KVM: x86 emulator: emulate nop and xchg reg, acc (opcodes 0x90 - 0x97)

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

1 files changed, 15 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index b90857c76569..28082913919e 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -140,8 +140,9 @@ static u16 opcode_table[256] = {
         ByteOp | DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
         DstMem | SrcReg | ModRM | Mov, ModRM | DstReg,
         DstReg | SrcMem | ModRM | Mov, Group | Group1A,
-        /* 0x90 - 0x9F */
-        0, 0, 0, 0, 0, 0, 0, 0,
+        /* 0x90 - 0x97 */
+        DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg,
+        /* 0x98 - 0x9F */
         0, 0, 0, 0, ImplicitOps | Stack, ImplicitOps | Stack, 0, 0,
         /* 0xA0 - 0xA7 */
         ByteOp | DstReg | SrcMem | Mov | MemAbs, DstReg | SrcMem | Mov | MemAbs,
@@ -1493,6 +1494,7 @@ special_insn:
                 emulate_2op_SrcV("test", c->src, c->dst, ctxt->eflags);
                 break;
         case 0x86 ... 0x87:     /* xchg */
+        xchg:
                 /* Write back the register source. */
                 switch (c->dst.bytes) {
                 case 1:
@@ -1560,6 +1562,17 @@ special_insn:
                 if (rc != 0)
                         goto done;
                 break;
+        case 0x90: /* nop / xchg r8,rax */
+                if (!(c->rex_prefix & 1)) { /* nop */
+                        c->dst.type = OP_NONE;
+                        break;
+                }
+        case 0x91 ... 0x97: /* xchg reg,rax */
+                c->src.type = c->dst.type = OP_REG;
+                c->src.bytes = c->dst.bytes = c->op_bytes;
+                c->src.ptr = (unsigned long *) &c->regs[VCPU_REGS_RAX];
+                c->src.val = *(c->src.ptr);
+                goto xchg;
         case 0x9c: /* pushf */
                 c->src.val =  (unsigned long) ctxt->eflags;
                 emulate_push(ctxt);