1 // SPDX-License-Identifier: GPL-2.0-or-later 1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* 2 /*
3 * Copyright 2013 Red Hat Inc. 3 * Copyright 2013 Red Hat Inc.
4 * 4 *
5 * Authors: Jérôme Glisse <jglisse@redhat.co 5 * Authors: Jérôme Glisse <jglisse@redhat.com>
6 */ 6 */
7 /* 7 /*
8 * Refer to include/linux/hmm.h for informatio 8 * Refer to include/linux/hmm.h for information about heterogeneous memory
9 * management or HMM for short. 9 * management or HMM for short.
10 */ 10 */
11 #include <linux/pagewalk.h> 11 #include <linux/pagewalk.h>
12 #include <linux/hmm.h> 12 #include <linux/hmm.h>
13 #include <linux/init.h> 13 #include <linux/init.h>
14 #include <linux/rmap.h> 14 #include <linux/rmap.h>
15 #include <linux/swap.h> 15 #include <linux/swap.h>
16 #include <linux/slab.h> 16 #include <linux/slab.h>
17 #include <linux/sched.h> 17 #include <linux/sched.h>
18 #include <linux/mmzone.h> 18 #include <linux/mmzone.h>
19 #include <linux/pagemap.h> 19 #include <linux/pagemap.h>
20 #include <linux/swapops.h> 20 #include <linux/swapops.h>
21 #include <linux/hugetlb.h> 21 #include <linux/hugetlb.h>
22 #include <linux/memremap.h> 22 #include <linux/memremap.h>
23 #include <linux/sched/mm.h> 23 #include <linux/sched/mm.h>
24 #include <linux/jump_label.h> 24 #include <linux/jump_label.h>
25 #include <linux/dma-mapping.h> 25 #include <linux/dma-mapping.h>
26 #include <linux/mmu_notifier.h> 26 #include <linux/mmu_notifier.h>
27 #include <linux/memory_hotplug.h> 27 #include <linux/memory_hotplug.h>
28 28
29 #include "internal.h" 29 #include "internal.h"
30 30
31 struct hmm_vma_walk { 31 struct hmm_vma_walk {
32 struct hmm_range *range; 32 struct hmm_range *range;
33 unsigned long last; 33 unsigned long last;
34 }; 34 };
35 35
36 enum { 36 enum {
37 HMM_NEED_FAULT = 1 << 0, 37 HMM_NEED_FAULT = 1 << 0,
38 HMM_NEED_WRITE_FAULT = 1 << 1, 38 HMM_NEED_WRITE_FAULT = 1 << 1,
39 HMM_NEED_ALL_BITS = HMM_NEED_FAULT | H 39 HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT,
40 }; 40 };
41 41
42 static int hmm_pfns_fill(unsigned long addr, u 42 static int hmm_pfns_fill(unsigned long addr, unsigned long end,
43 struct hmm_range *ran 43 struct hmm_range *range, unsigned long cpu_flags)
44 { 44 {
45 unsigned long i = (addr - range->start 45 unsigned long i = (addr - range->start) >> PAGE_SHIFT;
46 46
47 for (; addr < end; addr += PAGE_SIZE, 47 for (; addr < end; addr += PAGE_SIZE, i++)
48 range->hmm_pfns[i] = cpu_flags 48 range->hmm_pfns[i] = cpu_flags;
49 return 0; 49 return 0;
50 } 50 }
51 51
52 /* 52 /*
53 * hmm_vma_fault() - fault in a range lacking 53 * hmm_vma_fault() - fault in a range lacking valid pmd or pte(s)
54 * @addr: range virtual start address (inclusi 54 * @addr: range virtual start address (inclusive)
55 * @end: range virtual end address (exclusive) 55 * @end: range virtual end address (exclusive)
56 * @required_fault: HMM_NEED_* flags 56 * @required_fault: HMM_NEED_* flags
57 * @walk: mm_walk structure 57 * @walk: mm_walk structure
58 * Return: -EBUSY after page fault, or page fa 58 * Return: -EBUSY after page fault, or page fault error
59 * 59 *
60 * This function will be called whenever pmd_n 60 * This function will be called whenever pmd_none() or pte_none() returns true,
61 * or whenever there is no page directory cove 61 * or whenever there is no page directory covering the virtual address range.
