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#include <linux/cc_platform.h>
23
24#include <asm/tlbflush.h>
25#include <asm/fixmap.h>
26#include <asm/setup.h>
27#include <asm/bootparam.h>
28#include <asm/set_memory.h>
29#include <asm/cacheflush.h>
30#include <asm/processor-flags.h>
31#include <asm/msr.h>
32#include <asm/cmdline.h>
33
34#include "mm_internal.h"
35
36/*
37 * Since SME related variables are set early in the boot process they must
38 * reside in the .data section so as not to be zeroed out when the .bss
39 * section is later cleared.
40 */
41u64 sme_me_mask __section(".data") = 0;
42u64 sev_status __section(".data") = 0;
43u64 sev_check_data __section(".data") = 0;
44EXPORT_SYMBOL(sme_me_mask);
45DEFINE_STATIC_KEY_FALSE(sev_enable_key);
46EXPORT_SYMBOL_GPL(sev_enable_key);
47
48bool sev_enabled __section(".data");
49
50/* Buffer used for early in-place encryption by BSP, no locking needed */
51static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE);
52
53/*
54 * This routine does not change the underlying encryption setting of the
55 * page(s) that map this memory. It assumes that eventually the memory is
56 * meant to be accessed as either encrypted or decrypted but the contents
57 * are currently not in the desired state.
58 *
59 * This routine follows the steps outlined in the AMD64 Architecture
60 * Programmer's Manual Volume 2, Section 7.10.8 Encrypt-in-Place.
61 */
62static void __init __sme_early_enc_dec(resource_size_t paddr,
63				       unsigned long size, bool enc)
64{
65	void *src, *dst;
66	size_t len;
67
68	if (!sme_me_mask)
69		return;
70
71	wbinvd();
72
73	/*
74	 * There are limited number of early mapping slots, so map (at most)
75	 * one page at time.
76	 */
77	while (size) {
78		len = min_t(size_t, sizeof(sme_early_buffer), size);
79
80		/*
81		 * Create mappings for the current and desired format of
82		 * the memory. Use a write-protected mapping for the source.
83		 */
84		src = enc ? early_memremap_decrypted_wp(paddr, len) :
85			    early_memremap_encrypted_wp(paddr, len);
86
87		dst = enc ? early_memremap_encrypted(paddr, len) :
88			    early_memremap_decrypted(paddr, len);
89
90		/*
91		 * If a mapping can't be obtained to perform the operation,
92		 * then eventual access of that area in the desired mode
93		 * will cause a crash.
94		 */
95		BUG_ON(!src || !dst);
96
97		/*
98		 * Use a temporary buffer, of cache-line multiple size, to
99		 * avoid data corruption as documented in the APM.
100		 */
101		memcpy(sme_early_buffer, src, len);
102		memcpy(dst, sme_early_buffer, len);
103
104		early_memunmap(dst, len);
105		early_memunmap(src, len);
106
107		paddr += len;
108		size -= len;
109	}
110}
111
112void __init sme_early_encrypt(resource_size_t paddr, unsigned long size)
113{
114	__sme_early_enc_dec(paddr, size, true);
115}
116
117void __init sme_early_decrypt(resource_size_t paddr, unsigned long size)
118{
119	__sme_early_enc_dec(paddr, size, false);
120}
121
122static void __init __sme_early_map_unmap_mem(void *vaddr, unsigned long size,
123					     bool map)
124{
125	unsigned long paddr = (unsigned long)vaddr - __PAGE_OFFSET;
126	pmdval_t pmd_flags, pmd;
127
128	/* Use early_pmd_flags but remove the encryption mask */
129	pmd_flags = __sme_clr(early_pmd_flags);
130
131	do {
132		pmd = map ? (paddr & PMD_MASK) + pmd_flags : 0;
133		__early_make_pgtable((unsigned long)vaddr, pmd);
134
135		vaddr += PMD_SIZE;
136		paddr += PMD_SIZE;
137		size = (size <= PMD_SIZE) ? 0 : size - PMD_SIZE;
138	} while (size);
139
140	flush_tlb_local();
141}
142
143void __init sme_unmap_bootdata(char *real_mode_data)
144{
145	struct boot_params *boot_data;
146	unsigned long cmdline_paddr;
147
148	if (!sme_active())
149		return;
150
151	/* Get the command line address before unmapping the real_mode_data */
152	boot_data = (struct boot_params *)real_mode_data;
153	cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
154
155	__sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), false);
