1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AMD Memory Encryption Support
4 *
5 * Copyright (C) 2019 SUSE
6 *
7 * Author: Joerg Roedel <jroedel@suse.de>
8 */
9
10 #define pr_fmt(fmt) "SEV: " fmt
11
12 #include <linux/sched/debug.h> /* For show_regs() */
13 #include <linux/percpu-defs.h>
14 #include <linux/cc_platform.h>
15 #include <linux/printk.h>
16 #include <linux/mm_types.h>
17 #include <linux/set_memory.h>
18 #include <linux/memblock.h>
19 #include <linux/kernel.h>
20 #include <linux/mm.h>
21 #include <linux/cpumask.h>
22 #include <linux/efi.h>
23 #include <linux/platform_device.h>
24 #include <linux/io.h>
25 #include <linux/psp-sev.h>
26 #include <linux/dmi.h>
27 #include <uapi/linux/sev-guest.h>
28
29 #include <asm/init.h>
30 #include <asm/cpu_entry_area.h>
31 #include <asm/stacktrace.h>
32 #include <asm/sev.h>
33 #include <asm/insn-eval.h>
34 #include <asm/fpu/xcr.h>
35 #include <asm/processor.h>
36 #include <asm/realmode.h>
37 #include <asm/setup.h>
38 #include <asm/traps.h>
39 #include <asm/svm.h>
40 #include <asm/smp.h>
41 #include <asm/cpu.h>
42 #include <asm/apic.h>
43 #include <asm/cpuid.h>
44 #include <asm/cmdline.h>
45
46 #define DR7_RESET_VALUE 0x400
47
48 /* AP INIT values as documented in the APM2 section "Processor Initialization State" */
49 #define AP_INIT_CS_LIMIT 0xffff
50 #define AP_INIT_DS_LIMIT 0xffff
51 #define AP_INIT_LDTR_LIMIT 0xffff
52 #define AP_INIT_GDTR_LIMIT 0xffff
53 #define AP_INIT_IDTR_LIMIT 0xffff
54 #define AP_INIT_TR_LIMIT 0xffff
55 #define AP_INIT_RFLAGS_DEFAULT 0x2
56 #define AP_INIT_DR6_DEFAULT 0xffff0ff0
57 #define AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL
58 #define AP_INIT_XCR0_DEFAULT 0x1
59 #define AP_INIT_X87_FTW_DEFAULT 0x5555
60 #define AP_INIT_X87_FCW_DEFAULT 0x0040
61 #define AP_INIT_CR0_DEFAULT 0x60000010
62 #define AP_INIT_MXCSR_DEFAULT 0x1f80
63
64 static const char * const sev_status_feat_names[] = {
65 [MSR_AMD64_SEV_ENABLED_BIT] = "SEV",
66 [MSR_AMD64_SEV_ES_ENABLED_BIT] = "SEV-ES",
67 [MSR_AMD64_SEV_SNP_ENABLED_BIT] = "SEV-SNP",
68 [MSR_AMD64_SNP_VTOM_BIT] = "vTom",
69 [MSR_AMD64_SNP_REFLECT_VC_BIT] = "ReflectVC",
70 [MSR_AMD64_SNP_RESTRICTED_INJ_BIT] = "RI",
71 [MSR_AMD64_SNP_ALT_INJ_BIT] = "AI",
72 [MSR_AMD64_SNP_DEBUG_SWAP_BIT] = "DebugSwap",
73 [MSR_AMD64_SNP_PREVENT_HOST_IBS_BIT] = "NoHostIBS",
74 [MSR_AMD64_SNP_BTB_ISOLATION_BIT] = "BTBIsol",
75 [MSR_AMD64_SNP_VMPL_SSS_BIT] = "VmplSSS",
76 [MSR_AMD64_SNP_SECURE_TSC_BIT] = "SecureTSC",
77 [MSR_AMD64_SNP_VMGEXIT_PARAM_BIT] = "VMGExitParam",
78 [MSR_AMD64_SNP_IBS_VIRT_BIT] = "IBSVirt",
79 [MSR_AMD64_SNP_VMSA_REG_PROT_BIT] = "VMSARegProt",
80 [MSR_AMD64_SNP_SMT_PROT_BIT] = "SMTProt",
81 };
82
83 /* For early boot hypervisor communication in SEV-ES enabled guests */
84 static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE);
85
86 /*
87 * Needs to be in the .data section because we need it NULL before bss is
88 * cleared
89 */
90 static struct ghcb *boot_ghcb __section(".data");
91
92 /* Bitmap of SEV features supported by the hypervisor */
93 static u64 sev_hv_features __ro_after_init;
94
95 /* #VC handler runtime per-CPU data */
96 struct sev_es_runtime_data {
97 struct ghcb ghcb_page;
98
99 /*
100 * Reserve one page per CPU as backup storage for the unencrypted GHCB.
101 * It is needed when an NMI happens while the #VC handler uses the real
102 * GHCB, and the NMI handler itself is causing another #VC exception. In
103 * that case the GHCB content of the first handler needs to be backed up
104 * and restored.
105 */
106 struct ghcb backup_ghcb;
107
108 /*
109 * Mark the per-cpu GHCBs as in-use to detect nested #VC exceptions.
110 * There is no need for it to be atomic, because nothing is written to
111 * the GHCB between the read and the write of ghcb_active. So it is safe
112 * to use it when a nested #VC exception happens before the write.
113 *
114 * This is necessary for example in the #VC->NMI->#VC case when the NMI
115 * happens while the first #VC handler uses the GHCB. When the NMI code
116 * raises a second #VC handler it might overwrite the contents of the
117 * GHCB written by the first handler. To avoid this the content of the
118 * GHCB is saved and restored when the GHCB is detected to be in use
119 * already.
120 */
121 bool ghcb_active;
122 bool backup_ghcb_active;
123
124 /*
125 * Cached DR7 value - write it on DR7 writes and return it on reads.
126 * That value will never make it to the real hardware DR7 as debugging
127 * is currently unsupported in SEV-ES guests.
128 */
129 unsigned long dr7;
130 };
131
132 struct ghcb_state {
133 struct ghcb *ghcb;
134 };
135
136 static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data);
137 static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa);
138
139 struct sev_config {
140 __u64 debug : 1,
141
142 /*
143 * A flag used by __set_pages_state() that indicates when the
144 * per-CPU GHCB has been created and registered and thus can be
145 * used by the BSP instead of the early boot GHCB.
146 *
147 * For APs, the per-CPU GHCB is created before they are started
148 * and registered upon startup, so this flag can be used globally
149 * for the BSP and APs.
150 */
151 ghcbs_initialized : 1,
152
153 __reserved : 62;
154 };
155
156 static struct sev_config sev_cfg __read_mostly;
157
on_vc_stack(struct pt_regs * regs)158 static __always_inline bool on_vc_stack(struct pt_regs *regs)
159 {
160 unsigned long sp = regs->sp;
161
162 /* User-mode RSP is not trusted */
163 if (user_mode(regs))
164 return false;
165
166 /* SYSCALL gap still has user-mode RSP */
167 if (ip_within_syscall_gap(regs))
168 return false;
169
170 return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC)));
171 }
172
173 /*
174 * This function handles the case when an NMI is raised in the #VC
175 * exception handler entry code, before the #VC handler has switched off
176 * its IST stack. In this case, the IST entry for #VC must be adjusted,
177 * so that any nested #VC exception will not overwrite the stack
178 * contents of the interrupted #VC handler.
179 *
180 * The IST entry is adjusted unconditionally so that it can be also be
181 * unconditionally adjusted back in __sev_es_ist_exit(). Otherwise a
182 * nested sev_es_ist_exit() call may adjust back the IST entry too
183 * early.
184 *
185 * The __sev_es_ist_enter() and __sev_es_ist_exit() functions always run
186 * on the NMI IST stack, as they are only called from NMI handling code
187 * right now.
188 */
__sev_es_ist_enter(struct pt_regs * regs)189 void noinstr __sev_es_ist_enter(struct pt_regs *regs)
190 {
191 unsigned long old_ist, new_ist;
192
193 /* Read old IST entry */
194 new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
195
196 /*
197 * If NMI happened while on the #VC IST stack, set the new IST
198 * value below regs->sp, so that the interrupted stack frame is
199 * not overwritten by subsequent #VC exceptions.
200 */
201 if (on_vc_stack(regs))
202 new_ist = regs->sp;
203
204 /*
205 * Reserve additional 8 bytes and store old IST value so this
206 * adjustment can be unrolled in __sev_es_ist_exit().
207 */
208 new_ist -= sizeof(old_ist);
209 *(unsigned long *)new_ist = old_ist;
210
211 /* Set new IST entry */
212 this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist);
213 }
214
__sev_es_ist_exit(void)215 void noinstr __sev_es_ist_exit(void)
216 {
217 unsigned long ist;
218
219 /* Read IST entry */
220 ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
221
222 if (WARN_ON(ist == __this_cpu_ist_top_va(VC)))
223 return;
224
225 /* Read back old IST entry and write it to the TSS */
226 this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
227 }
228
229 /*
230 * Nothing shall interrupt this code path while holding the per-CPU
231 * GHCB. The backup GHCB is only for NMIs interrupting this path.
232 *
233 * Callers must disable local interrupts around it.
234 */
__sev_get_ghcb(struct ghcb_state * state)235 static noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state)
236 {
237 struct sev_es_runtime_data *data;
238 struct ghcb *ghcb;
239
240 WARN_ON(!irqs_disabled());
241
242 data = this_cpu_read(runtime_data);
243 ghcb = &data->ghcb_page;
244
245 if (unlikely(data->ghcb_active)) {
246 /* GHCB is already in use - save its contents */
247
248 if (unlikely(data->backup_ghcb_active)) {
249 /*
250 * Backup-GHCB is also already in use. There is no way
251 * to continue here so just kill the machine. To make
252 * panic() work, mark GHCBs inactive so that messages
253 * can be printed out.
