1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * AMD Encrypted Register State Support
4 *
5 * Author: Joerg Roedel <jroedel@suse.de>
6 *
7 * This file is not compiled stand-alone. It contains code shared
8 * between the pre-decompression boot code and the running Linux kernel
9 * and is included directly into both code-bases.
10 */
11
12 #ifndef __BOOT_COMPRESSED
13 #define error(v) pr_err(v)
14 #define has_cpuflag(f) boot_cpu_has(f)
15 #endif
16
sev_es_check_cpu_features(void)17 static bool __init sev_es_check_cpu_features(void)
18 {
19 if (!has_cpuflag(X86_FEATURE_RDRAND)) {
20 error("RDRAND instruction not supported - no trusted source of randomness available\n");
21 return false;
22 }
23
24 return true;
25 }
26
sev_es_terminate(unsigned int reason)27 static void __noreturn sev_es_terminate(unsigned int reason)
28 {
29 u64 val = GHCB_MSR_TERM_REQ;
30
31 /*
32 * Tell the hypervisor what went wrong - only reason-set 0 is
33 * currently supported.
34 */
35 val |= GHCB_SEV_TERM_REASON(0, reason);
36
37 /* Request Guest Termination from Hypvervisor */
38 sev_es_wr_ghcb_msr(val);
39 VMGEXIT();
40
41 while (true)
42 asm volatile("hlt\n" : : : "memory");
43 }
44
sev_es_negotiate_protocol(void)45 static bool sev_es_negotiate_protocol(void)
46 {
47 u64 val;
48
49 /* Do the GHCB protocol version negotiation */
50 sev_es_wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
51 VMGEXIT();
52 val = sev_es_rd_ghcb_msr();
53
54 if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)
55 return false;
56
57 if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTO_OUR ||
58 GHCB_MSR_PROTO_MIN(val) > GHCB_PROTO_OUR)
59 return false;
60
61 return true;
62 }
63
vc_ghcb_invalidate(struct ghcb * ghcb)64 static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb)
65 {
66 ghcb->save.sw_exit_code = 0;
67 memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
68 }
69
vc_decoding_needed(unsigned long exit_code)70 static bool vc_decoding_needed(unsigned long exit_code)
71 {
72 /* Exceptions don't require to decode the instruction */
73 return !(exit_code >= SVM_EXIT_EXCP_BASE &&
74 exit_code <= SVM_EXIT_LAST_EXCP);
75 }
76
vc_init_em_ctxt(struct es_em_ctxt * ctxt,struct pt_regs * regs,unsigned long exit_code)77 static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt,
78 struct pt_regs *regs,
79 unsigned long exit_code)
80 {
81 enum es_result ret = ES_OK;
82
83 memset(ctxt, 0, sizeof(*ctxt));
84 ctxt->regs = regs;
85
86 if (vc_decoding_needed(exit_code))
87 ret = vc_decode_insn(ctxt);
88
89 return ret;
90 }
91
vc_finish_insn(struct es_em_ctxt * ctxt)92 static void vc_finish_insn(struct es_em_ctxt *ctxt)
93 {
94 ctxt->regs->ip += ctxt->insn.length;
95 }
96
sev_es_ghcb_hv_call(struct ghcb * ghcb,struct es_em_ctxt * ctxt,u64 exit_code,u64 exit_info_1,u64 exit_info_2)97 static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
98 struct es_em_ctxt *ctxt,
99 u64 exit_code, u64 exit_info_1,
100 u64 exit_info_2)
101 {
102 enum es_result ret;
103
104 /* Fill in protocol and format specifiers */
105 ghcb->protocol_version = GHCB_PROTOCOL_MAX;
106 ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
107
108 ghcb_set_sw_exit_code(ghcb, exit_code);
109 ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
110 ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
111
112 sev_es_wr_ghcb_msr(__pa(ghcb));
113 VMGEXIT();
114
115 if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1) {
116 u64 info = ghcb->save.sw_exit_info_2;
117 unsigned long v;
118
119 info = ghcb->save.sw_exit_info_2;
120 v = info & SVM_EVTINJ_VEC_MASK;
121
122 /* Check if exception information from hypervisor is sane. */
123 if ((info & SVM_EVTINJ_VALID) &&
124 ((v == X86_TRAP_GP) || (v == X86_TRAP_UD)) &&
125 ((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) {
126 ctxt->fi.vector = v;
127 if (info & SVM_EVTINJ_VALID_ERR)
128 ctxt->fi.error_code = info >> 32;
129 ret = ES_EXCEPTION;
130 } else {
131 ret = ES_VMM_ERROR;
132 }
133 } else if (ghcb->save.sw_exit_info_1 & 0xffffffff) {
134 ret = ES_VMM_ERROR;
135 } else {
136 ret = ES_OK;
137 }
138
139 return ret;
140 }
141
142 /*
143 * Boot VC Handler - This is the first VC handler during boot, there is no GHCB
144 * page yet, so it only supports the MSR based communication with the
145 * hypervisor and only the CPUID exit-code.
