Commit | Line | Data |
---|---|---|
3b827c1b JF |
1 | /* |
2 | * Xen mmu operations | |
3 | * | |
4 | * This file contains the various mmu fetch and update operations. | |
5 | * The most important job they must perform is the mapping between the | |
6 | * domain's pfn and the overall machine mfns. | |
7 | * | |
8 | * Xen allows guests to directly update the pagetable, in a controlled | |
9 | * fashion. In other words, the guest modifies the same pagetable | |
10 | * that the CPU actually uses, which eliminates the overhead of having | |
11 | * a separate shadow pagetable. | |
12 | * | |
13 | * In order to allow this, it falls on the guest domain to map its | |
14 | * notion of a "physical" pfn - which is just a domain-local linear | |
15 | * address - into a real "machine address" which the CPU's MMU can | |
16 | * use. | |
17 | * | |
18 | * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be | |
19 | * inserted directly into the pagetable. When creating a new | |
20 | * pte/pmd/pgd, it converts the passed pfn into an mfn. Conversely, | |
21 | * when reading the content back with __(pgd|pmd|pte)_val, it converts | |
22 | * the mfn back into a pfn. | |
23 | * | |
24 | * The other constraint is that all pages which make up a pagetable | |
25 | * must be mapped read-only in the guest. This prevents uncontrolled | |
26 | * guest updates to the pagetable. Xen strictly enforces this, and | |
27 | * will disallow any pagetable update which will end up mapping a | |
28 | * pagetable page RW, and will disallow using any writable page as a | |
29 | * pagetable. | |
30 | * | |
31 | * Naively, when loading %cr3 with the base of a new pagetable, Xen | |
32 | * would need to validate the whole pagetable before going on. | |
33 | * Naturally, this is quite slow. The solution is to "pin" a | |
34 | * pagetable, which enforces all the constraints on the pagetable even | |
35 | * when it is not actively in use. This menas that Xen can be assured | |
36 | * that it is still valid when you do load it into %cr3, and doesn't | |
37 | * need to revalidate it. | |
38 | * | |
39 | * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 | |
40 | */ | |
f120f13e | 41 | #include <linux/sched.h> |
f4f97b3e | 42 | #include <linux/highmem.h> |
3b827c1b | 43 | #include <linux/bug.h> |
3b827c1b JF |
44 | |
45 | #include <asm/pgtable.h> | |
46 | #include <asm/tlbflush.h> | |
47 | #include <asm/mmu_context.h> | |
f4f97b3e | 48 | #include <asm/paravirt.h> |
3b827c1b JF |
49 | |
50 | #include <asm/xen/hypercall.h> | |
f4f97b3e | 51 | #include <asm/xen/hypervisor.h> |
3b827c1b JF |
52 | |
53 | #include <xen/page.h> | |
54 | #include <xen/interface/xen.h> | |
55 | ||
f4f97b3e | 56 | #include "multicalls.h" |
3b827c1b JF |
57 | #include "mmu.h" |
58 | ||
d451bb7a | 59 | #define P2M_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) |
cf0923ea | 60 | #define TOP_ENTRIES (MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE) |
d451bb7a | 61 | |
cf0923ea JF |
62 | /* Placeholder for holes in the address space */ |
63 | static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE] | |
64 | __attribute__((section(".data.page_aligned"))) = | |
65 | { [ 0 ... P2M_ENTRIES_PER_PAGE-1 ] = ~0UL }; | |
66 | ||
67 | /* Array of pointers to pages containing p2m entries */ | |
68 | static unsigned long *p2m_top[TOP_ENTRIES] | |
