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
67struct 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
76typedef u64 dart_iopte;
77
78
79static 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
94static 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
109static 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
123static 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
152static 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
173static 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
179static 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
186static 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
193static  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
213static 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
236static 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
298static 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
341static 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
366static struct dart_io_pgtable *
367dart_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
397static struct io_pgtable *
398apple_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
431out_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
439static 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
466struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
467	.alloc	= apple_dart_alloc_pgtable,
468	.free	= apple_dart_free_pgtable,
469};
470