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>

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index b90857c..2808291 100644 (file)
--- 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);