1 /*-
2 * Copyright (c) 2012 Sandvine, Inc.
3 * Copyright (c) 2012 NetApp, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: releng/11.0/sys/amd64/vmm/vmm_instruction_emul.c 299009 2016-05-03 22:07:18Z pfg $
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD: releng/11.0/sys/amd64/vmm/vmm_instruction_emul.c 299009 2016-05-03 22:07:18Z pfg $");
32
33 #ifdef _KERNEL
34 #include <sys/param.h>
35 #include <sys/pcpu.h>
36 #include <sys/systm.h>
37 #include <sys/proc.h>
38
39 #include <vm/vm.h>
40 #include <vm/pmap.h>
41
42 #include <machine/vmparam.h>
43 #include <machine/vmm.h>
44 #else /* !_KERNEL */
45 #include <sys/types.h>
46 #include <sys/errno.h>
47 #include <sys/_iovec.h>
48
49 #include <machine/vmm.h>
50
51 #include <assert.h>
52 #include <vmmapi.h>
53 #define KASSERT(exp,msg) assert((exp))
54 #endif /* _KERNEL */
55
56 #include <machine/vmm_instruction_emul.h>
57 #include <x86/psl.h>
58 #include <x86/specialreg.h>
59
60 /* struct vie_op.op_type */
61 enum {
62 VIE_OP_TYPE_NONE = 0,
63 VIE_OP_TYPE_MOV,
64 VIE_OP_TYPE_MOVSX,
65 VIE_OP_TYPE_MOVZX,
66 VIE_OP_TYPE_AND,
67 VIE_OP_TYPE_OR,
68 VIE_OP_TYPE_SUB,
69 VIE_OP_TYPE_TWO_BYTE,
70 VIE_OP_TYPE_PUSH,
71 VIE_OP_TYPE_CMP,
72 VIE_OP_TYPE_POP,
73 VIE_OP_TYPE_MOVS,
74 VIE_OP_TYPE_GROUP1,
75 VIE_OP_TYPE_STOS,
76 VIE_OP_TYPE_BITTEST,
77 VIE_OP_TYPE_LAST
78 };
79
80 /* struct vie_op.op_flags */
81 #define VIE_OP_F_IMM (1 << 0) /* 16/32-bit immediate operand */
82 #define VIE_OP_F_IMM8 (1 << 1) /* 8-bit immediate operand */
83 #define VIE_OP_F_MOFFSET (1 << 2) /* 16/32/64-bit immediate moffset */
84 #define VIE_OP_F_NO_MODRM (1 << 3)
85 #define VIE_OP_F_NO_GLA_VERIFICATION (1 << 4)
86
87 static const struct vie_op two_byte_opcodes[256] = {
88 [0xB6] = {
89 .op_byte = 0xB6,
90 .op_type = VIE_OP_TYPE_MOVZX,
91 },
92 [0xB7] = {
93 .op_byte = 0xB7,
94 .op_type = VIE_OP_TYPE_MOVZX,
95 },
96 [0xBA] = {
97 .op_byte = 0xBA,
98 .op_type = VIE_OP_TYPE_BITTEST,
99 .op_flags = VIE_OP_F_IMM8,
100 },
101 [0xBE] = {
102 .op_byte = 0xBE,
103 .op_type = VIE_OP_TYPE_MOVSX,
104 },
105 };
106
107 static const struct vie_op one_byte_opcodes[256] = {
108 [0x0F] = {
109 .op_byte = 0x0F,
110 .op_type = VIE_OP_TYPE_TWO_BYTE
111 },
112 [0x2B] = {
113 .op_byte = 0x2B,
114 .op_type = VIE_OP_TYPE_SUB,
115 },
116 [0x39] = {
117 .op_byte = 0x39,
118 .op_type = VIE_OP_TYPE_CMP,
119 },
120 [0x3B] = {
121 .op_byte = 0x3B,
122 .op_type = VIE_OP_TYPE_CMP,
123 },
124 [0x88] = {
125 .op_byte = 0x88,
126 .op_type = VIE_OP_TYPE_MOV,
127 },
128 [0x89] = {
129 .op_byte = 0x89,
130 .op_type = VIE_OP_TYPE_MOV,
131 },
132 [0x8A] = {
133 .op_byte = 0x8A,
134 .op_type = VIE_OP_TYPE_MOV,
135 },
136 [0x8B] = {
137 .op_byte = 0x8B,
138 .op_type = VIE_OP_TYPE_MOV,
139 },
140 [0xA1] = {
141 .op_byte = 0xA1,
142 .op_type = VIE_OP_TYPE_MOV,
143 .op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
144 },
145 [0xA3] = {
146 .op_byte = 0xA3,
147 .op_type = VIE_OP_TYPE_MOV,
148 .op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
149 },
150 [0xA4] = {
151 .op_byte = 0xA4,
152 .op_type = VIE_OP_TYPE_MOVS,
153 .op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
154 },
155 [0xA5] = {
156 .op_byte = 0xA5,
157 .op_type = VIE_OP_TYPE_MOVS,
158 .op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
159 },
160 [0xAA] = {
161 .op_byte = 0xAA,
162 .op_type = VIE_OP_TYPE_STOS,
163 .op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
164 },
165 [0xAB] = {
166 .op_byte = 0xAB,
167 .op_type = VIE_OP_TYPE_STOS,
168 .op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
169 },
170 [0xC6] = {
171 /* XXX Group 11 extended opcode - not just MOV */
172 .op_byte = 0xC6,
173 .op_type = VIE_OP_TYPE_MOV,
174 .op_flags = VIE_OP_F_IMM8,
175 },
176 [0xC7] = {
177 .op_byte = 0xC7,
178 .op_type = VIE_OP_TYPE_MOV,
179 .op_flags = VIE_OP_F_IMM,
180 },
181 [0x23] = {
182 .op_byte = 0x23,
183 .op_type = VIE_OP_TYPE_AND,
184 },
185 [0x80] = {
186 /* Group 1 extended opcode */
187 .op_byte = 0x80,
188 .op_type = VIE_OP_TYPE_GROUP1,
189 .op_flags = VIE_OP_F_IMM8,
190 },
191 [0x81] = {
192 /* Group 1 extended opcode */
193 .op_byte = 0x81,
194 .op_type = VIE_OP_TYPE_GROUP1,
195 .op_flags = VIE_OP_F_IMM,
196 },
197 [0x83] = {
198 /* Group 1 extended opcode */
199 .op_byte = 0x83,
200 .op_type = VIE_OP_TYPE_GROUP1,
201 .op_flags = VIE_OP_F_IMM8,
202 },
203 [0x8F] = {
204 /* XXX Group 1A extended opcode - not just POP */
205 .op_byte = 0x8F,
206 .op_type = VIE_OP_TYPE_POP,
207 },
208 [0xFF] = {
209 /* XXX Group 5 extended opcode - not just PUSH */
210 .op_byte = 0xFF,
211 .op_type = VIE_OP_TYPE_PUSH,
212 }
213 };
214
215 /* struct vie.mod */
216 #define VIE_MOD_INDIRECT 0
217 #define VIE_MOD_INDIRECT_DISP8 1
218 #define VIE_MOD_INDIRECT_DISP32 2
219 #define VIE_MOD_DIRECT 3
220
221 /* struct vie.rm */
222 #define VIE_RM_SIB 4
223 #define VIE_RM_DISP32 5
224
225 #define GB (1024 * 1024 * 1024)
226
227 static enum vm_reg_name gpr_map[16] = {
228 VM_REG_GUEST_RAX,
229 VM_REG_GUEST_RCX,
230 VM_REG_GUEST_RDX,
231 VM_REG_GUEST_RBX,
232 VM_REG_GUEST_RSP,
233 VM_REG_GUEST_RBP,
234 VM_REG_GUEST_RSI,
235 VM_REG_GUEST_RDI,
236 VM_REG_GUEST_R8,
237 VM_REG_GUEST_R9,
238 VM_REG_GUEST_R10,
239 VM_REG_GUEST_R11,
240 VM_REG_GUEST_R12,
241 VM_REG_GUEST_R13,
242 VM_REG_GUEST_R14,
243 VM_REG_GUEST_R15
244 };
245
246 static uint64_t size2mask[] = {
247 [1] = 0xff,
248 [2] = 0xffff,
249 [4] = 0xffffffff,
250 [8] = 0xffffffffffffffff,
251 };
252
253 static int
254 vie_read_register(void *vm, int vcpuid, enum vm_reg_name reg, uint64_t *rval)
255 {
256 int error;
257
258 error = vm_get_register(vm, vcpuid, reg, rval);
259
260 return (error);
261 }
262
263 static void
264 vie_calc_bytereg(struct vie *vie, enum vm_reg_name *reg, int *lhbr)
265 {
266 *lhbr = 0;
267 *reg = gpr_map[vie->reg];
268
269 /*
270 * 64-bit mode imposes limitations on accessing legacy high byte
271 * registers (lhbr).
272 *
273 * The legacy high-byte registers cannot be addressed if the REX
274 * prefix is present. In this case the values 4, 5, 6 and 7 of the
275 * 'ModRM:reg' field address %spl, %bpl, %sil and %dil respectively.
276 *
277 * If the REX prefix is not present then the values 4, 5, 6 and 7
278 * of the 'ModRM:reg' field address the legacy high-byte registers,
279 * %ah, %ch, %dh and %bh respectively.
280 */
281 if (!vie->rex_present) {
282 if (vie->reg & 0x4) {
283 *lhbr = 1;
284 *reg = gpr_map[vie->reg & 0x3];
285 }
286 }
287 }
288
289 static int
290 vie_read_bytereg(void *vm, int vcpuid, struct vie *vie, uint8_t *rval)
291 {
292 uint64_t val;
293 int error, lhbr;
294 enum vm_reg_name reg;
295
296 vie_calc_bytereg(vie, ®, &lhbr);
297 error = vm_get_register(vm, vcpuid, reg, &val);
298
299 /*
300 * To obtain the value of a legacy high byte register shift the
301 * base register right by 8 bits (%ah = %rax >> 8).
