xref: /openbmc/linux/mm/sparse-vmemmap.c (revision 40135fc7)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Virtual Memory Map support
4  *
5  * (C) 2007 sgi. Christoph Lameter.
6  *
7  * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
8  * virt_to_page, page_address() to be implemented as a base offset
9  * calculation without memory access.
10  *
11  * However, virtual mappings need a page table and TLBs. Many Linux
12  * architectures already map their physical space using 1-1 mappings
13  * via TLBs. For those arches the virtual memory map is essentially
14  * for free if we use the same page size as the 1-1 mappings. In that
15  * case the overhead consists of a few additional pages that are
16  * allocated to create a view of memory for vmemmap.
17  *
18  * The architecture is expected to provide a vmemmap_populate() function
19  * to instantiate the mapping.
20  */
21 #include <linux/mm.h>
22 #include <linux/mmzone.h>
23 #include <linux/memblock.h>
24 #include <linux/memremap.h>
25 #include <linux/highmem.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <linux/vmalloc.h>
29 #include <linux/sched.h>
30 
31 #include <asm/dma.h>
32 #include <asm/pgalloc.h>
33 
34 /*
35  * Allocate a block of memory to be used to back the virtual memory map
36  * or to back the page tables that are used to create the mapping.
37  * Uses the main allocators if they are available, else bootmem.
38  */
39 
__earlyonly_bootmem_alloc(int node,unsigned long size,unsigned long align,unsigned long goal)40 static void * __ref __earlyonly_bootmem_alloc(int node,
41 				unsigned long size,
42 				unsigned long align,
43 				unsigned long goal)
44 {
45 	return memblock_alloc_try_nid_raw(size, align, goal,
46 					       MEMBLOCK_ALLOC_ACCESSIBLE, node);
47 }
48 
vmemmap_alloc_block(unsigned long size,int node)49 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
50 {
51 	/* If the main allocator is up use that, fallback to bootmem. */
52 	if (slab_is_available()) {
53 		gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
54 		int order = get_order(size);
55 		static bool warned;
56 		struct page *page;
57 
58 		page = alloc_pages_node(node, gfp_mask, order);
59 		if (page)
60 			return page_address(page);
61 
62 		if (!warned) {
63 			warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
64 				   "vmemmap alloc failure: order:%u", order);
65 			warned = true;
66 		}
67 		return NULL;
68 	} else
69 		return __earlyonly_bootmem_alloc(node, size, size,
70 				__pa(MAX_DMA_ADDRESS));
71 }
72 
73 static void * __meminit altmap_alloc_block_buf(unsigned long size,
74 					       struct vmem_altmap *altmap);
75 
76 /* need to make sure size is all the same during early stage */
vmemmap_alloc_block_buf(unsigned long size,int node,struct vmem_altmap * altmap)77 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
78 					 struct vmem_altmap *altmap)
79 {
80 	void *ptr;
81 
82 	if (altmap)
83 		return altmap_alloc_block_buf(size, altmap);
84 
85 	ptr = sparse_buffer_alloc(size);
86 	if (!ptr)
87 		ptr = vmemmap_alloc_block(size, node);
88 	return ptr;
89 }
90 
vmem_altmap_next_pfn(struct vmem_altmap * altmap)91 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
92 {
93 	return altmap->base_pfn + altmap->reserve + altmap->alloc
94 		+ altmap->align;
95 }
96 
vmem_altmap_nr_free(struct vmem_altmap * altmap)97 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
98 {
99 	unsigned long allocated = altmap->alloc + altmap->align;
100 
101 	if (altmap->free > allocated)
102 		return altmap->free - allocated;
103 	return 0;
104 }
105 
altmap_alloc_block_buf(unsigned long size,struct vmem_altmap * altmap)106 static void * __meminit altmap_alloc_block_buf(unsigned long size,
107 					       struct vmem_altmap *altmap)
108 {
109 	unsigned long pfn, nr_pfns, nr_align;
