xref: /linux/drivers/iommu/io-pgtable-dart.c (revision 6093a688a07da07808f0122f9aa2a3eed250d853) 
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_TABLE_BITS	2
31 #define DART_MAX_TABLES		BIT(DART_MAX_TABLE_BITS)
32 #define DART_MAX_LEVELS		4 /* Includes TTBR level */
33 
34 /* Struct accessors */
35 #define io_pgtable_to_data(x)						\
36 	container_of((x), struct dart_io_pgtable, iop)
37 
38 #define io_pgtable_ops_to_data(x)					\
39 	io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))
40 
41 #define DART_GRANULE(d)						\
42 	(sizeof(dart_iopte) << (d)->bits_per_level)
43 #define DART_PTES_PER_TABLE(d)					\
44 	(DART_GRANULE(d) >> ilog2(sizeof(dart_iopte)))
45 
46 #define APPLE_DART_PTE_SUBPAGE_START   GENMASK_ULL(63, 52)
47 #define APPLE_DART_PTE_SUBPAGE_END     GENMASK_ULL(51, 40)
48 
49 #define APPLE_DART1_PADDR_MASK	GENMASK_ULL(35, 12)
50 #define APPLE_DART2_PADDR_MASK	GENMASK_ULL(37, 10)
51 #define APPLE_DART2_PADDR_SHIFT	(4)
52 
53 /* Apple DART1 protection bits */
54 #define APPLE_DART1_PTE_PROT_NO_READ	BIT(8)
55 #define APPLE_DART1_PTE_PROT_NO_WRITE	BIT(7)
56 #define APPLE_DART1_PTE_PROT_SP_DIS	BIT(1)
57 
58 /* Apple DART2 protection bits */
59 #define APPLE_DART2_PTE_PROT_NO_READ	BIT(3)
60 #define APPLE_DART2_PTE_PROT_NO_WRITE	BIT(2)
61 #define APPLE_DART2_PTE_PROT_NO_CACHE	BIT(1)
62 
63 /* marks PTE as valid */
64 #define APPLE_DART_PTE_VALID		BIT(0)
65 
66 /* IOPTE accessors */
67 #define iopte_deref(pte, d) __va(iopte_to_paddr(pte, d))
68 
69 struct dart_io_pgtable {
70 	struct io_pgtable	iop;
71 
72 	int			levels;
73 	int			tbl_bits;
74 	int			bits_per_level;
75 
76 	void			*pgd[DART_MAX_TABLES];
77 };
78 
79 typedef u64 dart_iopte;
80 
81 
82 static dart_iopte paddr_to_iopte(phys_addr_t paddr,
83 				     struct dart_io_pgtable *data)
84 {
85 	dart_iopte pte;
86 
87 	if (data->iop.fmt == APPLE_DART)
88 		return paddr & APPLE_DART1_PADDR_MASK;
89 
90 	/* format is APPLE_DART2 */
91 	pte = paddr >> APPLE_DART2_PADDR_SHIFT;
92 	pte &= APPLE_DART2_PADDR_MASK;
93 
94 	return pte;
95 }
96 
97 static phys_addr_t iopte_to_paddr(dart_iopte pte,
98 				  struct dart_io_pgtable *data)
99 {
100 	u64 paddr;
101 
102 	if (data->iop.fmt == APPLE_DART)
103 		return pte & APPLE_DART1_PADDR_MASK;
104 
105 	/* format is APPLE_DART2 */
106 	paddr = pte & APPLE_DART2_PADDR_MASK;
107 	paddr <<= APPLE_DART2_PADDR_SHIFT;
108 
109 	return paddr;
110 }
111 
112 static int dart_init_pte(struct dart_io_pgtable *data,
113 			     unsigned long iova, phys_addr_t paddr,
114 			     dart_iopte prot, int num_entries,
115 			     dart_iopte *ptep)
116 {
117 	int i;
118 	dart_iopte pte = prot;
119 	size_t sz = data->iop.cfg.pgsize_bitmap;
120 
121 	for (i = 0; i < num_entries; i++)
122 		if (ptep[i] & APPLE_DART_PTE_VALID) {
123 			/* We require an unmap first */
124 			WARN_ON(ptep[i] & APPLE_DART_PTE_VALID);
125 			return -EEXIST;
126 		}
127 
128 	/* subpage protection: always allow access to the entire page */
129 	pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0);
130 	pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff);
131 
132 	pte |= APPLE_DART_PTE_VALID;
133 
134 	for (i = 0; i < num_entries; i++)
135 		ptep[i] = pte | paddr_to_iopte(paddr + i * sz, data);
136 
137 	return 0;
138 }
139 
140 static dart_iopte dart_install_table(dart_iopte *table,
141 					     dart_iopte *ptep,
142 					     dart_iopte curr,
143 					     struct dart_io_pgtable *data)
144 {
145 	dart_iopte old, new;
146 
147 	new = paddr_to_iopte(__pa(table), data) | APPLE_DART_PTE_VALID;
148 
149 	/*
150 	 * Ensure the table itself is visible before its PTE can be.