62 */ 62 */
63 static int hmm_vma_fault(unsigned long addr, u 63 static int hmm_vma_fault(unsigned long addr, unsigned long end,
64 unsigned int required 64 unsigned int required_fault, struct mm_walk *walk)
65 { 65 {
66 struct hmm_vma_walk *hmm_vma_walk = wa 66 struct hmm_vma_walk *hmm_vma_walk = walk->private;
67 struct vm_area_struct *vma = walk->vma 67 struct vm_area_struct *vma = walk->vma;
68 unsigned int fault_flags = FAULT_FLAG_ 68 unsigned int fault_flags = FAULT_FLAG_REMOTE;
69 69
70 WARN_ON_ONCE(!required_fault); 70 WARN_ON_ONCE(!required_fault);
71 hmm_vma_walk->last = addr; 71 hmm_vma_walk->last = addr;
72 72
73 if (required_fault & HMM_NEED_WRITE_FA 73 if (required_fault & HMM_NEED_WRITE_FAULT) {
74 if (!(vma->vm_flags & VM_WRITE 74 if (!(vma->vm_flags & VM_WRITE))
75 return -EPERM; 75 return -EPERM;
76 fault_flags |= FAULT_FLAG_WRIT 76 fault_flags |= FAULT_FLAG_WRITE;
77 } 77 }
78 78
79 for (; addr < end; addr += PAGE_SIZE) 79 for (; addr < end; addr += PAGE_SIZE)
80 if (handle_mm_fault(vma, addr, 80 if (handle_mm_fault(vma, addr, fault_flags, NULL) &
81 VM_FAULT_ERROR) 81 VM_FAULT_ERROR)
82 return -EFAULT; 82 return -EFAULT;
83 return -EBUSY; 83 return -EBUSY;
84 } 84 }
85 85
86 static unsigned int hmm_pte_need_fault(const s 86 static unsigned int hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
87 unsigne 87 unsigned long pfn_req_flags,
88 unsigne 88 unsigned long cpu_flags)
89 { 89 {
90 struct hmm_range *range = hmm_vma_walk 90 struct hmm_range *range = hmm_vma_walk->range;
91 91
92 /* 92 /*
93 * So we not only consider the individ 93 * So we not only consider the individual per page request we also
94 * consider the default flags requeste 94 * consider the default flags requested for the range. The API can
95 * be used 2 ways. The first one where 95 * be used 2 ways. The first one where the HMM user coalesces
96 * multiple page faults into one reque 96 * multiple page faults into one request and sets flags per pfn for
97 * those faults. The second one where 97 * those faults. The second one where the HMM user wants to pre-
98 * fault a range with specific flags. 98 * fault a range with specific flags. For the latter one it is a
99 * waste to have the user pre-fill the 99 * waste to have the user pre-fill the pfn arrays with a default
100 * flags value. 100 * flags value.
101 */ 101 */
102 pfn_req_flags &= range->pfn_flags_mask 102 pfn_req_flags &= range->pfn_flags_mask;
103 pfn_req_flags |= range->default_flags; 103 pfn_req_flags |= range->default_flags;
104 104
105 /* We aren't ask to do anything ... */ 105 /* We aren't ask to do anything ... */
106 if (!(pfn_req_flags & HMM_PFN_REQ_FAUL 106 if (!(pfn_req_flags & HMM_PFN_REQ_FAULT))
107 return 0; 107 return 0;
108 108
109 /* Need to write fault ? */ 109 /* Need to write fault ? */
110 if ((pfn_req_flags & HMM_PFN_REQ_WRITE 110 if ((pfn_req_flags & HMM_PFN_REQ_WRITE) &&
111 !(cpu_flags & HMM_PFN_WRITE)) 111 !(cpu_flags & HMM_PFN_WRITE))
112 return HMM_NEED_FAULT | HMM_NE 112 return HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT;
113 113
114 /* If CPU page table is not valid then 114 /* If CPU page table is not valid then we need to fault */
115 if (!(cpu_flags & HMM_PFN_VALID)) 115 if (!(cpu_flags & HMM_PFN_VALID))
116 return HMM_NEED_FAULT; 116 return HMM_NEED_FAULT;
117 return 0; 117 return 0;
118 } 118 }
119 119
120 static unsigned int 120 static unsigned int
121 hmm_range_need_fault(const struct hmm_vma_walk 121 hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
122 const unsigned long hmm_p 122 const unsigned long hmm_pfns[], unsigned long npages,
123 unsigned long cpu_flags) 123 unsigned long cpu_flags)
124 { 124 {
125 struct hmm_range *range = hmm_vma_walk 125 struct hmm_range *range = hmm_vma_walk->range;
126 unsigned int required_fault = 0; 126 unsigned int required_fault = 0;
127 unsigned long i; 127 unsigned long i;
128 128
129 /* 129 /*
130 * If the default flags do not request 130 * If the default flags do not request to fault pages, and the mask does
131 * not allow for individual pages to b 131 * not allow for individual pages to be faulted, then
132 * hmm_pte_need_fault() will always re 132 * hmm_pte_need_fault() will always return 0.
