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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 *
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 *
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 
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