110 
111 	if (size & ~PAGE_MASK) {
112 		pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
113 				__func__, size);
114 		return NULL;
115 	}
116 
117 	pfn = vmem_altmap_next_pfn(altmap);
118 	nr_pfns = size >> PAGE_SHIFT;
119 	nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
120 	nr_align = ALIGN(pfn, nr_align) - pfn;
121 	if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
122 		return NULL;
123 
124 	altmap->alloc += nr_pfns;
125 	altmap->align += nr_align;
126 	pfn += nr_align;
127 
128 	pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
129 			__func__, pfn, altmap->alloc, altmap->align, nr_pfns);
130 	return __va(__pfn_to_phys(pfn));
131 }
132 
vmemmap_verify(pte_t * pte,int node,unsigned long start,unsigned long end)133 void __meminit vmemmap_verify(pte_t *pte, int node,
134 				unsigned long start, unsigned long end)
135 {
136 	unsigned long pfn = pte_pfn(ptep_get(pte));
137 	int actual_node = early_pfn_to_nid(pfn);
138 
139 	if (node_distance(actual_node, node) > LOCAL_DISTANCE)
140 		pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
141 			start, end - 1);
142 }
143 
vmemmap_pte_populate(pmd_t * pmd,unsigned long addr,int node,struct vmem_altmap * altmap,struct page * reuse)144 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
145 				       struct vmem_altmap *altmap,
146 				       struct page *reuse)
147 {
148 	pte_t *pte = pte_offset_kernel(pmd, addr);
149 	if (pte_none(ptep_get(pte))) {
150 		pte_t entry;
151 		void *p;
152 
153 		if (!reuse) {
154 			p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
155 			if (!p)
156 				return NULL;
157 		} else {
158 			/*
159 			 * When a PTE/PMD entry is freed from the init_mm
160 			 * there's a free_pages() call to this page allocated
161 			 * above. Thus this get_page() is paired with the
162 			 * put_page_testzero() on the freeing path.
163 			 * This can only called by certain ZONE_DEVICE path,
164 			 * and through vmemmap_populate_compound_pages() when
165 			 * slab is available.
166 			 */
167 			get_page(reuse);
168 			p = page_to_virt(reuse);
169 		}
170 		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
171 		set_pte_at(&init_mm, addr, pte, entry);
172 	}
173 	return pte;
174 }
175 
vmemmap_alloc_block_zero(unsigned long size,int node)176 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
177 {
178 	void *p = vmemmap_alloc_block(size, node);
179 
180 	if (!p)
181 		return NULL;
182 	memset(p, 0, size);
183 
184 	return p;
185 }
186 
vmemmap_pmd_populate(pud_t * pud,unsigned long addr,int node)187 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
188 {
189 	pmd_t *pmd = pmd_offset(pud, addr);
190 	if (pmd_none(*pmd)) {
191 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
192 		if (!p)
193 			return NULL;
194 		pmd_populate_kernel(&init_mm, pmd, p);
195 	}
196 	return pmd;
197 }
198 
pmd_init(void * addr)199 void __weak __meminit pmd_init(void *addr)
200 {
201 }
202 
vmemmap_pud_populate(p4d_t * p4d,unsigned long addr,int node)203 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
204 {
205 	pud_t *pud = pud_offset(p4d, addr);
206 	if (pud_none(*pud)) {
207 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
208 		if (!p)
209 			return NULL;
210 		pmd_init(p);
211 		pud_populate(&init_mm, pud, p);
212 	}
213 	return pud;
214 }
215 
pud_init(void * addr)216 void __weak __meminit pud_init(void *addr)
217 {
218 }
219 
vmemmap_p4d_populate(pgd_t * pgd,unsigned long addr,int node)220 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
221 {
222 	p4d_t *p4d = p4d_offset(pgd, addr);
223 	if (p4d_none(*p4d)) {
224 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
225 		if (!p)
226 			return NULL;
227 		pud_init(p);
228 		p4d_populate(&init_mm, p4d, p);
229 	}
230 	return p4d;
231 }
232 