151 	 * Whilst we could get away with cmpxchg64_release below, this
152 	 * doesn't have any ordering semantics when !CONFIG_SMP.
153 	 */
154 	dma_wmb();
155 
156 	old = cmpxchg64_relaxed(ptep, curr, new);
157 
158 	return old;
159 }
160 
161 static int dart_get_index(struct dart_io_pgtable *data, unsigned long iova, int level)
162 {
163 	return (iova >> (level * data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
164 		((1 << data->bits_per_level) - 1);
165 }
166 
167 static int dart_get_last_index(struct dart_io_pgtable *data, unsigned long iova)
168 {
169 
170 	return (iova >> (data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
171 		 ((1 << data->bits_per_level) - 1);
172 }
173 
174 static dart_iopte *dart_get_last(struct dart_io_pgtable *data, unsigned long iova)
175 {
176 	dart_iopte pte, *ptep;
177 	int level = data->levels;
178 	int tbl = dart_get_index(data, iova, level);
179 
180 	if (tbl >= (1 << data->tbl_bits))
181 		return NULL;
182 
183 	ptep = data->pgd[tbl];
184 	if (!ptep)
185 		return NULL;
186 
187 	while (--level > 1) {
188 		ptep += dart_get_index(data, iova, level);
189 		pte = READ_ONCE(*ptep);
190 
191 		/* Valid entry? */
192 		if (!pte)
193 			return NULL;
194 
195 		/* Deref to get next level table */
196 		ptep = iopte_deref(pte, data);
197 	}
198 
199 	return ptep;
200 }
201 
202 static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data,
203 					   int prot)
204 {
205 	dart_iopte pte = 0;
206 
207 	if (data->iop.fmt == APPLE_DART) {
208 		pte |= APPLE_DART1_PTE_PROT_SP_DIS;
209 		if (!(prot & IOMMU_WRITE))
210 			pte |= APPLE_DART1_PTE_PROT_NO_WRITE;
211 		if (!(prot & IOMMU_READ))
212 			pte |= APPLE_DART1_PTE_PROT_NO_READ;
213 	}
214 	if (data->iop.fmt == APPLE_DART2) {
215 		if (!(prot & IOMMU_WRITE))
216 			pte |= APPLE_DART2_PTE_PROT_NO_WRITE;
217 		if (!(prot & IOMMU_READ))
218 			pte |= APPLE_DART2_PTE_PROT_NO_READ;
219 		if (!(prot & IOMMU_CACHE))
220 			pte |= APPLE_DART2_PTE_PROT_NO_CACHE;
221 	}
222 
223 	return pte;
224 }
225 
226 static int dart_map_pages(struct io_pgtable_ops *ops, unsigned long iova,
227 			      phys_addr_t paddr, size_t pgsize, size_t pgcount,
228 			      int iommu_prot, gfp_t gfp, size_t *mapped)
229 {
230 	struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
231 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
232 	size_t tblsz = DART_GRANULE(data);
233 	int ret = 0, tbl, num_entries, max_entries, map_idx_start;
234 	dart_iopte pte, *cptep, *ptep;
235 	dart_iopte prot;
236 	int level = data->levels;
237 
238 	if (WARN_ON(pgsize != cfg->pgsize_bitmap))
239 		return -EINVAL;
240 
241 	if (WARN_ON(paddr >> cfg->oas))
242 		return -ERANGE;
243 
244 	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
245 		return -EINVAL;
246 
247 	tbl = dart_get_index(data, iova, level);
248 
249 	if (tbl >= (1 << data->tbl_bits))
250 		return -ENOMEM;
251 
252 	ptep = data->pgd[tbl];
253 	while (--level > 1) {
254 		ptep += dart_get_index(data, iova, level);
255 		pte = READ_ONCE(*ptep);
256 
257 		/* no table present */
