extractedLnx/linux-2.6.34/arch/x86/kvm/emulate.c_x86_emulate_insn.c

int
x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
{
	unsigned long memop = 0;
	u64 msr_data;
	unsigned long saved_eip = 0;
	struct decode_cache *c = &ctxt->decode;
	unsigned int port;
	int io_dir_in;
	int rc = 0;

	ctxt->interruptibility = 0;

	/* Shadow copy of register state. Committed on successful emulation.
	 * NOTE: we can copy them from vcpu as x86_decode_insn() doesn't
	 * modify them.
	 */

	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);
		goto done;
	}

	if (((c->d & ModRM) && (c->modrm_mod != 3)) || (c->d & MemAbs))
		memop = c->modrm_ea;

	if (c->rep_prefix && (c->d & String)) {
		/* All REP prefixes have the same first termination condition */
		if (c->regs[VCPU_REGS_RCX] == 0) {
			kvm_rip_write(ctxt->vcpu, c->eip);
			goto done;
		}
		/* The second termination condition only applies for REPE
		 * and REPNE. Test if the repeat string operation prefix is
		 * REPE/REPZ or REPNE/REPNZ and if it's the case it tests the
		 * corresponding termination condition according to:
		 * 	- if REPE/REPZ and ZF = 0 then done
		 * 	- if REPNE/REPNZ and ZF = 1 then done
		 */
		if ((c->b == 0xa6) || (c->b == 0xa7) ||
				(c->b == 0xae) || (c->b == 0xaf)) {
			if ((c->rep_prefix == REPE_PREFIX) &&
				((ctxt->eflags & EFLG_ZF) == 0)) {
					kvm_rip_write(ctxt->vcpu, c->eip);
					goto done;
			}
			if ((c->rep_prefix == REPNE_PREFIX) &&
				((ctxt->eflags & EFLG_ZF) == EFLG_ZF)) {
				kvm_rip_write(ctxt->vcpu, c->eip);
				goto done;
			}
		}
		c->regs[VCPU_REGS_RCX]--;
		c->eip = kvm_rip_read(ctxt->vcpu);
	}

	if (c->src.type == OP_MEM) {
		c->src.ptr = (unsigned long *)memop;
		c->src.val = 0;
		rc = ops->read_emulated((unsigned long)c->src.ptr,
					&c->src.val,
					c->src.bytes,
					ctxt->vcpu);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		c->src.orig_val = c->src.val;
	}

	if ((c->d & DstMask) == ImplicitOps)
		goto special_insn;


	if (c->dst.type == OP_MEM) {
		c->dst.ptr = (unsigned long *)memop;
		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->dst.val = 0;
		if (c->d & BitOp) {
			unsigned long mask = ~(c->dst.bytes * 8 - 1);

			c->dst.ptr = (void *)c->dst.ptr +
						   (c->src.val & mask) / 8;
		}
		if (!(c->d & Mov)) {
			/* optimisation - avoid slow emulated read */
			rc = ops->read_emulated((unsigned long)c->dst.ptr,
						&c->dst.val,
						c->dst.bytes,
						ctxt->vcpu);
			if (rc != X86EMUL_CONTINUE)
				goto done;
		}
	}
	c->dst.orig_val = c->dst.val;

special_insn:

	if (c->twobyte)
		goto twobyte_insn;