254 */
255 data->ghcb_active = false;
256 data->backup_ghcb_active = false;
257
258 instrumentation_begin();
259 panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
260 instrumentation_end();
261 }
262
263 /* Mark backup_ghcb active before writing to it */
264 data->backup_ghcb_active = true;
265
266 state->ghcb = &data->backup_ghcb;
267
268 /* Backup GHCB content */
269 *state->ghcb = *ghcb;
270 } else {
271 state->ghcb = NULL;
272 data->ghcb_active = true;
273 }
274
275 return ghcb;
276 }
277
sev_es_rd_ghcb_msr(void)278 static inline u64 sev_es_rd_ghcb_msr(void)
279 {
280 return __rdmsr(MSR_AMD64_SEV_ES_GHCB);
281 }
282
sev_es_wr_ghcb_msr(u64 val)283 static __always_inline void sev_es_wr_ghcb_msr(u64 val)
284 {
285 u32 low, high;
286
287 low = (u32)(val);
288 high = (u32)(val >> 32);
289
290 native_wrmsr(MSR_AMD64_SEV_ES_GHCB, low, high);
291 }
292
vc_fetch_insn_kernel(struct es_em_ctxt * ctxt,unsigned char * buffer)293 static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt,
294 unsigned char *buffer)
295 {
296 return copy_from_kernel_nofault(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
297 }
298
__vc_decode_user_insn(struct es_em_ctxt * ctxt)299 static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
300 {
301 char buffer[MAX_INSN_SIZE];
302 int insn_bytes;
303
304 insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
305 if (insn_bytes == 0) {
306 /* Nothing could be copied */
307 ctxt->fi.vector = X86_TRAP_PF;
308 ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
309 ctxt->fi.cr2 = ctxt->regs->ip;
310 return ES_EXCEPTION;
311 } else if (insn_bytes == -EINVAL) {
312 /* Effective RIP could not be calculated */
313 ctxt->fi.vector = X86_TRAP_GP;
314 ctxt->fi.error_code = 0;
315 ctxt->fi.cr2 = 0;
316 return ES_EXCEPTION;
317 }
318
319 if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, insn_bytes))
320 return ES_DECODE_FAILED;
321
322 if (ctxt->insn.immediate.got)
323 return ES_OK;
324 else
325 return ES_DECODE_FAILED;
326 }
327
__vc_decode_kern_insn(struct es_em_ctxt * ctxt)328 static enum es_result __vc_decode_kern_insn(struct es_em_ctxt *ctxt)
329 {
330 char buffer[MAX_INSN_SIZE];
331 int res, ret;
332
333 res = vc_fetch_insn_kernel(ctxt, buffer);
334 if (res) {
335 ctxt->fi.vector = X86_TRAP_PF;
336 ctxt->fi.error_code = X86_PF_INSTR;
337 ctxt->fi.cr2 = ctxt->regs->ip;
338 return ES_EXCEPTION;
339 }
340
341 ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
342 if (ret < 0)
343 return ES_DECODE_FAILED;
344 else
345 return ES_OK;
346 }
347
vc_decode_insn(struct es_em_ctxt * ctxt)348 static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
349 {
350 if (user_mode(ctxt->regs))
351 return __vc_decode_user_insn(ctxt);
352 else
353 return __vc_decode_kern_insn(ctxt);
354 }
355
vc_write_mem(struct es_em_ctxt * ctxt,char * dst,char * buf,size_t size)356 static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
357 char *dst, char *buf, size_t size)
358 {
359 unsigned long error_code = X86_PF_PROT | X86_PF_WRITE;
360
361 /*
362 * This function uses __put_user() independent of whether kernel or user
363 * memory is accessed. This works fine because __put_user() does no
364 * sanity checks of the pointer being accessed. All that it does is
365 * to report when the access failed.
366 *
367 * Also, this function runs in atomic context, so __put_user() is not
368 * allowed to sleep. The page-fault handler detects that it is running
369 * in atomic context and will not try to take mmap_sem and handle the
370 * fault, so additional pagefault_enable()/disable() calls are not
371 * needed.
372 *
373 * The access can't be done via copy_to_user() here because
374 * vc_write_mem() must not use string instructions to access unsafe
375 * memory. The reason is that MOVS is emulated by the #VC handler by
376 * splitting the move up into a read and a write and taking a nested #VC
377 * exception on whatever of them is the MMIO access. Using string
378 * instructions here would cause infinite nesting.
379 */
380 switch (size) {
381 case 1: {
382 u8 d1;
383 u8 __user *target = (u8 __user *)dst;
384
385 memcpy(&d1, buf, 1);
386 if (__put_user(d1, target))
387 goto fault;
388 break;
389 }
390 case 2: {
391 u16 d2;
392 u16 __user *target = (u16 __user *)dst;
393
394 memcpy(&d2, buf, 2);
395 if (__put_user(d2, target))
396 goto fault;
397 break;
398 }
399 case 4: {
400 u32 d4;
401 u32 __user *target = (u32 __user *)dst;
402
403 memcpy(&d4, buf, 4);
404 if (__put_user(d4, target))
405 goto fault;
406 break;
407 }
408 case 8: {
409 u64 d8;
410 u64 __user *target = (u64 __user *)dst;
411
412 memcpy(&d8, buf, 8);
413 if (__put_user(d8, target))
414 goto fault;
415 break;
416 }
417 default:
418 WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
419 return ES_UNSUPPORTED;
420 }
421
422 return ES_OK;
423
424 fault:
425 if (user_mode(ctxt->regs))
426 error_code |= X86_PF_USER;
427
428 ctxt->fi.vector = X86_TRAP_PF;
429 ctxt->fi.error_code = error_code;
430 ctxt->fi.cr2 = (unsigned long)dst;
431
432 return ES_EXCEPTION;
433 }
434
vc_read_mem(struct es_em_ctxt * ctxt,char * src,char * buf,size_t size)435 static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
436 char *src, char *buf, size_t size)
437 {
438 unsigned long error_code = X86_PF_PROT;
439
440 /*
441 * This function uses __get_user() independent of whether kernel or user
442 * memory is accessed. This works fine because __get_user() does no
443 * sanity checks of the pointer being accessed. All that it does is
444 * to report when the access failed.
445 *
446 * Also, this function runs in atomic context, so __get_user() is not
447 * allowed to sleep. The page-fault handler detects that it is running
448 * in atomic context and will not try to take mmap_sem and handle the
449 * fault, so additional pagefault_enable()/disable() calls are not
450 * needed.
451 *
452 * The access can't be done via copy_from_user() here because
453 * vc_read_mem() must not use string instructions to access unsafe
454 * memory. The reason is that MOVS is emulated by the #VC handler by
455 * splitting the move up into a read and a write and taking a nested #VC
456 * exception on whatever of them is the MMIO access. Using string
457 * instructions here would cause infinite nesting.
458 */
459 switch (size) {
460 case 1: {
461 u8 d1;
462 u8 __user *s = (u8 __user *)src;
463
464 if (__get_user(d1, s))
465 goto fault;
466 memcpy(buf, &d1, 1);
467 break;
468 }
469 case 2: {
470 u16 d2;
471 u16 __user *s = (u16 __user *)src;
472
473 if (__get_user(d2, s))
474 goto fault;
475 memcpy(buf, &d2, 2);
476 break;
477 }
478 case 4: {
479 u32 d4;
480 u32 __user *s = (u32 __user *)src;
481
482 if (__get_user(d4, s))
483 goto fault;
484 memcpy(buf, &d4, 4);
485 break;
486 }
487 case 8: {
488 u64 d8;
489 u64 __user *s = (u64 __user *)src;
490 if (__get_user(d8, s))
491 goto fault;
492 memcpy(buf, &d8, 8);
493 break;
494 }
495 default:
496 WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
497 return ES_UNSUPPORTED;
498 }
499
500 return ES_OK;
501
502 fault:
503 if (user_mode(ctxt->regs))
504 error_code |= X86_PF_USER;
505
506 ctxt->fi.vector = X86_TRAP_PF;
507 ctxt->fi.error_code = error_code;
508 ctxt->fi.cr2 = (unsigned long)src;
509
510 return ES_EXCEPTION;
511 }
512
vc_slow_virt_to_phys(struct ghcb * ghcb,struct es_em_ctxt * ctxt,unsigned long vaddr,phys_addr_t * paddr)513 static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
514 unsigned long vaddr, phys_addr_t *paddr)
515 {
516 unsigned long va = (unsigned long)vaddr;
517 unsigned int level;
518 phys_addr_t pa;
519 pgd_t *pgd;
520 pte_t *pte;
521
522 pgd = __va(read_cr3_pa());
523 pgd = &pgd[pgd_index(va)];
524 pte = lookup_address_in_pgd(pgd, va, &level);
525 if (!pte) {
526 ctxt->fi.vector = X86_TRAP_PF;
527 ctxt->fi.cr2 = vaddr;
528 ctxt->fi.error_code = 0;
529
530 if (user_mode(ctxt->regs))
531 ctxt->fi.error_code |= X86_PF_USER;
532
533 return ES_EXCEPTION;
534 }
535
536 if (WARN_ON_ONCE(pte_val(*pte) & _PAGE_ENC))
537 /* Emulated MMIO to/from encrypted memory not supported */
538 return ES_UNSUPPORTED;
539
540 pa = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
541 pa |= va & ~page_level_mask(level);
542
543 *paddr = pa;
544
545 return ES_OK;
546 }
547
vc_ioio_check(struct es_em_ctxt * ctxt,u16 port,size_t size)548 static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
549 {
550 BUG_ON(size > 4);
551
552 if (user_mode(ctxt->regs)) {
553 struct thread_struct *t = ¤t->thread;
554 struct io_bitmap *iobm = t->io_bitmap;
555 size_t idx;
556
557 if (!iobm)
558 goto fault;
559
560 for (idx = port; idx < port + size; ++idx) {
561 if (test_bit(idx, iobm->bitmap))
562 goto fault;
563 }
564 }
565
566 return ES_OK;
567
568 fault:
569 ctxt->fi.vector = X86_TRAP_GP;
570 ctxt->fi.error_code = 0;
571
572 return ES_EXCEPTION;
573 }
574
575 /* Include code shared with pre-decompression boot stage */
576 #include "sev-shared.c"
577
__sev_put_ghcb(struct ghcb_state * state)578 static noinstr void __sev_put_ghcb(struct ghcb_state *state)
579 {
580 struct sev_es_runtime_data *data;
581 struct ghcb *ghcb;
582
583 WARN_ON(!irqs_disabled());
584
585 data = this_cpu_read(runtime_data);
586 ghcb = &data->ghcb_page;
587
588 if (state->ghcb) {
589 /* Restore GHCB from Backup */
590 *ghcb = *state->ghcb;
591 data->backup_ghcb_active = false;
592 state->ghcb = NULL;
593 } else {
594 /*
595 * Invalidate the GHCB so a VMGEXIT instruction issued
596 * from userspace won't appear to be valid.