302 */
303 if (lhbr)
304 *rval = val >> 8;
305 else
306 *rval = val;
307 return (error);
308 }
309
310 static int
311 vie_write_bytereg(void *vm, int vcpuid, struct vie *vie, uint8_t byte)
312 {
313 uint64_t origval, val, mask;
314 int error, lhbr;
315 enum vm_reg_name reg;
316
317 vie_calc_bytereg(vie, ®, &lhbr);
318 error = vm_get_register(vm, vcpuid, reg, &origval);
319 if (error == 0) {
320 val = byte;
321 mask = 0xff;
322 if (lhbr) {
323 /*
324 * Shift left by 8 to store 'byte' in a legacy high
325 * byte register.
326 */
327 val <<= 8;
328 mask <<= 8;
329 }
330 val |= origval & ~mask;
331 error = vm_set_register(vm, vcpuid, reg, val);
332 }
333 return (error);
334 }
335
336 int
337 vie_update_register(void *vm, int vcpuid, enum vm_reg_name reg,
338 uint64_t val, int size)
339 {
340 int error;
341 uint64_t origval;
342
343 switch (size) {
344 case 1:
345 case 2:
346 error = vie_read_register(vm, vcpuid, reg, &origval);
347 if (error)
348 return (error);
349 val &= size2mask[size];
350 val |= origval & ~size2mask[size];
351 break;
352 case 4:
353 val &= 0xffffffffUL;
354 break;
355 case 8:
356 break;
357 default:
358 return (EINVAL);
359 }
360
361 error = vm_set_register(vm, vcpuid, reg, val);
362 return (error);
363 }
364
365 #define RFLAGS_STATUS_BITS (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_V)
366
367 /*
368 * Return the status flags that would result from doing (x - y).
369 */
370 #define GETCC(sz) \
371 static u_long \
372 getcc##sz(uint##sz##_t x, uint##sz##_t y) \
373 { \
374 u_long rflags; \
375 \
376 __asm __volatile("sub %2,%1; pushfq; popq %0" : \
377 "=r" (rflags), "+r" (x) : "m" (y)); \
378 return (rflags); \
379 } struct __hack
380
381 GETCC(8);
382 GETCC(16);
383 GETCC(32);
384 GETCC(64);
385
386 static u_long
387 getcc(int opsize, uint64_t x, uint64_t y)
388 {
389 KASSERT(opsize == 1 || opsize == 2 || opsize == 4 || opsize == 8,
390 ("getcc: invalid operand size %d", opsize));
391
392 if (opsize == 1)
393 return (getcc8(x, y));
394 else if (opsize == 2)
395 return (getcc16(x, y));
396 else if (opsize == 4)
397 return (getcc32(x, y));
398 else
399 return (getcc64(x, y));
400 }
401
402 static int
403 emulate_mov(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
404 mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
405 {
406 int error, size;
407 enum vm_reg_name reg;
408 uint8_t byte;
409 uint64_t val;
410
411 size = vie->opsize;
412 error = EINVAL;
413
414 switch (vie->op.op_byte) {
415 case 0x88:
416 /*
417 * MOV byte from reg (ModRM:reg) to mem (ModRM:r/m)
418 * 88/r: mov r/m8, r8
419 * REX + 88/r: mov r/m8, r8 (%ah, %ch, %dh, %bh not available)
420 */
421 size = 1; /* override for byte operation */
422 error = vie_read_bytereg(vm, vcpuid, vie, &byte);
423 if (error == 0)
424 error = memwrite(vm, vcpuid, gpa, byte, size, arg);
425 break;
426 case 0x89:
427 /*
428 * MOV from reg (ModRM:reg) to mem (ModRM:r/m)
429 * 89/r: mov r/m16, r16
430 * 89/r: mov r/m32, r32
431 * REX.W + 89/r mov r/m64, r64
432 */
433 reg = gpr_map[vie->reg];
434 error = vie_read_register(vm, vcpuid, reg, &val);
435 if (error == 0) {
436 val &= size2mask[size];
437 error = memwrite(vm, vcpuid, gpa, val, size, arg);
438 }
439 break;
440 case 0x8A:
441 /*
442 * MOV byte from mem (ModRM:r/m) to reg (ModRM:reg)
443 * 8A/r: mov r8, r/m8
444 * REX + 8A/r: mov r8, r/m8
445 */
446 size = 1; /* override for byte operation */
447 error = memread(vm, vcpuid, gpa, &val, size, arg);
448 if (error == 0)
449 error = vie_write_bytereg(vm, vcpuid, vie, val);
450 break;
451 case 0x8B:
452 /*
453 * MOV from mem (ModRM:r/m) to reg (ModRM:reg)
454 * 8B/r: mov r16, r/m16
455 * 8B/r: mov r32, r/m32
456 * REX.W 8B/r: mov r64, r/m64
457 */
458 error = memread(vm, vcpuid, gpa, &val, size, arg);
459 if (error == 0) {
460 reg = gpr_map[vie->reg];
461 error = vie_update_register(vm, vcpuid, reg, val, size);
462 }
463 break;
464 case 0xA1:
465 /*
466 * MOV from seg:moffset to AX/EAX/RAX
467 * A1: mov AX, moffs16
468 * A1: mov EAX, moffs32
469 * REX.W + A1: mov RAX, moffs64
470 */
471 error = memread(vm, vcpuid, gpa, &val, size, arg);
472 if (error == 0) {
473 reg = VM_REG_GUEST_RAX;
474 error = vie_update_register(vm, vcpuid, reg, val, size);
475 }
476 break;
477 case 0xA3:
478 /*
479 * MOV from AX/EAX/RAX to seg:moffset
480 * A3: mov moffs16, AX
481 * A3: mov moffs32, EAX
482 * REX.W + A3: mov moffs64, RAX
483 */
484 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RAX, &val);
485 if (error == 0) {
486 val &= size2mask[size];
487 error = memwrite(vm, vcpuid, gpa, val, size, arg);
488 }
489 break;
490 case 0xC6:
491 /*
492 * MOV from imm8 to mem (ModRM:r/m)
493 * C6/0 mov r/m8, imm8
494 * REX + C6/0 mov r/m8, imm8
495 */
496 size = 1; /* override for byte operation */
497 error = memwrite(vm, vcpuid, gpa, vie->immediate, size, arg);
498 break;
499 case 0xC7:
500 /*
501 * MOV from imm16/imm32 to mem (ModRM:r/m)
502 * C7/0 mov r/m16, imm16
503 * C7/0 mov r/m32, imm32
504 * REX.W + C7/0 mov r/m64, imm32 (sign-extended to 64-bits)
505 */
506 val = vie->immediate & size2mask[size];
507 error = memwrite(vm, vcpuid, gpa, val, size, arg);
508 break;
509 default:
510 break;
511 }
512
513 return (error);
514 }
515
516 static int
517 emulate_movx(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
518 mem_region_read_t memread, mem_region_write_t memwrite,
519 void *arg)
520 {
521 int error, size;
522 enum vm_reg_name reg;
523 uint64_t val;
524
525 size = vie->opsize;
526 error = EINVAL;
527
528 switch (vie->op.op_byte) {
529 case 0xB6:
530 /*
531 * MOV and zero extend byte from mem (ModRM:r/m) to
532 * reg (ModRM:reg).
533 *
534 * 0F B6/r movzx r16, r/m8
535 * 0F B6/r movzx r32, r/m8
536 * REX.W + 0F B6/r movzx r64, r/m8
537 */
538
539 /* get the first operand */
540 error = memread(vm, vcpuid, gpa, &val, 1, arg);
541 if (error)
542 break;
543
544 /* get the second operand */
545 reg = gpr_map[vie->reg];
546
547 /* zero-extend byte */
548 val = (uint8_t)val;
549
550 /* write the result */
551 error = vie_update_register(vm, vcpuid, reg, val, size);
552 break;
553 case 0xB7:
554 /*
555 * MOV and zero extend word from mem (ModRM:r/m) to
556 * reg (ModRM:reg).
557 *
558 * 0F B7/r movzx r32, r/m16
559 * REX.W + 0F B7/r movzx r64, r/m16
560 */
561 error = memread(vm, vcpuid, gpa, &val, 2, arg);
562 if (error)
563 return (error);
564
565 reg = gpr_map[vie->reg];
566
567 /* zero-extend word */
568 val = (uint16_t)val;
569
570 error = vie_update_register(vm, vcpuid, reg, val, size);
571 break;
572 case 0xBE:
573 /*
574 * MOV and sign extend byte from mem (ModRM:r/m) to
575 * reg (ModRM:reg).
576 *
577 * 0F BE/r movsx r16, r/m8
578 * 0F BE/r movsx r32, r/m8
579 * REX.W + 0F BE/r movsx r64, r/m8
580 */
581
582 /* get the first operand */
583 error = memread(vm, vcpuid, gpa, &val, 1, arg);
584 if (error)
585 break;
586
587 /* get the second operand */
588 reg = gpr_map[vie->reg];
589
590 /* sign extend byte */
591 val = (int8_t)val;
592
593 /* write the result */
594 error = vie_update_register(vm, vcpuid, reg, val, size);
595 break;
596 default:
597 break;
598 }
599 return (error);
600 }
601
602 /*
603 * Helper function to calculate and validate a linear address.