	switch (c->b) {
	case 0x00 ... 0x05:
	      add:		/* add */
		emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
		break;
	case 0x06:		/* push es */
		emulate_push_sreg(ctxt, VCPU_SREG_ES);
		break;
	case 0x07:		/* pop es */
		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
		if (rc != 0)
			goto done;
		break;
	case 0x08 ... 0x0d:
	      or:		/* or */
		emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
		break;
	case 0x0e:		/* push cs */
		emulate_push_sreg(ctxt, VCPU_SREG_CS);
		break;
	case 0x10 ... 0x15:
	      adc:		/* adc */
		emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
		break;
	case 0x16:		/* push ss */
		emulate_push_sreg(ctxt, VCPU_SREG_SS);
		break;
	case 0x17:		/* pop ss */
		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
		if (rc != 0)
			goto done;
		break;
	case 0x18 ... 0x1d:
	      sbb:		/* sbb */
		emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
		break;
	case 0x1e:		/* push ds */
		emulate_push_sreg(ctxt, VCPU_SREG_DS);
		break;
	case 0x1f:		/* pop ds */
		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
		if (rc != 0)
			goto done;
		break;
	case 0x20 ... 0x25:
	      and:		/* and */
		emulate_2op_SrcV("and", c->src, c->dst, ctxt->eflags);
		break;
	case 0x28 ... 0x2d:
	      sub:		/* sub */
		emulate_2op_SrcV("sub", c->src, c->dst, ctxt->eflags);
		break;
	case 0x30 ... 0x35:
	      xor:		/* xor */
		emulate_2op_SrcV("xor", c->src, c->dst, ctxt->eflags);
		break;
	case 0x38 ... 0x3d:
	      cmp:		/* cmp */
		emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);
		break;
	case 0x40 ... 0x47: /* inc r16/r32 */
		emulate_1op("inc", c->dst, ctxt->eflags);
		break;
	case 0x48 ... 0x4f: /* dec r16/r32 */
		emulate_1op("dec", c->dst, ctxt->eflags);
		break;
	case 0x50 ... 0x57:  /* push reg */
		emulate_push(ctxt);
		break;
	case 0x58 ... 0x5f: /* pop reg */
	pop_instruction:
		rc = emulate_pop(ctxt, ops, &c->dst.val, c->op_bytes);
		if (rc != 0)
			goto done;
		break;
	case 0x60:	/* pusha */
		emulate_pusha(ctxt);
		break;
	case 0x61:	/* popa */
		rc = emulate_popa(ctxt, ops);
		if (rc != 0)
			goto done;
		break;
	case 0x63:		/* movsxd */
		if (ctxt->mode != X86EMUL_MODE_PROT64)
			goto cannot_emulate;
		c->dst.val = (s32) c->src.val;
		break;
	case 0x68: /* push imm */
	case 0x6a: /* push imm8 */
		emulate_push(ctxt);
		break;
	case 0x6c:		/* insb */
	case 0x6d:		/* insw/insd */
		if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
					  (c->d & ByteOp) ? 1 : c->op_bytes)) {
			kvm_inject_gp(ctxt->vcpu, 0);
			goto done;
		}
		if (kvm_emulate_pio_string(ctxt->vcpu,
				1,
				(c->d & ByteOp) ? 1 : c->op_bytes,
				c->rep_prefix ?
				address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
				(ctxt->eflags & EFLG_DF),
				register_address(c, es_base(ctxt),
						 c->regs[VCPU_REGS_RDI]),
				c->rep_prefix,
				c->regs[VCPU_REGS_RDX]) == 0) {
			c->eip = saved_eip;
			return -1;
		}
		return 0;
	case 0x6e:		/* outsb */
	case 0x6f:		/* outsw/outsd */
		if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
					  (c->d & ByteOp) ? 1 : c->op_bytes)) {
			kvm_inject_gp(ctxt->vcpu, 0);
			goto done;
		}
		if (kvm_emulate_pio_string(ctxt->vcpu,
				0,
				(c->d & ByteOp) ? 1 : c->op_bytes,
				c->rep_prefix ?
				address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
				(ctxt->eflags & EFLG_DF),
					 register_address(c,
					  seg_override_base(ctxt, c),
						 c->regs[VCPU_REGS_RSI]),
				c->rep_prefix,
				c->regs[VCPU_REGS_RDX]) == 0) {
			c->eip = saved_eip;
			return -1;
		}
		return 0;
	case 0x70 ... 0x7f: /* jcc (short) */
		if (test_cc(c->b, ctxt->eflags))
			jmp_rel(c, c->src.val);
		break;
	case 0x80 ... 0x83:	/* Grp1 */
		switch (c->modrm_reg) {
		case 0:
			goto add;
		case 1:
			goto or;
		case 2:
			goto adc;
		case 3:
			goto sbb;
		case 4:
			goto and;
		case 5:
			goto sub;
		case 6:
			goto xor;
		case 7:
			goto cmp;
		}
		break;
	case 0x84 ... 0x85:
		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:
			*(u8 *) c->src.ptr = (u8) c->dst.val;
			break;
		case 2:
			*(u16 *) c->src.ptr = (u16) c->dst.val;
			break;
		case 4:
			*c->src.ptr = (u32) c->dst.val;
			break;	/* 64b reg: zero-extend */
		case 8:
			*c->src.ptr = c->dst.val;
			break;
		}
		/*
		 * Write back the memory destination with implicit LOCK
		 * prefix.
		 */
		c->dst.val = c->src.val;
		c->lock_prefix = 1;
		break;
	case 0x88 ... 0x8b:	/* mov */
		goto mov;
	case 0x8c: { /* mov r/m, sreg */
		struct kvm_segment segreg;