69 | __attribute__((section(".data.page_aligned"))) = | |
70 | { [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] }; | |
d451bb7a | 71 | |
d5edbc1f JF |
72 | /* Arrays of p2m arrays expressed in mfns used for save/restore */ |
73 | static unsigned long p2m_top_mfn[TOP_ENTRIES] | |
74 | __attribute__((section(".bss.page_aligned"))); | |
75 | ||
b20aeccd IM |
76 | static unsigned long p2m_top_mfn_list[ |
77 | PAGE_ALIGN(TOP_ENTRIES / P2M_ENTRIES_PER_PAGE)] | |
d5edbc1f JF |
78 | __attribute__((section(".bss.page_aligned"))); |
79 | ||
d451bb7a JF |
80 | static inline unsigned p2m_top_index(unsigned long pfn) |
81 | { | |
8006ec3e | 82 | BUG_ON(pfn >= MAX_DOMAIN_PAGES); |
d451bb7a JF |
83 | return pfn / P2M_ENTRIES_PER_PAGE; |
84 | } | |
85 | ||
86 | static inline unsigned p2m_index(unsigned long pfn) | |
87 | { | |
88 | return pfn % P2M_ENTRIES_PER_PAGE; | |
89 | } | |
90 | ||
d5edbc1f JF |
91 | /* Build the parallel p2m_top_mfn structures */ |
92 | void xen_setup_mfn_list_list(void) | |
93 | { | |
94 | unsigned pfn, idx; | |
95 | ||
96 | for(pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_ENTRIES_PER_PAGE) { | |
97 | unsigned topidx = p2m_top_index(pfn); | |
98 | ||
99 | p2m_top_mfn[topidx] = virt_to_mfn(p2m_top[topidx]); | |
100 | } | |
101 | ||
102 | for(idx = 0; idx < ARRAY_SIZE(p2m_top_mfn_list); idx++) { | |
103 | unsigned topidx = idx * P2M_ENTRIES_PER_PAGE; | |
104 | p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]); | |
105 | } | |
106 | ||
107 | BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); | |
108 | ||
109 | HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = | |
110 | virt_to_mfn(p2m_top_mfn_list); | |
111 | HYPERVISOR_shared_info->arch.max_pfn = xen_start_info->nr_pages; | |
112 | } | |
113 | ||
114 | /* Set up p2m_top to point to the domain-builder provided p2m pages */ | |
d451bb7a JF |
115 | void __init xen_build_dynamic_phys_to_machine(void) |
116 | { | |
d451bb7a | 117 | unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list; |
8006ec3e | 118 | unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages); |
d5edbc1f | 119 | unsigned pfn; |
d451bb7a | 120 | |
8006ec3e | 121 | for(pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) { |
d451bb7a JF |
122 | unsigned topidx = p2m_top_index(pfn); |
123 | ||
124 | p2m_top[topidx] = &mfn_list[pfn]; | |
125 | } | |
126 | } | |
127 | ||
128 | unsigned long get_phys_to_machine(unsigned long pfn) | |
129 | { | |
130 | unsigned topidx, idx; | |
131 | ||
8006ec3e JF |
132 | if (unlikely(pfn >= MAX_DOMAIN_PAGES)) |
133 | return INVALID_P2M_ENTRY; | |
134 | ||
d451bb7a | 135 | topidx = p2m_top_index(pfn); |
d451bb7a JF |
136 | idx = p2m_index(pfn); |
137 | return p2m_top[topidx][idx]; | |
138 | } | |
139 | ||
d5edbc1f | 140 | static void alloc_p2m(unsigned long **pp, unsigned long *mfnp) |
d451bb7a JF |
141 | { |
142 | unsigned long *p; | |
143 | unsigned i; | |
144 | ||
145 | p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL); | |
146 | BUG_ON(p == NULL); | |
147 | ||
148 | for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++) | |
149 | p[i] = INVALID_P2M_ENTRY; | |
150 | ||
cf0923ea | 151 | if (cmpxchg(pp, p2m_missing, p) != p2m_missing) |
d451bb7a | 152 | free_page((unsigned long)p); |
d5edbc1f JF |
153 | else |
154 | *mfnp = virt_to_mfn(p); | |
d451bb7a JF |
155 | } |
156 | ||