146 */
do_vc_no_ghcb(struct pt_regs * regs,unsigned long exit_code)147 void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
148 {
149 unsigned int fn = lower_bits(regs->ax, 32);
150 unsigned long val;
151
152 /* Only CPUID is supported via MSR protocol */
153 if (exit_code != SVM_EXIT_CPUID)
154 goto fail;
155
156 sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EAX));
157 VMGEXIT();
158 val = sev_es_rd_ghcb_msr();
159 if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
160 goto fail;
161 regs->ax = val >> 32;
162
163 sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EBX));
164 VMGEXIT();
165 val = sev_es_rd_ghcb_msr();
166 if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
167 goto fail;
168 regs->bx = val >> 32;
169
170 sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_ECX));
171 VMGEXIT();
172 val = sev_es_rd_ghcb_msr();
173 if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
174 goto fail;
175 regs->cx = val >> 32;
176
177 sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EDX));
178 VMGEXIT();
179 val = sev_es_rd_ghcb_msr();
180 if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
181 goto fail;
182 regs->dx = val >> 32;
183
184 /*
185 * This is a VC handler and the #VC is only raised when SEV-ES is
186 * active, which means SEV must be active too. Do sanity checks on the
187 * CPUID results to make sure the hypervisor does not trick the kernel
188 * into the no-sev path. This could map sensitive data unencrypted and
189 * make it accessible to the hypervisor.
190 *
191 * In particular, check for:
192 * - Availability of CPUID leaf 0x8000001f
193 * - SEV CPUID bit.
194 *
195 * The hypervisor might still report the wrong C-bit position, but this
196 * can't be checked here.
197 */
198
199 if (fn == 0x80000000 && (regs->ax < 0x8000001f))
200 /* SEV leaf check */
201 goto fail;
202 else if ((fn == 0x8000001f && !(regs->ax & BIT(1))))
203 /* SEV bit */
204 goto fail;
205
206 /* Skip over the CPUID two-byte opcode */
207 regs->ip += 2;
208
209 return;
210
211 fail:
212 /* Terminate the guest */
213 sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST);
214 }
215
vc_insn_string_check(struct es_em_ctxt * ctxt,unsigned long address,bool write)216 static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt,
217 unsigned long address,
218 bool write)
219 {
220 if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) {
221 ctxt->fi.vector = X86_TRAP_PF;
222 ctxt->fi.error_code = X86_PF_USER;
223 ctxt->fi.cr2 = address;
224 if (write)
225 ctxt->fi.error_code |= X86_PF_WRITE;
226
227 return ES_EXCEPTION;
228 }
229
230 return ES_OK;
231 }
232
vc_insn_string_read(struct es_em_ctxt * ctxt,void * src,char * buf,unsigned int data_size,unsigned int count,bool backwards)233 static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
234 void *src, char *buf,
235 unsigned int data_size,
236 unsigned int count,
237 bool backwards)
238 {
239 int i, b = backwards ? -1 : 1;
240 unsigned long address = (unsigned long)src;
241 enum es_result ret;
242
243 ret = vc_insn_string_check(ctxt, address, false);
244 if (ret != ES_OK)
245 return ret;
246
247 for (i = 0; i < count; i++) {
248 void *s = src + (i * data_size * b);
249 char *d = buf + (i * data_size);
250
251 ret = vc_read_mem(ctxt, s, d, data_size);
252 if (ret != ES_OK)
253 break;
254 }
255
256 return ret;
257 }
258
vc_insn_string_write(struct es_em_ctxt * ctxt,void * dst,char * buf,unsigned int data_size,unsigned int count,bool backwards)259 static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
260 void *dst, char *buf,
261 unsigned int data_size,
262 unsigned int count,
263 bool backwards)
264 {
265 int i, s = backwards ? -1 : 1;
266 unsigned long address = (unsigned long)dst;
