1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Apple DART page table allocator.
4 *
5 * Copyright (C) 2022 The Asahi Linux Contributors
6 *
7 * Based on io-pgtable-arm.
8 *
9 * Copyright (C) 2014 ARM Limited
10 *
11 * Author: Will Deacon <will.deacon@arm.com>
12 */
13
14 #define pr_fmt(fmt) "dart io-pgtable: " fmt
15
16 #include <linux/atomic.h>
17 #include <linux/bitfield.h>
18 #include <linux/bitops.h>
19 #include <linux/io-pgtable.h>
20 #include <linux/kernel.h>
21 #include <linux/sizes.h>
22 #include <linux/slab.h>
23 #include <linux/types.h>
24
25 #include <asm/barrier.h>
26
27 #define DART1_MAX_ADDR_BITS 36
28
29 #define DART_MAX_TABLES 4
30 #define DART_LEVELS 2
31
32 /* Struct accessors */
33 #define io_pgtable_to_data(x) \
34 container_of((x), struct dart_io_pgtable, iop)
35
36 #define io_pgtable_ops_to_data(x) \
37 io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))
38
39 #define DART_GRANULE(d) \
40 (sizeof(dart_iopte) << (d)->bits_per_level)
41 #define DART_PTES_PER_TABLE(d) \
42 (DART_GRANULE(d) >> ilog2(sizeof(dart_iopte)))
43
44 #define APPLE_DART_PTE_SUBPAGE_START GENMASK_ULL(63, 52)
45 #define APPLE_DART_PTE_SUBPAGE_END GENMASK_ULL(51, 40)
46
47 #define APPLE_DART1_PADDR_MASK GENMASK_ULL(35, 12)
48 #define APPLE_DART2_PADDR_MASK GENMASK_ULL(37, 10)
49 #define APPLE_DART2_PADDR_SHIFT (4)
50
51 /* Apple DART1 protection bits */
52 #define APPLE_DART1_PTE_PROT_NO_READ BIT(8)
53 #define APPLE_DART1_PTE_PROT_NO_WRITE BIT(7)
54 #define APPLE_DART1_PTE_PROT_SP_DIS BIT(1)
55
56 /* Apple DART2 protection bits */
57 #define APPLE_DART2_PTE_PROT_NO_READ BIT(3)
58 #define APPLE_DART2_PTE_PROT_NO_WRITE BIT(2)
59 #define APPLE_DART2_PTE_PROT_NO_CACHE BIT(1)
60
61 /* marks PTE as valid */
62 #define APPLE_DART_PTE_VALID BIT(0)
63
64 /* IOPTE accessors */
65 #define iopte_deref(pte, d) __va(iopte_to_paddr(pte, d))
66
67 struct dart_io_pgtable {
68 struct io_pgtable iop;
69
70 int tbl_bits;
71 int bits_per_level;
72
73 void *pgd[DART_MAX_TABLES];
74 };
75
76 typedef u64 dart_iopte;
77
78
paddr_to_iopte(phys_addr_t paddr,struct dart_io_pgtable * data)79 static dart_iopte paddr_to_iopte(phys_addr_t paddr,
80 struct dart_io_pgtable *data)
81 {
82 dart_iopte pte;
83
84 if (data->iop.fmt == APPLE_DART)
85 return paddr & APPLE_DART1_PADDR_MASK;
86
87 /* format is APPLE_DART2 */
88 pte = paddr >> APPLE_DART2_PADDR_SHIFT;
89 pte &= APPLE_DART2_PADDR_MASK;
90
91 return pte;
92 }
93
iopte_to_paddr(dart_iopte pte,struct dart_io_pgtable * data)94 static phys_addr_t iopte_to_paddr(dart_iopte pte,
95 struct dart_io_pgtable *data)
96 {
97 u64 paddr;
98
99 if (data->iop.fmt == APPLE_DART)
100 return pte & APPLE_DART1_PADDR_MASK;
101
102 /* format is APPLE_DART2 */
103 paddr = pte & APPLE_DART2_PADDR_MASK;
104 paddr <<= APPLE_DART2_PADDR_SHIFT;
105
106 return paddr;
107 }
108
__dart_alloc_pages(size_t size,gfp_t gfp,struct io_pgtable_cfg * cfg)109 static void *__dart_alloc_pages(size_t size, gfp_t gfp,
110 struct io_pgtable_cfg *cfg)
111 {
112 int order = get_order(size);
113 struct page *p;
114
115 VM_BUG_ON((gfp & __GFP_HIGHMEM));
116 p = alloc_pages(gfp | __GFP_ZERO, order);
117 if (!p)
118 return NULL;
119
120 return page_address(p);
121 }
122
dart_init_pte(struct dart_io_pgtable * data,unsigned long iova,phys_addr_t paddr,dart_iopte prot,int num_entries,dart_iopte * ptep)123 static int dart_init_pte(struct dart_io_pgtable *data,