133 */ 133 */
134 if (!((range->default_flags | range->p 134 if (!((range->default_flags | range->pfn_flags_mask) &
135 HMM_PFN_REQ_FAULT)) 135 HMM_PFN_REQ_FAULT))
136 return 0; 136 return 0;
137 137
138 for (i = 0; i < npages; ++i) { 138 for (i = 0; i < npages; ++i) {
139 required_fault |= hmm_pte_need 139 required_fault |= hmm_pte_need_fault(hmm_vma_walk, hmm_pfns[i],
140 140 cpu_flags);
141 if (required_fault == HMM_NEED 141 if (required_fault == HMM_NEED_ALL_BITS)
142 return required_fault; 142 return required_fault;
143 } 143 }
144 return required_fault; 144 return required_fault;
145 } 145 }
146 146
147 static int hmm_vma_walk_hole(unsigned long add 147 static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
148 __always_unused i 148 __always_unused int depth, struct mm_walk *walk)
149 { 149 {
150 struct hmm_vma_walk *hmm_vma_walk = wa 150 struct hmm_vma_walk *hmm_vma_walk = walk->private;
151 struct hmm_range *range = hmm_vma_walk 151 struct hmm_range *range = hmm_vma_walk->range;
152 unsigned int required_fault; 152 unsigned int required_fault;
153 unsigned long i, npages; 153 unsigned long i, npages;
154 unsigned long *hmm_pfns; 154 unsigned long *hmm_pfns;
155 155
156 i = (addr - range->start) >> PAGE_SHIF 156 i = (addr - range->start) >> PAGE_SHIFT;
157 npages = (end - addr) >> PAGE_SHIFT; 157 npages = (end - addr) >> PAGE_SHIFT;
158 hmm_pfns = &range->hmm_pfns[i]; 158 hmm_pfns = &range->hmm_pfns[i];
159 required_fault = 159 required_fault =
160 hmm_range_need_fault(hmm_vma_w 160 hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0);
161 if (!walk->vma) { 161 if (!walk->vma) {
162 if (required_fault) 162 if (required_fault)
163 return -EFAULT; 163 return -EFAULT;
164 return hmm_pfns_fill(addr, end 164 return hmm_pfns_fill(addr, end, range, HMM_PFN_ERROR);
165 } 165 }
166 if (required_fault) 166 if (required_fault)
167 return hmm_vma_fault(addr, end 167 return hmm_vma_fault(addr, end, required_fault, walk);
168 return hmm_pfns_fill(addr, end, range, 168 return hmm_pfns_fill(addr, end, range, 0);
169 } 169 }
170 170
171 static inline unsigned long hmm_pfn_flags_orde 171 static inline unsigned long hmm_pfn_flags_order(unsigned long order)
172 { 172 {
173 return order << HMM_PFN_ORDER_SHIFT; 173 return order << HMM_PFN_ORDER_SHIFT;
174 } 174 }
175 175
176 static inline unsigned long pmd_to_hmm_pfn_fla 176 static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
177 177 pmd_t pmd)
178 { 178 {
179 if (pmd_protnone(pmd)) 179 if (pmd_protnone(pmd))
180 return 0; 180 return 0;
181 return (pmd_write(pmd) ? (HMM_PFN_VALI 181 return (pmd_write(pmd) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
182 HMM_PFN_VALID 182 HMM_PFN_VALID) |
183 hmm_pfn_flags_order(PMD_SHIFT - 183 hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT);
184 } 184 }
185 185
186 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 186 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
187 static int hmm_vma_handle_pmd(struct mm_walk * 187 static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
188 unsigned long en 188 unsigned long end, unsigned long hmm_pfns[],
189 pmd_t pmd) 189 pmd_t pmd)
190 { 190 {
191 struct hmm_vma_walk *hmm_vma_walk = wa 191 struct hmm_vma_walk *hmm_vma_walk = walk->private;
192 struct hmm_range *range = hmm_vma_walk 192 struct hmm_range *range = hmm_vma_walk->range;
193 unsigned long pfn, npages, i; 193 unsigned long pfn, npages, i;
194 unsigned int required_fault; 194 unsigned int required_fault;
195 unsigned long cpu_flags; 195 unsigned long cpu_flags;
196 196
197 npages = (end - addr) >> PAGE_SHIFT; 197 npages = (end - addr) >> PAGE_SHIFT;
198 cpu_flags = pmd_to_hmm_pfn_flags(range 198 cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
199 required_fault = 199 required_fault =
200 hmm_range_need_fault(hmm_vma_w 200 hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, cpu_flags);
201 if (required_fault) 201 if (required_fault)
202 return hmm_vma_fault(addr, end 202 return hmm_vma_fault(addr, end, required_fault, walk);
203 203
204 pfn = pmd_pfn(pmd) + ((addr & ~PMD_MAS 204 pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
205 for (i = 0; addr < end; addr += PAGE_S 205 for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
206 hmm_pfns[i] = pfn | cpu_flags; 206 hmm_pfns[i] = pfn | cpu_flags;
207 return 0; 207 return 0;
208 } 208 }
209 #else /* CONFIG_TRANSPARENT_HUGEPAGE */ 209 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
210 /* stub to allow the code below to compile */ 210 /* stub to allow the code below to compile */