157 | void set_phys_to_machine(unsigned long pfn, unsigned long mfn) | |
158 | { | |
159 | unsigned topidx, idx; | |
160 | ||
161 | if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) { | |
162 | BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY); | |
8006ec3e JF |
163 | return; |
164 | } | |
165 | ||
166 | if (unlikely(pfn >= MAX_DOMAIN_PAGES)) { | |
167 | BUG_ON(mfn != INVALID_P2M_ENTRY); | |
d451bb7a JF |
168 | return; |
169 | } | |
170 | ||
171 | topidx = p2m_top_index(pfn); | |
cf0923ea | 172 | if (p2m_top[topidx] == p2m_missing) { |
d451bb7a JF |
173 | /* no need to allocate a page to store an invalid entry */ |
174 | if (mfn == INVALID_P2M_ENTRY) | |
175 | return; | |
d5edbc1f | 176 | alloc_p2m(&p2m_top[topidx], &p2m_top_mfn[topidx]); |
d451bb7a JF |
177 | } |
178 | ||
179 | idx = p2m_index(pfn); | |
180 | p2m_top[topidx][idx] = mfn; | |
181 | } | |
182 | ||
3b827c1b JF |
183 | xmaddr_t arbitrary_virt_to_machine(unsigned long address) |
184 | { | |
da7bfc50 | 185 | unsigned int level; |
f0646e43 | 186 | pte_t *pte = lookup_address(address, &level); |
3b827c1b JF |
187 | unsigned offset = address & PAGE_MASK; |
188 | ||
189 | BUG_ON(pte == NULL); | |
190 | ||
191 | return XMADDR((pte_mfn(*pte) << PAGE_SHIFT) + offset); | |
192 | } | |
193 | ||
194 | void make_lowmem_page_readonly(void *vaddr) | |
195 | { | |
196 | pte_t *pte, ptev; | |
197 | unsigned long address = (unsigned long)vaddr; | |
da7bfc50 | 198 | unsigned int level; |
3b827c1b | 199 | |
f0646e43 | 200 | pte = lookup_address(address, &level); |
3b827c1b JF |
201 | BUG_ON(pte == NULL); |
202 | ||
203 | ptev = pte_wrprotect(*pte); | |
204 | ||
205 | if (HYPERVISOR_update_va_mapping(address, ptev, 0)) | |
206 | BUG(); | |
207 | } | |
208 | ||
209 | void make_lowmem_page_readwrite(void *vaddr) | |
210 | { | |
211 | pte_t *pte, ptev; | |
212 | unsigned long address = (unsigned long)vaddr; | |
da7bfc50 | 213 | unsigned int level; |
3b827c1b | 214 | |
f0646e43 | 215 | pte = lookup_address(address, &level); |
3b827c1b JF |
216 | BUG_ON(pte == NULL); |
217 | ||
218 | ptev = pte_mkwrite(*pte); | |
219 | ||
220 | if (HYPERVISOR_update_va_mapping(address, ptev, 0)) | |
221 | BUG(); | |
222 | } | |
223 | ||
224 | ||
3b827c1b JF |
225 | void xen_set_pmd(pmd_t *ptr, pmd_t val) |
226 | { | |
d66bf8fc JF |
227 | struct multicall_space mcs; |
228 | struct mmu_update *u; | |
3b827c1b | 229 | |
d66bf8fc JF |
230 | preempt_disable(); |
231 | ||
232 | mcs = xen_mc_entry(sizeof(*u)); | |
233 | u = mcs.args; | |
234 | u->ptr = virt_to_machine(ptr).maddr; | |
235 | u->val = pmd_val_ma(val); | |
236 | MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); | |
237 | ||
238 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
239 | ||
240 | preempt_enable(); | |
3b827c1b JF |
241 | } |
242 | ||
3b827c1b JF |
243 | /* |
244 | * Associate a virtual page frame with a given physical page frame | |
245 | * and protection flags for that frame. | |
246 | */ | |
247 | void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) | |
248 | { | |
249 | pgd_t *pgd; | |
250 | pud_t *pud; | |
251 | pmd_t *pmd; | |
252 | pte_t *pte; | |
253 | ||
254 | pgd = swapper_pg_dir + pgd_index(vaddr); | |
255 | if (pgd_none(*pgd)) { | |
256 | BUG(); | |
257 | return; | |
258 | } | |
259 | pud = pud_offset(pgd, vaddr); | |
260 | if (pud_none(*pud)) { | |
261 | BUG(); | |
262 | return; | |
263 | } | |