		if (c->modrm_reg <= 5)
			kvm_get_segment(ctxt->vcpu, &segreg, c->modrm_reg);
		else {
			printk(KERN_INFO "0x8c: Invalid segreg in modrm byte 0x%02x\n",
			       c->modrm);
			goto cannot_emulate;
		}
		c->dst.val = segreg.selector;
		break;
	}
	case 0x8d: /* lea r16/r32, m */
		c->dst.val = c->modrm_ea;
		break;
	case 0x8e: { /* mov seg, r/m16 */
		uint16_t sel;

		sel = c->src.val;

		if (c->modrm_reg == VCPU_SREG_CS ||
		    c->modrm_reg > VCPU_SREG_GS) {
			kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
			goto done;
		}

		if (c->modrm_reg == VCPU_SREG_SS)
			toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS);

		rc = kvm_load_segment_descriptor(ctxt->vcpu, sel, c->modrm_reg);

		c->dst.type = OP_NONE;  /* Disable writeback. */
		break;
	}
	case 0x8f:		/* pop (sole member of Grp1a) */
		rc = emulate_grp1a(ctxt, ops);
		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);
		break;
	case 0x9d: /* popf */
		c->dst.type = OP_REG;
		c->dst.ptr = (unsigned long *) &ctxt->eflags;
		c->dst.bytes = c->op_bytes;
		rc = emulate_popf(ctxt, ops, &c->dst.val, c->op_bytes);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		break;
	case 0xa0 ... 0xa1:	/* mov */
		c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
		c->dst.val = c->src.val;
		break;
	case 0xa2 ... 0xa3:	/* mov */
		c->dst.val = (unsigned long)c->regs[VCPU_REGS_RAX];
		break;
	case 0xa4 ... 0xa5:	/* movs */
		c->dst.type = OP_MEM;
		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->dst.ptr = (unsigned long *)register_address(c,
						   es_base(ctxt),
						   c->regs[VCPU_REGS_RDI]);
		rc = ops->read_emulated(register_address(c,
						seg_override_base(ctxt, c),
						c->regs[VCPU_REGS_RSI]),
					&c->dst.val,
					c->dst.bytes, ctxt->vcpu);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		register_address_increment(c, &c->regs[VCPU_REGS_RSI],
				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
							   : c->dst.bytes);
		register_address_increment(c, &c->regs[VCPU_REGS_RDI],
				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
							   : c->dst.bytes);
		break;
	case 0xa6 ... 0xa7:	/* cmps */
		c->src.type = OP_NONE; /* Disable writeback. */
		c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->src.ptr = (unsigned long *)register_address(c,
				       seg_override_base(ctxt, c),
						   c->regs[VCPU_REGS_RSI]);
		rc = ops->read_emulated((unsigned long)c->src.ptr,
					&c->src.val,
					c->src.bytes,
					ctxt->vcpu);
		if (rc != X86EMUL_CONTINUE)
			goto done;

		c->dst.type = OP_NONE; /* Disable writeback. */
		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->dst.ptr = (unsigned long *)register_address(c,
						   es_base(ctxt),
						   c->regs[VCPU_REGS_RDI]);
		rc = ops->read_emulated((unsigned long)c->dst.ptr,
					&c->dst.val,
					c->dst.bytes,
					ctxt->vcpu);
		if (rc != X86EMUL_CONTINUE)
			goto done;