604 */
605 static int
606 get_gla(void *vm, int vcpuid, struct vie *vie, struct vm_guest_paging *paging,
607 int opsize, int addrsize, int prot, enum vm_reg_name seg,
608 enum vm_reg_name gpr, uint64_t *gla, int *fault)
609 {
610 struct seg_desc desc;
611 uint64_t cr0, val, rflags;
612 int error;
613
614 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_CR0, &cr0);
615 KASSERT(error == 0, ("%s: error %d getting cr0", __func__, error));
616
617 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
618 KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
619
620 error = vm_get_seg_desc(vm, vcpuid, seg, &desc);
621 KASSERT(error == 0, ("%s: error %d getting segment descriptor %d",
622 __func__, error, seg));
623
624 error = vie_read_register(vm, vcpuid, gpr, &val);
625 KASSERT(error == 0, ("%s: error %d getting register %d", __func__,
626 error, gpr));
627
628 if (vie_calculate_gla(paging->cpu_mode, seg, &desc, val, opsize,
629 addrsize, prot, gla)) {
630 if (seg == VM_REG_GUEST_SS)
631 vm_inject_ss(vm, vcpuid, 0);
632 else
633 vm_inject_gp(vm, vcpuid);
634 goto guest_fault;
635 }
636
637 if (vie_canonical_check(paging->cpu_mode, *gla)) {
638 if (seg == VM_REG_GUEST_SS)
639 vm_inject_ss(vm, vcpuid, 0);
640 else
641 vm_inject_gp(vm, vcpuid);
642 goto guest_fault;
643 }
644
645 if (vie_alignment_check(paging->cpl, opsize, cr0, rflags, *gla)) {
646 vm_inject_ac(vm, vcpuid, 0);
647 goto guest_fault;
648 }
649
650 *fault = 0;
651 return (0);
652
653 guest_fault:
654 *fault = 1;
655 return (0);
656 }
657
658 static int
659 emulate_movs(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
660 struct vm_guest_paging *paging, mem_region_read_t memread,
661 mem_region_write_t memwrite, void *arg)
662 {
663 #ifdef _KERNEL
664 struct vm_copyinfo copyinfo[2];
665 #else
666 struct iovec copyinfo[2];
667 #endif
668 uint64_t dstaddr, srcaddr, dstgpa, srcgpa, val;
669 uint64_t rcx, rdi, rsi, rflags;
670 int error, fault, opsize, seg, repeat;
671
672 opsize = (vie->op.op_byte == 0xA4) ? 1 : vie->opsize;
673 val = 0;
674 error = 0;
675
676 /*
677 * XXX although the MOVS instruction is only supposed to be used with
678 * the "rep" prefix some guests like FreeBSD will use "repnz" instead.
679 *
680 * Empirically the "repnz" prefix has identical behavior to "rep"
681 * and the zero flag does not make a difference.
682 */
683 repeat = vie->repz_present | vie->repnz_present;
684
685 if (repeat) {
686 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RCX, &rcx);
687 KASSERT(!error, ("%s: error %d getting rcx", __func__, error));
688
689 /*
690 * The count register is %rcx, %ecx or %cx depending on the
691 * address size of the instruction.
692 */
693 if ((rcx & vie_size2mask(vie->addrsize)) == 0) {
694 error = 0;
695 goto done;
696 }
697 }
698
699 /*
700 * Source Destination Comments
701 * --------------------------------------------
702 * (1) memory memory n/a
703 * (2) memory mmio emulated
704 * (3) mmio memory emulated
705 * (4) mmio mmio emulated
706 *
707 * At this point we don't have sufficient information to distinguish
708 * between (2), (3) and (4). We use 'vm_copy_setup()' to tease this
709 * out because it will succeed only when operating on regular memory.
710 *
711 * XXX the emulation doesn't properly handle the case where 'gpa'
712 * is straddling the boundary between the normal memory and MMIO.
713 */
714
715 seg = vie->segment_override ? vie->segment_register : VM_REG_GUEST_DS;
716 error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
717 PROT_READ, seg, VM_REG_GUEST_RSI, &srcaddr, &fault);
718 if (error || fault)
719 goto done;
720
721 error = vm_copy_setup(vm, vcpuid, paging, srcaddr, opsize, PROT_READ,
722 copyinfo, nitems(copyinfo), &fault);
723 if (error == 0) {
724 if (fault)
725 goto done; /* Resume guest to handle fault */
726
727 /*
728 * case (2): read from system memory and write to mmio.
729 */
730 vm_copyin(vm, vcpuid, copyinfo, &val, opsize);
731 vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
732 error = memwrite(vm, vcpuid, gpa, val, opsize, arg);
733 if (error)
734 goto done;
735 } else {
736 /*
737 * 'vm_copy_setup()' is expected to fail for cases (3) and (4)
738 * if 'srcaddr' is in the mmio space.
739 */
740
741 error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
742 PROT_WRITE, VM_REG_GUEST_ES, VM_REG_GUEST_RDI, &dstaddr,
743 &fault);
744 if (error || fault)
745 goto done;
746
747 error = vm_copy_setup(vm, vcpuid, paging, dstaddr, opsize,
748 PROT_WRITE, copyinfo, nitems(copyinfo), &fault);
749 if (error == 0) {
750 if (fault)
751 goto done; /* Resume guest to handle fault */
752
753 /*
754 * case (3): read from MMIO and write to system memory.
755 *
756 * A MMIO read can have side-effects so we
757 * commit to it only after vm_copy_setup() is
758 * successful. If a page-fault needs to be
759 * injected into the guest then it will happen
760 * before the MMIO read is attempted.
761 */
762 error = memread(vm, vcpuid, gpa, &val, opsize, arg);
763 if (error)
764 goto done;
765
766 vm_copyout(vm, vcpuid, &val, copyinfo, opsize);
767 vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
768 } else {
769 /*
770 * Case (4): read from and write to mmio.
771 *
772 * Commit to the MMIO read/write (with potential
773 * side-effects) only after we are sure that the
774 * instruction is not going to be restarted due
775 * to address translation faults.
776 */
777 error = vm_gla2gpa(vm, vcpuid, paging, srcaddr,
778 PROT_READ, &srcgpa, &fault);
779 if (error || fault)
780 goto done;
781
782 error = vm_gla2gpa(vm, vcpuid, paging, dstaddr,
783 PROT_WRITE, &dstgpa, &fault);
784 if (error || fault)
785 goto done;
786
787 error = memread(vm, vcpuid, srcgpa, &val, opsize, arg);
788 if (error)
789 goto done;
790
791 error = memwrite(vm, vcpuid, dstgpa, val, opsize, arg);
792 if (error)
793 goto done;
794 }
795 }
796
797 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RSI, &rsi);
798 KASSERT(error == 0, ("%s: error %d getting rsi", __func__, error));
799
800 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RDI, &rdi);
801 KASSERT(error == 0, ("%s: error %d getting rdi", __func__, error));
802
803 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
804 KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
805
806 if (rflags & PSL_D) {
807 rsi -= opsize;
808 rdi -= opsize;
809 } else {
810 rsi += opsize;
811 rdi += opsize;
812 }
813
814 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RSI, rsi,
815 vie->addrsize);
816 KASSERT(error == 0, ("%s: error %d updating rsi", __func__, error));
817
818 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RDI, rdi,
819 vie->addrsize);
820 KASSERT(error == 0, ("%s: error %d updating rdi", __func__, error));
821
822 if (repeat) {
823 rcx = rcx - 1;
824 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RCX,
825 rcx, vie->addrsize);
826 KASSERT(!error, ("%s: error %d updating rcx", __func__, error));
827
828 /*
829 * Repeat the instruction if the count register is not zero.
830 */
831 if ((rcx & vie_size2mask(vie->addrsize)) != 0)
832 vm_restart_instruction(vm, vcpuid);
833 }
834 done:
835 KASSERT(error == 0 || error == EFAULT, ("%s: unexpected error %d",
836 __func__, error));
837 return (error);
838 }
839
840 static int
841 emulate_stos(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
842 struct vm_guest_paging *paging, mem_region_read_t memread,
843 mem_region_write_t memwrite, void *arg)
844 {
845 int error, opsize, repeat;
846 uint64_t val;
847 uint64_t rcx, rdi, rflags;
848
849 opsize = (vie->op.op_byte == 0xAA) ? 1 : vie->opsize;
850 repeat = vie->repz_present | vie->repnz_present;
851
852 if (repeat) {
853 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RCX, &rcx);
854 KASSERT(!error, ("%s: error %d getting rcx", __func__, error));
855
856 /*
857 * The count register is %rcx, %ecx or %cx depending on the
858 * address size of the instruction.
859 */
860 if ((rcx & vie_size2mask(vie->addrsize)) == 0)
861 return (0);
862 }
863
864 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RAX, &val);
865 KASSERT(!error, ("%s: error %d getting rax", __func__, error));
866
867 error = memwrite(vm, vcpuid, gpa, val, opsize, arg);
868 if (error)
869 return (error);
870
871 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RDI, &rdi);
872 KASSERT(error == 0, ("%s: error %d getting rdi", __func__, error));
873
874 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
875 KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
876
877 if (rflags & PSL_D)
878 rdi -= opsize;
879 else
880 rdi += opsize;
881
882 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RDI, rdi,
883 vie->addrsize);
884 KASSERT(error == 0, ("%s: error %d updating rdi", __func__, error));
885
886 if (repeat) {
887 rcx = rcx - 1;
888 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RCX,
889 rcx, vie->addrsize);
890 KASSERT(!error, ("%s: error %d updating rcx", __func__, error));
891
892 /*
893 * Repeat the instruction if the count register is not zero.
894 */
895 if ((rcx & vie_size2mask(vie->addrsize)) != 0)
896 vm_restart_instruction(vm, vcpuid);
897 }
898
899 return (0);
900 }
901
902 static int
903 emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
904 mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
905 {
906 int error, size;
907 enum vm_reg_name reg;
908 uint64_t result, rflags, rflags2, val1, val2;
909
910 size = vie->opsize;
911 error = EINVAL;
912
913 switch (vie->op.op_byte) {
914 case 0x23:
915 /*
916 * AND reg (ModRM:reg) and mem (ModRM:r/m) and store the
917 * result in reg.
918 *
919 * 23/r and r16, r/m16
920 * 23/r and r32, r/m32
921 * REX.W + 23/r and r64, r/m64
922 */
923
924 /* get the first operand */
925 reg = gpr_map[vie->reg];
926 error = vie_read_register(vm, vcpuid, reg, &val1);
927 if (error)
928 break;
929
930 /* get the second operand */
931 error = memread(vm, vcpuid, gpa, &val2, size, arg);
932 if (error)
933 break;
934
935 /* perform the operation and write the result */
936 result = val1 & val2;
937 error = vie_update_register(vm, vcpuid, reg, result, size);
938 break;
939 case 0x81:
940 case 0x83:
941 /*
942 * AND mem (ModRM:r/m) with immediate and store the
943 * result in mem.
