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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AMD Memory Encryption Support
4 *
5 * Copyright (C) 2016 Advanced Micro Devices, Inc.
6 *
7 * Author: Tom Lendacky <thomas.lendacky@amd.com>
8 */
9
10#define DISABLE_BRANCH_PROFILING
11
12#include <linux/linkage.h>
13#include <linux/init.h>
14#include <linux/mm.h>
15#include <linux/dma-direct.h>
16#include <linux/swiotlb.h>
17#include <linux/mem_encrypt.h>
18#include <linux/device.h>
19#include <linux/kernel.h>
20#include <linux/bitops.h>
21#include <linux/dma-mapping.h>
22
23#include <asm/tlbflush.h>
24#include <asm/fixmap.h>
25#include <asm/setup.h>
26#include <asm/bootparam.h>
27#include <asm/set_memory.h>
28#include <asm/cacheflush.h>
29#include <asm/processor-flags.h>
30#include <asm/msr.h>
31#include <asm/cmdline.h>
32
33#include "mm_internal.h"
34
35/*
36 * Since SME related variables are set early in the boot process they must
37 * reside in the .data section so as not to be zeroed out when the .bss
38 * section is later cleared.
39 */
40u64 sme_me_mask __section(.data) = 0;
41EXPORT_SYMBOL(sme_me_mask);
42DEFINE_STATIC_KEY_FALSE(sev_enable_key);
43EXPORT_SYMBOL_GPL(sev_enable_key);
44
45bool sev_enabled __section(.data);
46
47/* Buffer used for early in-place encryption by BSP, no locking needed */
48static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE);
49
50/*
51 * This routine does not change the underlying encryption setting of the
52 * page(s) that map this memory. It assumes that eventually the memory is
53 * meant to be accessed as either encrypted or decrypted but the contents
54 * are currently not in the desired state.
55 *
56 * This routine follows the steps outlined in the AMD64 Architecture
57 * Programmer's Manual Volume 2, Section 7.10.8 Encrypt-in-Place.
58 */
59static void __init __sme_early_enc_dec(resource_size_t paddr,
60 unsigned long size, bool enc)
61{
62 void *src, *dst;
63 size_t len;
64
65 if (!sme_me_mask)
66 return;
67
68 wbinvd();
69
70 /*
71 * There are limited number of early mapping slots, so map (at most)
72 * one page at time.
73 */
74 while (size) {
75 len = min_t(size_t, sizeof(sme_early_buffer), size);
76
77 /*
78 * Create mappings for the current and desired format of
79 * the memory. Use a write-protected mapping for the source.
80 */
81 src = enc ? early_memremap_decrypted_wp(paddr, len) :
82 early_memremap_encrypted_wp(paddr, len);
83
84 dst = enc ? early_memremap_encrypted(paddr, len) :
85 early_memremap_decrypted(paddr, len);
86
87 /*
88 * If a mapping can't be obtained to perform the operation,
89 * then eventual access of that area in the desired mode
90 * will cause a crash.
91 */
92 BUG_ON(!src || !dst);
93
94 /*
95 * Use a temporary buffer, of cache-line multiple size, to
96 * avoid data corruption as documented in the APM.