264 | pmd = pmd_offset(pud, vaddr); | |
265 | if (pmd_none(*pmd)) { | |
266 | BUG(); | |
267 | return; | |
268 | } | |
269 | pte = pte_offset_kernel(pmd, vaddr); | |
270 | /* <mfn,flags> stored as-is, to permit clearing entries */ | |
271 | xen_set_pte(pte, mfn_pte(mfn, flags)); | |
272 | ||
273 | /* | |
274 | * It's enough to flush this one mapping. | |
275 | * (PGE mappings get flushed as well) | |
276 | */ | |
277 | __flush_tlb_one(vaddr); | |
278 | } | |
279 | ||
280 | void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, | |
281 | pte_t *ptep, pte_t pteval) | |
282 | { | |
2bd50036 JF |
283 | /* updates to init_mm may be done without lock */ |
284 | if (mm == &init_mm) | |
285 | preempt_disable(); | |
286 | ||
d66bf8fc | 287 | if (mm == current->mm || mm == &init_mm) { |
8965c1c0 | 288 | if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { |
d66bf8fc JF |
289 | struct multicall_space mcs; |
290 | mcs = xen_mc_entry(0); | |
291 | ||
292 | MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); | |
293 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
2bd50036 | 294 | goto out; |
d66bf8fc JF |
295 | } else |
296 | if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) | |
2bd50036 | 297 | goto out; |
d66bf8fc JF |
298 | } |
299 | xen_set_pte(ptep, pteval); | |
2bd50036 JF |
300 | |
301 | out: | |
302 | if (mm == &init_mm) | |
303 | preempt_enable(); | |
3b827c1b JF |
304 | } |
305 | ||
947a69c9 JF |
306 | pteval_t xen_pte_val(pte_t pte) |
307 | { | |
308 | pteval_t ret = pte.pte; | |
309 | ||
310 | if (ret & _PAGE_PRESENT) | |
311 | ret = machine_to_phys(XMADDR(ret)).paddr | _PAGE_PRESENT; | |
312 | ||
313 | return ret; | |
314 | } | |
315 | ||
316 | pgdval_t xen_pgd_val(pgd_t pgd) | |
317 | { | |
318 | pgdval_t ret = pgd.pgd; | |
319 | if (ret & _PAGE_PRESENT) | |
320 | ret = machine_to_phys(XMADDR(ret)).paddr | _PAGE_PRESENT; | |
321 | return ret; | |
322 | } | |
323 | ||
324 | pte_t xen_make_pte(pteval_t pte) | |
325 | { | |
326 | if (pte & _PAGE_PRESENT) { | |
327 | pte = phys_to_machine(XPADDR(pte)).maddr; | |
328 | pte &= ~(_PAGE_PCD | _PAGE_PWT); | |
329 | } | |
330 | ||
331 | return (pte_t){ .pte = pte }; | |
332 | } | |
333 | ||
334 | pgd_t xen_make_pgd(pgdval_t pgd) | |
335 | { | |
336 | if (pgd & _PAGE_PRESENT) | |
337 | pgd = phys_to_machine(XPADDR(pgd)).maddr; | |
338 | ||
339 | return (pgd_t){ pgd }; | |
340 | } | |
341 | ||
342 | pmdval_t xen_pmd_val(pmd_t pmd) | |
343 | { | |
344 | pmdval_t ret = native_pmd_val(pmd); | |
345 | if (ret & _PAGE_PRESENT) | |
346 | ret = machine_to_phys(XMADDR(ret)).paddr | _PAGE_PRESENT; | |
347 | return ret; | |
348 | } | |
3843fc25 | 349 | |
f4f97b3e JF |
350 | void xen_set_pud(pud_t *ptr, pud_t val) |
351 | { | |
d66bf8fc JF |
352 | struct multicall_space mcs; |
353 | struct mmu_update *u; | |
f4f97b3e | 354 | |
d66bf8fc JF |
355 | preempt_disable(); |
356 | ||
357 | mcs = xen_mc_entry(sizeof(*u)); | |
358 | u = mcs.args; | |
359 | u->ptr = virt_to_machine(ptr).maddr; | |
360 | u->val = pud_val_ma(val); | |
361 | MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); | |
362 | ||
363 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
364 | ||
365 | preempt_enable(); | |
f4f97b3e JF |
366 | } |
367 | ||
368 | void xen_set_pte(pte_t *ptep, pte_t pte) | |
369 | { | |
370 | ptep->pte_high = pte.pte_high; | |
371 | smp_wmb(); | |