		DPRINTF("cmps: mem1=0x%p mem2=0x%p\n", c->src.ptr, c->dst.ptr);

		emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);

		register_address_increment(c, &c->regs[VCPU_REGS_RSI],
				       (ctxt->eflags & EFLG_DF) ? -c->src.bytes
								  : c->src.bytes);
		register_address_increment(c, &c->regs[VCPU_REGS_RDI],
				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
								  : c->dst.bytes);

		break;
	case 0xaa ... 0xab:	/* stos */
		c->dst.type = OP_MEM;
		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->dst.ptr = (unsigned long *)register_address(c,
						   es_base(ctxt),
						   c->regs[VCPU_REGS_RDI]);
		c->dst.val = c->regs[VCPU_REGS_RAX];
		register_address_increment(c, &c->regs[VCPU_REGS_RDI],
				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
							   : c->dst.bytes);
		break;
	case 0xac ... 0xad:	/* lods */
		c->dst.type = OP_REG;
		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
		c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
		rc = ops->read_emulated(register_address(c,
						seg_override_base(ctxt, c),
						c->regs[VCPU_REGS_RSI]),
					&c->dst.val,
					c->dst.bytes,
					ctxt->vcpu);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		register_address_increment(c, &c->regs[VCPU_REGS_RSI],
				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
							   : c->dst.bytes);
		break;
	case 0xae ... 0xaf:	/* scas */
		DPRINTF("Urk! I don't handle SCAS.\n");
		goto cannot_emulate;
	case 0xb0 ... 0xbf: /* mov r, imm */
		goto mov;
	case 0xc0 ... 0xc1:
		emulate_grp2(ctxt);
		break;
	case 0xc3: /* ret */
		c->dst.type = OP_REG;
		c->dst.ptr = &c->eip;
		c->dst.bytes = c->op_bytes;
		goto pop_instruction;
	case 0xc6 ... 0xc7:	/* mov (sole member of Grp11) */
	mov:
		c->dst.val = c->src.val;
		break;
	case 0xcb:		/* ret far */
		rc = emulate_ret_far(ctxt, ops);
		if (rc)
			goto done;
		break;
	case 0xd0 ... 0xd1:	/* Grp2 */
		c->src.val = 1;
		emulate_grp2(ctxt);
		break;
	case 0xd2 ... 0xd3:	/* Grp2 */
		c->src.val = c->regs[VCPU_REGS_RCX];
		emulate_grp2(ctxt);
		break;
	case 0xe4: 	/* inb */
	case 0xe5: 	/* in */
		port = c->src.val;
		io_dir_in = 1;
		goto do_io;
	case 0xe6: /* outb */
	case 0xe7: /* out */
		port = c->src.val;
		io_dir_in = 0;
		goto do_io;
	case 0xe8: /* call (near) */ {
		long int rel = c->src.val;
		c->src.val = (unsigned long) c->eip;
		jmp_rel(c, rel);
		emulate_push(ctxt);
		break;
	}
	case 0xe9: /* jmp rel */
		goto jmp;
	case 0xea: /* jmp far */
		if (kvm_load_segment_descriptor(ctxt->vcpu, c->src2.val,
						VCPU_SREG_CS))
			goto done;