97 */
98 memcpy(sme_early_buffer, src, len);
99 memcpy(dst, sme_early_buffer, len);
100
101 early_memunmap(dst, len);
102 early_memunmap(src, len);
103
104 paddr += len;
105 size -= len;
106 }
107}
108
109void __init sme_early_encrypt(resource_size_t paddr, unsigned long size)
110{
111 __sme_early_enc_dec(paddr, size, true);
112}
113
114void __init sme_early_decrypt(resource_size_t paddr, unsigned long size)
115{
116 __sme_early_enc_dec(paddr, size, false);
117}
118
119static void __init __sme_early_map_unmap_mem(void *vaddr, unsigned long size,
120 bool map)
121{
122 unsigned long paddr = (unsigned long)vaddr - __PAGE_OFFSET;
123 pmdval_t pmd_flags, pmd;
124
125 /* Use early_pmd_flags but remove the encryption mask */
126 pmd_flags = __sme_clr(early_pmd_flags);
127
128 do {
129 pmd = map ? (paddr & PMD_MASK) + pmd_flags : 0;
130 __early_make_pgtable((unsigned long)vaddr, pmd);
131
132 vaddr += PMD_SIZE;
133 paddr += PMD_SIZE;
134 size = (size <= PMD_SIZE) ? 0 : size - PMD_SIZE;
135 } while (size);
136
137 __native_flush_tlb();
138}
139
140void __init sme_unmap_bootdata(char *real_mode_data)
141{
142 struct boot_params *boot_data;
143 unsigned long cmdline_paddr;
144
145 if (!sme_active())
146 return;
147
148 /* Get the command line address before unmapping the real_mode_data */
149 boot_data = (struct boot_params *)real_mode_data;
150 cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
151
152 __sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), false);
153
154 if (!cmdline_paddr)
155 return;
156
157 __sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, false);
158}
159
160void __init sme_map_bootdata(char *real_mode_data)
161{
162 struct boot_params *boot_data;
163 unsigned long cmdline_paddr;
164
165 if (!sme_active())
166 return;
167
168 __sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), true);
169
170 /* Get the command line address after mapping the real_mode_data */
171 boot_data = (struct boot_params *)real_mode_data;
172 cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
173
174 if (!cmdline_paddr)
175 return;
176
177 __sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
178}
179
180void __init sme_early_init(void)
181{
182 unsigned int i;
183
184 if (!sme_me_mask)
185 return;
186
187 early_pmd_flags = __sme_set(early_pmd_flags);
188
189 __supported_pte_mask = __sme_set(__supported_pte_mask);
190
191 /* Update the protection map with memory encryption mask */
192 for (i = 0; i < ARRAY_SIZE(protection_map); i++)
193 protection_map[i] = pgprot_encrypted(protection_map[i]);
194
195 if (sev_active())
196 swiotlb_force = SWIOTLB_FORCE;
197}
198
199static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
200{
201 pgprot_t old_prot, new_prot;
202 unsigned long pfn, pa, size;
203 pte_t new_pte;
204
205 switch (level) {
206 case PG_LEVEL_4K:
207 pfn = pte_pfn(*kpte);
208 old_prot = pte_pgprot(*kpte);
209 break;
210 case PG_LEVEL_2M:
211 pfn = pmd_pfn(*(pmd_t *)kpte);
212 old_prot = pmd_pgprot(*(pmd_t *)kpte);
213 break;
214 case PG_LEVEL_1G:
215 pfn = pud_pfn(*(pud_t *)kpte);
216 old_prot = pud_pgprot(*(pud_t *)kpte);
217 break;
218 default:
219 return;
220 }
221
222 new_prot = old_prot;
223 if (enc)
224 pgprot_val(new_prot) |= _PAGE_ENC;
225 else
226 pgprot_val(new_prot) &= ~_PAGE_ENC;
227
228 /* If prot is same then do nothing. */
229 if (pgprot_val(old_prot) == pgprot_val(new_prot))
230 return;
231
232 pa = pfn << page_level_shift(level);
233 size = page_level_size(level);
234
235 /*
236 * We are going to perform in-place en-/decryption and change the
237 * physical page attribute from C=1 to C=0 or vice versa. Flush the
238 * caches to ensure that data gets accessed with the correct C-bit.
239 */
240 clflush_cache_range(__va(pa), size);
241
242 /* Encrypt/decrypt the contents in-place */
243 if (enc)
244 sme_early_encrypt(pa, size);
245 else
246 sme_early_decrypt(pa, size);
247
248 /* Change the page encryption mask. */
249 new_pte = pfn_pte(pfn, new_prot);
250 set_pte_atomic(kpte, new_pte);
251}
252
253static int __init early_set_memory_enc_dec(unsigned long vaddr,
254 unsigned long size, bool enc)
255{
256 unsigned long vaddr_end, vaddr_next;
257 unsigned long psize, pmask;
258 int split_page_size_mask;
259 int level, ret;
260 pte_t *kpte;
261
262 vaddr_next = vaddr;
263 vaddr_end = vaddr + size;
264
265 for (; vaddr < vaddr_end; vaddr = vaddr_next) {
266 kpte = lookup_address(vaddr, &level);
267 if (!kpte || pte_none(*kpte)) {
268 ret = 1;
269 goto out;
270 }
271
272 if (level == PG_LEVEL_4K) {
273 __set_clr_pte_enc(kpte, level, enc);
274 vaddr_next = (vaddr & PAGE_MASK) + PAGE_SIZE;
275 continue;
276 }
277
278 psize = page_level_size(level);
279 pmask = page_level_mask(level);
280
281 /*
282 * Check whether we can change the large page in one go.