944 *
945 * 81 /4 and r/m16, imm16
946 * 81 /4 and r/m32, imm32
947 * REX.W + 81 /4 and r/m64, imm32 sign-extended to 64
948 *
949 * 83 /4 and r/m16, imm8 sign-extended to 16
950 * 83 /4 and r/m32, imm8 sign-extended to 32
951 * REX.W + 83/4 and r/m64, imm8 sign-extended to 64
952 */
953
954 /* get the first operand */
955 error = memread(vm, vcpuid, gpa, &val1, size, arg);
956 if (error)
957 break;
958
959 /*
960 * perform the operation with the pre-fetched immediate
961 * operand and write the result
962 */
963 result = val1 & vie->immediate;
964 error = memwrite(vm, vcpuid, gpa, result, size, arg);
965 break;
966 default:
967 break;
968 }
969 if (error)
970 return (error);
971
972 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
973 if (error)
974 return (error);
975
976 /*
977 * OF and CF are cleared; the SF, ZF and PF flags are set according
978 * to the result; AF is undefined.
979 *
980 * The updated status flags are obtained by subtracting 0 from 'result'.
981 */
982 rflags2 = getcc(size, result, 0);
983 rflags &= ~RFLAGS_STATUS_BITS;
984 rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
985
986 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
987 return (error);
988 }
989
990 static int
991 emulate_or(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
992 mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
993 {
994 int error, size;
995 uint64_t val1, result, rflags, rflags2;
996
997 size = vie->opsize;
998 error = EINVAL;
999
1000 switch (vie->op.op_byte) {
1001 case 0x81:
1002 case 0x83:
1003 /*
1004 * OR mem (ModRM:r/m) with immediate and store the
1005 * result in mem.
1006 *
1007 * 81 /1 or r/m16, imm16
1008 * 81 /1 or r/m32, imm32
1009 * REX.W + 81 /1 or r/m64, imm32 sign-extended to 64
1010 *
1011 * 83 /1 or r/m16, imm8 sign-extended to 16
1012 * 83 /1 or r/m32, imm8 sign-extended to 32
1013 * REX.W + 83/1 or r/m64, imm8 sign-extended to 64
1014 */
1015
1016 /* get the first operand */
1017 error = memread(vm, vcpuid, gpa, &val1, size, arg);
1018 if (error)
1019 break;
1020
1021 /*
1022 * perform the operation with the pre-fetched immediate
1023 * operand and write the result
1024 */
1025 result = val1 | vie->immediate;
1026 error = memwrite(vm, vcpuid, gpa, result, size, arg);
1027 break;
1028 default:
1029 break;
1030 }
1031 if (error)
1032 return (error);
1033
1034 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
1035 if (error)
1036 return (error);
1037
1038 /*
1039 * OF and CF are cleared; the SF, ZF and PF flags are set according
1040 * to the result; AF is undefined.
1041 *
1042 * The updated status flags are obtained by subtracting 0 from 'result'.
1043 */
1044 rflags2 = getcc(size, result, 0);
1045 rflags &= ~RFLAGS_STATUS_BITS;
1046 rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
1047
1048 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
1049 return (error);
1050 }
1051
1052 static int
1053 emulate_cmp(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
1054 mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
1055 {
1056 int error, size;
1057 uint64_t regop, memop, op1, op2, rflags, rflags2;
1058 enum vm_reg_name reg;
1059
1060 size = vie->opsize;
1061 switch (vie->op.op_byte) {
1062 case 0x39:
1063 case 0x3B:
1064 /*
1065 * 39/r CMP r/m16, r16
1066 * 39/r CMP r/m32, r32
1067 * REX.W 39/r CMP r/m64, r64
1068 *
1069 * 3B/r CMP r16, r/m16
1070 * 3B/r CMP r32, r/m32
1071 * REX.W + 3B/r CMP r64, r/m64
1072 *
1073 * Compare the first operand with the second operand and
1074 * set status flags in EFLAGS register. The comparison is
1075 * performed by subtracting the second operand from the first
1076 * operand and then setting the status flags.
1077 */
1078
1079 /* Get the register operand */
1080 reg = gpr_map[vie->reg];
1081 error = vie_read_register(vm, vcpuid, reg, ®op);
1082 if (error)
1083 return (error);
1084
1085 /* Get the memory operand */
1086 error = memread(vm, vcpuid, gpa, &memop, size, arg);
1087 if (error)
1088 return (error);
1089
1090 if (vie->op.op_byte == 0x3B) {
1091 op1 = regop;
1092 op2 = memop;
1093 } else {
1094 op1 = memop;
1095 op2 = regop;
1096 }
1097 rflags2 = getcc(size, op1, op2);
1098 break;
1099 case 0x80:
1100 case 0x81:
1101 case 0x83:
1102 /*
1103 * 80 /7 cmp r/m8, imm8
1104 * REX + 80 /7 cmp r/m8, imm8
1105 *
1106 * 81 /7 cmp r/m16, imm16
1107 * 81 /7 cmp r/m32, imm32
1108 * REX.W + 81 /7 cmp r/m64, imm32 sign-extended to 64
1109 *
1110 * 83 /7 cmp r/m16, imm8 sign-extended to 16
1111 * 83 /7 cmp r/m32, imm8 sign-extended to 32
1112 * REX.W + 83 /7 cmp r/m64, imm8 sign-extended to 64
1113 *
1114 * Compare mem (ModRM:r/m) with immediate and set
1115 * status flags according to the results. The
1116 * comparison is performed by subtracting the
1117 * immediate from the first operand and then setting
1118 * the status flags.
1119 *
1120 */
1121 if (vie->op.op_byte == 0x80)
1122 size = 1;
1123
1124 /* get the first operand */
1125 error = memread(vm, vcpuid, gpa, &op1, size, arg);
1126 if (error)
1127 return (error);
1128
1129 rflags2 = getcc(size, op1, vie->immediate);
1130 break;
1131 default:
1132 return (EINVAL);
1133 }
1134 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
1135 if (error)
1136 return (error);
1137 rflags &= ~RFLAGS_STATUS_BITS;
1138 rflags |= rflags2 & RFLAGS_STATUS_BITS;
1139
1140 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
1141 return (error);
1142 }
1143
1144 static int
1145 emulate_sub(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
1146 mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
1147 {
1148 int error, size;
1149 uint64_t nval, rflags, rflags2, val1, val2;
1150 enum vm_reg_name reg;
1151
1152 size = vie->opsize;
1153 error = EINVAL;
1154
1155 switch (vie->op.op_byte) {
1156 case 0x2B:
1157 /*
1158 * SUB r/m from r and store the result in r
1159 *
1160 * 2B/r SUB r16, r/m16
1161 * 2B/r SUB r32, r/m32
1162 * REX.W + 2B/r SUB r64, r/m64
1163 */
1164
1165 /* get the first operand */
1166 reg = gpr_map[vie->reg];
1167 error = vie_read_register(vm, vcpuid, reg, &val1);
1168 if (error)
1169 break;
1170
1171 /* get the second operand */
1172 error = memread(vm, vcpuid, gpa, &val2, size, arg);
1173 if (error)
1174 break;
1175
1176 /* perform the operation and write the result */
1177 nval = val1 - val2;
1178 error = vie_update_register(vm, vcpuid, reg, nval, size);
1179 break;
1180 default:
1181 break;
1182 }
1183
1184 if (!error) {
1185 rflags2 = getcc(size, val1, val2);
1186 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS,
1187 &rflags);
1188 if (error)
1189 return (error);
1190
1191 rflags &= ~RFLAGS_STATUS_BITS;
1192 rflags |= rflags2 & RFLAGS_STATUS_BITS;
1193 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS,
1194 rflags, 8);
1195 }
1196
1197 return (error);
1198 }
1199
1200 static int
1201 emulate_stack_op(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
1202 struct vm_guest_paging *paging, mem_region_read_t memread,
1203 mem_region_write_t memwrite, void *arg)
1204 {
1205 #ifdef _KERNEL
1206 struct vm_copyinfo copyinfo[2];
1207 #else
1208 struct iovec copyinfo[2];
1209 #endif
1210 struct seg_desc ss_desc;
1211 uint64_t cr0, rflags, rsp, stack_gla, val;
1212 int error, fault, size, stackaddrsize, pushop;
1213
1214 val = 0;
1215 size = vie->opsize;
1216 pushop = (vie->op.op_type == VIE_OP_TYPE_PUSH) ? 1 : 0;
1217
1218 /*
1219 * From "Address-Size Attributes for Stack Accesses", Intel SDL, Vol 1
1220 */
1221 if (paging->cpu_mode == CPU_MODE_REAL) {
1222 stackaddrsize = 2;
1223 } else if (paging->cpu_mode == CPU_MODE_64BIT) {
1224 /*
1225 * "Stack Manipulation Instructions in 64-bit Mode", SDM, Vol 3
1226 * - Stack pointer size is always 64-bits.
1227 * - PUSH/POP of 32-bit values is not possible in 64-bit mode.
1228 * - 16-bit PUSH/POP is supported by using the operand size
1229 * override prefix (66H).
1230 */
1231 stackaddrsize = 8;
1232 size = vie->opsize_override ? 2 : 8;
1233 } else {
1234 /*
1235 * In protected or compatibility mode the 'B' flag in the
1236 * stack-segment descriptor determines the size of the
1237 * stack pointer.