372 | ptep->pte_low = pte.pte_low; | |
373 | } | |
374 | ||
3b827c1b JF |
375 | void xen_set_pte_atomic(pte_t *ptep, pte_t pte) |
376 | { | |
377 | set_64bit((u64 *)ptep, pte_val_ma(pte)); | |
378 | } | |
379 | ||
380 | void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) | |
381 | { | |
382 | ptep->pte_low = 0; | |
383 | smp_wmb(); /* make sure low gets written first */ | |
384 | ptep->pte_high = 0; | |
385 | } | |
386 | ||
387 | void xen_pmd_clear(pmd_t *pmdp) | |
388 | { | |
389 | xen_set_pmd(pmdp, __pmd(0)); | |
390 | } | |
391 | ||
abf33038 | 392 | pmd_t xen_make_pmd(pmdval_t pmd) |
3b827c1b | 393 | { |
430442e3 | 394 | if (pmd & _PAGE_PRESENT) |
3b827c1b JF |
395 | pmd = phys_to_machine(XPADDR(pmd)).maddr; |
396 | ||
947a69c9 | 397 | return native_make_pmd(pmd); |
3b827c1b | 398 | } |
3b827c1b | 399 | |
f4f97b3e JF |
400 | /* |
401 | (Yet another) pagetable walker. This one is intended for pinning a | |
402 | pagetable. This means that it walks a pagetable and calls the | |
403 | callback function on each page it finds making up the page table, | |
404 | at every level. It walks the entire pagetable, but it only bothers | |
405 | pinning pte pages which are below pte_limit. In the normal case | |
406 | this will be TASK_SIZE, but at boot we need to pin up to | |
407 | FIXADDR_TOP. But the important bit is that we don't pin beyond | |
408 | there, because then we start getting into Xen's ptes. | |
409 | */ | |
74260714 | 410 | static int pgd_walk(pgd_t *pgd_base, int (*func)(struct page *, enum pt_level), |
f4f97b3e | 411 | unsigned long limit) |
3b827c1b JF |
412 | { |
413 | pgd_t *pgd = pgd_base; | |
f4f97b3e JF |
414 | int flush = 0; |
415 | unsigned long addr = 0; | |
416 | unsigned long pgd_next; | |
417 | ||
418 | BUG_ON(limit > FIXADDR_TOP); | |
3b827c1b JF |
419 | |
420 | if (xen_feature(XENFEAT_auto_translated_physmap)) | |
f4f97b3e JF |
421 | return 0; |
422 | ||
423 | for (; addr != FIXADDR_TOP; pgd++, addr = pgd_next) { | |
424 | pud_t *pud; | |
425 | unsigned long pud_limit, pud_next; | |
3b827c1b | 426 | |
f4f97b3e JF |
427 | pgd_next = pud_limit = pgd_addr_end(addr, FIXADDR_TOP); |
428 | ||
429 | if (!pgd_val(*pgd)) | |
3b827c1b | 430 | continue; |
f4f97b3e | 431 | |
3b827c1b JF |
432 | pud = pud_offset(pgd, 0); |
433 | ||
434 | if (PTRS_PER_PUD > 1) /* not folded */ | |
74260714 | 435 | flush |= (*func)(virt_to_page(pud), PT_PUD); |
f4f97b3e JF |
436 | |
437 | for (; addr != pud_limit; pud++, addr = pud_next) { | |
438 | pmd_t *pmd; | |
439 | unsigned long pmd_limit; | |
440 | ||
441 | pud_next = pud_addr_end(addr, pud_limit); | |
442 | ||
443 | if (pud_next < limit) | |
444 | pmd_limit = pud_next; | |
445 | else | |
446 | pmd_limit = limit; | |
3b827c1b | 447 | |
3b827c1b JF |
448 | if (pud_none(*pud)) |
449 | continue; | |
f4f97b3e | 450 | |
3b827c1b JF |
451 | pmd = pmd_offset(pud, 0); |
452 | ||
453 | if (PTRS_PER_PMD > 1) /* not folded */ | |
74260714 | 454 | flush |= (*func)(virt_to_page(pmd), PT_PMD); |
f4f97b3e JF |
455 | |
456 | for (; addr != pmd_limit; pmd++) { | |
457 | addr += (PAGE_SIZE * PTRS_PER_PTE); | |
458 | if ((pmd_limit-1) < (addr-1)) { | |
459 | addr = pmd_limit; | |
460 | break; | |
461 | } | |
3b827c1b | 462 | |
3b827c1b JF |
463 | if (pmd_none(*pmd)) |
464 | continue; | |
465 | ||
74260714 | 466 | flush |= (*func)(pmd_page(*pmd), PT_PTE); |
3b827c1b JF |
467 | } |