156
157	if (!cmdline_paddr)
158		return;
159
160	__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, false);
161}
162
163void __init sme_map_bootdata(char *real_mode_data)
164{
165	struct boot_params *boot_data;
166	unsigned long cmdline_paddr;
167
168	if (!sme_active())
169		return;
170
171	__sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), true);
172
173	/* Get the command line address after mapping the real_mode_data */
174	boot_data = (struct boot_params *)real_mode_data;
175	cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
176
177	if (!cmdline_paddr)
178		return;
179
180	__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
181}
182
183void __init sme_early_init(void)
184{
185	unsigned int i;
186
187	if (!sme_me_mask)
188		return;
189
190	early_pmd_flags = __sme_set(early_pmd_flags);
191
192	__supported_pte_mask = __sme_set(__supported_pte_mask);
193
194	/* Update the protection map with memory encryption mask */
195	for (i = 0; i < ARRAY_SIZE(protection_map); i++)
196		protection_map[i] = pgprot_encrypted(protection_map[i]);
197
198	if (sev_active())
199		swiotlb_force = SWIOTLB_FORCE;
200}
201
202static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
203{
204	pgprot_t old_prot, new_prot;
205	unsigned long pfn, pa, size;
206	pte_t new_pte;
207
208	switch (level) {
209	case PG_LEVEL_4K:
210		pfn = pte_pfn(*kpte);
211		old_prot = pte_pgprot(*kpte);
212		break;
213	case PG_LEVEL_2M:
214		pfn = pmd_pfn(*(pmd_t *)kpte);
215		old_prot = pmd_pgprot(*(pmd_t *)kpte);
216		break;
217	case PG_LEVEL_1G:
218		pfn = pud_pfn(*(pud_t *)kpte);
219		old_prot = pud_pgprot(*(pud_t *)kpte);
220		break;
221	default:
222		return;
223	}
224
225	new_prot = old_prot;
226	if (enc)
227		pgprot_val(new_prot) |= _PAGE_ENC;
228	else
229		pgprot_val(new_prot) &= ~_PAGE_ENC;
230
231	/* If prot is same then do nothing. */
232	if (pgprot_val(old_prot) == pgprot_val(new_prot))
233		return;
234
235	pa = pfn << PAGE_SHIFT;
236	size = page_level_size(level);
237
238	/*
239	 * We are going to perform in-place en-/decryption and change the
240	 * physical page attribute from C=1 to C=0 or vice versa. Flush the
241	 * caches to ensure that data gets accessed with the correct C-bit.
242	 */
243	clflush_cache_range(__va(pa), size);
244
245	/* Encrypt/decrypt the contents in-place */
246	if (enc)
247		sme_early_encrypt(pa, size);
248	else
249		sme_early_decrypt(pa, size);
250
251	/* Change the page encryption mask. */
252	new_pte = pfn_pte(pfn, new_prot);
253	set_pte_atomic(kpte, new_pte);
254}
255
256static int __init early_set_memory_enc_dec(unsigned long vaddr,
257					   unsigned long size, bool enc)
258{
259	unsigned long vaddr_end, vaddr_next;
260	unsigned long psize, pmask;
261	int split_page_size_mask;
262	int level, ret;
263	pte_t *kpte;
264
265	vaddr_next = vaddr;
266	vaddr_end = vaddr + size;
267
268	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
269		kpte = lookup_address(vaddr, &level);
270		if (!kpte || pte_none(*kpte)) {
271			ret = 1;
272			goto out;
273		}
274
275		if (level == PG_LEVEL_4K) {
276			__set_clr_pte_enc(kpte, level, enc);
277			vaddr_next = (vaddr & PAGE_MASK) + PAGE_SIZE;
278			continue;
279		}
280
281		psize = page_level_size(level);
282		pmask = page_level_mask(level);
283
284		/*
285		 * Check whether we can change the large page in one go.
286		 * We request a split when the address is not aligned and
287		 * the number of pages to set/clear encryption bit is smaller
288		 * than the number of pages in the large page.
289		 */
290		if (vaddr == (vaddr & pmask) &&
291		    ((vaddr_end - vaddr) >= psize)) {
292			__set_clr_pte_enc(kpte, level, enc);
293			vaddr_next = (vaddr & pmask) + psize;
294			continue;
295		}
296
297		/*
298		 * The virtual address is part of a larger page, create the next
299		 * level page table mapping (4K or 2M). If it is part of a 2M
300		 * page then we request a split of the large page into 4K
301		 * chunks. A 1GB large page is split into 2M pages, resp.