211 int hmm_vma_handle_pmd(struct mm_walk *walk, u 211 int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
212 unsigned long end, unsigned lo 212 unsigned long end, unsigned long hmm_pfns[], pmd_t pmd);
213 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 213 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
214 214
215 static inline unsigned long pte_to_hmm_pfn_fla 215 static inline unsigned long pte_to_hmm_pfn_flags(struct hmm_range *range,
216 216 pte_t pte)
217 { 217 {
218 if (pte_none(pte) || !pte_present(pte) 218 if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
219 return 0; 219 return 0;
220 return pte_write(pte) ? (HMM_PFN_VALID 220 return pte_write(pte) ? (HMM_PFN_VALID | HMM_PFN_WRITE) : HMM_PFN_VALID;
221 } 221 }
222 222
223 static int hmm_vma_handle_pte(struct mm_walk * 223 static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
224 unsigned long en 224 unsigned long end, pmd_t *pmdp, pte_t *ptep,
225 unsigned long *h 225 unsigned long *hmm_pfn)
226 { 226 {
227 struct hmm_vma_walk *hmm_vma_walk = wa 227 struct hmm_vma_walk *hmm_vma_walk = walk->private;
228 struct hmm_range *range = hmm_vma_walk 228 struct hmm_range *range = hmm_vma_walk->range;
229 unsigned int required_fault; 229 unsigned int required_fault;
230 unsigned long cpu_flags; 230 unsigned long cpu_flags;
231 pte_t pte = ptep_get(ptep); !! 231 pte_t pte = *ptep;
232 uint64_t pfn_req_flags = *hmm_pfn; 232 uint64_t pfn_req_flags = *hmm_pfn;
233 233
234 if (pte_none_mostly(pte)) { !! 234 if (pte_none(pte)) {
235 required_fault = 235 required_fault =
236 hmm_pte_need_fault(hmm 236 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
237 if (required_fault) 237 if (required_fault)
238 goto fault; 238 goto fault;
239 *hmm_pfn = 0; 239 *hmm_pfn = 0;
240 return 0; 240 return 0;
241 } 241 }
242 242
243 if (!pte_present(pte)) { 243 if (!pte_present(pte)) {
244 swp_entry_t entry = pte_to_swp 244 swp_entry_t entry = pte_to_swp_entry(pte);
245 245
246 /* 246 /*
247 * Don't fault in device priva 247 * Don't fault in device private pages owned by the caller,
248 * just report the PFN. 248 * just report the PFN.
249 */ 249 */
250 if (is_device_private_entry(en 250 if (is_device_private_entry(entry) &&
251 pfn_swap_entry_to_page(ent 251 pfn_swap_entry_to_page(entry)->pgmap->owner ==
252 range->dev_private_owner) 252 range->dev_private_owner) {
253 cpu_flags = HMM_PFN_VA 253 cpu_flags = HMM_PFN_VALID;
254 if (is_writable_device 254 if (is_writable_device_private_entry(entry))
255 cpu_flags |= H 255 cpu_flags |= HMM_PFN_WRITE;
256 *hmm_pfn = swp_offset_ !! 256 *hmm_pfn = swp_offset(entry) | cpu_flags;
257 return 0; 257 return 0;
258 } 258 }
259 259
260 required_fault = 260 required_fault =
261 hmm_pte_need_fault(hmm 261 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
262 if (!required_fault) { 262 if (!required_fault) {
263 *hmm_pfn = 0; 263 *hmm_pfn = 0;
264 return 0; 264 return 0;
265 } 265 }
266 266
267 if (!non_swap_entry(entry)) 267 if (!non_swap_entry(entry))
268 goto fault; 268 goto fault;
269 269
270 if (is_device_private_entry(en 270 if (is_device_private_entry(entry))
271 goto fault; 271 goto fault;
272 272
273 if (is_device_exclusive_entry( 273 if (is_device_exclusive_entry(entry))
274 goto fault; 274 goto fault;
275 275
276 if (is_migration_entry(entry)) 276 if (is_migration_entry(entry)) {
277 pte_unmap(ptep); 277 pte_unmap(ptep);
278 hmm_vma_walk->last = a 278 hmm_vma_walk->last = addr;
279 migration_entry_wait(w 279 migration_entry_wait(walk->mm, pmdp, addr);
280 return -EBUSY; 280 return -EBUSY;
281 } 281 }
282 282
283 /* Report error for everything 283 /* Report error for everything else */
284 pte_unmap(ptep); 284 pte_unmap(ptep);
285 return -EFAULT; 285 return -EFAULT;
286 } 286 }
287 287
288 cpu_flags = pte_to_hmm_pfn_flags(range 288 cpu_flags = pte_to_hmm_pfn_flags(range, pte);
289 required_fault = 289 required_fault =
290 hmm_pte_need_fault(hmm_vma_wal 290 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
291 if (required_fault) 291 if (required_fault)
292 goto fault; 292 goto fault;
293 293
294 /* 294 /*
295 * Bypass devmap pte such as DAX page 295 * Bypass devmap pte such as DAX page when all pfn requested
296 * flags(pfn_req_flags) are fulfilled. 296 * flags(pfn_req_flags) are fulfilled.
297 * Since each architecture defines a s 297 * Since each architecture defines a struct page for the zero page, just
298 * fall through and treat it like a no 298 * fall through and treat it like a normal page.