124 unsigned long iova, phys_addr_t paddr,
125 dart_iopte prot, int num_entries,
126 dart_iopte *ptep)
127 {
128 int i;
129 dart_iopte pte = prot;
130 size_t sz = data->iop.cfg.pgsize_bitmap;
131
132 for (i = 0; i < num_entries; i++)
133 if (ptep[i] & APPLE_DART_PTE_VALID) {
134 /* We require an unmap first */
135 WARN_ON(ptep[i] & APPLE_DART_PTE_VALID);
136 return -EEXIST;
137 }
138
139 /* subpage protection: always allow access to the entire page */
140 pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0);
141 pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff);
142
143 pte |= APPLE_DART1_PTE_PROT_SP_DIS;
144 pte |= APPLE_DART_PTE_VALID;
145
146 for (i = 0; i < num_entries; i++)
147 ptep[i] = pte | paddr_to_iopte(paddr + i * sz, data);
148
149 return 0;
150 }
151
dart_install_table(dart_iopte * table,dart_iopte * ptep,dart_iopte curr,struct dart_io_pgtable * data)152 static dart_iopte dart_install_table(dart_iopte *table,
153 dart_iopte *ptep,
154 dart_iopte curr,
155 struct dart_io_pgtable *data)
156 {
157 dart_iopte old, new;
158
159 new = paddr_to_iopte(__pa(table), data) | APPLE_DART_PTE_VALID;
160
161 /*
162 * Ensure the table itself is visible before its PTE can be.
163 * Whilst we could get away with cmpxchg64_release below, this
164 * doesn't have any ordering semantics when !CONFIG_SMP.
165 */
166 dma_wmb();
167
168 old = cmpxchg64_relaxed(ptep, curr, new);
169
170 return old;
171 }
172
dart_get_table(struct dart_io_pgtable * data,unsigned long iova)173 static int dart_get_table(struct dart_io_pgtable *data, unsigned long iova)
174 {
175 return (iova >> (3 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
176 ((1 << data->tbl_bits) - 1);
177 }
178
dart_get_l1_index(struct dart_io_pgtable * data,unsigned long iova)179 static int dart_get_l1_index(struct dart_io_pgtable *data, unsigned long iova)
180 {
181
182 return (iova >> (2 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
183 ((1 << data->bits_per_level) - 1);
184 }
185
dart_get_l2_index(struct dart_io_pgtable * data,unsigned long iova)186 static int dart_get_l2_index(struct dart_io_pgtable *data, unsigned long iova)
187 {
188
189 return (iova >> (data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
190 ((1 << data->bits_per_level) - 1);
191 }
192
dart_get_l2(struct dart_io_pgtable * data,unsigned long iova)193 static dart_iopte *dart_get_l2(struct dart_io_pgtable *data, unsigned long iova)
194 {
195 dart_iopte pte, *ptep;
196 int tbl = dart_get_table(data, iova);
197
198 ptep = data->pgd[tbl];
199 if (!ptep)
200 return NULL;
201
202 ptep += dart_get_l1_index(data, iova);
203 pte = READ_ONCE(*ptep);
204
205 /* Valid entry? */
206 if (!pte)
207 return NULL;
208
209 /* Deref to get level 2 table */
210 return iopte_deref(pte, data);
211 }
212
dart_prot_to_pte(struct dart_io_pgtable * data,int prot)213 static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data,
214 int prot)
215 {
216 dart_iopte pte = 0;
217
218 if (data->iop.fmt == APPLE_DART) {
219 if (!(prot & IOMMU_WRITE))
220 pte |= APPLE_DART1_PTE_PROT_NO_WRITE;
221 if (!(prot & IOMMU_READ))
222 pte |= APPLE_DART1_PTE_PROT_NO_READ;
223 }
224 if (data->iop.fmt == APPLE_DART2) {
225 if (!(prot & IOMMU_WRITE))
226 pte |= APPLE_DART2_PTE_PROT_NO_WRITE;
227 if (!(prot & IOMMU_READ))
228 pte |= APPLE_DART2_PTE_PROT_NO_READ;