283 * We request a split when the address is not aligned and
284 * the number of pages to set/clear encryption bit is smaller
285 * than the number of pages in the large page.
286 */
287 if (vaddr == (vaddr & pmask) &&
288 ((vaddr_end - vaddr) >= psize)) {
289 __set_clr_pte_enc(kpte, level, enc);
290 vaddr_next = (vaddr & pmask) + psize;
291 continue;
292 }
293
294 /*
295 * The virtual address is part of a larger page, create the next
296 * level page table mapping (4K or 2M). If it is part of a 2M
297 * page then we request a split of the large page into 4K
298 * chunks. A 1GB large page is split into 2M pages, resp.
299 */
300 if (level == PG_LEVEL_2M)
301 split_page_size_mask = 0;
302 else
303 split_page_size_mask = 1 << PG_LEVEL_2M;
304
305 /*
306 * kernel_physical_mapping_change() does not flush the TLBs, so
307 * a TLB flush is required after we exit from the for loop.
308 */
309 kernel_physical_mapping_change(__pa(vaddr & pmask),
310 __pa((vaddr_end & pmask) + psize),
311 split_page_size_mask);
312 }
313
314 ret = 0;
315
316out:
317 __flush_tlb_all();
318 return ret;
319}
320
321int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size)
322{
323 return early_set_memory_enc_dec(vaddr, size, false);
324}
325
326int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size)
327{
328 return early_set_memory_enc_dec(vaddr, size, true);
329}
330
331/*
332 * SME and SEV are very similar but they are not the same, so there are
333 * times that the kernel will need to distinguish between SME and SEV. The
334 * sme_active() and sev_active() functions are used for this. When a
335 * distinction isn't needed, the mem_encrypt_active() function can be used.
336 *
337 * The trampoline code is a good example for this requirement. Before
338 * paging is activated, SME will access all memory as decrypted, but SEV
339 * will access all memory as encrypted. So, when APs are being brought
340 * up under SME the trampoline area cannot be encrypted, whereas under SEV
341 * the trampoline area must be encrypted.
342 */
343bool sme_active(void)
344{
345 return sme_me_mask && !sev_enabled;
346}
347
348bool sev_active(void)
349{
350 return sme_me_mask && sev_enabled;
351}
352
353/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
354bool force_dma_unencrypted(struct device *dev)
355{
356 /*
357 * For SEV, all DMA must be to unencrypted addresses.
358 */
359 if (sev_active())
360 return true;
361
362 /*
363 * For SME, all DMA must be to unencrypted addresses if the
364 * device does not support DMA to addresses that include the
365 * encryption mask.
366 */
367 if (sme_active()) {
368 u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
369 u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
370 dev->bus_dma_mask);
371
372 if (dma_dev_mask <= dma_enc_mask)
373 return true;
374 }
375
376 return false;
377}
378
379/* Architecture __weak replacement functions */
380void __init mem_encrypt_free_decrypted_mem(void)
381{
382 unsigned long vaddr, vaddr_end, npages;
383 int r;
384
385 vaddr = (unsigned long)__start_bss_decrypted_unused;
386 vaddr_end = (unsigned long)__end_bss_decrypted;
387 npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
388
389 /*
390 * The unused memory range was mapped decrypted, change the encryption
391 * attribute from decrypted to encrypted before freeing it.
