x86asm: Add vm* and iret[wlq] insns

The no-operand vm* instructions can be interpreted as having a
funny modrm byte, but unlike no-operand OPC_MODRM it's also the
r/m field which selects the insn, not (only) the reg field (aka group),
so we need another insn type.

i386-asm.c

@@ -40,6 +40,8 @@
 #define OPC_ARITH      0x30 /* arithmetic opcodes */
 #define OPC_FARITH     0x40 /* FPU arithmetic opcodes */
 #define OPC_TEST       0x50 /* test opcodes */
+#define OPC_0F01       0x60 /* 0x0f01XX (group 7, XX is 2nd opcode,
+                               no operands and unstructured mod/rm) */
 #define OPCT_IS(v,i) (((v) & OPCT_MASK) == (i))
 
 #define OPC_0F        0x100 /* Is secondary map (0x0f prefix) */
@@ -1072,6 +1074,8 @@ again:
     }
     if (OPCT_IS(pa->instr_type, OPC_TEST))
         v += test_bits[opcode - pa->sym];
+    else if (OPCT_IS(pa->instr_type, OPC_0F01))
+        v |= 0x0f0100;
     op1 = v >> 16;
     if (op1)
         g(op1);

tests/asmtest.S

@@ -632,10 +632,19 @@ int $0x10
     leave
     int3
     iret
+    iretw
+    iretl
+#ifdef __x86_64__
+    iretq
+#endif
     rsm
     hlt
     wait
     nop
+    vmcall
+    vmlaunch
+    vmresume
+    vmxoff
 
     /* XXX: handle prefixes */
 #if 0

x86_64-asm.h

@@ -30,6 +30,9 @@
      DEF_ASM_OP0(int3, 0xcc)
      DEF_ASM_OP0(into, 0xce)
      DEF_ASM_OP0(iret, 0xcf)
+     DEF_ASM_OP0(iretw, 0x66cf)
+     DEF_ASM_OP0(iretl, 0xcf)
+     DEF_ASM_OP0(iretq, 0x48cf)
      DEF_ASM_OP0(rsm, 0x0faa)
      DEF_ASM_OP0(hlt, 0xf4)
      DEF_ASM_OP0(wait, 0x9b)
@@ -37,6 +40,11 @@
      DEF_ASM_OP0(pause, 0xf390)
      DEF_ASM_OP0(xlat, 0xd7)
 
+    DEF_ASM_OP0L(vmcall, 0xc1, 0, OPC_0F01)
+    DEF_ASM_OP0L(vmlaunch, 0xc2, 0, OPC_0F01)
+    DEF_ASM_OP0L(vmresume, 0xc3, 0, OPC_0F01)
+    DEF_ASM_OP0L(vmxoff, 0xc4, 0, OPC_0F01)
+
      /* strings */
 ALT(DEF_ASM_OP0L(cmpsb, 0xa6, 0, OPC_BWLX))
 ALT(DEF_ASM_OP0L(scmpb, 0xa6, 0, OPC_BWLX))