229 if (!(prot & IOMMU_CACHE))
230 pte |= APPLE_DART2_PTE_PROT_NO_CACHE;
231 }
232
233 return pte;
234 }
235
dart_map_pages(struct io_pgtable_ops * ops,unsigned long iova,phys_addr_t paddr,size_t pgsize,size_t pgcount,int iommu_prot,gfp_t gfp,size_t * mapped)236 static int dart_map_pages(struct io_pgtable_ops *ops, unsigned long iova,
237 phys_addr_t paddr, size_t pgsize, size_t pgcount,
238 int iommu_prot, gfp_t gfp, size_t *mapped)
239 {
240 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
241 struct io_pgtable_cfg *cfg = &data->iop.cfg;
242 size_t tblsz = DART_GRANULE(data);
243 int ret = 0, tbl, num_entries, max_entries, map_idx_start;
244 dart_iopte pte, *cptep, *ptep;
245 dart_iopte prot;
246
247 if (WARN_ON(pgsize != cfg->pgsize_bitmap))
248 return -EINVAL;
249
250 if (WARN_ON(paddr >> cfg->oas))
251 return -ERANGE;
252
253 /* If no access, then nothing to do */
254 if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
255 return 0;
256
257 tbl = dart_get_table(data, iova);
258
259 ptep = data->pgd[tbl];
260 ptep += dart_get_l1_index(data, iova);
261 pte = READ_ONCE(*ptep);
262
263 /* no L2 table present */
264 if (!pte) {
265 cptep = __dart_alloc_pages(tblsz, gfp, cfg);
266 if (!cptep)
267 return -ENOMEM;
268
269 pte = dart_install_table(cptep, ptep, 0, data);
270 if (pte)
271 free_pages((unsigned long)cptep, get_order(tblsz));
272
273 /* L2 table is present (now) */
274 pte = READ_ONCE(*ptep);
275 }
276
277 ptep = iopte_deref(pte, data);
278
279 /* install a leaf entries into L2 table */
280 prot = dart_prot_to_pte(data, iommu_prot);
281 map_idx_start = dart_get_l2_index(data, iova);
282 max_entries = DART_PTES_PER_TABLE(data) - map_idx_start;
283 num_entries = min_t(int, pgcount, max_entries);
284 ptep += map_idx_start;
285 ret = dart_init_pte(data, iova, paddr, prot, num_entries, ptep);
286 if (!ret && mapped)
287 *mapped += num_entries * pgsize;
288
289 /*
290 * Synchronise all PTE updates for the new mapping before there's
291 * a chance for anything to kick off a table walk for the new iova.
292 */
293 wmb();
294
295 return ret;
296 }
297
dart_unmap_pages(struct io_pgtable_ops * ops,unsigned long iova,size_t pgsize,size_t pgcount,struct iommu_iotlb_gather * gather)298 static size_t dart_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
299 size_t pgsize, size_t pgcount,
300 struct iommu_iotlb_gather *gather)
301 {
302 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
303 struct io_pgtable_cfg *cfg = &data->iop.cfg;
304 int i = 0, num_entries, max_entries, unmap_idx_start;
305 dart_iopte pte, *ptep;
306
307 if (WARN_ON(pgsize != cfg->pgsize_bitmap || !pgcount))
308 return 0;
309
310 ptep = dart_get_l2(data, iova);
311
312 /* Valid L2 IOPTE pointer? */
313 if (WARN_ON(!ptep))
314 return 0;
315
316 unmap_idx_start = dart_get_l2_index(data, iova);
317 ptep += unmap_idx_start;
318
319 max_entries = DART_PTES_PER_TABLE(data) - unmap_idx_start;
320 num_entries = min_t(int, pgcount, max_entries);
321
322 while (i < num_entries) {
323 pte = READ_ONCE(*ptep);
324 if (WARN_ON(!pte))
325 break;
326
327 /* clear pte */
328 *ptep = 0;
329
330 if (!iommu_iotlb_gather_queued(gather))
331 io_pgtable_tlb_add_page(&data->iop, gather,
332 iova + i * pgsize, pgsize);
333
334 ptep++;
335 i++;
336 }
337
338 return i * pgsize;
339 }
340