597 */
598 vc_ghcb_invalidate(ghcb);
599 data->ghcb_active = false;
600 }
601 }
602
__sev_es_nmi_complete(void)603 void noinstr __sev_es_nmi_complete(void)
604 {
605 struct ghcb_state state;
606 struct ghcb *ghcb;
607
608 ghcb = __sev_get_ghcb(&state);
609
610 vc_ghcb_invalidate(ghcb);
611 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE);
612 ghcb_set_sw_exit_info_1(ghcb, 0);
613 ghcb_set_sw_exit_info_2(ghcb, 0);
614
615 sev_es_wr_ghcb_msr(__pa_nodebug(ghcb));
616 VMGEXIT();
617
618 __sev_put_ghcb(&state);
619 }
620
get_secrets_page(void)621 static u64 __init get_secrets_page(void)
622 {
623 u64 pa_data = boot_params.cc_blob_address;
624 struct cc_blob_sev_info info;
625 void *map;
626
627 /*
628 * The CC blob contains the address of the secrets page, check if the
629 * blob is present.
630 */
631 if (!pa_data)
632 return 0;
633
634 map = early_memremap(pa_data, sizeof(info));
635 if (!map) {
636 pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n");
637 return 0;
638 }
639 memcpy(&info, map, sizeof(info));
640 early_memunmap(map, sizeof(info));
641
642 /* smoke-test the secrets page passed */
643 if (!info.secrets_phys || info.secrets_len != PAGE_SIZE)
644 return 0;
645
646 return info.secrets_phys;
647 }
648
get_snp_jump_table_addr(void)649 static u64 __init get_snp_jump_table_addr(void)
650 {
651 struct snp_secrets_page *secrets;
652 void __iomem *mem;
653 u64 pa, addr;
654
655 pa = get_secrets_page();
656 if (!pa)
657 return 0;
658
659 mem = ioremap_encrypted(pa, PAGE_SIZE);
660 if (!mem) {
661 pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n");
662 return 0;
663 }
664
665 secrets = (__force struct snp_secrets_page *)mem;
666
667 addr = secrets->os_area.ap_jump_table_pa;
668 iounmap(mem);
669
670 return addr;
671 }
672
get_jump_table_addr(void)673 static u64 __init get_jump_table_addr(void)
674 {
675 struct ghcb_state state;
676 unsigned long flags;
677 struct ghcb *ghcb;
678 u64 ret = 0;
679
680 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
681 return get_snp_jump_table_addr();
682
683 local_irq_save(flags);
684
685 ghcb = __sev_get_ghcb(&state);
686
687 vc_ghcb_invalidate(ghcb);
688 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE);
689 ghcb_set_sw_exit_info_1(ghcb, SVM_VMGEXIT_GET_AP_JUMP_TABLE);
690 ghcb_set_sw_exit_info_2(ghcb, 0);
691
692 sev_es_wr_ghcb_msr(__pa(ghcb));
693 VMGEXIT();
694
695 if (ghcb_sw_exit_info_1_is_valid(ghcb) &&
696 ghcb_sw_exit_info_2_is_valid(ghcb))
697 ret = ghcb->save.sw_exit_info_2;
698
699 __sev_put_ghcb(&state);
700
701 local_irq_restore(flags);
702
703 return ret;
704 }
705
706 static void __head
early_set_pages_state(unsigned long vaddr,unsigned long paddr,unsigned long npages,enum psc_op op)707 early_set_pages_state(unsigned long vaddr, unsigned long paddr,
708 unsigned long npages, enum psc_op op)
709 {
710 unsigned long paddr_end;
711 u64 val;
712 int ret;
713
714 vaddr = vaddr & PAGE_MASK;
715
716 paddr = paddr & PAGE_MASK;
717 paddr_end = paddr + (npages << PAGE_SHIFT);
718
719 while (paddr < paddr_end) {
720 if (op == SNP_PAGE_STATE_SHARED) {
721 /* Page validation must be rescinded before changing to shared */
722 ret = pvalidate(vaddr, RMP_PG_SIZE_4K, false);
723 if (WARN(ret, "Failed to validate address 0x%lx ret %d", paddr, ret))
724 goto e_term;
725 }
726
727 /*
728 * Use the MSR protocol because this function can be called before
729 * the GHCB is established.
730 */
731 sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op));
732 VMGEXIT();
733
734 val = sev_es_rd_ghcb_msr();
735
736 if (WARN(GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP,
737 "Wrong PSC response code: 0x%x\n",
738 (unsigned int)GHCB_RESP_CODE(val)))
739 goto e_term;
740
741 if (WARN(GHCB_MSR_PSC_RESP_VAL(val),
742 "Failed to change page state to '%s' paddr 0x%lx error 0x%llx\n",
743 op == SNP_PAGE_STATE_PRIVATE ? "private" : "shared",
744 paddr, GHCB_MSR_PSC_RESP_VAL(val)))
745 goto e_term;
746
747 if (op == SNP_PAGE_STATE_PRIVATE) {
748 /* Page validation must be performed after changing to private */
749 ret = pvalidate(vaddr, RMP_PG_SIZE_4K, true);
750 if (WARN(ret, "Failed to validate address 0x%lx ret %d", paddr, ret))
751 goto e_term;
752 }
753
754 vaddr += PAGE_SIZE;
755 paddr += PAGE_SIZE;
756 }
757
758 return;
759
760 e_term:
761 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC);
762 }
763
early_snp_set_memory_private(unsigned long vaddr,unsigned long paddr,unsigned long npages)764 void __head early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
765 unsigned long npages)
766 {
767 /*
768 * This can be invoked in early boot while running identity mapped, so
769 * use an open coded check for SNP instead of using cc_platform_has().
770 * This eliminates worries about jump tables or checking boot_cpu_data
771 * in the cc_platform_has() function.
772 */
773 if (!(RIP_REL_REF(sev_status) & MSR_AMD64_SEV_SNP_ENABLED))
774 return;
775
776 /*
777 * Ask the hypervisor to mark the memory pages as private in the RMP
778 * table.
779 */
780 early_set_pages_state(vaddr, paddr, npages, SNP_PAGE_STATE_PRIVATE);
781 }
782
early_snp_set_memory_shared(unsigned long vaddr,unsigned long paddr,unsigned long npages)783 void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr,
784 unsigned long npages)
785 {
786 /*
787 * This can be invoked in early boot while running identity mapped, so
788 * use an open coded check for SNP instead of using cc_platform_has().
789 * This eliminates worries about jump tables or checking boot_cpu_data
790 * in the cc_platform_has() function.
791 */
792 if (!(RIP_REL_REF(sev_status) & MSR_AMD64_SEV_SNP_ENABLED))
793 return;
794
795 /* Ask hypervisor to mark the memory pages shared in the RMP table. */
796 early_set_pages_state(vaddr, paddr, npages, SNP_PAGE_STATE_SHARED);
797 }
798
__set_pages_state(struct snp_psc_desc * data,unsigned long vaddr,unsigned long vaddr_end,int op)799 static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr,
800 unsigned long vaddr_end, int op)
801 {
802 struct ghcb_state state;
803 bool use_large_entry;
804 struct psc_hdr *hdr;
805 struct psc_entry *e;
806 unsigned long flags;
807 unsigned long pfn;
808 struct ghcb *ghcb;
809 int i;
810
811 hdr = &data->hdr;
812 e = data->entries;
813
814 memset(data, 0, sizeof(*data));
815 i = 0;
816
817 while (vaddr < vaddr_end && i < ARRAY_SIZE(data->entries)) {
818 hdr->end_entry = i;
819
820 if (is_vmalloc_addr((void *)vaddr)) {
821 pfn = vmalloc_to_pfn((void *)vaddr);
822 use_large_entry = false;
823 } else {
824 pfn = __pa(vaddr) >> PAGE_SHIFT;
825 use_large_entry = true;
826 }
827
828 e->gfn = pfn;
829 e->operation = op;
830
831 if (use_large_entry && IS_ALIGNED(vaddr, PMD_SIZE) &&
832 (vaddr_end - vaddr) >= PMD_SIZE) {
833 e->pagesize = RMP_PG_SIZE_2M;
834 vaddr += PMD_SIZE;
835 } else {
836 e->pagesize = RMP_PG_SIZE_4K;
837 vaddr += PAGE_SIZE;
838 }
839
840 e++;
841 i++;
842 }
843
844 /* Page validation must be rescinded before changing to shared */
845 if (op == SNP_PAGE_STATE_SHARED)
846 pvalidate_pages(data);
847
848 local_irq_save(flags);
849
850 if (sev_cfg.ghcbs_initialized)
851 ghcb = __sev_get_ghcb(&state);
852 else
853 ghcb = boot_ghcb;
854
855 /* Invoke the hypervisor to perform the page state changes */
856 if (!ghcb || vmgexit_psc(ghcb, data))
857 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC);
858
859 if (sev_cfg.ghcbs_initialized)
860 __sev_put_ghcb(&state);
861
862 local_irq_restore(flags);
863
864 /* Page validation must be performed after changing to private */
865 if (op == SNP_PAGE_STATE_PRIVATE)
866 pvalidate_pages(data);
867
868 return vaddr;
869 }
870
set_pages_state(unsigned long vaddr,unsigned long npages,int op)871 static void set_pages_state(unsigned long vaddr, unsigned long npages, int op)
872 {
873 struct snp_psc_desc desc;
874 unsigned long vaddr_end;
875
876 /* Use the MSR protocol when a GHCB is not available. */
877 if (!boot_ghcb)
878 return early_set_pages_state(vaddr, __pa(vaddr), npages, op);
879
880 vaddr = vaddr & PAGE_MASK;
881 vaddr_end = vaddr + (npages << PAGE_SHIFT);
882
883 while (vaddr < vaddr_end)
884 vaddr = __set_pages_state(&desc, vaddr, vaddr_end, op);
885 }
886
snp_set_memory_shared(unsigned long vaddr,unsigned long npages)887 void snp_set_memory_shared(unsigned long vaddr, unsigned long npages)
888 {
889 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
890 return;
891
892 set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED);
893 }
894
snp_set_memory_private(unsigned long vaddr,unsigned long npages)895 void snp_set_memory_private(unsigned long vaddr, unsigned long npages)
896 {
897 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
898 return;
899
900 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE);
901 }
902
snp_accept_memory(phys_addr_t start,phys_addr_t end)903 void snp_accept_memory(phys_addr_t start, phys_addr_t end)
904 {
905 unsigned long vaddr, npages;
906
907 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
908 return;
909
910 vaddr = (unsigned long)__va(start);
911 npages = (end - start) >> PAGE_SHIFT;
912
913 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE);
914 }
915
snp_set_vmsa(void * va,bool vmsa)916 static int snp_set_vmsa(void *va, bool vmsa)
917 {
918 u64 attrs;
919
920 /*
921 * Running at VMPL0 allows the kernel to change the VMSA bit for a page
922 * using the RMPADJUST instruction. However, for the instruction to
923 * succeed it must target the permissions of a lesser privileged
924 * (higher numbered) VMPL level, so use VMPL1 (refer to the RMPADJUST
925 * instruction in the AMD64 APM Volume 3).