299 */ 299 */
300 if (!vm_normal_page(walk->vma, addr, p 300 if (!vm_normal_page(walk->vma, addr, pte) &&
301 !pte_devmap(pte) && 301 !pte_devmap(pte) &&
302 !is_zero_pfn(pte_pfn(pte))) { 302 !is_zero_pfn(pte_pfn(pte))) {
303 if (hmm_pte_need_fault(hmm_vma 303 if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) {
304 pte_unmap(ptep); 304 pte_unmap(ptep);
305 return -EFAULT; 305 return -EFAULT;
306 } 306 }
307 *hmm_pfn = HMM_PFN_ERROR; 307 *hmm_pfn = HMM_PFN_ERROR;
308 return 0; 308 return 0;
309 } 309 }
310 310
311 *hmm_pfn = pte_pfn(pte) | cpu_flags; 311 *hmm_pfn = pte_pfn(pte) | cpu_flags;
312 return 0; 312 return 0;
313 313
314 fault: 314 fault:
315 pte_unmap(ptep); 315 pte_unmap(ptep);
316 /* Fault any virtual address we were a 316 /* Fault any virtual address we were asked to fault */
317 return hmm_vma_fault(addr, end, requir 317 return hmm_vma_fault(addr, end, required_fault, walk);
318 } 318 }
319 319
320 static int hmm_vma_walk_pmd(pmd_t *pmdp, 320 static int hmm_vma_walk_pmd(pmd_t *pmdp,
321 unsigned long star 321 unsigned long start,
322 unsigned long end, 322 unsigned long end,
323 struct mm_walk *wa 323 struct mm_walk *walk)
324 { 324 {
325 struct hmm_vma_walk *hmm_vma_walk = wa 325 struct hmm_vma_walk *hmm_vma_walk = walk->private;
326 struct hmm_range *range = hmm_vma_walk 326 struct hmm_range *range = hmm_vma_walk->range;
327 unsigned long *hmm_pfns = 327 unsigned long *hmm_pfns =
328 &range->hmm_pfns[(start - rang 328 &range->hmm_pfns[(start - range->start) >> PAGE_SHIFT];
329 unsigned long npages = (end - start) > 329 unsigned long npages = (end - start) >> PAGE_SHIFT;
330 unsigned long addr = start; 330 unsigned long addr = start;
331 pte_t *ptep; 331 pte_t *ptep;
332 pmd_t pmd; 332 pmd_t pmd;
333 333
334 again: 334 again:
335 pmd = pmdp_get_lockless(pmdp); !! 335 pmd = READ_ONCE(*pmdp);
336 if (pmd_none(pmd)) 336 if (pmd_none(pmd))
337 return hmm_vma_walk_hole(start 337 return hmm_vma_walk_hole(start, end, -1, walk);
338 338
339 if (thp_migration_supported() && is_pm 339 if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
340 if (hmm_range_need_fault(hmm_v 340 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0)) {
341 hmm_vma_walk->last = a 341 hmm_vma_walk->last = addr;
342 pmd_migration_entry_wa 342 pmd_migration_entry_wait(walk->mm, pmdp);
343 return -EBUSY; 343 return -EBUSY;
344 } 344 }
345 return hmm_pfns_fill(start, en 345 return hmm_pfns_fill(start, end, range, 0);
346 } 346 }
347 347
348 if (!pmd_present(pmd)) { 348 if (!pmd_present(pmd)) {
349 if (hmm_range_need_fault(hmm_v 349 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
350 return -EFAULT; 350 return -EFAULT;
351 return hmm_pfns_fill(start, en 351 return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
352 } 352 }
353 353
354 if (pmd_devmap(pmd) || pmd_trans_huge( 354 if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
355 /* 355 /*
356 * No need to take pmd_lock he 356 * No need to take pmd_lock here, even if some other thread
357 * is splitting the huge pmd w 357 * is splitting the huge pmd we will get that event through
358 * mmu_notifier callback. 358 * mmu_notifier callback.
359 * 359 *
360 * So just read pmd value and 360 * So just read pmd value and check again it's a transparent
361 * huge or device mapping one 361 * huge or device mapping one and compute corresponding pfn
362 * values. 362 * values.
363 */ 363 */
364 pmd = pmdp_get_lockless(pmdp); !! 364 pmd = pmd_read_atomic(pmdp);
>> 365 barrier();
365 if (!pmd_devmap(pmd) && !pmd_t 366 if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
366 goto again; 367 goto again;
367 368
368 return hmm_vma_handle_pmd(walk 369 return hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd);
369 } 370 }
370 371
371 /* 372 /*
372 * We have handled all the valid cases 373 * We have handled all the valid cases above ie either none, migration,
373 * huge or transparent huge. At this p 374 * huge or transparent huge. At this point either it is a valid pmd
374 * entry pointing to pte directory or 375 * entry pointing to pte directory or it is a bad pmd that will not
375 * recover. 376 * recover.