468 | } | |
469 | } | |
470 | ||
74260714 | 471 | flush |= (*func)(virt_to_page(pgd_base), PT_PGD); |
f4f97b3e JF |
472 | |
473 | return flush; | |
3b827c1b JF |
474 | } |
475 | ||
74260714 JF |
476 | static spinlock_t *lock_pte(struct page *page) |
477 | { | |
478 | spinlock_t *ptl = NULL; | |
479 | ||
480 | #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS | |
481 | ptl = __pte_lockptr(page); | |
482 | spin_lock(ptl); | |
483 | #endif | |
484 | ||
485 | return ptl; | |
486 | } | |
487 | ||
488 | static void do_unlock(void *v) | |
489 | { | |
490 | spinlock_t *ptl = v; | |
491 | spin_unlock(ptl); | |
492 | } | |
493 | ||
494 | static void xen_do_pin(unsigned level, unsigned long pfn) | |
495 | { | |
496 | struct mmuext_op *op; | |
497 | struct multicall_space mcs; | |
498 | ||
499 | mcs = __xen_mc_entry(sizeof(*op)); | |
500 | op = mcs.args; | |
501 | op->cmd = level; | |
502 | op->arg1.mfn = pfn_to_mfn(pfn); | |
503 | MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); | |
504 | } | |
505 | ||
506 | static int pin_page(struct page *page, enum pt_level level) | |
f4f97b3e | 507 | { |
d60cd46b | 508 | unsigned pgfl = TestSetPagePinned(page); |
f4f97b3e JF |
509 | int flush; |
510 | ||
511 | if (pgfl) | |
512 | flush = 0; /* already pinned */ | |
513 | else if (PageHighMem(page)) | |
514 | /* kmaps need flushing if we found an unpinned | |
515 | highpage */ | |
516 | flush = 1; | |
517 | else { | |
518 | void *pt = lowmem_page_address(page); | |
519 | unsigned long pfn = page_to_pfn(page); | |
520 | struct multicall_space mcs = __xen_mc_entry(0); | |
74260714 | 521 | spinlock_t *ptl; |
f4f97b3e JF |
522 | |
523 | flush = 0; | |
524 | ||
74260714 JF |
525 | ptl = NULL; |
526 | if (level == PT_PTE) | |
527 | ptl = lock_pte(page); | |
528 | ||
f4f97b3e JF |
529 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, |
530 | pfn_pte(pfn, PAGE_KERNEL_RO), | |
74260714 JF |
531 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
532 | ||
533 | if (level == PT_PTE) | |
534 | xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn); | |
535 | ||
536 | if (ptl) { | |
537 | /* Queue a deferred unlock for when this batch | |
538 | is completed. */ | |
539 | xen_mc_callback(do_unlock, ptl); | |
540 | } | |
f4f97b3e JF |
541 | } |
542 | ||
543 | return flush; | |
544 | } | |
3b827c1b | 545 | |
f4f97b3e JF |
546 | /* This is called just after a mm has been created, but it has not |
547 | been used yet. We need to make sure that its pagetable is all | |
548 | read-only, and can be pinned. */ | |
3b827c1b JF |
549 | void xen_pgd_pin(pgd_t *pgd) |
550 | { | |
f4f97b3e | 551 | xen_mc_batch(); |
3b827c1b | 552 | |
f87e4cac JF |
553 | if (pgd_walk(pgd, pin_page, TASK_SIZE)) { |
554 | /* re-enable interrupts for kmap_flush_unused */ | |
555 | xen_mc_issue(0); | |
f4f97b3e | 556 | kmap_flush_unused(); |
f87e4cac JF |
557 | xen_mc_batch(); |
558 | } | |
f4f97b3e | 559 | |
3843fc25 | 560 | xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e | 561 | xen_mc_issue(0); |
3b827c1b JF |
562 | } |
563 | ||
0e91398f JF |
564 | /* |
565 | * On save, we need to pin all pagetables to make sure they get their | |
566 | * mfns turned into pfns. Search the list for any unpinned pgds and pin | |
567 | * them (unpinned pgds are not currently in use, probably because the | |
568 | * process is under construction or destruction). | |