dart_iova_to_phys(struct io_pgtable_ops * ops,unsigned long iova)341 static phys_addr_t dart_iova_to_phys(struct io_pgtable_ops *ops,
342 unsigned long iova)
343 {
344 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
345 dart_iopte pte, *ptep;
346
347 ptep = dart_get_l2(data, iova);
348
349 /* Valid L2 IOPTE pointer? */
350 if (!ptep)
351 return 0;
352
353 ptep += dart_get_l2_index(data, iova);
354
355 pte = READ_ONCE(*ptep);
356 /* Found translation */
357 if (pte) {
358 iova &= (data->iop.cfg.pgsize_bitmap - 1);
359 return iopte_to_paddr(pte, data) | iova;
360 }
361
362 /* Ran out of page tables to walk */
363 return 0;
364 }
365
366 static struct dart_io_pgtable *
dart_alloc_pgtable(struct io_pgtable_cfg * cfg)367 dart_alloc_pgtable(struct io_pgtable_cfg *cfg)
368 {
369 struct dart_io_pgtable *data;
370 int tbl_bits, bits_per_level, va_bits, pg_shift;
371
372 pg_shift = __ffs(cfg->pgsize_bitmap);
373 bits_per_level = pg_shift - ilog2(sizeof(dart_iopte));
374
375 va_bits = cfg->ias - pg_shift;
376
377 tbl_bits = max_t(int, 0, va_bits - (bits_per_level * DART_LEVELS));
378 if ((1 << tbl_bits) > DART_MAX_TABLES)
379 return NULL;
380
381 data = kzalloc(sizeof(*data), GFP_KERNEL);
382 if (!data)
383 return NULL;
384
385 data->tbl_bits = tbl_bits;
386 data->bits_per_level = bits_per_level;
387
388 data->iop.ops = (struct io_pgtable_ops) {
389 .map_pages = dart_map_pages,
390 .unmap_pages = dart_unmap_pages,
391 .iova_to_phys = dart_iova_to_phys,
392 };
393
394 return data;
395 }
396
397 static struct io_pgtable *
apple_dart_alloc_pgtable(struct io_pgtable_cfg * cfg,void * cookie)398 apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
399 {
400 struct dart_io_pgtable *data;
401 int i;
402
403 if (!cfg->coherent_walk)
404 return NULL;
405
406 if (cfg->oas != 36 && cfg->oas != 42)
407 return NULL;
408
409 if (cfg->ias > cfg->oas)
410 return NULL;
411
412 if (!(cfg->pgsize_bitmap == SZ_4K || cfg->pgsize_bitmap == SZ_16K))
413 return NULL;
414
415 data = dart_alloc_pgtable(cfg);
416 if (!data)
417 return NULL;
418
419 cfg->apple_dart_cfg.n_ttbrs = 1 << data->tbl_bits;
420
421 for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i) {
422 data->pgd[i] = __dart_alloc_pages(DART_GRANULE(data), GFP_KERNEL,
423 cfg);
424 if (!data->pgd[i])
425 goto out_free_data;
426 cfg->apple_dart_cfg.ttbr[i] = virt_to_phys(data->pgd[i]);
427 }
428
429 return &data->iop;
430
431 out_free_data:
432 while (--i >= 0)
433 free_pages((unsigned long)data->pgd[i],
434 get_order(DART_GRANULE(data)));
435 kfree(data);
436 return NULL;
437 }
438
apple_dart_free_pgtable(struct io_pgtable * iop)439 static void apple_dart_free_pgtable(struct io_pgtable *iop)
440 {
441 struct dart_io_pgtable *data = io_pgtable_to_data(iop);
442 dart_iopte *ptep, *end;
443 int i;
444
445 for (i = 0; i < (1 << data->tbl_bits) && data->pgd[i]; ++i) {
446 ptep = data->pgd[i];
447 end = (void *)ptep + DART_GRANULE(data);
448
449 while (ptep != end) {
450 dart_iopte pte = *ptep++;
451
452 if (pte) {
453 unsigned long page =
454 (unsigned long)iopte_deref(pte, data);
455
456 free_pages(page, get_order(DART_GRANULE(data)));
457 }
458 }
459 free_pages((unsigned long)data->pgd[i],
460 get_order(DART_GRANULE(data)));
461 }
462
463 kfree(data);
464 }
465
466 struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
467 .alloc = apple_dart_alloc_pgtable,
468 .free = apple_dart_free_pgtable,
469 };
470