392 */
393 if (mem_encrypt_active()) {
394 r = set_memory_encrypted(vaddr, npages);
395 if (r) {
396 pr_warn("failed to free unused decrypted pages\n");
397 return;
398 }
399 }
400
401 free_init_pages("unused decrypted", vaddr, vaddr_end);
402}
403
404void __init mem_encrypt_init(void)
405{
406 if (!sme_me_mask)
407 return;
408
409 /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
410 swiotlb_update_mem_attributes();
411
412 /*
413 * With SEV, we need to unroll the rep string I/O instructions.
414 */
415 if (sev_active())
416 static_branch_enable(&sev_enable_key);
417
418 pr_info("AMD %s active\n",
419 sev_active() ? "Secure Encrypted Virtualization (SEV)"
420 : "Secure Memory Encryption (SME)");
421}
422
1/*
2 * AMD Memory Encryption Support
3 *
4 * Copyright (C) 2016 Advanced Micro Devices, Inc.
5 *
6 * Author: Tom Lendacky <thomas.lendacky@amd.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#define DISABLE_BRANCH_PROFILING
14
15#include <linux/linkage.h>
16#include <linux/init.h>
17#include <linux/mm.h>
18#include <linux/dma-direct.h>
19#include <linux/swiotlb.h>
20#include <linux/mem_encrypt.h>
21
22#include <asm/tlbflush.h>
23#include <asm/fixmap.h>
24#include <asm/setup.h>
25#include <asm/bootparam.h>
26#include <asm/set_memory.h>
27#include <asm/cacheflush.h>
28#include <asm/processor-flags.h>
29#include <asm/msr.h>
30#include <asm/cmdline.h>
31
32#include "mm_internal.h"
33
34/*
35 * Since SME related variables are set early in the boot process they must
36 * reside in the .data section so as not to be zeroed out when the .bss
37 * section is later cleared.
38 */
39u64 sme_me_mask __section(.data) = 0;
40EXPORT_SYMBOL(sme_me_mask);
41DEFINE_STATIC_KEY_FALSE(sev_enable_key);
42EXPORT_SYMBOL_GPL(sev_enable_key);
43
44bool sev_enabled __section(.data);
45
46/* Buffer used for early in-place encryption by BSP, no locking needed */
47static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE);
48
49/*
50 * This routine does not change the underlying encryption setting of the
51 * page(s) that map this memory. It assumes that eventually the memory is
52 * meant to be accessed as either encrypted or decrypted but the contents
53 * are currently not in the desired state.
54 *
55 * This routine follows the steps outlined in the AMD64 Architecture
56 * Programmer's Manual Volume 2, Section 7.10.8 Encrypt-in-Place.
57 */
58static void __init __sme_early_enc_dec(resource_size_t paddr,
59 unsigned long size, bool enc)
60{
61 void *src, *dst;
62 size_t len;
63
64 if (!sme_me_mask)
65 return;
66
67 wbinvd();
68
69 /*
70 * There are limited number of early mapping slots, so map (at most)
71 * one page at time.
72 */
73 while (size) {
74 len = min_t(size_t, sizeof(sme_early_buffer), size);
75
76 /*
77 * Create mappings for the current and desired format of
78 * the memory. Use a write-protected mapping for the source.
79 */
80 src = enc ? early_memremap_decrypted_wp(paddr, len) :
81 early_memremap_encrypted_wp(paddr, len);
82
83 dst = enc ? early_memremap_encrypted(paddr, len) :
84 early_memremap_decrypted(paddr, len);
85
86 /*
87 * If a mapping can't be obtained to perform the operation,
88 * then eventual access of that area in the desired mode
89 * will cause a crash.
90 */
91 BUG_ON(!src || !dst);
92
93 /*
94 * Use a temporary buffer, of cache-line multiple size, to
95 * avoid data corruption as documented in the APM.