926 */
927 attrs = 1;
928 if (vmsa)
929 attrs |= RMPADJUST_VMSA_PAGE_BIT;
930
931 return rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs);
932 }
933
934 #define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK)
935 #define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK)
936 #define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK)
937
938 #define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2)
939 #define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3)
940
snp_alloc_vmsa_page(int cpu)941 static void *snp_alloc_vmsa_page(int cpu)
942 {
943 struct page *p;
944
945 /*
946 * Allocate VMSA page to work around the SNP erratum where the CPU will
947 * incorrectly signal an RMP violation #PF if a large page (2MB or 1GB)
948 * collides with the RMP entry of VMSA page. The recommended workaround
949 * is to not use a large page.
950 *
951 * Allocate an 8k page which is also 8k-aligned.
952 */
953 p = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1);
954 if (!p)
955 return NULL;
956
957 split_page(p, 1);
958
959 /* Free the first 4k. This page may be 2M/1G aligned and cannot be used. */
960 __free_page(p);
961
962 return page_address(p + 1);
963 }
964
snp_cleanup_vmsa(struct sev_es_save_area * vmsa)965 static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa)
966 {
967 int err;
968
969 err = snp_set_vmsa(vmsa, false);
970 if (err)
971 pr_err("clear VMSA page failed (%u), leaking page\n", err);
972 else
973 free_page((unsigned long)vmsa);
974 }
975
wakeup_cpu_via_vmgexit(u32 apic_id,unsigned long start_ip)976 static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip)
977 {
978 struct sev_es_save_area *cur_vmsa, *vmsa;
979 struct ghcb_state state;
980 unsigned long flags;
981 struct ghcb *ghcb;
982 u8 sipi_vector;
983 int cpu, ret;
984 u64 cr4;
985
986 /*
987 * The hypervisor SNP feature support check has happened earlier, just check
988 * the AP_CREATION one here.
989 */
990 if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION))
991 return -EOPNOTSUPP;
992
993 /*
994 * Verify the desired start IP against the known trampoline start IP
995 * to catch any future new trampolines that may be introduced that
996 * would require a new protected guest entry point.
997 */
998 if (WARN_ONCE(start_ip != real_mode_header->trampoline_start,
999 "Unsupported SNP start_ip: %lx\n", start_ip))
1000 return -EINVAL;
1001
1002 /* Override start_ip with known protected guest start IP */
1003 start_ip = real_mode_header->sev_es_trampoline_start;
1004
1005 /* Find the logical CPU for the APIC ID */
1006 for_each_present_cpu(cpu) {
1007 if (arch_match_cpu_phys_id(cpu, apic_id))
1008 break;
1009 }
1010 if (cpu >= nr_cpu_ids)
1011 return -EINVAL;
1012
1013 cur_vmsa = per_cpu(sev_vmsa, cpu);
1014
1015 /*
1016 * A new VMSA is created each time because there is no guarantee that
1017 * the current VMSA is the kernels or that the vCPU is not running. If
1018 * an attempt was done to use the current VMSA with a running vCPU, a
1019 * #VMEXIT of that vCPU would wipe out all of the settings being done
1020 * here.
1021 */
1022 vmsa = (struct sev_es_save_area *)snp_alloc_vmsa_page(cpu);
1023 if (!vmsa)
1024 return -ENOMEM;
1025
1026 /* CR4 should maintain the MCE value */
1027 cr4 = native_read_cr4() & X86_CR4_MCE;
1028
1029 /* Set the CS value based on the start_ip converted to a SIPI vector */
1030 sipi_vector = (start_ip >> 12);
1031 vmsa->cs.base = sipi_vector << 12;
1032 vmsa->cs.limit = AP_INIT_CS_LIMIT;
1033 vmsa->cs.attrib = INIT_CS_ATTRIBS;
1034 vmsa->cs.selector = sipi_vector << 8;
1035
1036 /* Set the RIP value based on start_ip */
1037 vmsa->rip = start_ip & 0xfff;
1038
1039 /* Set AP INIT defaults as documented in the APM */
1040 vmsa->ds.limit = AP_INIT_DS_LIMIT;
1041 vmsa->ds.attrib = INIT_DS_ATTRIBS;
1042 vmsa->es = vmsa->ds;
1043 vmsa->fs = vmsa->ds;
1044 vmsa->gs = vmsa->ds;
1045 vmsa->ss = vmsa->ds;
1046
1047 vmsa->gdtr.limit = AP_INIT_GDTR_LIMIT;
1048 vmsa->ldtr.limit = AP_INIT_LDTR_LIMIT;
1049 vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS;
1050 vmsa->idtr.limit = AP_INIT_IDTR_LIMIT;
1051 vmsa->tr.limit = AP_INIT_TR_LIMIT;
1052 vmsa->tr.attrib = INIT_TR_ATTRIBS;
1053
1054 vmsa->cr4 = cr4;
1055 vmsa->cr0 = AP_INIT_CR0_DEFAULT;
1056 vmsa->dr7 = DR7_RESET_VALUE;
1057 vmsa->dr6 = AP_INIT_DR6_DEFAULT;
1058 vmsa->rflags = AP_INIT_RFLAGS_DEFAULT;
1059 vmsa->g_pat = AP_INIT_GPAT_DEFAULT;
1060 vmsa->xcr0 = AP_INIT_XCR0_DEFAULT;
1061 vmsa->mxcsr = AP_INIT_MXCSR_DEFAULT;
1062 vmsa->x87_ftw = AP_INIT_X87_FTW_DEFAULT;
1063 vmsa->x87_fcw = AP_INIT_X87_FCW_DEFAULT;
1064
1065 /* SVME must be set. */
1066 vmsa->efer = EFER_SVME;
1067
1068 /*
1069 * Set the SNP-specific fields for this VMSA:
1070 * VMPL level
1071 * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits)
1072 */
1073 vmsa->vmpl = 0;
1074 vmsa->sev_features = sev_status >> 2;
1075
1076 /* Switch the page over to a VMSA page now that it is initialized */
1077 ret = snp_set_vmsa(vmsa, true);
1078 if (ret) {
1079 pr_err("set VMSA page failed (%u)\n", ret);
1080 free_page((unsigned long)vmsa);
1081
1082 return -EINVAL;
1083 }
1084
1085 /* Issue VMGEXIT AP Creation NAE event */
1086 local_irq_save(flags);
1087
1088 ghcb = __sev_get_ghcb(&state);
1089
1090 vc_ghcb_invalidate(ghcb);
1091 ghcb_set_rax(ghcb, vmsa->sev_features);
1092 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION);
1093 ghcb_set_sw_exit_info_1(ghcb, ((u64)apic_id << 32) | SVM_VMGEXIT_AP_CREATE);
1094 ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa));
1095
1096 sev_es_wr_ghcb_msr(__pa(ghcb));
1097 VMGEXIT();
1098
1099 if (!ghcb_sw_exit_info_1_is_valid(ghcb) ||
1100 lower_32_bits(ghcb->save.sw_exit_info_1)) {
1101 pr_err("SNP AP Creation error\n");
1102 ret = -EINVAL;
1103 }
1104
1105 __sev_put_ghcb(&state);
1106
1107 local_irq_restore(flags);
1108
1109 /* Perform cleanup if there was an error */
1110 if (ret) {
1111 snp_cleanup_vmsa(vmsa);
1112 vmsa = NULL;
1113 }
1114
1115 /* Free up any previous VMSA page */
1116 if (cur_vmsa)
1117 snp_cleanup_vmsa(cur_vmsa);
1118
1119 /* Record the current VMSA page */
1120 per_cpu(sev_vmsa, cpu) = vmsa;
1121
1122 return ret;
1123 }
1124
snp_set_wakeup_secondary_cpu(void)1125 void __init snp_set_wakeup_secondary_cpu(void)
1126 {
1127 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
1128 return;
1129
1130 /*
1131 * Always set this override if SNP is enabled. This makes it the
1132 * required method to start APs under SNP. If the hypervisor does
1133 * not support AP creation, then no APs will be started.