376 */ 377 */
377 if (pmd_bad(pmd)) { 378 if (pmd_bad(pmd)) {
378 if (hmm_range_need_fault(hmm_v 379 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
379 return -EFAULT; 380 return -EFAULT;
380 return hmm_pfns_fill(start, en 381 return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
381 } 382 }
382 383
383 ptep = pte_offset_map(pmdp, addr); 384 ptep = pte_offset_map(pmdp, addr);
384 if (!ptep) <<
385 goto again; <<
386 for (; addr < end; addr += PAGE_SIZE, 385 for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) {
387 int r; 386 int r;
388 387
389 r = hmm_vma_handle_pte(walk, a 388 r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, hmm_pfns);
390 if (r) { 389 if (r) {
391 /* hmm_vma_handle_pte( 390 /* hmm_vma_handle_pte() did pte_unmap() */
392 return r; 391 return r;
393 } 392 }
394 } 393 }
395 pte_unmap(ptep - 1); 394 pte_unmap(ptep - 1);
396 return 0; 395 return 0;
397 } 396 }
398 397
399 #if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \ 398 #if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
400 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEP 399 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
401 static inline unsigned long pud_to_hmm_pfn_fla 400 static inline unsigned long pud_to_hmm_pfn_flags(struct hmm_range *range,
402 401 pud_t pud)
403 { 402 {
404 if (!pud_present(pud)) 403 if (!pud_present(pud))
405 return 0; 404 return 0;
406 return (pud_write(pud) ? (HMM_PFN_VALI 405 return (pud_write(pud) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
407 HMM_PFN_VALID 406 HMM_PFN_VALID) |
408 hmm_pfn_flags_order(PUD_SHIFT - 407 hmm_pfn_flags_order(PUD_SHIFT - PAGE_SHIFT);
409 } 408 }
410 409
411 static int hmm_vma_walk_pud(pud_t *pudp, unsig 410 static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
412 struct mm_walk *walk) 411 struct mm_walk *walk)
413 { 412 {
414 struct hmm_vma_walk *hmm_vma_walk = wa 413 struct hmm_vma_walk *hmm_vma_walk = walk->private;
415 struct hmm_range *range = hmm_vma_walk 414 struct hmm_range *range = hmm_vma_walk->range;
416 unsigned long addr = start; 415 unsigned long addr = start;
417 pud_t pud; 416 pud_t pud;
418 spinlock_t *ptl = pud_trans_huge_lock( 417 spinlock_t *ptl = pud_trans_huge_lock(pudp, walk->vma);
419 418
420 if (!ptl) 419 if (!ptl)
421 return 0; 420 return 0;
422 421
423 /* Normally we don't want to split the 422 /* Normally we don't want to split the huge page */
424 walk->action = ACTION_CONTINUE; 423 walk->action = ACTION_CONTINUE;
425 424
426 pud = READ_ONCE(*pudp); 425 pud = READ_ONCE(*pudp);
427 if (!pud_present(pud)) { !! 426 if (pud_none(pud)) {
428 spin_unlock(ptl); 427 spin_unlock(ptl);
429 return hmm_vma_walk_hole(start 428 return hmm_vma_walk_hole(start, end, -1, walk);
430 } 429 }
431 430
432 if (pud_leaf(pud) && pud_devmap(pud)) !! 431 if (pud_huge(pud) && pud_devmap(pud)) {
433 unsigned long i, npages, pfn; 432 unsigned long i, npages, pfn;
434 unsigned int required_fault; 433 unsigned int required_fault;
435 unsigned long *hmm_pfns; 434 unsigned long *hmm_pfns;
436 unsigned long cpu_flags; 435 unsigned long cpu_flags;
437 436
>> 437 if (!pud_present(pud)) {
>> 438 spin_unlock(ptl);
>> 439 return hmm_vma_walk_hole(start, end, -1, walk);
>> 440 }
>> 441
438 i = (addr - range->start) >> P 442 i = (addr - range->start) >> PAGE_SHIFT;
439 npages = (end - addr) >> PAGE_ 443 npages = (end - addr) >> PAGE_SHIFT;
440 hmm_pfns = &range->hmm_pfns[i] 444 hmm_pfns = &range->hmm_pfns[i];
441 445
442 cpu_flags = pud_to_hmm_pfn_fla 446 cpu_flags = pud_to_hmm_pfn_flags(range, pud);
443 required_fault = hmm_range_nee 447 required_fault = hmm_range_need_fault(hmm_vma_walk, hmm_pfns,
444 448 npages, cpu_flags);
445 if (required_fault) { 449 if (required_fault) {
446 spin_unlock(ptl); 450 spin_unlock(ptl);
447 return hmm_vma_fault(a 451 return hmm_vma_fault(addr, end, required_fault, walk);
448 } 452 }
449 453
450 pfn = pud_pfn(pud) + ((addr & 454 pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
451 for (i = 0; i < npages; ++i, + 455 for (i = 0; i < npages; ++i, ++pfn)
452 hmm_pfns[i] = pfn | cp 456 hmm_pfns[i] = pfn | cpu_flags;