258 		if (!pte) {
259 			cptep = iommu_alloc_pages_sz(gfp, tblsz);
260 			if (!cptep)
261 				return -ENOMEM;
262 
263 			pte = dart_install_table(cptep, ptep, 0, data);
264 			if (pte)
265 				iommu_free_pages(cptep);
266 
267 			/* L2 table is present (now) */
268 			pte = READ_ONCE(*ptep);
269 		}
270 
271 		ptep = iopte_deref(pte, data);
272 	}
273 
274 	/* install a leaf entries into L2 table */
275 	prot = dart_prot_to_pte(data, iommu_prot);
276 	map_idx_start = dart_get_last_index(data, iova);
277 	max_entries = DART_PTES_PER_TABLE(data) - map_idx_start;
278 	num_entries = min_t(int, pgcount, max_entries);
279 	ptep += map_idx_start;
280 	ret = dart_init_pte(data, iova, paddr, prot, num_entries, ptep);
281 	if (!ret && mapped)
282 		*mapped += num_entries * pgsize;
283 
284 	/*
285 	 * Synchronise all PTE updates for the new mapping before there's
286 	 * a chance for anything to kick off a table walk for the new iova.
287 	 */
288 	wmb();
289 
290 	return ret;
291 }
292 
293 static size_t dart_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
294 				   size_t pgsize, size_t pgcount,
295 				   struct iommu_iotlb_gather *gather)
296 {
297 	struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
298 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
299 	int i = 0, num_entries, max_entries, unmap_idx_start;
300 	dart_iopte pte, *ptep;
301 
302 	if (WARN_ON(pgsize != cfg->pgsize_bitmap || !pgcount))
303 		return 0;
304 
305 	ptep = dart_get_last(data, iova);
306 
307 	/* Valid L2 IOPTE pointer? */
308 	if (WARN_ON(!ptep))
309 		return 0;
310 
311 	unmap_idx_start = dart_get_last_index(data, iova);
312 	ptep += unmap_idx_start;
313 
314 	max_entries = DART_PTES_PER_TABLE(data) - unmap_idx_start;
315 	num_entries = min_t(int, pgcount, max_entries);
316 
317 	while (i < num_entries) {
318 		pte = READ_ONCE(*ptep);
319 		if (WARN_ON(!pte))
320 			break;
321 
322 		/* clear pte */
323 		*ptep = 0;
324 
325 		if (!iommu_iotlb_gather_queued(gather))
326 			io_pgtable_tlb_add_page(&data->iop, gather,
327 						iova + i * pgsize, pgsize);
328 
329 		ptep++;
330 		i++;
331 	}
332 
333 	return i * pgsize;
334 }
335 
336 static phys_addr_t dart_iova_to_phys(struct io_pgtable_ops *ops,
337 					 unsigned long iova)
338 {
339 	struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
340 	dart_iopte pte, *ptep;
341 
342 	ptep = dart_get_last(data, iova);
343 
344 	/* Valid L2 IOPTE pointer? */
345 	if (!ptep)
346 		return 0;
347 
348 	ptep += dart_get_last_index(data, iova);
349 
350 	pte = READ_ONCE(*ptep);
351 	/* Found translation */
352 	if (pte) {
353 		iova &= (data->iop.cfg.pgsize_bitmap - 1);
354 		return iopte_to_paddr(pte, data) | iova;
355 	}
356 
357 	/* Ran out of page tables to walk */
358 	return 0;
359 }
360 
361 static struct dart_io_pgtable *
362 dart_alloc_pgtable(struct io_pgtable_cfg *cfg)
363 {
364 	struct dart_io_pgtable *data;
365 	int levels, max_tbl_bits, tbl_bits, bits_per_level, va_bits, pg_shift;
366 
367 	/*
368 	 * Old 4K page DARTs can use up to 4 top-level tables.