96 */
97 memcpy(sme_early_buffer, src, len);
98 memcpy(dst, sme_early_buffer, len);
99
100 early_memunmap(dst, len);
101 early_memunmap(src, len);
102
103 paddr += len;
104 size -= len;
105 }
106}
107
108void __init sme_early_encrypt(resource_size_t paddr, unsigned long size)
109{
110 __sme_early_enc_dec(paddr, size, true);
111}
112
113void __init sme_early_decrypt(resource_size_t paddr, unsigned long size)
114{
115 __sme_early_enc_dec(paddr, size, false);
116}
117
118static void __init __sme_early_map_unmap_mem(void *vaddr, unsigned long size,
119 bool map)
120{
121 unsigned long paddr = (unsigned long)vaddr - __PAGE_OFFSET;
122 pmdval_t pmd_flags, pmd;
123
124 /* Use early_pmd_flags but remove the encryption mask */
125 pmd_flags = __sme_clr(early_pmd_flags);
126
127 do {
128 pmd = map ? (paddr & PMD_MASK) + pmd_flags : 0;
129 __early_make_pgtable((unsigned long)vaddr, pmd);
130
131 vaddr += PMD_SIZE;
132 paddr += PMD_SIZE;
133 size = (size <= PMD_SIZE) ? 0 : size - PMD_SIZE;
134 } while (size);
135
136 __native_flush_tlb();
137}
138
139void __init sme_unmap_bootdata(char *real_mode_data)
140{
141 struct boot_params *boot_data;
142 unsigned long cmdline_paddr;
143
144 if (!sme_active())
145 return;
146
147 /* Get the command line address before unmapping the real_mode_data */
148 boot_data = (struct boot_params *)real_mode_data;
149 cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
150
151 __sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), false);
152
153 if (!cmdline_paddr)
154 return;
155
156 __sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, false);
157}
158
159void __init sme_map_bootdata(char *real_mode_data)
160{
161 struct boot_params *boot_data;
162 unsigned long cmdline_paddr;
163
164 if (!sme_active())
165 return;
166
167 __sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), true);
168
169 /* Get the command line address after mapping the real_mode_data */
170 boot_data = (struct boot_params *)real_mode_data;
171 cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
172
173 if (!cmdline_paddr)
174 return;
175
176 __sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
177}
178
179void __init sme_early_init(void)
180{
181 unsigned int i;
182
183 if (!sme_me_mask)
184 return;
185
186 early_pmd_flags = __sme_set(early_pmd_flags);
187
188 __supported_pte_mask = __sme_set(__supported_pte_mask);
189
190 /* Update the protection map with memory encryption mask */
191 for (i = 0; i < ARRAY_SIZE(protection_map); i++)
192 protection_map[i] = pgprot_encrypted(protection_map[i]);
193
194 if (sev_active())
195 swiotlb_force = SWIOTLB_FORCE;
196}
197
198static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
199{
200 pgprot_t old_prot, new_prot;
201 unsigned long pfn, pa, size;
202 pte_t new_pte;
203
204 switch (level) {
205 case PG_LEVEL_4K:
206 pfn = pte_pfn(*kpte);
207 old_prot = pte_pgprot(*kpte);
208 break;
209 case PG_LEVEL_2M:
210 pfn = pmd_pfn(*(pmd_t *)kpte);
211 old_prot = pmd_pgprot(*(pmd_t *)kpte);
212 break;
213 case PG_LEVEL_1G:
214 pfn = pud_pfn(*(pud_t *)kpte);
215 old_prot = pud_pgprot(*(pud_t *)kpte);
216 break;
217 default:
218 return;
219 }
220
221 new_prot = old_prot;
222 if (enc)
223 pgprot_val(new_prot) |= _PAGE_ENC;
224 else
225 pgprot_val(new_prot) &= ~_PAGE_ENC;
226
227 /* If prot is same then do nothing. */
228 if (pgprot_val(old_prot) == pgprot_val(new_prot))
229 return;
230
231 pa = pfn << page_level_shift(level);
232 size = page_level_size(level);
233
234 /*
235 * We are going to perform in-place en-/decryption and change the
236 * physical page attribute from C=1 to C=0 or vice versa. Flush the
237 * caches to ensure that data gets accessed with the correct C-bit.