453 goto out_unlock; 457 goto out_unlock;
454 } 458 }
455 459
456 /* Ask for the PUD to be split */ 460 /* Ask for the PUD to be split */
457 walk->action = ACTION_SUBTREE; 461 walk->action = ACTION_SUBTREE;
458 462
459 out_unlock: 463 out_unlock:
460 spin_unlock(ptl); 464 spin_unlock(ptl);
461 return 0; 465 return 0;
462 } 466 }
463 #else 467 #else
464 #define hmm_vma_walk_pud NULL 468 #define hmm_vma_walk_pud NULL
465 #endif 469 #endif
466 470
467 #ifdef CONFIG_HUGETLB_PAGE 471 #ifdef CONFIG_HUGETLB_PAGE
468 static int hmm_vma_walk_hugetlb_entry(pte_t *p 472 static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
469 unsigned 473 unsigned long start, unsigned long end,
470 struct m 474 struct mm_walk *walk)
471 { 475 {
472 unsigned long addr = start, i, pfn; 476 unsigned long addr = start, i, pfn;
473 struct hmm_vma_walk *hmm_vma_walk = wa 477 struct hmm_vma_walk *hmm_vma_walk = walk->private;
474 struct hmm_range *range = hmm_vma_walk 478 struct hmm_range *range = hmm_vma_walk->range;
475 struct vm_area_struct *vma = walk->vma 479 struct vm_area_struct *vma = walk->vma;
476 unsigned int required_fault; 480 unsigned int required_fault;
477 unsigned long pfn_req_flags; 481 unsigned long pfn_req_flags;
478 unsigned long cpu_flags; 482 unsigned long cpu_flags;
479 spinlock_t *ptl; 483 spinlock_t *ptl;
480 pte_t entry; 484 pte_t entry;
481 485
482 ptl = huge_pte_lock(hstate_vma(vma), w 486 ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
483 entry = huge_ptep_get(walk->mm, addr, !! 487 entry = huge_ptep_get(pte);
484 488
485 i = (start - range->start) >> PAGE_SHI 489 i = (start - range->start) >> PAGE_SHIFT;
486 pfn_req_flags = range->hmm_pfns[i]; 490 pfn_req_flags = range->hmm_pfns[i];
487 cpu_flags = pte_to_hmm_pfn_flags(range 491 cpu_flags = pte_to_hmm_pfn_flags(range, entry) |
488 hmm_pfn_flags_order(huge_p 492 hmm_pfn_flags_order(huge_page_order(hstate_vma(vma)));
489 required_fault = 493 required_fault =
490 hmm_pte_need_fault(hmm_vma_wal 494 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
491 if (required_fault) { 495 if (required_fault) {
492 int ret; <<
493 <<
494 spin_unlock(ptl); 496 spin_unlock(ptl);
495 hugetlb_vma_unlock_read(vma); !! 497 return hmm_vma_fault(addr, end, required_fault, walk);
496 /* <<
497 * Avoid deadlock: drop the vm <<
498 * hmm_vma_fault(), which will <<
499 * drop the vma lock. This is <<
500 * protection point of view, b <<
501 * use here of either pte or p <<
502 * lock. <<
503 */ <<
504 ret = hmm_vma_fault(addr, end, <<
505 hugetlb_vma_lock_read(vma); <<
506 return ret; <<
507 } 498 }
508 499
509 pfn = pte_pfn(entry) + ((start & ~hmas 500 pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
510 for (; addr < end; addr += PAGE_SIZE, 501 for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
511 range->hmm_pfns[i] = pfn | cpu 502 range->hmm_pfns[i] = pfn | cpu_flags;
512 503
513 spin_unlock(ptl); 504 spin_unlock(ptl);
514 return 0; 505 return 0;
515 } 506 }
516 #else 507 #else
517 #define hmm_vma_walk_hugetlb_entry NULL 508 #define hmm_vma_walk_hugetlb_entry NULL
518 #endif /* CONFIG_HUGETLB_PAGE */ 509 #endif /* CONFIG_HUGETLB_PAGE */
519 510
520 static int hmm_vma_walk_test(unsigned long sta 511 static int hmm_vma_walk_test(unsigned long start, unsigned long end,
521 struct mm_walk *w 512 struct mm_walk *walk)
522 { 513 {
523 struct hmm_vma_walk *hmm_vma_walk = wa 514 struct hmm_vma_walk *hmm_vma_walk = walk->private;
524 struct hmm_range *range = hmm_vma_walk 515 struct hmm_range *range = hmm_vma_walk->range;
525 struct vm_area_struct *vma = walk->vma 516 struct vm_area_struct *vma = walk->vma;
526 517
527 if (!(vma->vm_flags & (VM_IO | VM_PFNM 518 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) &&
528 vma->vm_flags & VM_READ) 519 vma->vm_flags & VM_READ)
529 return 0; 520 return 0;
530 521
531 /* 522 /*
532 * vma ranges that don't have struct p 523 * vma ranges that don't have struct page backing them or map I/O
533 * devices directly cannot be handled 524 * devices directly cannot be handled by hmm_range_fault().