1238 */
1239 error = vm_get_seg_desc(vm, vcpuid, VM_REG_GUEST_SS, &ss_desc);
1240 KASSERT(error == 0, ("%s: error %d getting SS descriptor",
1241 __func__, error));
1242 if (SEG_DESC_DEF32(ss_desc.access))
1243 stackaddrsize = 4;
1244 else
1245 stackaddrsize = 2;
1246 }
1247
1248 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_CR0, &cr0);
1249 KASSERT(error == 0, ("%s: error %d getting cr0", __func__, error));
1250
1251 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
1252 KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
1253
1254 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RSP, &rsp);
1255 KASSERT(error == 0, ("%s: error %d getting rsp", __func__, error));
1256 if (pushop) {
1257 rsp -= size;
1258 }
1259
1260 if (vie_calculate_gla(paging->cpu_mode, VM_REG_GUEST_SS, &ss_desc,
1261 rsp, size, stackaddrsize, pushop ? PROT_WRITE : PROT_READ,
1262 &stack_gla)) {
1263 vm_inject_ss(vm, vcpuid, 0);
1264 return (0);
1265 }
1266
1267 if (vie_canonical_check(paging->cpu_mode, stack_gla)) {
1268 vm_inject_ss(vm, vcpuid, 0);
1269 return (0);
1270 }
1271
1272 if (vie_alignment_check(paging->cpl, size, cr0, rflags, stack_gla)) {
1273 vm_inject_ac(vm, vcpuid, 0);
1274 return (0);
1275 }
1276
1277 error = vm_copy_setup(vm, vcpuid, paging, stack_gla, size,
1278 pushop ? PROT_WRITE : PROT_READ, copyinfo, nitems(copyinfo),
1279 &fault);
1280 if (error || fault)
1281 return (error);
1282
1283 if (pushop) {
1284 error = memread(vm, vcpuid, mmio_gpa, &val, size, arg);
1285 if (error == 0)
1286 vm_copyout(vm, vcpuid, &val, copyinfo, size);
1287 } else {
1288 vm_copyin(vm, vcpuid, copyinfo, &val, size);
1289 error = memwrite(vm, vcpuid, mmio_gpa, val, size, arg);
1290 rsp += size;
1291 }
1292 vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
1293
1294 if (error == 0) {
1295 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RSP, rsp,
1296 stackaddrsize);
1297 KASSERT(error == 0, ("error %d updating rsp", error));
1298 }
1299 return (error);
1300 }
1301
1302 static int
1303 emulate_push(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
1304 struct vm_guest_paging *paging, mem_region_read_t memread,
1305 mem_region_write_t memwrite, void *arg)
1306 {
1307 int error;
1308
1309 /*
1310 * Table A-6, "Opcode Extensions", Intel SDM, Vol 2.
1311 *
1312 * PUSH is part of the group 5 extended opcodes and is identified
1313 * by ModRM:reg = b110.
1314 */
1315 if ((vie->reg & 7) != 6)
1316 return (EINVAL);
1317
1318 error = emulate_stack_op(vm, vcpuid, mmio_gpa, vie, paging, memread,
1319 memwrite, arg);
1320 return (error);
1321 }
1322
1323 static int
1324 emulate_pop(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
1325 struct vm_guest_paging *paging, mem_region_read_t memread,
1326 mem_region_write_t memwrite, void *arg)
1327 {
1328 int error;
1329
1330 /*
1331 * Table A-6, "Opcode Extensions", Intel SDM, Vol 2.
1332 *
1333 * POP is part of the group 1A extended opcodes and is identified
1334 * by ModRM:reg = b000.
1335 */
1336 if ((vie->reg & 7) != 0)
1337 return (EINVAL);
1338
1339 error = emulate_stack_op(vm, vcpuid, mmio_gpa, vie, paging, memread,
1340 memwrite, arg);
1341 return (error);
1342 }
1343
1344 static int
1345 emulate_group1(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
1346 struct vm_guest_paging *paging, mem_region_read_t memread,
1347 mem_region_write_t memwrite, void *memarg)
1348 {
1349 int error;
1350
1351 switch (vie->reg & 7) {
1352 case 0x1: /* OR */
1353 error = emulate_or(vm, vcpuid, gpa, vie,
1354 memread, memwrite, memarg);
1355 break;
1356 case 0x4: /* AND */
1357 error = emulate_and(vm, vcpuid, gpa, vie,
1358 memread, memwrite, memarg);
1359 break;
1360 case 0x7: /* CMP */
1361 error = emulate_cmp(vm, vcpuid, gpa, vie,
1362 memread, memwrite, memarg);
1363 break;
1364 default:
1365 error = EINVAL;
1366 break;
1367 }
1368
1369 return (error);
1370 }
1371
1372 static int
1373 emulate_bittest(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
1374 mem_region_read_t memread, mem_region_write_t memwrite, void *memarg)
1375 {
1376 uint64_t val, rflags;
1377 int error, bitmask, bitoff;
1378
1379 /*
1380 * 0F BA is a Group 8 extended opcode.
1381 *
1382 * Currently we only emulate the 'Bit Test' instruction which is
1383 * identified by a ModR/M:reg encoding of 100b.
1384 */
1385 if ((vie->reg & 7) != 4)
1386 return (EINVAL);
1387
1388 error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
1389 KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
1390
1391 error = memread(vm, vcpuid, gpa, &val, vie->opsize, memarg);
1392 if (error)
1393 return (error);
1394
1395 /*
1396 * Intel SDM, Vol 2, Table 3-2:
1397 * "Range of Bit Positions Specified by Bit Offset Operands"
1398 */
1399 bitmask = vie->opsize * 8 - 1;
1400 bitoff = vie->immediate & bitmask;
1401
1402 /* Copy the bit into the Carry flag in %rflags */
1403 if (val & (1UL << bitoff))
1404 rflags |= PSL_C;
1405 else
1406 rflags &= ~PSL_C;
1407
1408 error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
1409 KASSERT(error == 0, ("%s: error %d updating rflags", __func__, error));
1410
1411 return (0);
1412 }
1413
1414 int
1415 vmm_emulate_instruction(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
1416 struct vm_guest_paging *paging, mem_region_read_t memread,
1417 mem_region_write_t memwrite, void *memarg)
1418 {
1419 int error;
1420
1421 if (!vie->decoded)
1422 return (EINVAL);
1423
1424 switch (vie->op.op_type) {
1425 case VIE_OP_TYPE_GROUP1:
1426 error = emulate_group1(vm, vcpuid, gpa, vie, paging, memread,
1427 memwrite, memarg);
1428 break;
1429 case VIE_OP_TYPE_POP:
1430 error = emulate_pop(vm, vcpuid, gpa, vie, paging, memread,
1431 memwrite, memarg);
1432 break;
1433 case VIE_OP_TYPE_PUSH:
1434 error = emulate_push(vm, vcpuid, gpa, vie, paging, memread,
1435 memwrite, memarg);
1436 break;
1437 case VIE_OP_TYPE_CMP:
1438 error = emulate_cmp(vm, vcpuid, gpa, vie,
1439 memread, memwrite, memarg);
1440 break;
1441 case VIE_OP_TYPE_MOV:
1442 error = emulate_mov(vm, vcpuid, gpa, vie,
1443 memread, memwrite, memarg);
1444 break;
1445 case VIE_OP_TYPE_MOVSX:
1446 case VIE_OP_TYPE_MOVZX:
1447 error = emulate_movx(vm, vcpuid, gpa, vie,
1448 memread, memwrite, memarg);
1449 break;
1450 case VIE_OP_TYPE_MOVS:
1451 error = emulate_movs(vm, vcpuid, gpa, vie, paging, memread,
1452 memwrite, memarg);
1453 break;
1454 case VIE_OP_TYPE_STOS:
1455 error = emulate_stos(vm, vcpuid, gpa, vie, paging, memread,
1456 memwrite, memarg);
1457 break;
1458 case VIE_OP_TYPE_AND:
1459 error = emulate_and(vm, vcpuid, gpa, vie,
1460 memread, memwrite, memarg);
1461 break;
1462 case VIE_OP_TYPE_OR:
1463 error = emulate_or(vm, vcpuid, gpa, vie,
1464 memread, memwrite, memarg);
1465 break;
1466 case VIE_OP_TYPE_SUB:
1467 error = emulate_sub(vm, vcpuid, gpa, vie,
1468 memread, memwrite, memarg);
1469 break;
1470 case VIE_OP_TYPE_BITTEST:
1471 error = emulate_bittest(vm, vcpuid, gpa, vie,
1472 memread, memwrite, memarg);
1473 break;
1474 default:
1475 error = EINVAL;
1476 break;
1477 }
1478
1479 return (error);
1480 }
1481
1482 int
1483 vie_alignment_check(int cpl, int size, uint64_t cr0, uint64_t rf, uint64_t gla)
1484 {
1485 KASSERT(size == 1 || size == 2 || size == 4 || size == 8,
1486 ("%s: invalid size %d", __func__, size));
1487 KASSERT(cpl >= 0 && cpl <= 3, ("%s: invalid cpl %d", __func__, cpl));
1488
1489 if (cpl != 3 || (cr0 & CR0_AM) == 0 || (rf & PSL_AC) == 0)
1490 return (0);
1491
1492 return ((gla & (size - 1)) ? 1 : 0);
1493 }
1494
1495 int
1496 vie_canonical_check(enum vm_cpu_mode cpu_mode, uint64_t gla)
1497 {
1498 uint64_t mask;
1499
1500 if (cpu_mode != CPU_MODE_64BIT)
1501 return (0);
1502
1503 /*
1504 * The value of the bit 47 in the 'gla' should be replicated in the
1505 * most significant 16 bits.
1506 */
1507 mask = ~((1UL << 48) - 1);
1508 if (gla & (1UL << 47))
1509 return ((gla & mask) != mask);
1510 else
1511 return ((gla & mask) != 0);
1512 }
1513
1514 uint64_t
1515 vie_size2mask(int size)
1516 {
1517 KASSERT(size == 1 || size == 2 || size == 4 || size == 8,
1518 ("vie_size2mask: invalid size %d", size));
1519 return (size2mask[size]);
1520 }
1521
1522 int
1523 vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum vm_reg_name seg,
1524 struct seg_desc *desc, uint64_t offset, int length, int addrsize,
1525 int prot, uint64_t *gla)
1526 {
1527 uint64_t firstoff, low_limit, high_limit, segbase;
1528 int glasize, type;
1529
1530 KASSERT(seg >= VM_REG_GUEST_ES && seg <= VM_REG_GUEST_GS,
1531 ("%s: invalid segment %d", __func__, seg));
1532 KASSERT(length == 1 || length == 2 || length == 4 || length == 8,
1533 ("%s: invalid operand size %d", __func__, length));
1534 KASSERT((prot & ~(PROT_READ | PROT_WRITE)) == 0,
1535 ("%s: invalid prot %#x", __func__, prot));
1536
1537 firstoff = offset;
1538 if (cpu_mode == CPU_MODE_64BIT) {
1539 KASSERT(addrsize == 4 || addrsize == 8, ("%s: invalid address "
1540 "size %d for cpu_mode %d", __func__, addrsize, cpu_mode));
1541 glasize = 8;
1542 } else {
1543 KASSERT(addrsize == 2 || addrsize == 4, ("%s: invalid address "
1544 "size %d for cpu mode %d", __func__, addrsize, cpu_mode));
1545 glasize = 4;
1546 /*
1547 * If the segment selector is loaded with a NULL selector
1548 * then the descriptor is unusable and attempting to use
1549 * it results in a #GP(0).