		c->eip = c->src.val;
		break;
	case 0xeb:
	      jmp:		/* jmp rel short */
		jmp_rel(c, c->src.val);
		c->dst.type = OP_NONE; /* Disable writeback. */
		break;
	case 0xec: /* in al,dx */
	case 0xed: /* in (e/r)ax,dx */
		port = c->regs[VCPU_REGS_RDX];
		io_dir_in = 1;
		goto do_io;
	case 0xee: /* out al,dx */
	case 0xef: /* out (e/r)ax,dx */
		port = c->regs[VCPU_REGS_RDX];
		io_dir_in = 0;
	do_io:
		if (!emulator_io_permited(ctxt, ops, port,
					  (c->d & ByteOp) ? 1 : c->op_bytes)) {
			kvm_inject_gp(ctxt->vcpu, 0);
			goto done;
		}
		if (kvm_emulate_pio(ctxt->vcpu, io_dir_in,
				   (c->d & ByteOp) ? 1 : c->op_bytes,
				   port) != 0) {
			c->eip = saved_eip;
			goto cannot_emulate;
		}
		break;
	case 0xf4:              /* hlt */
		ctxt->vcpu->arch.halt_request = 1;
		break;
	case 0xf5:	/* cmc */
		/* complement carry flag from eflags reg */
		ctxt->eflags ^= EFLG_CF;
		c->dst.type = OP_NONE;	/* Disable writeback. */
		break;
	case 0xf6 ... 0xf7:	/* Grp3 */
		rc = emulate_grp3(ctxt, ops);
		if (rc != 0)
			goto done;
		break;
	case 0xf8: /* clc */
		ctxt->eflags &= ~EFLG_CF;
		c->dst.type = OP_NONE;	/* Disable writeback. */
		break;
	case 0xfa: /* cli */
		if (emulator_bad_iopl(ctxt))
			kvm_inject_gp(ctxt->vcpu, 0);
		else {
			ctxt->eflags &= ~X86_EFLAGS_IF;
			c->dst.type = OP_NONE;	/* Disable writeback. */
		}
		break;
	case 0xfb: /* sti */
		if (emulator_bad_iopl(ctxt))
			kvm_inject_gp(ctxt->vcpu, 0);
		else {
			toggle_interruptibility(ctxt, X86_SHADOW_INT_STI);
			ctxt->eflags |= X86_EFLAGS_IF;
			c->dst.type = OP_NONE;	/* Disable writeback. */
		}
		break;
	case 0xfc: /* cld */
		ctxt->eflags &= ~EFLG_DF;
		c->dst.type = OP_NONE;	/* Disable writeback. */
		break;
	case 0xfd: /* std */
		ctxt->eflags |= EFLG_DF;
		c->dst.type = OP_NONE;	/* Disable writeback. */
		break;
	case 0xfe ... 0xff:	/* Grp4/Grp5 */
		rc = emulate_grp45(ctxt, ops);
		if (rc != 0)
			goto done;
		break;
	}

writeback:
	rc = writeback(ctxt, ops);
	if (rc != 0)
		goto done;

	/* Commit shadow register state. */
	memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);
	kvm_rip_write(ctxt->vcpu, c->eip);

done:
	if (rc == X86EMUL_UNHANDLEABLE) {
		c->eip = saved_eip;
		return -1;
	}
	return 0;

twobyte_insn:
	switch (c->b) {
	case 0x01: /* lgdt, lidt, lmsw */
		switch (c->modrm_reg) {
			u16 size;
			unsigned long address;

		case 0: /* vmcall */
			if (c->modrm_mod != 3 || c->modrm_rm != 1)
				goto cannot_emulate;

			rc = kvm_fix_hypercall(ctxt->vcpu);
			if (rc)
				goto done;