569 | */ | |
570 | void xen_mm_pin_all(void) | |
571 | { | |
572 | unsigned long flags; | |
573 | struct page *page; | |
574 | ||
575 | spin_lock_irqsave(&pgd_lock, flags); | |
576 | ||
577 | list_for_each_entry(page, &pgd_list, lru) { | |
578 | if (!PagePinned(page)) { | |
579 | xen_pgd_pin((pgd_t *)page_address(page)); | |
580 | SetPageSavePinned(page); | |
581 | } | |
582 | } | |
583 | ||
584 | spin_unlock_irqrestore(&pgd_lock, flags); | |
585 | } | |
586 | ||
f4f97b3e JF |
587 | /* The init_mm pagetable is really pinned as soon as its created, but |
588 | that's before we have page structures to store the bits. So do all | |
589 | the book-keeping now. */ | |
74260714 | 590 | static __init int mark_pinned(struct page *page, enum pt_level level) |
3b827c1b | 591 | { |
f4f97b3e JF |
592 | SetPagePinned(page); |
593 | return 0; | |
594 | } | |
3b827c1b | 595 | |
f4f97b3e JF |
596 | void __init xen_mark_init_mm_pinned(void) |
597 | { | |
598 | pgd_walk(init_mm.pgd, mark_pinned, FIXADDR_TOP); | |
599 | } | |
3b827c1b | 600 | |
74260714 | 601 | static int unpin_page(struct page *page, enum pt_level level) |
f4f97b3e | 602 | { |
d60cd46b | 603 | unsigned pgfl = TestClearPagePinned(page); |
3b827c1b | 604 | |
f4f97b3e JF |
605 | if (pgfl && !PageHighMem(page)) { |
606 | void *pt = lowmem_page_address(page); | |
607 | unsigned long pfn = page_to_pfn(page); | |
74260714 JF |
608 | spinlock_t *ptl = NULL; |
609 | struct multicall_space mcs; | |
610 | ||
611 | if (level == PT_PTE) { | |
612 | ptl = lock_pte(page); | |
613 | ||
614 | xen_do_pin(MMUEXT_UNPIN_TABLE, pfn); | |
615 | } | |
616 | ||
617 | mcs = __xen_mc_entry(0); | |
f4f97b3e JF |
618 | |
619 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, | |
620 | pfn_pte(pfn, PAGE_KERNEL), | |
74260714 JF |
621 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
622 | ||
623 | if (ptl) { | |
624 | /* unlock when batch completed */ | |
625 | xen_mc_callback(do_unlock, ptl); | |
626 | } | |
f4f97b3e JF |
627 | } |
628 | ||
629 | return 0; /* never need to flush on unpin */ | |
3b827c1b JF |
630 | } |
631 | ||
f4f97b3e JF |
632 | /* Release a pagetables pages back as normal RW */ |
633 | static void xen_pgd_unpin(pgd_t *pgd) | |
634 | { | |
f4f97b3e JF |
635 | xen_mc_batch(); |
636 | ||
74260714 | 637 | xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e JF |
638 | |
639 | pgd_walk(pgd, unpin_page, TASK_SIZE); | |
640 | ||
641 | xen_mc_issue(0); | |
642 | } | |
3b827c1b | 643 | |
0e91398f JF |
644 | /* |
645 | * On resume, undo any pinning done at save, so that the rest of the | |
646 | * kernel doesn't see any unexpected pinned pagetables. | |
647 | */ | |
648 | void xen_mm_unpin_all(void) | |
649 | { | |
650 | unsigned long flags; | |
651 | struct page *page; | |
652 | ||
653 | spin_lock_irqsave(&pgd_lock, flags); | |
654 | ||
655 | list_for_each_entry(page, &pgd_list, lru) { | |
656 | if (PageSavePinned(page)) { | |
657 | BUG_ON(!PagePinned(page)); | |
658 | printk("unpinning pinned %p\n", page_address(page)); | |
659 | xen_pgd_unpin((pgd_t *)page_address(page)); | |
660 | ClearPageSavePinned(page); | |
661 | } | |
662 | } | |
663 | ||
664 | spin_unlock_irqrestore(&pgd_lock, flags); | |
665 | } | |
666 | ||
3b827c1b JF |
667 | void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) |
668 | { | |
f4f97b3e | 669 | spin_lock(&next->page_table_lock); |