1550 */
1551 if (SEG_DESC_UNUSABLE(desc->access))
1552 return (-1);
1553
1554 /*
1555 * The processor generates a #NP exception when a segment
1556 * register is loaded with a selector that points to a
1557 * descriptor that is not present. If this was the case then
1558 * it would have been checked before the VM-exit.
1559 */
1560 KASSERT(SEG_DESC_PRESENT(desc->access),
1561 ("segment %d not present: %#x", seg, desc->access));
1562
1563 /*
1564 * The descriptor type must indicate a code/data segment.
1565 */
1566 type = SEG_DESC_TYPE(desc->access);
1567 KASSERT(type >= 16 && type <= 31, ("segment %d has invalid "
1568 "descriptor type %#x", seg, type));
1569
1570 if (prot & PROT_READ) {
1571 /* #GP on a read access to a exec-only code segment */
1572 if ((type & 0xA) == 0x8)
1573 return (-1);
1574 }
1575
1576 if (prot & PROT_WRITE) {
1577 /*
1578 * #GP on a write access to a code segment or a
1579 * read-only data segment.
1580 */
1581 if (type & 0x8) /* code segment */
1582 return (-1);
1583
1584 if ((type & 0xA) == 0) /* read-only data seg */
1585 return (-1);
1586 }
1587
1588 /*
1589 * 'desc->limit' is fully expanded taking granularity into
1590 * account.
1591 */
1592 if ((type & 0xC) == 0x4) {
1593 /* expand-down data segment */
1594 low_limit = desc->limit + 1;
1595 high_limit = SEG_DESC_DEF32(desc->access) ?
1596 0xffffffff : 0xffff;
1597 } else {
1598 /* code segment or expand-up data segment */
1599 low_limit = 0;
1600 high_limit = desc->limit;
1601 }
1602
1603 while (length > 0) {
1604 offset &= vie_size2mask(addrsize);
1605 if (offset < low_limit || offset > high_limit)
1606 return (-1);
1607 offset++;
1608 length--;
1609 }
1610 }
1611
1612 /*
1613 * In 64-bit mode all segments except %fs and %gs have a segment
1614 * base address of 0.
1615 */
1616 if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS &&
1617 seg != VM_REG_GUEST_GS) {
1618 segbase = 0;
1619 } else {
1620 segbase = desc->base;
1621 }
1622
1623 /*
1624 * Truncate 'firstoff' to the effective address size before adding
1625 * it to the segment base.
1626 */
1627 firstoff &= vie_size2mask(addrsize);
1628 *gla = (segbase + firstoff) & vie_size2mask(glasize);
1629 return (0);
1630 }
1631
1632 #ifdef _KERNEL
1633 void
1634 vie_init(struct vie *vie, const char *inst_bytes, int inst_length)
1635 {
1636 KASSERT(inst_length >= 0 && inst_length <= VIE_INST_SIZE,
1637 ("%s: invalid instruction length (%d)", __func__, inst_length));
1638
1639 bzero(vie, sizeof(struct vie));
1640
1641 vie->base_register = VM_REG_LAST;
1642 vie->index_register = VM_REG_LAST;
1643 vie->segment_register = VM_REG_LAST;
1644
1645 if (inst_length) {
1646 bcopy(inst_bytes, vie->inst, inst_length);
1647 vie->num_valid = inst_length;
1648 }
1649 }
1650
1651 static int
1652 pf_error_code(int usermode, int prot, int rsvd, uint64_t pte)
1653 {
1654 int error_code = 0;
1655
1656 if (pte & PG_V)
1657 error_code |= PGEX_P;
1658 if (prot & VM_PROT_WRITE)
1659 error_code |= PGEX_W;
1660 if (usermode)
1661 error_code |= PGEX_U;
1662 if (rsvd)
1663 error_code |= PGEX_RSV;
1664 if (prot & VM_PROT_EXECUTE)
1665 error_code |= PGEX_I;
1666
1667 return (error_code);
1668 }
1669
1670 static void
1671 ptp_release(void **cookie)
1672 {
1673 if (*cookie != NULL) {
1674 vm_gpa_release(*cookie);
1675 *cookie = NULL;
1676 }
1677 }
1678
1679 static void *
1680 ptp_hold(struct vm *vm, int vcpu, vm_paddr_t ptpphys, size_t len, void **cookie)
1681 {
1682 void *ptr;
1683
1684 ptp_release(cookie);
1685 ptr = vm_gpa_hold(vm, vcpu, ptpphys, len, VM_PROT_RW, cookie);
1686 return (ptr);
1687 }
1688
1689 int
1690 vm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
1691 uint64_t gla, int prot, uint64_t *gpa, int *guest_fault)
1692 {
1693 int nlevels, pfcode, ptpshift, ptpindex, retval, usermode, writable;
1694 u_int retries;
1695 uint64_t *ptpbase, ptpphys, pte, pgsize;
1696 uint32_t *ptpbase32, pte32;
1697 void *cookie;
1698
1699 *guest_fault = 0;
1700
1701 usermode = (paging->cpl == 3 ? 1 : 0);
1702 writable = prot & VM_PROT_WRITE;
1703 cookie = NULL;
1704 retval = 0;
1705 retries = 0;
1706 restart:
1707 ptpphys = paging->cr3; /* root of the page tables */
1708 ptp_release(&cookie);
1709 if (retries++ > 0)
1710 maybe_yield();
1711
1712 if (vie_canonical_check(paging->cpu_mode, gla)) {
1713 /*
1714 * XXX assuming a non-stack reference otherwise a stack fault
1715 * should be generated.
1716 */
1717 vm_inject_gp(vm, vcpuid);
1718 goto fault;
1719 }
1720
1721 if (paging->paging_mode == PAGING_MODE_FLAT) {
1722 *gpa = gla;
1723 goto done;
1724 }
1725
1726 if (paging->paging_mode == PAGING_MODE_32) {
1727 nlevels = 2;
1728 while (--nlevels >= 0) {
1729 /* Zero out the lower 12 bits. */
1730 ptpphys &= ~0xfff;
1731
1732 ptpbase32 = ptp_hold(vm, vcpuid, ptpphys, PAGE_SIZE,
1733 &cookie);
1734
1735 if (ptpbase32 == NULL)
1736 goto error;
1737
1738 ptpshift = PAGE_SHIFT + nlevels * 10;
1739 ptpindex = (gla >> ptpshift) & 0x3FF;
1740 pgsize = 1UL << ptpshift;
1741
1742 pte32 = ptpbase32[ptpindex];
1743
1744 if ((pte32 & PG_V) == 0 ||
1745 (usermode && (pte32 & PG_U) == 0) ||
1746 (writable && (pte32 & PG_RW) == 0)) {
1747 pfcode = pf_error_code(usermode, prot, 0,
1748 pte32);
1749 vm_inject_pf(vm, vcpuid, pfcode, gla);
1750 goto fault;
1751 }
1752
1753 /*
1754 * Emulate the x86 MMU's management of the accessed
1755 * and dirty flags. While the accessed flag is set
1756 * at every level of the page table, the dirty flag
1757 * is only set at the last level providing the guest
1758 * physical address.