vmemmap_pgd_populate(unsigned long addr,int node)233 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
234 {
235 	pgd_t *pgd = pgd_offset_k(addr);
236 	if (pgd_none(*pgd)) {
237 		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
238 		if (!p)
239 			return NULL;
240 		pgd_populate(&init_mm, pgd, p);
241 	}
242 	return pgd;
243 }
244 
vmemmap_populate_address(unsigned long addr,int node,struct vmem_altmap * altmap,struct page * reuse)245 static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
246 					      struct vmem_altmap *altmap,
247 					      struct page *reuse)
248 {
249 	pgd_t *pgd;
250 	p4d_t *p4d;
251 	pud_t *pud;
252 	pmd_t *pmd;
253 	pte_t *pte;
254 
255 	pgd = vmemmap_pgd_populate(addr, node);
256 	if (!pgd)
257 		return NULL;
258 	p4d = vmemmap_p4d_populate(pgd, addr, node);
259 	if (!p4d)
260 		return NULL;
261 	pud = vmemmap_pud_populate(p4d, addr, node);
262 	if (!pud)
263 		return NULL;
264 	pmd = vmemmap_pmd_populate(pud, addr, node);
265 	if (!pmd)
266 		return NULL;
267 	pte = vmemmap_pte_populate(pmd, addr, node, altmap, reuse);
268 	if (!pte)
269 		return NULL;
270 	vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
271 
272 	return pte;
273 }
274 
vmemmap_populate_range(unsigned long start,unsigned long end,int node,struct vmem_altmap * altmap,struct page * reuse)275 static int __meminit vmemmap_populate_range(unsigned long start,
276 					    unsigned long end, int node,
277 					    struct vmem_altmap *altmap,
278 					    struct page *reuse)
279 {
280 	unsigned long addr = start;
281 	pte_t *pte;
282 
283 	for (; addr < end; addr += PAGE_SIZE) {
284 		pte = vmemmap_populate_address(addr, node, altmap, reuse);
285 		if (!pte)
286 			return -ENOMEM;
287 	}
288 
289 	return 0;
290 }
291 
vmemmap_populate_basepages(unsigned long start,unsigned long end,int node,struct vmem_altmap * altmap)292 int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
293 					 int node, struct vmem_altmap *altmap)
294 {
295 	return vmemmap_populate_range(start, end, node, altmap, NULL);
296 }
297 
vmemmap_set_pmd(pmd_t * pmd,void * p,int node,unsigned long addr,unsigned long next)298 void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
299 				      unsigned long addr, unsigned long next)
300 {
301 }
302 
vmemmap_check_pmd(pmd_t * pmd,int node,unsigned long addr,unsigned long next)303 int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
304 				       unsigned long addr, unsigned long next)
305 {
306 	return 0;
307 }
308 
vmemmap_populate_hugepages(unsigned long start,unsigned long end,int node,struct vmem_altmap * altmap)309 int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
310 					 int node, struct vmem_altmap *altmap)
311 {
312 	unsigned long addr;
313 	unsigned long next;
314 	pgd_t *pgd;
315 	p4d_t *p4d;
316 	pud_t *pud;
317 	pmd_t *pmd;
318 
319 	for (addr = start; addr < end; addr = next) {
320 		next = pmd_addr_end(addr, end);
321 
322 		pgd = vmemmap_pgd_populate(addr, node);
323 		if (!pgd)
324 			return -ENOMEM;
325 
326 		p4d = vmemmap_p4d_populate(pgd, addr, node);
327 		if (!p4d)
328 			return -ENOMEM;
329 
330 		pud = vmemmap_pud_populate(p4d, addr, node);
331 		if (!pud)
332 			return -ENOMEM;
333 
334 		pmd = pmd_offset(pud, addr);
335 		if (pmd_none(READ_ONCE(*pmd))) {
336 			void *p;
337 
338 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
339 			if (p) {
340 				vmemmap_set_pmd(pmd, p, node, addr, next);
341 				continue;
342 			} else if (altmap) {
343 				/*
344 				 * No fallback: In any case we care about, the
345 				 * altmap should be reasonably sized and aligned
346 				 * such that vmemmap_alloc_block_buf() will always
347 				 * succeed. For consistency with the PTE case,
348 				 * return an error here as failure could indicate
349 				 * a configuration issue with the size of the altmap.