1134 */
1135 apic_update_callback(wakeup_secondary_cpu, wakeup_cpu_via_vmgexit);
1136 }
1137
sev_es_setup_ap_jump_table(struct real_mode_header * rmh)1138 int __init sev_es_setup_ap_jump_table(struct real_mode_header *rmh)
1139 {
1140 u16 startup_cs, startup_ip;
1141 phys_addr_t jump_table_pa;
1142 u64 jump_table_addr;
1143 u16 __iomem *jump_table;
1144
1145 jump_table_addr = get_jump_table_addr();
1146
1147 /* On UP guests there is no jump table so this is not a failure */
1148 if (!jump_table_addr)
1149 return 0;
1150
1151 /* Check if AP Jump Table is page-aligned */
1152 if (jump_table_addr & ~PAGE_MASK)
1153 return -EINVAL;
1154
1155 jump_table_pa = jump_table_addr & PAGE_MASK;
1156
1157 startup_cs = (u16)(rmh->trampoline_start >> 4);
1158 startup_ip = (u16)(rmh->sev_es_trampoline_start -
1159 rmh->trampoline_start);
1160
1161 jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE);
1162 if (!jump_table)
1163 return -EIO;
1164
1165 writew(startup_ip, &jump_table[0]);
1166 writew(startup_cs, &jump_table[1]);
1167
1168 iounmap(jump_table);
1169
1170 return 0;
1171 }
1172
1173 /*
1174 * This is needed by the OVMF UEFI firmware which will use whatever it finds in
1175 * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu
1176 * runtime GHCBs used by the kernel are also mapped in the EFI page-table.
1177 */
sev_es_efi_map_ghcbs(pgd_t * pgd)1178 int __init sev_es_efi_map_ghcbs(pgd_t *pgd)
1179 {
1180 struct sev_es_runtime_data *data;
1181 unsigned long address, pflags;
1182 int cpu;
1183 u64 pfn;
1184
1185 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
1186 return 0;
1187
1188 pflags = _PAGE_NX | _PAGE_RW;
1189
1190 for_each_possible_cpu(cpu) {
1191 data = per_cpu(runtime_data, cpu);
1192
1193 address = __pa(&data->ghcb_page);
1194 pfn = address >> PAGE_SHIFT;
1195
1196 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags))
1197 return 1;
1198 }
1199
1200 return 0;
1201 }
1202
vc_handle_msr(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1203 static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
1204 {
1205 struct pt_regs *regs = ctxt->regs;
1206 enum es_result ret;
1207 u64 exit_info_1;
1208
1209 /* Is it a WRMSR? */
1210 exit_info_1 = (ctxt->insn.opcode.bytes[1] == 0x30) ? 1 : 0;
1211
1212 ghcb_set_rcx(ghcb, regs->cx);
1213 if (exit_info_1) {
1214 ghcb_set_rax(ghcb, regs->ax);
1215 ghcb_set_rdx(ghcb, regs->dx);
1216 }
1217
1218 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
1219
1220 if ((ret == ES_OK) && (!exit_info_1)) {
1221 regs->ax = ghcb->save.rax;
1222 regs->dx = ghcb->save.rdx;
1223 }
1224
1225 return ret;
1226 }
1227
snp_register_per_cpu_ghcb(void)1228 static void snp_register_per_cpu_ghcb(void)
1229 {
1230 struct sev_es_runtime_data *data;
1231 struct ghcb *ghcb;
1232
1233 data = this_cpu_read(runtime_data);
1234 ghcb = &data->ghcb_page;
1235
1236 snp_register_ghcb_early(__pa(ghcb));
1237 }
1238
setup_ghcb(void)1239 void setup_ghcb(void)
1240 {
1241 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
1242 return;
1243
1244 /*
1245 * Check whether the runtime #VC exception handler is active. It uses
1246 * the per-CPU GHCB page which is set up by sev_es_init_vc_handling().
1247 *
1248 * If SNP is active, register the per-CPU GHCB page so that the runtime
1249 * exception handler can use it.
1250 */
1251 if (initial_vc_handler == (unsigned long)kernel_exc_vmm_communication) {
1252 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
1253 snp_register_per_cpu_ghcb();
1254
1255 sev_cfg.ghcbs_initialized = true;
1256
1257 return;
1258 }
1259
1260 /*
1261 * Make sure the hypervisor talks a supported protocol.
1262 * This gets called only in the BSP boot phase.
1263 */
1264 if (!sev_es_negotiate_protocol())
1265 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
1266
1267 /*
1268 * Clear the boot_ghcb. The first exception comes in before the bss
1269 * section is cleared.
1270 */
1271 memset(&boot_ghcb_page, 0, PAGE_SIZE);
1272
1273 /* Alright - Make the boot-ghcb public */
1274 boot_ghcb = &boot_ghcb_page;
1275
1276 /* SNP guest requires that GHCB GPA must be registered. */
1277 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
1278 snp_register_ghcb_early(__pa(&boot_ghcb_page));
1279 }
1280
1281 #ifdef CONFIG_HOTPLUG_CPU
sev_es_ap_hlt_loop(void)1282 static void sev_es_ap_hlt_loop(void)
1283 {
1284 struct ghcb_state state;
1285 struct ghcb *ghcb;
1286
1287 ghcb = __sev_get_ghcb(&state);
1288
1289 while (true) {
1290 vc_ghcb_invalidate(ghcb);
1291 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP);
1292 ghcb_set_sw_exit_info_1(ghcb, 0);
1293 ghcb_set_sw_exit_info_2(ghcb, 0);
1294
1295 sev_es_wr_ghcb_msr(__pa(ghcb));
1296 VMGEXIT();
1297
1298 /* Wakeup signal? */
1299 if (ghcb_sw_exit_info_2_is_valid(ghcb) &&
1300 ghcb->save.sw_exit_info_2)
1301 break;
1302 }
1303
1304 __sev_put_ghcb(&state);
1305 }
1306
1307 /*
1308 * Play_dead handler when running under SEV-ES. This is needed because
1309 * the hypervisor can't deliver an SIPI request to restart the AP.
1310 * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the
1311 * hypervisor wakes it up again.
1312 */
sev_es_play_dead(void)1313 static void sev_es_play_dead(void)
1314 {
1315 play_dead_common();
1316
1317 /* IRQs now disabled */
1318
1319 sev_es_ap_hlt_loop();
1320
1321 /*
1322 * If we get here, the VCPU was woken up again. Jump to CPU
1323 * startup code to get it back online.
1324 */
1325 soft_restart_cpu();
1326 }
1327 #else /* CONFIG_HOTPLUG_CPU */
1328 #define sev_es_play_dead native_play_dead
1329 #endif /* CONFIG_HOTPLUG_CPU */
1330
1331 #ifdef CONFIG_SMP
sev_es_setup_play_dead(void)1332 static void __init sev_es_setup_play_dead(void)
1333 {
1334 smp_ops.play_dead = sev_es_play_dead;
1335 }
1336 #else
sev_es_setup_play_dead(void)1337 static inline void sev_es_setup_play_dead(void) { }
1338 #endif
1339
alloc_runtime_data(int cpu)1340 static void __init alloc_runtime_data(int cpu)
1341 {
1342 struct sev_es_runtime_data *data;
1343
1344 data = memblock_alloc_node(sizeof(*data), PAGE_SIZE, cpu_to_node(cpu));
1345 if (!data)
1346 panic("Can't allocate SEV-ES runtime data");
1347
1348 per_cpu(runtime_data, cpu) = data;
1349 }
1350
init_ghcb(int cpu)1351 static void __init init_ghcb(int cpu)
1352 {
1353 struct sev_es_runtime_data *data;
1354 int err;
1355
1356 data = per_cpu(runtime_data, cpu);
1357
1358 err = early_set_memory_decrypted((unsigned long)&data->ghcb_page,
1359 sizeof(data->ghcb_page));
1360 if (err)
1361 panic("Can't map GHCBs unencrypted");
1362
1363 memset(&data->ghcb_page, 0, sizeof(data->ghcb_page));
1364
1365 data->ghcb_active = false;
1366 data->backup_ghcb_active = false;
1367 }
1368
sev_es_init_vc_handling(void)1369 void __init sev_es_init_vc_handling(void)
1370 {
1371 int cpu;
1372
1373 BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE);
1374
1375 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
1376 return;
1377
1378 if (!sev_es_check_cpu_features())
1379 panic("SEV-ES CPU Features missing");
1380
1381 /*
1382 * SNP is supported in v2 of the GHCB spec which mandates support for HV
1383 * features.
1384 */
1385 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
1386 sev_hv_features = get_hv_features();
1387
1388 if (!(sev_hv_features & GHCB_HV_FT_SNP))
1389 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
1390 }
1391
1392 /* Initialize per-cpu GHCB pages */
1393 for_each_possible_cpu(cpu) {
1394 alloc_runtime_data(cpu);
1395 init_ghcb(cpu);
1396 }
1397
1398 sev_es_setup_play_dead();
1399
1400 /* Secondary CPUs use the runtime #VC handler */
1401 initial_vc_handler = (unsigned long)kernel_exc_vmm_communication;
1402 }
1403
vc_early_forward_exception(struct es_em_ctxt * ctxt)1404 static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt)
1405 {
1406 int trapnr = ctxt->fi.vector;
1407
1408 if (trapnr == X86_TRAP_PF)
1409 native_write_cr2(ctxt->fi.cr2);
1410
1411 ctxt->regs->orig_ax = ctxt->fi.error_code;
1412 do_early_exception(ctxt->regs, trapnr);
1413 }
1414
vc_insn_get_rm(struct es_em_ctxt * ctxt)1415 static long *vc_insn_get_rm(struct es_em_ctxt *ctxt)
1416 {
1417 long *reg_array;
1418 int offset;
1419
1420 reg_array = (long *)ctxt->regs;
1421 offset = insn_get_modrm_rm_off(&ctxt->insn, ctxt->regs);
1422
1423 if (offset < 0)
1424 return NULL;
1425
1426 offset /= sizeof(long);
1427
1428 return reg_array + offset;
1429 }
vc_do_mmio(struct ghcb * ghcb,struct es_em_ctxt * ctxt,unsigned int bytes,bool read)1430 static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
1431 unsigned int bytes, bool read)
1432 {
1433 u64 exit_code, exit_info_1, exit_info_2;
1434 unsigned long ghcb_pa = __pa(ghcb);
1435 enum es_result res;
1436 phys_addr_t paddr;
1437 void __user *ref;
1438
1439 ref = insn_get_addr_ref(&ctxt->insn, ctxt->regs);
1440 if (ref == (void __user *)-1L)
1441 return ES_UNSUPPORTED;
1442
1443 exit_code = read ? SVM_VMGEXIT_MMIO_READ : SVM_VMGEXIT_MMIO_WRITE;
1444
1445 res = vc_slow_virt_to_phys(ghcb, ctxt, (unsigned long)ref, &paddr);
1446 if (res != ES_OK) {
1447 if (res == ES_EXCEPTION && !read)
1448 ctxt->fi.error_code |= X86_PF_WRITE;
1449
1450 return res;
1451 }
1452
1453 exit_info_1 = paddr;
1454 /* Can never be greater than 8 */
1455 exit_info_2 = bytes;
1456
1457 ghcb_set_sw_scratch(ghcb, ghcb_pa + offsetof(struct ghcb, shared_buffer));
1458
1459 return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2);
1460 }
1461
1462 /*
1463 * The MOVS instruction has two memory operands, which raises the
1464 * problem that it is not known whether the access to the source or the
1465 * destination caused the #VC exception (and hence whether an MMIO read
1466 * or write operation needs to be emulated).