1759 */
1760 if ((pte32 & PG_A) == 0) {
1761 if (atomic_cmpset_32(&ptpbase32[ptpindex],
1762 pte32, pte32 | PG_A) == 0) {
1763 goto restart;
1764 }
1765 }
1766
1767 /* XXX must be ignored if CR4.PSE=0 */
1768 if (nlevels > 0 && (pte32 & PG_PS) != 0)
1769 break;
1770
1771 ptpphys = pte32;
1772 }
1773
1774 /* Set the dirty bit in the page table entry if necessary */
1775 if (writable && (pte32 & PG_M) == 0) {
1776 if (atomic_cmpset_32(&ptpbase32[ptpindex],
1777 pte32, pte32 | PG_M) == 0) {
1778 goto restart;
1779 }
1780 }
1781
1782 /* Zero out the lower 'ptpshift' bits */
1783 pte32 >>= ptpshift; pte32 <<= ptpshift;
1784 *gpa = pte32 | (gla & (pgsize - 1));
1785 goto done;
1786 }
1787
1788 if (paging->paging_mode == PAGING_MODE_PAE) {
1789 /* Zero out the lower 5 bits and the upper 32 bits */
1790 ptpphys &= 0xffffffe0UL;
1791
1792 ptpbase = ptp_hold(vm, vcpuid, ptpphys, sizeof(*ptpbase) * 4,
1793 &cookie);
1794 if (ptpbase == NULL)
1795 goto error;
1796
1797 ptpindex = (gla >> 30) & 0x3;
1798
1799 pte = ptpbase[ptpindex];
1800
1801 if ((pte & PG_V) == 0) {
1802 pfcode = pf_error_code(usermode, prot, 0, pte);
1803 vm_inject_pf(vm, vcpuid, pfcode, gla);
1804 goto fault;
1805 }
1806
1807 ptpphys = pte;
1808
1809 nlevels = 2;
1810 } else
1811 nlevels = 4;
1812 while (--nlevels >= 0) {
1813 /* Zero out the lower 12 bits and the upper 12 bits */
1814 ptpphys >>= 12; ptpphys <<= 24; ptpphys >>= 12;
1815
1816 ptpbase = ptp_hold(vm, vcpuid, ptpphys, PAGE_SIZE, &cookie);
1817 if (ptpbase == NULL)
1818 goto error;
1819
1820 ptpshift = PAGE_SHIFT + nlevels * 9;
1821 ptpindex = (gla >> ptpshift) & 0x1FF;
1822 pgsize = 1UL << ptpshift;
1823
1824 pte = ptpbase[ptpindex];
1825
1826 if ((pte & PG_V) == 0 ||
1827 (usermode && (pte & PG_U) == 0) ||
1828 (writable && (pte & PG_RW) == 0)) {
1829 pfcode = pf_error_code(usermode, prot, 0, pte);
1830 vm_inject_pf(vm, vcpuid, pfcode, gla);
1831 goto fault;
1832 }
1833
1834 /* Set the accessed bit in the page table entry */
1835 if ((pte & PG_A) == 0) {
1836 if (atomic_cmpset_64(&ptpbase[ptpindex],
1837 pte, pte | PG_A) == 0) {
1838 goto restart;
1839 }
1840 }
1841
1842 if (nlevels > 0 && (pte & PG_PS) != 0) {
1843 if (pgsize > 1 * GB) {
1844 pfcode = pf_error_code(usermode, prot, 1, pte);
1845 vm_inject_pf(vm, vcpuid, pfcode, gla);
1846 goto fault;
1847 }
1848 break;
1849 }
1850
1851 ptpphys = pte;
1852 }
1853
1854 /* Set the dirty bit in the page table entry if necessary */
1855 if (writable && (pte & PG_M) == 0) {
1856 if (atomic_cmpset_64(&ptpbase[ptpindex], pte, pte | PG_M) == 0)
1857 goto restart;
1858 }
1859
1860 /* Zero out the lower 'ptpshift' bits and the upper 12 bits */
1861 pte >>= ptpshift; pte <<= (ptpshift + 12); pte >>= 12;
1862 *gpa = pte | (gla & (pgsize - 1));
1863 done:
1864 ptp_release(&cookie);
1865 KASSERT(retval == 0 || retval == EFAULT, ("%s: unexpected retval %d",
1866 __func__, retval));
1867 return (retval);
1868 error:
1869 retval = EFAULT;
1870 goto done;
1871 fault:
1872 *guest_fault = 1;
1873 goto done;
1874 }
1875
1876 int
1877 vmm_fetch_instruction(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
1878 uint64_t rip, int inst_length, struct vie *vie, int *faultptr)
1879 {
1880 struct vm_copyinfo copyinfo[2];
1881 int error, prot;
1882
1883 if (inst_length > VIE_INST_SIZE)
1884 panic("vmm_fetch_instruction: invalid length %d", inst_length);
1885
1886 prot = PROT_READ | PROT_EXEC;
1887 error = vm_copy_setup(vm, vcpuid, paging, rip, inst_length, prot,
1888 copyinfo, nitems(copyinfo), faultptr);
1889 if (error || *faultptr)
1890 return (error);
1891
1892 vm_copyin(vm, vcpuid, copyinfo, vie->inst, inst_length);
1893 vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
1894 vie->num_valid = inst_length;
1895 return (0);
1896 }
1897
1898 static int
1899 vie_peek(struct vie *vie, uint8_t *x)
1900 {
1901
1902 if (vie->num_processed < vie->num_valid) {
1903 *x = vie->inst[vie->num_processed];
1904 return (0);
1905 } else
1906 return (-1);
1907 }
1908
1909 static void
1910 vie_advance(struct vie *vie)
1911 {
1912
1913 vie->num_processed++;
1914 }
1915
1916 static bool
1917 segment_override(uint8_t x, int *seg)
1918 {
1919
1920 switch (x) {
1921 case 0x2E:
1922 *seg = VM_REG_GUEST_CS;
1923 break;
1924 case 0x36:
1925 *seg = VM_REG_GUEST_SS;
1926 break;
1927 case 0x3E:
1928 *seg = VM_REG_GUEST_DS;
1929 break;
1930 case 0x26:
1931 *seg = VM_REG_GUEST_ES;
1932 break;
1933 case 0x64:
1934 *seg = VM_REG_GUEST_FS;
1935 break;
1936 case 0x65:
1937 *seg = VM_REG_GUEST_GS;
1938 break;
1939 default:
1940 return (false);
1941 }
1942 return (true);
1943 }
1944
1945 static int
1946 decode_prefixes(struct vie *vie, enum vm_cpu_mode cpu_mode, int cs_d)
1947 {
1948 uint8_t x;
1949
1950 while (1) {
1951 if (vie_peek(vie, &x))
1952 return (-1);
1953
1954 if (x == 0x66)
1955 vie->opsize_override = 1;
1956 else if (x == 0x67)
1957 vie->addrsize_override = 1;
1958 else if (x == 0xF3)
1959 vie->repz_present = 1;
1960 else if (x == 0xF2)
1961 vie->repnz_present = 1;
1962 else if (segment_override(x, &vie->segment_register))
1963 vie->segment_override = 1;
1964 else
1965 break;
1966
1967 vie_advance(vie);
1968 }
1969
1970 /*
1971 * From section 2.2.1, "REX Prefixes", Intel SDM Vol 2:
1972 * - Only one REX prefix is allowed per instruction.
1973 * - The REX prefix must immediately precede the opcode byte or the
1974 * escape opcode byte.
1975 * - If an instruction has a mandatory prefix (0x66, 0xF2 or 0xF3)
1976 * the mandatory prefix must come before the REX prefix.
1977 */
1978 if (cpu_mode == CPU_MODE_64BIT && x >= 0x40 && x <= 0x4F) {
1979 vie->rex_present = 1;
1980 vie->rex_w = x & 0x8 ? 1 : 0;
1981 vie->rex_r = x & 0x4 ? 1 : 0;
1982 vie->rex_x = x & 0x2 ? 1 : 0;
1983 vie->rex_b = x & 0x1 ? 1 : 0;
1984 vie_advance(vie);
1985 }
1986
1987 /*
1988 * Section "Operand-Size And Address-Size Attributes", Intel SDM, Vol 1
1989 */
1990 if (cpu_mode == CPU_MODE_64BIT) {
1991 /*
1992 * Default address size is 64-bits and default operand size
1993 * is 32-bits.
1994 */
1995 vie->addrsize = vie->addrsize_override ? 4 : 8;
1996 if (vie->rex_w)
1997 vie->opsize = 8;
1998 else if (vie->opsize_override)
1999 vie->opsize = 2;
2000 else
2001 vie->opsize = 4;
2002 } else if (cs_d) {
2003 /* Default address and operand sizes are 32-bits */
2004 vie->addrsize = vie->addrsize_override ? 2 : 4;
2005 vie->opsize = vie->opsize_override ? 2 : 4;
2006 } else {
2007 /* Default address and operand sizes are 16-bits */
2008 vie->addrsize = vie->addrsize_override ? 4 : 2;
2009 vie->opsize = vie->opsize_override ? 4 : 2;
2010 }
2011 return (0);
2012 }
2013
2014 static int
2015 decode_two_byte_opcode(struct vie *vie)
2016 {
2017 uint8_t x;
2018
2019 if (vie_peek(vie, &x))
2020 return (-1);
2021
2022 vie->op = two_byte_opcodes[x];
2023
2024 if (vie->op.op_type == VIE_OP_TYPE_NONE)
2025 return (-1);
2026
2027 vie_advance(vie);
2028 return (0);
2029 }
2030
2031 static int
2032 decode_opcode(struct vie *vie)
2033 {
2034 uint8_t x;
2035
2036 if (vie_peek(vie, &x))
2037 return (-1);
2038
2039 vie->op = one_byte_opcodes[x];
2040
2041 if (vie->op.op_type == VIE_OP_TYPE_NONE)
2042 return (-1);
2043
2044 vie_advance(vie);
2045
2046 if (vie->op.op_type == VIE_OP_TYPE_TWO_BYTE)
2047 return (decode_two_byte_opcode(vie));
2048
2049 return (0);
2050 }
2051
2052 static int
2053 decode_modrm(struct vie *vie, enum vm_cpu_mode cpu_mode)
2054 {
2055 uint8_t x;
2056
2057 if (vie->op.op_flags & VIE_OP_F_NO_MODRM)
2058 return (0);
2059
2060 if (cpu_mode == CPU_MODE_REAL)
2061 return (-1);
2062
2063 if (vie_peek(vie, &x))
2064 return (-1);
2065
2066 vie->mod = (x >> 6) & 0x3;
2067 vie->rm = (x >> 0) & 0x7;
2068 vie->reg = (x >> 3) & 0x7;
2069
2070 /*
2071 * A direct addressing mode makes no sense in the context of an EPT
2072 * fault. There has to be a memory access involved to cause the
2073 * EPT fault.
2074 */
2075 if (vie->mod == VIE_MOD_DIRECT)
2076 return (-1);
2077
2078 if ((vie->mod == VIE_MOD_INDIRECT && vie->rm == VIE_RM_DISP32) ||
2079 (vie->mod != VIE_MOD_DIRECT && vie->rm == VIE_RM_SIB)) {
2080 /*
2081 * Table 2-5: Special Cases of REX Encodings
2082 *
2083 * mod=0, r/m=5 is used in the compatibility mode to
2084 * indicate a disp32 without a base register.
2085 *
2086 * mod!=3, r/m=4 is used in the compatibility mode to
2087 * indicate that the SIB byte is present.
2088 *
2089 * The 'b' bit in the REX prefix is don't care in
2090 * this case.
2091 */
2092 } else {
2093 vie->rm |= (vie->rex_b << 3);
2094 }
2095
2096 vie->reg |= (vie->rex_r << 3);
2097
2098 /* SIB */
2099 if (vie->mod != VIE_MOD_DIRECT && vie->rm == VIE_RM_SIB)
2100 goto done;
2101
2102 vie->base_register = gpr_map[vie->rm];
2103
2104 switch (vie->mod) {
2105 case VIE_MOD_INDIRECT_DISP8:
2106 vie->disp_bytes = 1;
2107 break;
2108 case VIE_MOD_INDIRECT_DISP32:
2109 vie->disp_bytes = 4;
2110 break;
2111 case VIE_MOD_INDIRECT:
2112 if (vie->rm == VIE_RM_DISP32) {
2113 vie->disp_bytes = 4;
2114 /*
2115 * Table 2-7. RIP-Relative Addressing
2116 *
2117 * In 64-bit mode mod=00 r/m=101 implies [rip] + disp32
2118 * whereas in compatibility mode it just implies disp32.