369 	 * Newer ones only ever use a maximum of 1.
370 	 */
371 	if (cfg->pgsize_bitmap == SZ_4K)
372 		max_tbl_bits = DART_MAX_TABLE_BITS;
373 	else
374 		max_tbl_bits = 0;
375 
376 	pg_shift = __ffs(cfg->pgsize_bitmap);
377 	bits_per_level = pg_shift - ilog2(sizeof(dart_iopte));
378 
379 	va_bits = cfg->ias - pg_shift;
380 
381 	levels = max_t(int, 2, (va_bits - max_tbl_bits + bits_per_level - 1) / bits_per_level);
382 
383 	if (levels > (DART_MAX_LEVELS - 1))
384 		return NULL;
385 
386 	tbl_bits = max_t(int, 0, va_bits - (bits_per_level * levels));
387 
388 	if (tbl_bits > max_tbl_bits)
389 		return NULL;
390 
391 	data = kzalloc(sizeof(*data), GFP_KERNEL);
392 	if (!data)
393 		return NULL;
394 
395 	data->levels = levels + 1; /* Table level counts as one level */
396 	data->tbl_bits = tbl_bits;
397 	data->bits_per_level = bits_per_level;
398 
399 	data->iop.ops = (struct io_pgtable_ops) {
400 		.map_pages	= dart_map_pages,
401 		.unmap_pages	= dart_unmap_pages,
402 		.iova_to_phys	= dart_iova_to_phys,
403 	};
404 
405 	return data;
406 }
407 
408 static struct io_pgtable *
409 apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
410 {
411 	struct dart_io_pgtable *data;
412 	int i;
413 
414 	if (!cfg->coherent_walk)
415 		return NULL;
416 
417 	if (cfg->oas != 36 && cfg->oas != 42)
418 		return NULL;
419 
420 	if (cfg->ias > cfg->oas)
421 		return NULL;
422 
423 	if (!(cfg->pgsize_bitmap == SZ_4K || cfg->pgsize_bitmap == SZ_16K))
424 		return NULL;
425 
426 	data = dart_alloc_pgtable(cfg);
427 	if (!data)
428 		return NULL;
429 
430 	cfg->apple_dart_cfg.n_ttbrs = 1 << data->tbl_bits;
431 	cfg->apple_dart_cfg.n_levels = data->levels;
432 
433 	for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i) {
434 		data->pgd[i] =
435 			iommu_alloc_pages_sz(GFP_KERNEL, DART_GRANULE(data));
436 		if (!data->pgd[i])
437 			goto out_free_data;
438 		cfg->apple_dart_cfg.ttbr[i] = virt_to_phys(data->pgd[i]);
439 	}
440 
441 	return &data->iop;
442 
443 out_free_data:
444 	while (--i >= 0) {
445 		iommu_free_pages(data->pgd[i]);
446 	}
447 	kfree(data);
448 	return NULL;
449 }
450 
451 static void apple_dart_free_pgtables(struct dart_io_pgtable *data, dart_iopte *ptep, int level)
452 {
453 	dart_iopte *end;
454 	dart_iopte *start = ptep;
455 
456 	if (level > 1) {
457 		end = (void *)ptep + DART_GRANULE(data);
458 
459 		while (ptep != end) {
460 			dart_iopte pte = *ptep++;
461 
462 			if (pte)
463 				apple_dart_free_pgtables(data, iopte_deref(pte, data), level - 1);
464 		}
465 	}
466 	iommu_free_pages(start);
467 }
468 
469 static void apple_dart_free_pgtable(struct io_pgtable *iop)
470 {
471 	struct dart_io_pgtable *data = io_pgtable_to_data(iop);
472 	int i;
473 
474 	for (i = 0; i < (1 << data->tbl_bits) && data->pgd[i]; ++i)
475 		apple_dart_free_pgtables(data, data->pgd[i], data->levels - 1);
476 
477 	kfree(data);
478 }
479 
480 struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
481 	.alloc	= apple_dart_alloc_pgtable,
482 	.free	= apple_dart_free_pgtable,
483 };
484