350 				 */
351 				return -ENOMEM;
352 			}
353 		} else if (vmemmap_check_pmd(pmd, node, addr, next))
354 			continue;
355 		if (vmemmap_populate_basepages(addr, next, node, altmap))
356 			return -ENOMEM;
357 	}
358 	return 0;
359 }
360 
361 #ifndef vmemmap_populate_compound_pages
362 /*
363  * For compound pages bigger than section size (e.g. x86 1G compound
364  * pages with 2M subsection size) fill the rest of sections as tail
365  * pages.
366  *
367  * Note that memremap_pages() resets @nr_range value and will increment
368  * it after each range successful onlining. Thus the value or @nr_range
369  * at section memmap populate corresponds to the in-progress range
370  * being onlined here.
371  */
reuse_compound_section(unsigned long start_pfn,struct dev_pagemap * pgmap)372 static bool __meminit reuse_compound_section(unsigned long start_pfn,
373 					     struct dev_pagemap *pgmap)
374 {
375 	unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
376 	unsigned long offset = start_pfn -
377 		PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
378 
379 	return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
380 }
381 
compound_section_tail_page(unsigned long addr)382 static pte_t * __meminit compound_section_tail_page(unsigned long addr)
383 {
384 	pte_t *pte;
385 
386 	addr -= PAGE_SIZE;
387 
388 	/*
389 	 * Assuming sections are populated sequentially, the previous section's
390 	 * page data can be reused.
391 	 */
392 	pte = pte_offset_kernel(pmd_off_k(addr), addr);
393 	if (!pte)
394 		return NULL;
395 
396 	return pte;
397 }
398 
vmemmap_populate_compound_pages(unsigned long start_pfn,unsigned long start,unsigned long end,int node,struct dev_pagemap * pgmap)399 static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
400 						     unsigned long start,
401 						     unsigned long end, int node,
402 						     struct dev_pagemap *pgmap)
403 {
404 	unsigned long size, addr;
405 	pte_t *pte;
406 	int rc;
407 
408 	if (reuse_compound_section(start_pfn, pgmap)) {
409 		pte = compound_section_tail_page(start);
410 		if (!pte)
411 			return -ENOMEM;
412 
413 		/*
414 		 * Reuse the page that was populated in the prior iteration
415 		 * with just tail struct pages.
416 		 */
417 		return vmemmap_populate_range(start, end, node, NULL,
418 					      pte_page(ptep_get(pte)));
419 	}
420 
421 	size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
422 	for (addr = start; addr < end; addr += size) {
423 		unsigned long next, last = addr + size;
424 
425 		/* Populate the head page vmemmap page */
426 		pte = vmemmap_populate_address(addr, node, NULL, NULL);
427 		if (!pte)
428 			return -ENOMEM;
429 
430 		/* Populate the tail pages vmemmap page */
431 		next = addr + PAGE_SIZE;
432 		pte = vmemmap_populate_address(next, node, NULL, NULL);
433 		if (!pte)
434 			return -ENOMEM;
435 
436 		/*
437 		 * Reuse the previous page for the rest of tail pages
438 		 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
439 		 */
440 		next += PAGE_SIZE;
441 		rc = vmemmap_populate_range(next, last, node, NULL,
442 					    pte_page(ptep_get(pte)));
443 		if (rc)
444 			return -ENOMEM;
445 	}
446 
447 	return 0;
448 }
449 
450 #endif
451 
__populate_section_memmap(unsigned long pfn,unsigned long nr_pages,int nid,struct vmem_altmap * altmap,struct dev_pagemap * pgmap)452 struct page * __meminit __populate_section_memmap(unsigned long pfn,
453 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
454 		struct dev_pagemap *pgmap)
455 {
456 	unsigned long start = (unsigned long) pfn_to_page(pfn);
457 	unsigned long end = start + nr_pages * sizeof(struct page);
458 	int r;
459 
460 	if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
461 		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
462 		return NULL;
463 
464 	if (vmemmap_can_optimize(altmap, pgmap))
465 		r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
466 	else
467 		r = vmemmap_populate(start, end, nid, altmap);
468 
469 	if (r < 0)
470 		return NULL;
471 
472 	return pfn_to_page(pfn);
473 }
474