2119 */
2120
2121 if (cpu_mode == CPU_MODE_64BIT)
2122 vie->base_register = VM_REG_GUEST_RIP;
2123 else
2124 vie->base_register = VM_REG_LAST;
2125 }
2126 break;
2127 }
2128
2129 done:
2130 vie_advance(vie);
2131
2132 return (0);
2133 }
2134
2135 static int
2136 decode_sib(struct vie *vie)
2137 {
2138 uint8_t x;
2139
2140 /* Proceed only if SIB byte is present */
2141 if (vie->mod == VIE_MOD_DIRECT || vie->rm != VIE_RM_SIB)
2142 return (0);
2143
2144 if (vie_peek(vie, &x))
2145 return (-1);
2146
2147 /* De-construct the SIB byte */
2148 vie->ss = (x >> 6) & 0x3;
2149 vie->index = (x >> 3) & 0x7;
2150 vie->base = (x >> 0) & 0x7;
2151
2152 /* Apply the REX prefix modifiers */
2153 vie->index |= vie->rex_x << 3;
2154 vie->base |= vie->rex_b << 3;
2155
2156 switch (vie->mod) {
2157 case VIE_MOD_INDIRECT_DISP8:
2158 vie->disp_bytes = 1;
2159 break;
2160 case VIE_MOD_INDIRECT_DISP32:
2161 vie->disp_bytes = 4;
2162 break;
2163 }
2164
2165 if (vie->mod == VIE_MOD_INDIRECT &&
2166 (vie->base == 5 || vie->base == 13)) {
2167 /*
2168 * Special case when base register is unused if mod = 0
2169 * and base = %rbp or %r13.
2170 *
2171 * Documented in:
2172 * Table 2-3: 32-bit Addressing Forms with the SIB Byte
2173 * Table 2-5: Special Cases of REX Encodings
2174 */
2175 vie->disp_bytes = 4;
2176 } else {
2177 vie->base_register = gpr_map[vie->base];
2178 }
2179
2180 /*
2181 * All encodings of 'index' are valid except for %rsp (4).
2182 *
2183 * Documented in:
2184 * Table 2-3: 32-bit Addressing Forms with the SIB Byte
2185 * Table 2-5: Special Cases of REX Encodings
2186 */
2187 if (vie->index != 4)
2188 vie->index_register = gpr_map[vie->index];
2189
2190 /* 'scale' makes sense only in the context of an index register */
2191 if (vie->index_register < VM_REG_LAST)
2192 vie->scale = 1 << vie->ss;
2193
2194 vie_advance(vie);
2195
2196 return (0);
2197 }
2198
2199 static int
2200 decode_displacement(struct vie *vie)
2201 {
2202 int n, i;
2203 uint8_t x;
2204
2205 union {
2206 char buf[4];
2207 int8_t signed8;
2208 int32_t signed32;
2209 } u;
2210
2211 if ((n = vie->disp_bytes) == 0)
2212 return (0);
2213
2214 if (n != 1 && n != 4)
2215 panic("decode_displacement: invalid disp_bytes %d", n);
2216
2217 for (i = 0; i < n; i++) {
2218 if (vie_peek(vie, &x))
2219 return (-1);
2220
2221 u.buf[i] = x;
2222 vie_advance(vie);
2223 }
2224
2225 if (n == 1)
2226 vie->displacement = u.signed8; /* sign-extended */
2227 else
2228 vie->displacement = u.signed32; /* sign-extended */
2229
2230 return (0);
2231 }
2232
2233 static int
2234 decode_immediate(struct vie *vie)
2235 {
2236 int i, n;
2237 uint8_t x;
2238 union {
2239 char buf[4];
2240 int8_t signed8;
2241 int16_t signed16;
2242 int32_t signed32;
2243 } u;
2244
2245 /* Figure out immediate operand size (if any) */
2246 if (vie->op.op_flags & VIE_OP_F_IMM) {
2247 /*
2248 * Section 2.2.1.5 "Immediates", Intel SDM:
2249 * In 64-bit mode the typical size of immediate operands
2250 * remains 32-bits. When the operand size if 64-bits, the
2251 * processor sign-extends all immediates to 64-bits prior
2252 * to their use.
2253 */
2254 if (vie->opsize == 4 || vie->opsize == 8)
2255 vie->imm_bytes = 4;
2256 else
2257 vie->imm_bytes = 2;
2258 } else if (vie->op.op_flags & VIE_OP_F_IMM8) {
2259 vie->imm_bytes = 1;
2260 }
2261
2262 if ((n = vie->imm_bytes) == 0)
2263 return (0);
2264
2265 KASSERT(n == 1 || n == 2 || n == 4,
2266 ("%s: invalid number of immediate bytes: %d", __func__, n));
2267
2268 for (i = 0; i < n; i++) {
2269 if (vie_peek(vie, &x))
2270 return (-1);
2271
2272 u.buf[i] = x;
2273 vie_advance(vie);
2274 }
2275
2276 /* sign-extend the immediate value before use */
2277 if (n == 1)
2278 vie->immediate = u.signed8;
2279 else if (n == 2)
2280 vie->immediate = u.signed16;
2281 else
2282 vie->immediate = u.signed32;
2283
2284 return (0);
2285 }
2286
2287 static int
2288 decode_moffset(struct vie *vie)
2289 {
2290 int i, n;
2291 uint8_t x;
2292 union {
2293 char buf[8];
2294 uint64_t u64;
2295 } u;
2296
2297 if ((vie->op.op_flags & VIE_OP_F_MOFFSET) == 0)
2298 return (0);
2299
2300 /*
2301 * Section 2.2.1.4, "Direct Memory-Offset MOVs", Intel SDM:
2302 * The memory offset size follows the address-size of the instruction.
2303 */
2304 n = vie->addrsize;
2305 KASSERT(n == 2 || n == 4 || n == 8, ("invalid moffset bytes: %d", n));
2306
2307 u.u64 = 0;
2308 for (i = 0; i < n; i++) {
2309 if (vie_peek(vie, &x))
2310 return (-1);
2311
2312 u.buf[i] = x;
2313 vie_advance(vie);
2314 }
2315 vie->displacement = u.u64;
2316 return (0);
2317 }
2318
2319 /*
2320 * Verify that the 'guest linear address' provided as collateral of the nested
2321 * page table fault matches with our instruction decoding.
2322 */
2323 static int
2324 verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie,
2325 enum vm_cpu_mode cpu_mode)
2326 {
2327 int error;
2328 uint64_t base, segbase, idx, gla2;
2329 enum vm_reg_name seg;
2330 struct seg_desc desc;
2331
2332 /* Skip 'gla' verification */
2333 if (gla == VIE_INVALID_GLA)
2334 return (0);
2335
2336 base = 0;
2337 if (vie->base_register != VM_REG_LAST) {
2338 error = vm_get_register(vm, cpuid, vie->base_register, &base);
2339 if (error) {
2340 printf("verify_gla: error %d getting base reg %d\n",
2341 error, vie->base_register);
2342 return (-1);
2343 }
2344
2345 /*
2346 * RIP-relative addressing starts from the following
2347 * instruction
2348 */
2349 if (vie->base_register == VM_REG_GUEST_RIP)
2350 base += vie->num_processed;
2351 }
2352
2353 idx = 0;
2354 if (vie->index_register != VM_REG_LAST) {
2355 error = vm_get_register(vm, cpuid, vie->index_register, &idx);
2356 if (error) {
2357 printf("verify_gla: error %d getting index reg %d\n",
2358 error, vie->index_register);
2359 return (-1);
2360 }
2361 }
2362
2363 /*
2364 * From "Specifying a Segment Selector", Intel SDM, Vol 1
2365 *
2366 * In 64-bit mode, segmentation is generally (but not
2367 * completely) disabled. The exceptions are the FS and GS
2368 * segments.
2369 *
2370 * In legacy IA-32 mode, when the ESP or EBP register is used
2371 * as the base, the SS segment is the default segment. For
2372 * other data references, except when relative to stack or
2373 * string destination the DS segment is the default. These
2374 * can be overridden to allow other segments to be accessed.
2375 */
2376 if (vie->segment_override)
2377 seg = vie->segment_register;
2378 else if (vie->base_register == VM_REG_GUEST_RSP ||
2379 vie->base_register == VM_REG_GUEST_RBP)
2380 seg = VM_REG_GUEST_SS;
2381 else
2382 seg = VM_REG_GUEST_DS;
2383 if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS &&
2384 seg != VM_REG_GUEST_GS) {
2385 segbase = 0;
2386 } else {
2387 error = vm_get_seg_desc(vm, cpuid, seg, &desc);
2388 if (error) {
2389 printf("verify_gla: error %d getting segment"
2390 " descriptor %d", error,
2391 vie->segment_register);
2392 return (-1);
2393 }
2394 segbase = desc.base;
2395 }
2396
2397 gla2 = segbase + base + vie->scale * idx + vie->displacement;
2398 gla2 &= size2mask[vie->addrsize];
2399 if (gla != gla2) {
2400 printf("verify_gla mismatch: segbase(0x%0lx)"
2401 "base(0x%0lx), scale(%d), index(0x%0lx), "
2402 "disp(0x%0lx), gla(0x%0lx), gla2(0x%0lx)\n",
2403 segbase, base, vie->scale, idx, vie->displacement,
2404 gla, gla2);
2405 return (-1);
2406 }
2407
2408 return (0);
2409 }
2410
2411 int
2412 vmm_decode_instruction(struct vm *vm, int cpuid, uint64_t gla,
2413 enum vm_cpu_mode cpu_mode, int cs_d, struct vie *vie)
2414 {
2415
2416 if (decode_prefixes(vie, cpu_mode, cs_d))
2417 return (-1);
2418
2419 if (decode_opcode(vie))
2420 return (-1);
2421
2422 if (decode_modrm(vie, cpu_mode))
2423 return (-1);
2424
2425 if (decode_sib(vie))
2426 return (-1);
2427
2428 if (decode_displacement(vie))
2429 return (-1);
2430
2431 if (decode_immediate(vie))
2432 return (-1);
2433
2434 if (decode_moffset(vie))
2435 return (-1);
2436
2437 if ((vie->op.op_flags & VIE_OP_F_NO_GLA_VERIFICATION) == 0) {
2438 if (verify_gla(vm, cpuid, gla, vie, cpu_mode))
2439 return (-1);
2440 }
2441
2442 vie->decoded = 1; /* success */
2443
2444 return (0);
2445 }
2446 #endif /* _KERNEL */
Cache object: cc588ddb5922addfe07c5471a421e08b
|