302		 */
303		if (level == PG_LEVEL_2M)
304			split_page_size_mask = 0;
305		else
306			split_page_size_mask = 1 << PG_LEVEL_2M;
307
308		/*
309		 * kernel_physical_mapping_change() does not flush the TLBs, so
310		 * a TLB flush is required after we exit from the for loop.
311		 */
312		kernel_physical_mapping_change(__pa(vaddr & pmask),
313					       __pa((vaddr_end & pmask) + psize),
314					       split_page_size_mask);
315	}
316
317	ret = 0;
318
319out:
320	__flush_tlb_all();
321	return ret;
322}
323
324int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size)
325{
326	return early_set_memory_enc_dec(vaddr, size, false);
327}
328
329int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size)
330{
331	return early_set_memory_enc_dec(vaddr, size, true);
332}
333
334/*
335 * SME and SEV are very similar but they are not the same, so there are
336 * times that the kernel will need to distinguish between SME and SEV. The
337 * sme_active() and sev_active() functions are used for this.  When a
338 * distinction isn't needed, the mem_encrypt_active() function can be used.
339 *
340 * The trampoline code is a good example for this requirement.  Before
341 * paging is activated, SME will access all memory as decrypted, but SEV
342 * will access all memory as encrypted.  So, when APs are being brought
343 * up under SME the trampoline area cannot be encrypted, whereas under SEV
344 * the trampoline area must be encrypted.
345 */
346bool sme_active(void)
347{
348	return sme_me_mask && !sev_enabled;
349}
350
351bool sev_active(void)
352{
353	return sev_status & MSR_AMD64_SEV_ENABLED;
354}
355EXPORT_SYMBOL_GPL(sev_active);
356
357/* Needs to be called from non-instrumentable code */
358bool noinstr sev_es_active(void)
359{
360	return sev_status & MSR_AMD64_SEV_ES_ENABLED;
361}
362
363/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
364bool force_dma_unencrypted(struct device *dev)
365{
366	/*
367	 * For SEV, all DMA must be to unencrypted addresses.
368	 */
369	if (sev_active())
370		return true;
371
372	/*
373	 * For SME, all DMA must be to unencrypted addresses if the
374	 * device does not support DMA to addresses that include the
375	 * encryption mask.
376	 */
377	if (sme_active()) {
378		u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
379		u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
380						dev->bus_dma_limit);
381
382		if (dma_dev_mask <= dma_enc_mask)
383			return true;
384	}
385
386	return false;
387}
388
389void __init mem_encrypt_free_decrypted_mem(void)
390{
391	unsigned long vaddr, vaddr_end, npages;
392	int r;
393
394	vaddr = (unsigned long)__start_bss_decrypted_unused;
395	vaddr_end = (unsigned long)__end_bss_decrypted;
396	npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
397
398	/*
399	 * The unused memory range was mapped decrypted, change the encryption
400	 * attribute from decrypted to encrypted before freeing it.
401	 */
402	if (mem_encrypt_active()) {
403		r = set_memory_encrypted(vaddr, npages);
404		if (r) {
405			pr_warn("failed to free unused decrypted pages\n");
406			return;
407		}
408	}
409
410	free_init_pages("unused decrypted", vaddr, vaddr_end);
411}
412
413static void print_mem_encrypt_feature_info(void)
414{
415	pr_info("AMD Memory Encryption Features active:");
416
417	/* Secure Memory Encryption */
418	if (sme_active()) {
419		/*
420		 * SME is mutually exclusive with any of the SEV
421		 * features below.
422		 */
423		pr_cont(" SME\n");
424		return;
425	}
426
427	/* Secure Encrypted Virtualization */
428	if (sev_active())
429		pr_cont(" SEV");
430
431	/* Encrypted Register State */
432	if (sev_es_active())
433		pr_cont(" SEV-ES");
434
435	pr_cont("\n");
436}
437
438/* Architecture __weak replacement functions */
439void __init mem_encrypt_init(void)
440{
441	if (!sme_me_mask)
442		return;
443
444	/* Call into SWIOTLB to update the SWIOTLB DMA buffers */
445	swiotlb_update_mem_attributes();
446
447	/*
448	 * With SEV, we need to unroll the rep string I/O instructions.
449	 */
450	if (sev_active())
451		static_branch_enable(&sev_enable_key);
452
453	print_mem_encrypt_feature_info();
454}
455
456