267 enum es_result ret;
268
269 ret = vc_insn_string_check(ctxt, address, true);
270 if (ret != ES_OK)
271 return ret;
272
273 for (i = 0; i < count; i++) {
274 void *d = dst + (i * data_size * s);
275 char *b = buf + (i * data_size);
276
277 ret = vc_write_mem(ctxt, d, b, data_size);
278 if (ret != ES_OK)
279 break;
280 }
281
282 return ret;
283 }
284
285 #define IOIO_TYPE_STR BIT(2)
286 #define IOIO_TYPE_IN 1
287 #define IOIO_TYPE_INS (IOIO_TYPE_IN | IOIO_TYPE_STR)
288 #define IOIO_TYPE_OUT 0
289 #define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
290
291 #define IOIO_REP BIT(3)
292
293 #define IOIO_ADDR_64 BIT(9)
294 #define IOIO_ADDR_32 BIT(8)
295 #define IOIO_ADDR_16 BIT(7)
296
297 #define IOIO_DATA_32 BIT(6)
298 #define IOIO_DATA_16 BIT(5)
299 #define IOIO_DATA_8 BIT(4)
300
301 #define IOIO_SEG_ES (0 << 10)
302 #define IOIO_SEG_DS (3 << 10)
303
vc_ioio_exitinfo(struct es_em_ctxt * ctxt,u64 * exitinfo)304 static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
305 {
306 struct insn *insn = &ctxt->insn;
307 size_t size;
308 u64 port;
309
310 *exitinfo = 0;
311
312 switch (insn->opcode.bytes[0]) {
313 /* INS opcodes */
314 case 0x6c:
315 case 0x6d:
316 *exitinfo |= IOIO_TYPE_INS;
317 *exitinfo |= IOIO_SEG_ES;
318 port = ctxt->regs->dx & 0xffff;
319 break;
320
321 /* OUTS opcodes */
322 case 0x6e:
323 case 0x6f:
324 *exitinfo |= IOIO_TYPE_OUTS;
325 *exitinfo |= IOIO_SEG_DS;
326 port = ctxt->regs->dx & 0xffff;
327 break;
328
329 /* IN immediate opcodes */
330 case 0xe4:
331 case 0xe5:
332 *exitinfo |= IOIO_TYPE_IN;
333 port = (u8)insn->immediate.value & 0xffff;
334 break;
335
336 /* OUT immediate opcodes */
337 case 0xe6:
338 case 0xe7:
339 *exitinfo |= IOIO_TYPE_OUT;
340 port = (u8)insn->immediate.value & 0xffff;
341 break;
342
343 /* IN register opcodes */
344 case 0xec:
345 case 0xed:
346 *exitinfo |= IOIO_TYPE_IN;
347 port = ctxt->regs->dx & 0xffff;
348 break;
349
350 /* OUT register opcodes */
351 case 0xee:
352 case 0xef:
353 *exitinfo |= IOIO_TYPE_OUT;
354 port = ctxt->regs->dx & 0xffff;
355 break;
356
357 default:
358 return ES_DECODE_FAILED;
359 }
360
361 *exitinfo |= port << 16;
362
363 switch (insn->opcode.bytes[0]) {
364 case 0x6c:
365 case 0x6e:
366 case 0xe4:
367 case 0xe6:
368 case 0xec:
369 case 0xee:
370 /* Single byte opcodes */
371 *exitinfo |= IOIO_DATA_8;
372 size = 1;
373 break;
374 default:
375 /* Length determined by instruction parsing */
376 *exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
377 : IOIO_DATA_32;
378 size = (insn->opnd_bytes == 2) ? 2 : 4;
379 }
380
381 switch (insn->addr_bytes) {
382 case 2:
383 *exitinfo |= IOIO_ADDR_16;
384 break;
385 case 4:
386 *exitinfo |= IOIO_ADDR_32;
387 break;
388 case 8:
389 *exitinfo |= IOIO_ADDR_64;
390 break;
391 }
392
393 if (insn_has_rep_prefix(insn))
394 *exitinfo |= IOIO_REP;
395
396 return vc_ioio_check(ctxt, (u16)port, size);
397 }
398
vc_handle_ioio(struct ghcb * ghcb,struct es_em_ctxt * ctxt)399 static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
400 {
401 struct pt_regs *regs = ctxt->regs;
402 u64 exit_info_1, exit_info_2;
403 enum es_result ret;
404
405 ret = vc_ioio_exitinfo(ctxt, &exit_info_1);
406 if (ret != ES_OK)
407 return ret;
408
409 if (exit_info_1 & IOIO_TYPE_STR) {
410
411 /* (REP) INS/OUTS */
412
413 bool df = ((regs->flags & X86_EFLAGS_DF) == X86_EFLAGS_DF);
414 unsigned int io_bytes, exit_bytes;
415 unsigned int ghcb_count, op_count;
416 unsigned long es_base;
417 u64 sw_scratch;
418
419 /*
420 * For the string variants with rep prefix the amount of in/out
421 * operations per #VC exception is limited so that the kernel
422 * has a chance to take interrupts and re-schedule while the
423 * instruction is emulated.
