              /* push ds */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 emulate_push_sreg(ctxt, VCPU_SREG_DS);
                 break;
         case 0x1f:              /* pop ds */
-                if (ctxt->mode == X86EMUL_MODE_PROT64)
-                        goto cannot_emulate;
-
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
                 if (rc != 0)
                         goto done;