238 */
239 clflush_cache_range(__va(pa), size);
240
241 /* Encrypt/decrypt the contents in-place */
242 if (enc)
243 sme_early_encrypt(pa, size);
244 else
245 sme_early_decrypt(pa, size);
246
247 /* Change the page encryption mask. */
248 new_pte = pfn_pte(pfn, new_prot);
249 set_pte_atomic(kpte, new_pte);
250}
251
252static int __init early_set_memory_enc_dec(unsigned long vaddr,
253 unsigned long size, bool enc)
254{
255 unsigned long vaddr_end, vaddr_next;
256 unsigned long psize, pmask;
257 int split_page_size_mask;
258 int level, ret;
259 pte_t *kpte;
260
261 vaddr_next = vaddr;
262 vaddr_end = vaddr + size;
263
264 for (; vaddr < vaddr_end; vaddr = vaddr_next) {
265 kpte = lookup_address(vaddr, &level);
266 if (!kpte || pte_none(*kpte)) {
267 ret = 1;
268 goto out;
269 }
270
271 if (level == PG_LEVEL_4K) {
272 __set_clr_pte_enc(kpte, level, enc);
273 vaddr_next = (vaddr & PAGE_MASK) + PAGE_SIZE;
274 continue;
275 }
276
277 psize = page_level_size(level);
278 pmask = page_level_mask(level);
279
280 /*
281 * Check whether we can change the large page in one go.
282 * We request a split when the address is not aligned and
283 * the number of pages to set/clear encryption bit is smaller
284 * than the number of pages in the large page.
285 */
286 if (vaddr == (vaddr & pmask) &&
287 ((vaddr_end - vaddr) >= psize)) {
288 __set_clr_pte_enc(kpte, level, enc);
289 vaddr_next = (vaddr & pmask) + psize;
290 continue;
291 }
292
293 /*
294 * The virtual address is part of a larger page, create the next
295 * level page table mapping (4K or 2M). If it is part of a 2M
296 * page then we request a split of the large page into 4K
297 * chunks. A 1GB large page is split into 2M pages, resp.
298 */
299 if (level == PG_LEVEL_2M)
300 split_page_size_mask = 0;
301 else
302 split_page_size_mask = 1 << PG_LEVEL_2M;
303
304 kernel_physical_mapping_init(__pa(vaddr & pmask),
305 __pa((vaddr_end & pmask) + psize),
306 split_page_size_mask);
307 }
308
309 ret = 0;
310
311out:
312 __flush_tlb_all();
313 return ret;
314}
315
316int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size)
317{
318 return early_set_memory_enc_dec(vaddr, size, false);
319}
320
321int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size)
322{
323 return early_set_memory_enc_dec(vaddr, size, true);
324}
325
326/*
327 * SME and SEV are very similar but they are not the same, so there are
328 * times that the kernel will need to distinguish between SME and SEV. The
329 * sme_active() and sev_active() functions are used for this. When a
330 * distinction isn't needed, the mem_encrypt_active() function can be used.
331 *
332 * The trampoline code is a good example for this requirement. Before
333 * paging is activated, SME will access all memory as decrypted, but SEV
334 * will access all memory as encrypted. So, when APs are being brought
335 * up under SME the trampoline area cannot be encrypted, whereas under SEV
336 * the trampoline area must be encrypted.
337 */
338bool sme_active(void)
339{
340 return sme_me_mask && !sev_enabled;
341}
342EXPORT_SYMBOL(sme_active);
343
344bool sev_active(void)
345{
346 return sme_me_mask && sev_enabled;
347}
348EXPORT_SYMBOL(sev_active);
349
350/* Architecture __weak replacement functions */
351void __init mem_encrypt_init(void)
352{
353 if (!sme_me_mask)
354 return;
355
356 /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
357 swiotlb_update_mem_attributes();
358
359 /*
360 * With SEV, DMA operations cannot use encryption, we need to use
361 * SWIOTLB to bounce buffer DMA operation.
362 */
363 if (sev_active())
364 dma_ops = &swiotlb_dma_ops;
365
366 /*
367 * With SEV, we need to unroll the rep string I/O instructions.
368 */
369 if (sev_active())
370 static_branch_enable(&sev_enable_key);
371
372 pr_info("AMD %s active\n",
373 sev_active() ? "Secure Encrypted Virtualization (SEV)"
374 : "Secure Memory Encryption (SME)");
375}
376