424 */
425 io_bytes = (exit_info_1 >> 4) & 0x7;
426 ghcb_count = sizeof(ghcb->shared_buffer) / io_bytes;
427
428 op_count = (exit_info_1 & IOIO_REP) ? regs->cx : 1;
429 exit_info_2 = min(op_count, ghcb_count);
430 exit_bytes = exit_info_2 * io_bytes;
431
432 es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
433
434 /* Read bytes of OUTS into the shared buffer */
435 if (!(exit_info_1 & IOIO_TYPE_IN)) {
436 ret = vc_insn_string_read(ctxt,
437 (void *)(es_base + regs->si),
438 ghcb->shared_buffer, io_bytes,
439 exit_info_2, df);
440 if (ret)
441 return ret;
442 }
443
444 /*
445 * Issue an VMGEXIT to the HV to consume the bytes from the
446 * shared buffer or to have it write them into the shared buffer
447 * depending on the instruction: OUTS or INS.
448 */
449 sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer);
450 ghcb_set_sw_scratch(ghcb, sw_scratch);
451 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO,
452 exit_info_1, exit_info_2);
453 if (ret != ES_OK)
454 return ret;
455
456 /* Read bytes from shared buffer into the guest's destination. */
457 if (exit_info_1 & IOIO_TYPE_IN) {
458 ret = vc_insn_string_write(ctxt,
459 (void *)(es_base + regs->di),
460 ghcb->shared_buffer, io_bytes,
461 exit_info_2, df);
462 if (ret)
463 return ret;
464
465 if (df)
466 regs->di -= exit_bytes;
467 else
468 regs->di += exit_bytes;
469 } else {
470 if (df)
471 regs->si -= exit_bytes;
472 else
473 regs->si += exit_bytes;
474 }
475
476 if (exit_info_1 & IOIO_REP)
477 regs->cx -= exit_info_2;
478
479 ret = regs->cx ? ES_RETRY : ES_OK;
480
481 } else {
482
483 /* IN/OUT into/from rAX */
484
485 int bits = (exit_info_1 & 0x70) >> 1;
486 u64 rax = 0;
487
488 if (!(exit_info_1 & IOIO_TYPE_IN))
489 rax = lower_bits(regs->ax, bits);
490
491 ghcb_set_rax(ghcb, rax);
492
493 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
494 if (ret != ES_OK)
495 return ret;
496
497 if (exit_info_1 & IOIO_TYPE_IN) {
498 if (!ghcb_rax_is_valid(ghcb))
499 return ES_VMM_ERROR;
500 regs->ax = lower_bits(ghcb->save.rax, bits);
501 }
502 }
503
504 return ret;
505 }
506
vc_handle_cpuid(struct ghcb * ghcb,struct es_em_ctxt * ctxt)507 static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
508 struct es_em_ctxt *ctxt)
509 {
510 struct pt_regs *regs = ctxt->regs;
511 u32 cr4 = native_read_cr4();
512 enum es_result ret;
513
514 ghcb_set_rax(ghcb, regs->ax);
515 ghcb_set_rcx(ghcb, regs->cx);
516
517 if (cr4 & X86_CR4_OSXSAVE)
518 /* Safe to read xcr0 */
519 ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
520 else
521 /* xgetbv will cause #GP - use reset value for xcr0 */
522 ghcb_set_xcr0(ghcb, 1);
523
524 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
525 if (ret != ES_OK)
526 return ret;
527
528 if (!(ghcb_rax_is_valid(ghcb) &&
529 ghcb_rbx_is_valid(ghcb) &&
530 ghcb_rcx_is_valid(ghcb) &&
531 ghcb_rdx_is_valid(ghcb)))
532 return ES_VMM_ERROR;
533
534 regs->ax = ghcb->save.rax;
535 regs->bx = ghcb->save.rbx;
536 regs->cx = ghcb->save.rcx;
537 regs->dx = ghcb->save.rdx;
538
539 return ES_OK;
540 }
541
vc_handle_rdtsc(struct ghcb * ghcb,struct es_em_ctxt * ctxt,unsigned long exit_code)542 static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
543 struct es_em_ctxt *ctxt,
544 unsigned long exit_code)
545 {
546 bool rdtscp = (exit_code == SVM_EXIT_RDTSCP);
547 enum es_result ret;
548
549 ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0);
550 if (ret != ES_OK)
551 return ret;
552
553 if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb) &&
554 (!rdtscp || ghcb_rcx_is_valid(ghcb))))
555 return ES_VMM_ERROR;
556
557 ctxt->regs->ax = ghcb->save.rax;
558 ctxt->regs->dx = ghcb->save.rdx;
559 if (rdtscp)
560 ctxt->regs->cx = ghcb->save.rcx;
561
562 return ES_OK;
563 }
564