1467 *
1468 * Instead of playing games with walking page-tables and trying to guess
1469 * whether the source or destination is an MMIO range, split the move
1470 * into two operations, a read and a write with only one memory operand.
1471 * This will cause a nested #VC exception on the MMIO address which can
1472 * then be handled.
1473 *
1474 * This implementation has the benefit that it also supports MOVS where
1475 * source _and_ destination are MMIO regions.
1476 *
1477 * It will slow MOVS on MMIO down a lot, but in SEV-ES guests it is a
1478 * rare operation. If it turns out to be a performance problem the split
1479 * operations can be moved to memcpy_fromio() and memcpy_toio().
1480 */
vc_handle_mmio_movs(struct es_em_ctxt * ctxt,unsigned int bytes)1481 static enum es_result vc_handle_mmio_movs(struct es_em_ctxt *ctxt,
1482 unsigned int bytes)
1483 {
1484 unsigned long ds_base, es_base;
1485 unsigned char *src, *dst;
1486 unsigned char buffer[8];
1487 enum es_result ret;
1488 bool rep;
1489 int off;
1490
1491 ds_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_DS);
1492 es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
1493
1494 if (ds_base == -1L || es_base == -1L) {
1495 ctxt->fi.vector = X86_TRAP_GP;
1496 ctxt->fi.error_code = 0;
1497 return ES_EXCEPTION;
1498 }
1499
1500 src = ds_base + (unsigned char *)ctxt->regs->si;
1501 dst = es_base + (unsigned char *)ctxt->regs->di;
1502
1503 ret = vc_read_mem(ctxt, src, buffer, bytes);
1504 if (ret != ES_OK)
1505 return ret;
1506
1507 ret = vc_write_mem(ctxt, dst, buffer, bytes);
1508 if (ret != ES_OK)
1509 return ret;
1510
1511 if (ctxt->regs->flags & X86_EFLAGS_DF)
1512 off = -bytes;
1513 else
1514 off = bytes;
1515
1516 ctxt->regs->si += off;
1517 ctxt->regs->di += off;
1518
1519 rep = insn_has_rep_prefix(&ctxt->insn);
1520 if (rep)
1521 ctxt->regs->cx -= 1;
1522
1523 if (!rep || ctxt->regs->cx == 0)
1524 return ES_OK;
1525 else
1526 return ES_RETRY;
1527 }
1528
vc_handle_mmio(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1529 static enum es_result vc_handle_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
1530 {
1531 struct insn *insn = &ctxt->insn;
1532 enum insn_mmio_type mmio;
1533 unsigned int bytes = 0;
1534 enum es_result ret;
1535 u8 sign_byte;
1536 long *reg_data;
1537
1538 mmio = insn_decode_mmio(insn, &bytes);
1539 if (mmio == INSN_MMIO_DECODE_FAILED)
1540 return ES_DECODE_FAILED;
1541
1542 if (mmio != INSN_MMIO_WRITE_IMM && mmio != INSN_MMIO_MOVS) {
1543 reg_data = insn_get_modrm_reg_ptr(insn, ctxt->regs);
1544 if (!reg_data)
1545 return ES_DECODE_FAILED;
1546 }
1547
1548 if (user_mode(ctxt->regs))
1549 return ES_UNSUPPORTED;
1550
1551 switch (mmio) {
1552 case INSN_MMIO_WRITE:
1553 memcpy(ghcb->shared_buffer, reg_data, bytes);
1554 ret = vc_do_mmio(ghcb, ctxt, bytes, false);
1555 break;
1556 case INSN_MMIO_WRITE_IMM:
1557 memcpy(ghcb->shared_buffer, insn->immediate1.bytes, bytes);
1558 ret = vc_do_mmio(ghcb, ctxt, bytes, false);
1559 break;
1560 case INSN_MMIO_READ:
1561 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
1562 if (ret)
1563 break;
1564
1565 /* Zero-extend for 32-bit operation */
1566 if (bytes == 4)
1567 *reg_data = 0;
1568
1569 memcpy(reg_data, ghcb->shared_buffer, bytes);
1570 break;
1571 case INSN_MMIO_READ_ZERO_EXTEND:
1572 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
1573 if (ret)
1574 break;
1575
1576 /* Zero extend based on operand size */
1577 memset(reg_data, 0, insn->opnd_bytes);
1578 memcpy(reg_data, ghcb->shared_buffer, bytes);
1579 break;
1580 case INSN_MMIO_READ_SIGN_EXTEND:
1581 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
1582 if (ret)
1583 break;
1584
1585 if (bytes == 1) {
1586 u8 *val = (u8 *)ghcb->shared_buffer;
1587
1588 sign_byte = (*val & 0x80) ? 0xff : 0x00;
1589 } else {
1590 u16 *val = (u16 *)ghcb->shared_buffer;
1591
1592 sign_byte = (*val & 0x8000) ? 0xff : 0x00;
1593 }
1594
1595 /* Sign extend based on operand size */
1596 memset(reg_data, sign_byte, insn->opnd_bytes);
1597 memcpy(reg_data, ghcb->shared_buffer, bytes);
1598 break;
1599 case INSN_MMIO_MOVS:
1600 ret = vc_handle_mmio_movs(ctxt, bytes);
1601 break;
1602 default:
1603 ret = ES_UNSUPPORTED;
1604 break;
1605 }
1606
1607 return ret;
1608 }
1609
vc_handle_dr7_write(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1610 static enum es_result vc_handle_dr7_write(struct ghcb *ghcb,
1611 struct es_em_ctxt *ctxt)
1612 {
1613 struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
1614 long val, *reg = vc_insn_get_rm(ctxt);
1615 enum es_result ret;
1616
1617 if (sev_status & MSR_AMD64_SNP_DEBUG_SWAP)
1618 return ES_VMM_ERROR;
1619
1620 if (!reg)
1621 return ES_DECODE_FAILED;
1622
1623 val = *reg;
1624
1625 /* Upper 32 bits must be written as zeroes */
1626 if (val >> 32) {
1627 ctxt->fi.vector = X86_TRAP_GP;
1628 ctxt->fi.error_code = 0;
1629 return ES_EXCEPTION;
1630 }
1631
1632 /* Clear out other reserved bits and set bit 10 */
1633 val = (val & 0xffff23ffL) | BIT(10);
1634
1635 /* Early non-zero writes to DR7 are not supported */
1636 if (!data && (val & ~DR7_RESET_VALUE))
1637 return ES_UNSUPPORTED;
1638
1639 /* Using a value of 0 for ExitInfo1 means RAX holds the value */
1640 ghcb_set_rax(ghcb, val);
1641 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WRITE_DR7, 0, 0);
1642 if (ret != ES_OK)
1643 return ret;
1644
1645 if (data)
1646 data->dr7 = val;
1647
1648 return ES_OK;
1649 }
1650
vc_handle_dr7_read(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1651 static enum es_result vc_handle_dr7_read(struct ghcb *ghcb,
1652 struct es_em_ctxt *ctxt)
1653 {
1654 struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
1655 long *reg = vc_insn_get_rm(ctxt);
1656
1657 if (sev_status & MSR_AMD64_SNP_DEBUG_SWAP)
1658 return ES_VMM_ERROR;
1659
1660 if (!reg)
1661 return ES_DECODE_FAILED;
1662
1663 if (data)
1664 *reg = data->dr7;
1665 else
1666 *reg = DR7_RESET_VALUE;
1667
1668 return ES_OK;
1669 }
1670
vc_handle_wbinvd(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1671 static enum es_result vc_handle_wbinvd(struct ghcb *ghcb,
1672 struct es_em_ctxt *ctxt)
1673 {
1674 return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0);
1675 }
1676
vc_handle_rdpmc(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1677 static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
1678 {
1679 enum es_result ret;
1680
1681 ghcb_set_rcx(ghcb, ctxt->regs->cx);
1682
1683 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDPMC, 0, 0);
1684 if (ret != ES_OK)
1685 return ret;
1686
1687 if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb)))
1688 return ES_VMM_ERROR;
1689
1690 ctxt->regs->ax = ghcb->save.rax;
1691 ctxt->regs->dx = ghcb->save.rdx;
1692
1693 return ES_OK;
1694 }
1695
vc_handle_monitor(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1696 static enum es_result vc_handle_monitor(struct ghcb *ghcb,
1697 struct es_em_ctxt *ctxt)
1698 {
1699 /*
1700 * Treat it as a NOP and do not leak a physical address to the
1701 * hypervisor.