534 * 525 *
535 * If the vma does not allow read acce 526 * If the vma does not allow read access, then assume that it does not
536 * allow write access either. HMM does 527 * allow write access either. HMM does not support architectures that
537 * allow write without read. 528 * allow write without read.
538 * 529 *
539 * If a fault is requested for an unsu 530 * If a fault is requested for an unsupported range then it is a hard
540 * failure. 531 * failure.
541 */ 532 */
542 if (hmm_range_need_fault(hmm_vma_walk, 533 if (hmm_range_need_fault(hmm_vma_walk,
543 range->hmm_pf 534 range->hmm_pfns +
544 ((sta 535 ((start - range->start) >> PAGE_SHIFT),
545 (end - start) 536 (end - start) >> PAGE_SHIFT, 0))
546 return -EFAULT; 537 return -EFAULT;
547 538
548 hmm_pfns_fill(start, end, range, HMM_P 539 hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
549 540
550 /* Skip this vma and continue processi 541 /* Skip this vma and continue processing the next vma. */
551 return 1; 542 return 1;
552 } 543 }
553 544
554 static const struct mm_walk_ops hmm_walk_ops = 545 static const struct mm_walk_ops hmm_walk_ops = {
555 .pud_entry = hmm_vma_walk_pud, 546 .pud_entry = hmm_vma_walk_pud,
556 .pmd_entry = hmm_vma_walk_pmd, 547 .pmd_entry = hmm_vma_walk_pmd,
557 .pte_hole = hmm_vma_walk_hole, 548 .pte_hole = hmm_vma_walk_hole,
558 .hugetlb_entry = hmm_vma_walk_hugetlb 549 .hugetlb_entry = hmm_vma_walk_hugetlb_entry,
559 .test_walk = hmm_vma_walk_test, 550 .test_walk = hmm_vma_walk_test,
560 .walk_lock = PGWALK_RDLOCK, <<
561 }; 551 };
562 552
563 /** 553 /**
564 * hmm_range_fault - try to fault some address 554 * hmm_range_fault - try to fault some address in a virtual address range
565 * @range: argument structure 555 * @range: argument structure
566 * 556 *
567 * Returns 0 on success or one of the followin 557 * Returns 0 on success or one of the following error codes:
568 * 558 *
569 * -EINVAL: Invalid arguments or mm or vir 559 * -EINVAL: Invalid arguments or mm or virtual address is in an invalid vma
570 * (e.g., device file vma). 560 * (e.g., device file vma).
571 * -ENOMEM: Out of memory. 561 * -ENOMEM: Out of memory.
572 * -EPERM: Invalid permission (e.g., aski 562 * -EPERM: Invalid permission (e.g., asking for write and range is read
573 * only). 563 * only).
574 * -EBUSY: The range has been invalidated 564 * -EBUSY: The range has been invalidated and the caller needs to wait for
575 * the invalidation to finish. 565 * the invalidation to finish.
576 * -EFAULT: A page was requested to be val 566 * -EFAULT: A page was requested to be valid and could not be made valid
577 * ie it has no backing VMA or it 567 * ie it has no backing VMA or it is illegal to access
578 * 568 *
579 * This is similar to get_user_pages(), except 569 * This is similar to get_user_pages(), except that it can read the page tables
580 * without mutating them (ie causing faults). 570 * without mutating them (ie causing faults).
581 */ 571 */
582 int hmm_range_fault(struct hmm_range *range) 572 int hmm_range_fault(struct hmm_range *range)
583 { 573 {
584 struct hmm_vma_walk hmm_vma_walk = { 574 struct hmm_vma_walk hmm_vma_walk = {
585 .range = range, 575 .range = range,
586 .last = range->start, 576 .last = range->start,
587 }; 577 };
588 struct mm_struct *mm = range->notifier 578 struct mm_struct *mm = range->notifier->mm;
589 int ret; 579 int ret;
590 580
591 mmap_assert_locked(mm); 581 mmap_assert_locked(mm);
592 582
593 do { 583 do {
594 /* If range is no longer valid 584 /* If range is no longer valid force retry. */
595 if (mmu_interval_check_retry(r 585 if (mmu_interval_check_retry(range->notifier,
596 r 586 range->notifier_seq))
597 return -EBUSY; 587 return -EBUSY;
598 ret = walk_page_range(mm, hmm_ 588 ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
599 &hmm_wal 589 &hmm_walk_ops, &hmm_vma_walk);
600 /* 590 /*
601 * When -EBUSY is returned the 591 * When -EBUSY is returned the loop restarts with
602 * hmm_vma_walk.last set to an 592 * hmm_vma_walk.last set to an address that has not been stored
603 * in pfns. All entries < last 593 * in pfns. All entries < last in the pfn array are set to their
604 * output, and all >= are stil 594 * output, and all >= are still at their input values.
605 */ 595 */
606 } while (ret == -EBUSY); 596 } while (ret == -EBUSY);
607 return ret; 597 return ret;
608 } 598 }
609 EXPORT_SYMBOL(hmm_range_fault); 599 EXPORT_SYMBOL(hmm_range_fault);
610 600
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