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 (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
254 		return -EINVAL;
255 
256 	tbl = dart_get_table(data, iova);
257 
258 	ptep = data->pgd[tbl];
259 	ptep += dart_get_l1_index(data, iova);
260 	pte = READ_ONCE(*ptep);
261 
262 	/* no L2 table present */
263 	if (!pte) {
264 		cptep = __dart_alloc_pages(tblsz, gfp, cfg);
265 		if (!cptep)
266 			return -ENOMEM;
267 
268 		pte = dart_install_table(cptep, ptep, 0, data);
269 		if (pte)
270 			free_pages((unsigned long)cptep, get_order(tblsz));
271 
272 		/* L2 table is present (now) */
273 		pte = READ_ONCE(*ptep);
274 	}
275 
276 	ptep = iopte_deref(pte, data);
277 
278 	/* install a leaf entries into L2 table */
279 	prot = dart_prot_to_pte(data, iommu_prot);
280 	map_idx_start = dart_get_l2_index(data, iova);
281 	max_entries = DART_PTES_PER_TABLE(data) - map_idx_start;
282 	num_entries = min_t(int, pgcount, max_entries);
283 	ptep += map_idx_start;
284 	ret = dart_init_pte(data, iova, paddr, prot, num_entries, ptep);
285 	if (!ret && mapped)
286 		*mapped += num_entries * pgsize;
287 
288 	/*
289 	 * Synchronise all PTE updates for the new mapping before there's
290 	 * a chance for anything to kick off a table walk for the new iova.
291 	 */
292 	wmb();
293 
294 	return ret;
295 }
296 
297 static size_t dart_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
298 				   size_t pgsize, size_t pgcount,
299 				   struct iommu_iotlb_gather *gather)
300 {
301 	struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
302 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
303 	int i = 0, num_entries, max_entries, unmap_idx_start;
304 	dart_iopte pte, *ptep;
305 
306 	if (WARN_ON(pgsize != cfg->pgsize_bitmap || !pgcount))
307 		return 0;
308 
309 	ptep = dart_get_l2(data, iova);
310 
311 	/* Valid L2 IOPTE pointer? */
312 	if (WARN_ON(!ptep))
313 		return 0;
314 
315 	unmap_idx_start = dart_get_l2_index(data, iova);
316 	ptep += unmap_idx_start;
317 
318 	max_entries = DART_PTES_PER_TABLE(data) - unmap_idx_start;
319 	num_entries = min_t(int, pgcount, max_entries);
320 
321 	while (i < num_entries) {
322 		pte = READ_ONCE(*ptep);
323 		if (WARN_ON(!pte))
324 			break;
325 
326 		/* clear pte */
327 		*ptep = 0;
328 
329 		if (!iommu_iotlb_gather_queued(gather))
330 			io_pgtable_tlb_add_page(&data->iop, gather,
331 						iova + i * pgsize, pgsize);
332 
333 		ptep++;
334 		i++;
335 	}
336 
337 	return i * pgsize;
338 }
339 
340 static phys_addr_t dart_iova_to_phys(struct io_pgtable_ops *ops,
341 					 unsigned long iova)
342 {
343 	struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops);
344 	dart_iopte pte, *ptep;
345 
346 	ptep = dart_get_l2(data, iova);
347 
348 	/* Valid L2 IOPTE pointer? */
349 	if (!ptep)
350 		return 0;
351 
352 	ptep += dart_get_l2_index(data, iova);
353 
354 	pte = READ_ONCE(*ptep);
355 	/* Found translation */
356 	if (pte) {
357 		iova &= (data->iop.cfg.pgsize_bitmap - 1);
358 		return iopte_to_paddr(pte, data) | iova;
359 	}
360 
361 	/* Ran out of page tables to walk */
362 	return 0;
363 }
364 
365 static struct dart_io_pgtable *
366 dart_alloc_pgtable(struct io_pgtable_cfg *cfg)
367 {
368 	struct dart_io_pgtable *data;
369 	int tbl_bits, bits_per_level, va_bits, pg_shift;
370 
371 	pg_shift = __ffs(cfg->pgsize_bitmap);
372 	bits_per_level = pg_shift - ilog2(sizeof(dart_iopte));
373 
374 	va_bits = cfg->ias - pg_shift;
375 
376 	tbl_bits = max_t(int, 0, va_bits - (bits_per_level * DART_LEVELS));
377 	if ((1 << tbl_bits) > DART_MAX_TABLES)
378 		return NULL;
379 
380 	data = kzalloc(sizeof(*data), GFP_KERNEL);
381 	if (!data)
382 		return NULL;
383 
384 	data->tbl_bits = tbl_bits;
385 	data->bits_per_level = bits_per_level;
386 
387 	data->iop.ops = (struct io_pgtable_ops) {
388 		.map_pages	= dart_map_pages,
389 		.unmap_pages	= dart_unmap_pages,
390 		.iova_to_phys	= dart_iova_to_phys,
391 	};
392 
393 	return data;
394 }
395 
396 static struct io_pgtable *
397 apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
398 {
399 	struct dart_io_pgtable *data;
400 	int i;
401 
402 	if (!cfg->coherent_walk)
403 		return NULL;
404 
405 	if (cfg->oas != 36 && cfg->oas != 42)
406 		return NULL;
407 
408 	if (cfg->ias > cfg->oas)
409 		return NULL;
410 
411 	if (!(cfg->pgsize_bitmap == SZ_4K || cfg->pgsize_bitmap == SZ_16K))
412 		return NULL;
413 
414 	data = dart_alloc_pgtable(cfg);
415 	if (!data)
416 		return NULL;
417 
418 	cfg->apple_dart_cfg.n_ttbrs = 1 << data->tbl_bits;
419 
420 	for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i) {
421 		data->pgd[i] = __dart_alloc_pages(DART_GRANULE(data), GFP_KERNEL,
422 					   cfg);
423 		if (!data->pgd[i])
424 			goto out_free_data;
425 		cfg->apple_dart_cfg.ttbr[i] = virt_to_phys(data->pgd[i]);
426 	}
427 
428 	return &data->iop;
429 
430 out_free_data:
431 	while (--i >= 0)
432 		free_pages((unsigned long)data->pgd[i],
433 			   get_order(DART_GRANULE(data)));
434 	kfree(data);
435 	return NULL;
436 }
437 
438 static void apple_dart_free_pgtable(struct io_pgtable *iop)
439 {
440 	struct dart_io_pgtable *data = io_pgtable_to_data(iop);
441 	dart_iopte *ptep, *end;
442 	int i;
443 
444 	for (i = 0; i < (1 << data->tbl_bits) && data->pgd[i]; ++i) {
445 		ptep = data->pgd[i];
446 		end = (void *)ptep + DART_GRANULE(data);
447 
448 		while (ptep != end) {
449 			dart_iopte pte = *ptep++;
450 
451 			if (pte) {
452 				unsigned long page =
453 					(unsigned long)iopte_deref(pte, data);
454 
455 				free_pages(page, get_order(DART_GRANULE(data)));
456 			}
457 		}
458 		free_pages((unsigned long)data->pgd[i],
459 			   get_order(DART_GRANULE(data)));
460 	}
461 
462 	kfree(data);
463 }
464 
465 struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
466 	.alloc	= apple_dart_alloc_pgtable,
467 	.free	= apple_dart_free_pgtable,
468 };
469