1702 */
1703 return ES_OK;
1704 }
1705
vc_handle_mwait(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1706 static enum es_result vc_handle_mwait(struct ghcb *ghcb,
1707 struct es_em_ctxt *ctxt)
1708 {
1709 /* Treat the same as MONITOR/MONITORX */
1710 return ES_OK;
1711 }
1712
vc_handle_vmmcall(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1713 static enum es_result vc_handle_vmmcall(struct ghcb *ghcb,
1714 struct es_em_ctxt *ctxt)
1715 {
1716 enum es_result ret;
1717
1718 ghcb_set_rax(ghcb, ctxt->regs->ax);
1719 ghcb_set_cpl(ghcb, user_mode(ctxt->regs) ? 3 : 0);
1720
1721 if (x86_platform.hyper.sev_es_hcall_prepare)
1722 x86_platform.hyper.sev_es_hcall_prepare(ghcb, ctxt->regs);
1723
1724 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0);
1725 if (ret != ES_OK)
1726 return ret;
1727
1728 if (!ghcb_rax_is_valid(ghcb))
1729 return ES_VMM_ERROR;
1730
1731 ctxt->regs->ax = ghcb->save.rax;
1732
1733 /*
1734 * Call sev_es_hcall_finish() after regs->ax is already set.
1735 * This allows the hypervisor handler to overwrite it again if
1736 * necessary.
1737 */
1738 if (x86_platform.hyper.sev_es_hcall_finish &&
1739 !x86_platform.hyper.sev_es_hcall_finish(ghcb, ctxt->regs))
1740 return ES_VMM_ERROR;
1741
1742 return ES_OK;
1743 }
1744
vc_handle_trap_ac(struct ghcb * ghcb,struct es_em_ctxt * ctxt)1745 static enum es_result vc_handle_trap_ac(struct ghcb *ghcb,
1746 struct es_em_ctxt *ctxt)
1747 {
1748 /*
1749 * Calling ecx_alignment_check() directly does not work, because it
1750 * enables IRQs and the GHCB is active. Forward the exception and call
1751 * it later from vc_forward_exception().
1752 */
1753 ctxt->fi.vector = X86_TRAP_AC;
1754 ctxt->fi.error_code = 0;
1755 return ES_EXCEPTION;
1756 }
1757
vc_handle_exitcode(struct es_em_ctxt * ctxt,struct ghcb * ghcb,unsigned long exit_code)1758 static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
1759 struct ghcb *ghcb,
1760 unsigned long exit_code)
1761 {
1762 enum es_result result = vc_check_opcode_bytes(ctxt, exit_code);
1763
1764 if (result != ES_OK)
1765 return result;
1766
1767 switch (exit_code) {
1768 case SVM_EXIT_READ_DR7:
1769 result = vc_handle_dr7_read(ghcb, ctxt);
1770 break;
1771 case SVM_EXIT_WRITE_DR7:
1772 result = vc_handle_dr7_write(ghcb, ctxt);
1773 break;
1774 case SVM_EXIT_EXCP_BASE + X86_TRAP_AC:
1775 result = vc_handle_trap_ac(ghcb, ctxt);
1776 break;
1777 case SVM_EXIT_RDTSC:
1778 case SVM_EXIT_RDTSCP:
1779 result = vc_handle_rdtsc(ghcb, ctxt, exit_code);
1780 break;
1781 case SVM_EXIT_RDPMC:
1782 result = vc_handle_rdpmc(ghcb, ctxt);
1783 break;
1784 case SVM_EXIT_INVD:
1785 pr_err_ratelimited("#VC exception for INVD??? Seriously???\n");
1786 result = ES_UNSUPPORTED;
1787 break;
1788 case SVM_EXIT_CPUID:
1789 result = vc_handle_cpuid(ghcb, ctxt);
1790 break;
1791 case SVM_EXIT_IOIO:
1792 result = vc_handle_ioio(ghcb, ctxt);
1793 break;
1794 case SVM_EXIT_MSR:
1795 result = vc_handle_msr(ghcb, ctxt);
1796 break;
1797 case SVM_EXIT_VMMCALL:
1798 result = vc_handle_vmmcall(ghcb, ctxt);
1799 break;
1800 case SVM_EXIT_WBINVD:
1801 result = vc_handle_wbinvd(ghcb, ctxt);
1802 break;
1803 case SVM_EXIT_MONITOR:
1804 result = vc_handle_monitor(ghcb, ctxt);
1805 break;
1806 case SVM_EXIT_MWAIT:
1807 result = vc_handle_mwait(ghcb, ctxt);
1808 break;
1809 case SVM_EXIT_NPF:
1810 result = vc_handle_mmio(ghcb, ctxt);
1811 break;
1812 default:
1813 /*
1814 * Unexpected #VC exception
1815 */
1816 result = ES_UNSUPPORTED;
1817 }
1818
1819 return result;
1820 }
1821
vc_forward_exception(struct es_em_ctxt * ctxt)1822 static __always_inline void vc_forward_exception(struct es_em_ctxt *ctxt)
1823 {
1824 long error_code = ctxt->fi.error_code;
1825 int trapnr = ctxt->fi.vector;
1826
1827 ctxt->regs->orig_ax = ctxt->fi.error_code;
1828
1829 switch (trapnr) {
1830 case X86_TRAP_GP:
1831 exc_general_protection(ctxt->regs, error_code);
1832 break;
1833 case X86_TRAP_UD:
1834 exc_invalid_op(ctxt->regs);
1835 break;
1836 case X86_TRAP_PF:
1837 write_cr2(ctxt->fi.cr2);
1838 exc_page_fault(ctxt->regs, error_code);
1839 break;
1840 case X86_TRAP_AC:
1841 exc_alignment_check(ctxt->regs, error_code);
1842 break;
1843 default:
1844 pr_emerg("Unsupported exception in #VC instruction emulation - can't continue\n");
1845 BUG();
1846 }
1847 }
1848
is_vc2_stack(unsigned long sp)1849 static __always_inline bool is_vc2_stack(unsigned long sp)
1850 {
1851 return (sp >= __this_cpu_ist_bottom_va(VC2) && sp < __this_cpu_ist_top_va(VC2));
1852 }
1853
vc_from_invalid_context(struct pt_regs * regs)1854 static __always_inline bool vc_from_invalid_context(struct pt_regs *regs)
1855 {
1856 unsigned long sp, prev_sp;
1857
1858 sp = (unsigned long)regs;
1859 prev_sp = regs->sp;
1860
1861 /*
1862 * If the code was already executing on the VC2 stack when the #VC
1863 * happened, let it proceed to the normal handling routine. This way the
1864 * code executing on the VC2 stack can cause #VC exceptions to get handled.
1865 */
1866 return is_vc2_stack(sp) && !is_vc2_stack(prev_sp);
1867 }
1868
vc_raw_handle_exception(struct pt_regs * regs,unsigned long error_code)1869 static bool vc_raw_handle_exception(struct pt_regs *regs, unsigned long error_code)
1870 {
1871 struct ghcb_state state;
1872 struct es_em_ctxt ctxt;
1873 enum es_result result;
1874 struct ghcb *ghcb;
1875 bool ret = true;
1876
1877 ghcb = __sev_get_ghcb(&state);
1878
1879 vc_ghcb_invalidate(ghcb);
1880 result = vc_init_em_ctxt(&ctxt, regs, error_code);
1881
1882 if (result == ES_OK)
1883 result = vc_handle_exitcode(&ctxt, ghcb, error_code);
1884
1885 __sev_put_ghcb(&state);
1886
1887 /* Done - now check the result */
1888 switch (result) {
1889 case ES_OK:
1890 vc_finish_insn(&ctxt);
1891 break;
1892 case ES_UNSUPPORTED:
1893 pr_err_ratelimited("Unsupported exit-code 0x%02lx in #VC exception (IP: 0x%lx)\n",
1894 error_code, regs->ip);
1895 ret = false;
1896 break;
1897 case ES_VMM_ERROR:
1898 pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n",
1899 error_code, regs->ip);
1900 ret = false;
1901 break;
1902 case ES_DECODE_FAILED:
1903 pr_err_ratelimited("Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n",
1904 error_code, regs->ip);
1905 ret = false;
1906 break;
1907 case ES_EXCEPTION:
1908 vc_forward_exception(&ctxt);
1909 break;
1910 case ES_RETRY:
1911 /* Nothing to do */
1912 break;
1913 default:
1914 pr_emerg("Unknown result in %s():%d\n", __func__, result);
1915 /*
1916 * Emulating the instruction which caused the #VC exception
1917 * failed - can't continue so print debug information
1918 */
1919 BUG();
1920 }
1921
1922 return ret;
1923 }
1924
vc_is_db(unsigned long error_code)1925 static __always_inline bool vc_is_db(unsigned long error_code)
1926 {
1927 return error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB;
1928 }
1929
1930 /*
1931 * Runtime #VC exception handler when raised from kernel mode. Runs in NMI mode
1932 * and will panic when an error happens.
1933 */
DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)1934 DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)
1935 {
1936 irqentry_state_t irq_state;
1937
1938 /*
1939 * With the current implementation it is always possible to switch to a
1940 * safe stack because #VC exceptions only happen at known places, like
1941 * intercepted instructions or accesses to MMIO areas/IO ports. They can
1942 * also happen with code instrumentation when the hypervisor intercepts
1943 * #DB, but the critical paths are forbidden to be instrumented, so #DB
1944 * exceptions currently also only happen in safe places.
1945 *
1946 * But keep this here in case the noinstr annotations are violated due
1947 * to bug elsewhere.
1948 */
1949 if (unlikely(vc_from_invalid_context(regs))) {
1950 instrumentation_begin();
1951 panic("Can't handle #VC exception from unsupported context\n");
1952 instrumentation_end();
1953 }
1954
1955 /*
1956 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
1957 */
1958 if (vc_is_db(error_code)) {
1959 exc_debug(regs);
1960 return;
1961 }
1962
1963 irq_state = irqentry_nmi_enter(regs);
1964
1965 instrumentation_begin();
1966
1967 if (!vc_raw_handle_exception(regs, error_code)) {
1968 /* Show some debug info */
1969 show_regs(regs);
1970
1971 /* Ask hypervisor to sev_es_terminate */
1972 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
1973
1974 /* If that fails and we get here - just panic */
1975 panic("Returned from Terminate-Request to Hypervisor\n");
1976 }
1977
1978 instrumentation_end();
1979 irqentry_nmi_exit(regs, irq_state);
1980 }
1981
1982 /*
1983 * Runtime #VC exception handler when raised from user mode. Runs in IRQ mode
1984 * and will kill the current task with SIGBUS when an error happens.
