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