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