			/* Let the processor re-execute the fixed hypercall */
			c->eip = kvm_rip_read(ctxt->vcpu);
			/* Disable writeback. */
			c->dst.type = OP_NONE;
			break;
		case 2: /* lgdt */
			rc = read_descriptor(ctxt, ops, c->src.ptr,
					     &size, &address, c->op_bytes);
			if (rc)
				goto done;
			realmode_lgdt(ctxt->vcpu, size, address);
			/* Disable writeback. */
			c->dst.type = OP_NONE;
			break;
		case 3: /* lidt/vmmcall */
			if (c->modrm_mod == 3) {
				switch (c->modrm_rm) {
				case 1:
					rc = kvm_fix_hypercall(ctxt->vcpu);
					if (rc)
						goto done;
					break;
				default:
					goto cannot_emulate;
				}
			} else {
				rc = read_descriptor(ctxt, ops, c->src.ptr,
						     &size, &address,
						     c->op_bytes);
				if (rc)
					goto done;
				realmode_lidt(ctxt->vcpu, size, address);
			}
			/* Disable writeback. */
			c->dst.type = OP_NONE;
			break;
		case 4: /* smsw */
			c->dst.bytes = 2;
			c->dst.val = realmode_get_cr(ctxt->vcpu, 0);
			break;
		case 6: /* lmsw */
			realmode_lmsw(ctxt->vcpu, (u16)c->src.val,
				      &ctxt->eflags);
			c->dst.type = OP_NONE;
			break;
		case 7: /* invlpg*/
			emulate_invlpg(ctxt->vcpu, memop);
			/* Disable writeback. */
			c->dst.type = OP_NONE;
			break;
		default:
			goto cannot_emulate;
		}
		break;
	case 0x05: 		/* syscall */
		rc = emulate_syscall(ctxt);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		else
			goto writeback;
		break;
	case 0x06:
		emulate_clts(ctxt->vcpu);
		c->dst.type = OP_NONE;
		break;
	case 0x08:		/* invd */
	case 0x09:		/* wbinvd */
	case 0x0d:		/* GrpP (prefetch) */
	case 0x18:		/* Grp16 (prefetch/nop) */
		c->dst.type = OP_NONE;
		break;
	case 0x20: /* mov cr, reg */
		if (c->modrm_mod != 3)
			goto cannot_emulate;
		c->regs[c->modrm_rm] =
				realmode_get_cr(ctxt->vcpu, c->modrm_reg);
		c->dst.type = OP_NONE;	/* no writeback */
		break;
	case 0x21: /* mov from dr to reg */
		if (c->modrm_mod != 3)
			goto cannot_emulate;
		rc = emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]);
		if (rc)
			goto cannot_emulate;
		c->dst.type = OP_NONE;	/* no writeback */
		break;
	case 0x22: /* mov reg, cr */
		if (c->modrm_mod != 3)
			goto cannot_emulate;
		realmode_set_cr(ctxt->vcpu,
				c->modrm_reg, c->modrm_val, &ctxt->eflags);
		c->dst.type = OP_NONE;
		break;
	case 0x23: /* mov from reg to dr */
		if (c->modrm_mod != 3)
			goto cannot_emulate;
		rc = emulator_set_dr(ctxt, c->modrm_reg,
				     c->regs[c->modrm_rm]);
		if (rc)
			goto cannot_emulate;
		c->dst.type = OP_NONE;	/* no writeback */
		break;
	case 0x30:
		/* wrmsr */
		msr_data = (u32)c->regs[VCPU_REGS_RAX]
			| ((u64)c->regs[VCPU_REGS_RDX] << 32);
		rc = kvm_set_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], msr_data);
		if (rc) {
			kvm_inject_gp(ctxt->vcpu, 0);
			c->eip = kvm_rip_read(ctxt->vcpu);
		}
		rc = X86EMUL_CONTINUE;
		c->dst.type = OP_NONE;
		break;
	case 0x32:
		/* rdmsr */
		rc = kvm_get_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], &msr_data);
		if (rc) {
			kvm_inject_gp(ctxt->vcpu, 0);
			c->eip = kvm_rip_read(ctxt->vcpu);
		} else {
			c->regs[VCPU_REGS_RAX] = (u32)msr_data;
			c->regs[VCPU_REGS_RDX] = msr_data >> 32;
		}
		rc = X86EMUL_CONTINUE;
		c->dst.type = OP_NONE;
		break;
	case 0x34:		/* sysenter */
		rc = emulate_sysenter(ctxt);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		else