1985 */
DEFINE_IDTENTRY_VC_USER(exc_vmm_communication)1986 DEFINE_IDTENTRY_VC_USER(exc_vmm_communication)
1987 {
1988 /*
1989 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
1990 */
1991 if (vc_is_db(error_code)) {
1992 noist_exc_debug(regs);
1993 return;
1994 }
1995
1996 irqentry_enter_from_user_mode(regs);
1997 instrumentation_begin();
1998
1999 if (!vc_raw_handle_exception(regs, error_code)) {
2000 /*
2001 * Do not kill the machine if user-space triggered the
2002 * exception. Send SIGBUS instead and let user-space deal with
2003 * it.
2004 */
2005 force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0);
2006 }
2007
2008 instrumentation_end();
2009 irqentry_exit_to_user_mode(regs);
2010 }
2011
handle_vc_boot_ghcb(struct pt_regs * regs)2012 bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
2013 {
2014 unsigned long exit_code = regs->orig_ax;
2015 struct es_em_ctxt ctxt;
2016 enum es_result result;
2017
2018 vc_ghcb_invalidate(boot_ghcb);
2019
2020 result = vc_init_em_ctxt(&ctxt, regs, exit_code);
2021 if (result == ES_OK)
2022 result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code);
2023
2024 /* Done - now check the result */
2025 switch (result) {
2026 case ES_OK:
2027 vc_finish_insn(&ctxt);
2028 break;
2029 case ES_UNSUPPORTED:
2030 early_printk("PANIC: Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n",
2031 exit_code, regs->ip);
2032 goto fail;
2033 case ES_VMM_ERROR:
2034 early_printk("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n",
2035 exit_code, regs->ip);
2036 goto fail;
2037 case ES_DECODE_FAILED:
2038 early_printk("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n",
2039 exit_code, regs->ip);
2040 goto fail;
2041 case ES_EXCEPTION:
2042 vc_early_forward_exception(&ctxt);
2043 break;
2044 case ES_RETRY:
2045 /* Nothing to do */
2046 break;
2047 default:
2048 BUG();
2049 }
2050
2051 return true;
2052
2053 fail:
2054 show_regs(regs);
2055
2056 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
2057 }
2058
2059 /*
2060 * Initial set up of SNP relies on information provided by the
2061 * Confidential Computing blob, which can be passed to the kernel
2062 * in the following ways, depending on how it is booted:
2063 *
2064 * - when booted via the boot/decompress kernel:
2065 * - via boot_params
2066 *
2067 * - when booted directly by firmware/bootloader (e.g. CONFIG_PVH):
2068 * - via a setup_data entry, as defined by the Linux Boot Protocol
2069 *
2070 * Scan for the blob in that order.
2071 */
find_cc_blob(struct boot_params * bp)2072 static __head struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
2073 {
2074 struct cc_blob_sev_info *cc_info;
2075
2076 /* Boot kernel would have passed the CC blob via boot_params. */
2077 if (bp->cc_blob_address) {
2078 cc_info = (struct cc_blob_sev_info *)(unsigned long)bp->cc_blob_address;
2079 goto found_cc_info;
2080 }
2081
2082 /*
2083 * If kernel was booted directly, without the use of the
2084 * boot/decompression kernel, the CC blob may have been passed via
2085 * setup_data instead.
2086 */
2087 cc_info = find_cc_blob_setup_data(bp);
2088 if (!cc_info)
2089 return NULL;
2090
2091 found_cc_info:
2092 if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
2093 snp_abort();
2094
2095 return cc_info;
2096 }
2097
snp_init(struct boot_params * bp)2098 bool __head snp_init(struct boot_params *bp)
2099 {
2100 struct cc_blob_sev_info *cc_info;
2101
2102 if (!bp)
2103 return false;
2104
2105 cc_info = find_cc_blob(bp);
2106 if (!cc_info)
2107 return false;
2108
2109 setup_cpuid_table(cc_info);
2110
2111 /*
2112 * The CC blob will be used later to access the secrets page. Cache
2113 * it here like the boot kernel does.
2114 */
2115 bp->cc_blob_address = (u32)(unsigned long)cc_info;
2116
2117 return true;
2118 }
2119
snp_abort(void)2120 void __head __noreturn snp_abort(void)
2121 {
2122 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
2123 }
2124
2125 /*
2126 * SEV-SNP guests should only execute dmi_setup() if EFI_CONFIG_TABLES are
2127 * enabled, as the alternative (fallback) logic for DMI probing in the legacy
2128 * ROM region can cause a crash since this region is not pre-validated.
2129 */
snp_dmi_setup(void)2130 void __init snp_dmi_setup(void)
2131 {
2132 if (efi_enabled(EFI_CONFIG_TABLES))
2133 dmi_setup();
2134 }
2135
dump_cpuid_table(void)2136 static void dump_cpuid_table(void)
2137 {
2138 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
2139 int i = 0;
2140
2141 pr_info("count=%d reserved=0x%x reserved2=0x%llx\n",
2142 cpuid_table->count, cpuid_table->__reserved1, cpuid_table->__reserved2);
2143
2144 for (i = 0; i < SNP_CPUID_COUNT_MAX; i++) {
2145 const struct snp_cpuid_fn *fn = &cpuid_table->fn[i];
2146
2147 pr_info("index=%3d fn=0x%08x subfn=0x%08x: eax=0x%08x ebx=0x%08x ecx=0x%08x edx=0x%08x xcr0_in=0x%016llx xss_in=0x%016llx reserved=0x%016llx\n",
2148 i, fn->eax_in, fn->ecx_in, fn->eax, fn->ebx, fn->ecx,
2149 fn->edx, fn->xcr0_in, fn->xss_in, fn->__reserved);
2150 }
2151 }
2152
2153 /*
2154 * It is useful from an auditing/testing perspective to provide an easy way
2155 * for the guest owner to know that the CPUID table has been initialized as
2156 * expected, but that initialization happens too early in boot to print any
2157 * sort of indicator, and there's not really any other good place to do it,
2158 * so do it here.
2159 */
report_cpuid_table(void)2160 static int __init report_cpuid_table(void)
2161 {
2162 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
2163
2164 if (!cpuid_table->count)
2165 return 0;
2166
2167 pr_info("Using SNP CPUID table, %d entries present.\n",
2168 cpuid_table->count);
2169
2170 if (sev_cfg.debug)
2171 dump_cpuid_table();
2172
2173 return 0;
2174 }
2175 arch_initcall(report_cpuid_table);
2176
init_sev_config(char * str)2177 static int __init init_sev_config(char *str)
2178 {
2179 char *s;
2180
2181 while ((s = strsep(&str, ","))) {
2182 if (!strcmp(s, "debug")) {
2183 sev_cfg.debug = true;
2184 continue;
2185 }
2186
2187 pr_info("SEV command-line option '%s' was not recognized\n", s);
2188 }
2189
2190 return 1;
2191 }
2192 __setup("sev=", init_sev_config);
2193
snp_issue_guest_request(u64 exit_code,struct snp_req_data * input,struct snp_guest_request_ioctl * rio)2194 int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
2195 {
2196 struct ghcb_state state;
2197 struct es_em_ctxt ctxt;
2198 unsigned long flags;
2199 struct ghcb *ghcb;
2200 int ret;
2201
2202 rio->exitinfo2 = SEV_RET_NO_FW_CALL;
2203
2204 /*
2205 * __sev_get_ghcb() needs to run with IRQs disabled because it is using
2206 * a per-CPU GHCB.
2207 */
2208 local_irq_save(flags);
2209
2210 ghcb = __sev_get_ghcb(&state);
2211 if (!ghcb) {
2212 ret = -EIO;
2213 goto e_restore_irq;
2214 }
2215
2216 vc_ghcb_invalidate(ghcb);
2217
2218 if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
2219 ghcb_set_rax(ghcb, input->data_gpa);
2220 ghcb_set_rbx(ghcb, input->data_npages);
2221 }
2222
2223 ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
2224 if (ret)
2225 goto e_put;
2226
2227 rio->exitinfo2 = ghcb->save.sw_exit_info_2;
2228 switch (rio->exitinfo2) {
2229 case 0:
2230 break;
2231
2232 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY):
2233 ret = -EAGAIN;
2234 break;
2235
2236 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
2237 /* Number of expected pages are returned in RBX */
2238 if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
2239 input->data_npages = ghcb_get_rbx(ghcb);
2240 ret = -ENOSPC;
2241 break;
2242 }
2243 fallthrough;
2244 default:
2245 ret = -EIO;
2246 break;
2247 }
2248
2249 e_put:
2250 __sev_put_ghcb(&state);
2251 e_restore_irq:
2252 local_irq_restore(flags);
2253
2254 return ret;
2255 }
2256 EXPORT_SYMBOL_GPL(snp_issue_guest_request);
2257
2258 static struct platform_device sev_guest_device = {
2259 .name = "sev-guest",
2260 .id = -1,
2261 };
2262
snp_init_platform_device(void)2263 static int __init snp_init_platform_device(void)
2264 {
2265 struct sev_guest_platform_data data;
2266 u64 gpa;
2267
2268 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
2269 return -ENODEV;
2270
2271 gpa = get_secrets_page();
2272 if (!gpa)
2273 return -ENODEV;
2274
2275 data.secrets_gpa = gpa;
2276 if (platform_device_add_data(&sev_guest_device, &data, sizeof(data)))
2277 return -ENODEV;
2278
2279 if (platform_device_register(&sev_guest_device))
2280 return -ENODEV;
2281
2282 pr_info("SNP guest platform device initialized.\n");
2283 return 0;
2284 }
2285 device_initcall(snp_init_platform_device);
2286
sev_show_status(void)2287 void sev_show_status(void)
2288 {
2289 int i;
2290
2291 pr_info("Status: ");
2292 for (i = 0; i < MSR_AMD64_SNP_RESV_BIT; i++) {
2293 if (sev_status & BIT_ULL(i)) {
2294 if (!sev_status_feat_names[i])
2295 continue;
2296
2297 pr_cont("%s ", sev_status_feat_names[i]);
2298 }
2299 }
2300 pr_cont("\n");
2301 }
2302