			goto writeback;
		break;
	case 0x35:		/* sysexit */
		rc = emulate_sysexit(ctxt);
		if (rc != X86EMUL_CONTINUE)
			goto done;
		else
			goto writeback;
		break;
	case 0x40 ... 0x4f:	/* cmov */
		c->dst.val = c->dst.orig_val = c->src.val;
		if (!test_cc(c->b, ctxt->eflags))
			c->dst.type = OP_NONE; /* no writeback */
		break;
	case 0x80 ... 0x8f: /* jnz rel, etc*/
		if (test_cc(c->b, ctxt->eflags))
			jmp_rel(c, c->src.val);
		c->dst.type = OP_NONE;
		break;
	case 0xa0:	  /* push fs */
		emulate_push_sreg(ctxt, VCPU_SREG_FS);
		break;
	case 0xa1:	 /* pop fs */
		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
		if (rc != 0)
			goto done;
		break;
	case 0xa3:
	      bt:		/* bt */
		c->dst.type = OP_NONE;
		/* only subword offset */
		c->src.val &= (c->dst.bytes << 3) - 1;
		emulate_2op_SrcV_nobyte("bt", c->src, c->dst, ctxt->eflags);
		break;
	case 0xa4: /* shld imm8, r, r/m */
	case 0xa5: /* shld cl, r, r/m */
		emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);
		break;
	case 0xa8:	/* push gs */
		emulate_push_sreg(ctxt, VCPU_SREG_GS);
		break;
	case 0xa9:	/* pop gs */
		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
		if (rc != 0)
			goto done;
		break;
	case 0xab:
	      bts:		/* bts */
		/* only subword offset */
		c->src.val &= (c->dst.bytes << 3) - 1;
		emulate_2op_SrcV_nobyte("bts", c->src, c->dst, ctxt->eflags);
		break;
	case 0xac: /* shrd imm8, r, r/m */
	case 0xad: /* shrd cl, r, r/m */
		emulate_2op_cl("shrd", c->src2, c->src, c->dst, ctxt->eflags);
		break;
	case 0xae:              /* clflush */
		break;
	case 0xb0 ... 0xb1:	/* cmpxchg */
		/*
		 * Save real source value, then compare EAX against
		 * destination.
		 */
		c->src.orig_val = c->src.val;
		c->src.val = c->regs[VCPU_REGS_RAX];
		emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);
		if (ctxt->eflags & EFLG_ZF) {
			/* Success: write back to memory. */
			c->dst.val = c->src.orig_val;
		} else {
			/* Failure: write the value we saw to EAX. */
			c->dst.type = OP_REG;
			c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
		}
		break;
	case 0xb3:
	      btr:		/* btr */
		/* only subword offset */
		c->src.val &= (c->dst.bytes << 3) - 1;
		emulate_2op_SrcV_nobyte("btr", c->src, c->dst, ctxt->eflags);
		break;
	case 0xb6 ... 0xb7:	/* movzx */
		c->dst.bytes = c->op_bytes;
		c->dst.val = (c->d & ByteOp) ? (u8) c->src.val
						       : (u16) c->src.val;
		break;
	case 0xba:		/* Grp8 */
		switch (c->modrm_reg & 3) {
		case 0:
			goto bt;
		case 1:
			goto bts;
		case 2:
			goto btr;
		case 3:
			goto btc;
		}
		break;
	case 0xbb:
	      btc:		/* btc */
		/* only subword offset */
		c->src.val &= (c->dst.bytes << 3) - 1;
		emulate_2op_SrcV_nobyte("btc", c->src, c->dst, ctxt->eflags);
		break;
	case 0xbe ... 0xbf:	/* movsx */
		c->dst.bytes = c->op_bytes;
		c->dst.val = (c->d & ByteOp) ? (s8) c->src.val :
							(s16) c->src.val;
		break;
	case 0xc3:		/* movnti */
		c->dst.bytes = c->op_bytes;
		c->dst.val = (c->op_bytes == 4) ? (u32) c->src.val :
							(u64) c->src.val;
		break;
	case 0xc7:		/* Grp9 (cmpxchg8b) */
		rc = emulate_grp9(ctxt, ops, memop);
		if (rc != 0)
			goto done;
		c->dst.type = OP_NONE;
		break;
	}
	goto writeback;

cannot_emulate:
	DPRINTF("Cannot emulate %02x\n", c->b);
	c->eip = saved_eip;
	return -1;
}