3b827c1b | 670 | xen_pgd_pin(next->pgd); |
f4f97b3e | 671 | spin_unlock(&next->page_table_lock); |
3b827c1b JF |
672 | } |
673 | ||
674 | void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) | |
675 | { | |
f4f97b3e | 676 | spin_lock(&mm->page_table_lock); |
3b827c1b | 677 | xen_pgd_pin(mm->pgd); |
f4f97b3e | 678 | spin_unlock(&mm->page_table_lock); |
3b827c1b JF |
679 | } |
680 | ||
3b827c1b | 681 | |
f87e4cac JF |
682 | #ifdef CONFIG_SMP |
683 | /* Another cpu may still have their %cr3 pointing at the pagetable, so | |
684 | we need to repoint it somewhere else before we can unpin it. */ | |
685 | static void drop_other_mm_ref(void *info) | |
686 | { | |
687 | struct mm_struct *mm = info; | |
3b827c1b | 688 | |
f87e4cac JF |
689 | if (__get_cpu_var(cpu_tlbstate).active_mm == mm) |
690 | leave_mm(smp_processor_id()); | |
9f79991d JF |
691 | |
692 | /* If this cpu still has a stale cr3 reference, then make sure | |
693 | it has been flushed. */ | |
694 | if (x86_read_percpu(xen_current_cr3) == __pa(mm->pgd)) { | |
695 | load_cr3(swapper_pg_dir); | |
696 | arch_flush_lazy_cpu_mode(); | |
697 | } | |
f87e4cac | 698 | } |
3b827c1b | 699 | |
f87e4cac JF |
700 | static void drop_mm_ref(struct mm_struct *mm) |
701 | { | |
9f79991d JF |
702 | cpumask_t mask; |
703 | unsigned cpu; | |
704 | ||
f87e4cac JF |
705 | if (current->active_mm == mm) { |
706 | if (current->mm == mm) | |
707 | load_cr3(swapper_pg_dir); | |
708 | else | |
709 | leave_mm(smp_processor_id()); | |
9f79991d JF |
710 | arch_flush_lazy_cpu_mode(); |
711 | } | |
712 | ||
713 | /* Get the "official" set of cpus referring to our pagetable. */ | |
714 | mask = mm->cpu_vm_mask; | |
715 | ||
716 | /* It's possible that a vcpu may have a stale reference to our | |
717 | cr3, because its in lazy mode, and it hasn't yet flushed | |
718 | its set of pending hypercalls yet. In this case, we can | |
719 | look at its actual current cr3 value, and force it to flush | |
720 | if needed. */ | |
721 | for_each_online_cpu(cpu) { | |
722 | if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd)) | |
723 | cpu_set(cpu, mask); | |
3b827c1b JF |
724 | } |
725 | ||
9f79991d JF |
726 | if (!cpus_empty(mask)) |
727 | xen_smp_call_function_mask(mask, drop_other_mm_ref, mm, 1); | |
f87e4cac JF |
728 | } |
729 | #else | |
730 | static void drop_mm_ref(struct mm_struct *mm) | |
731 | { | |
732 | if (current->active_mm == mm) | |
733 | load_cr3(swapper_pg_dir); | |
734 | } | |
735 | #endif | |
736 | ||
737 | /* | |
738 | * While a process runs, Xen pins its pagetables, which means that the | |
739 | * hypervisor forces it to be read-only, and it controls all updates | |
740 | * to it. This means that all pagetable updates have to go via the | |
741 | * hypervisor, which is moderately expensive. | |
742 | * | |
743 | * Since we're pulling the pagetable down, we switch to use init_mm, | |
744 | * unpin old process pagetable and mark it all read-write, which | |
745 | * allows further operations on it to be simple memory accesses. | |
746 | * | |
747 | * The only subtle point is that another CPU may be still using the | |
748 | * pagetable because of lazy tlb flushing. This means we need need to | |
749 | * switch all CPUs off this pagetable before we can unpin it. | |
750 | */ | |
751 | void xen_exit_mmap(struct mm_struct *mm) | |
752 | { | |
753 | get_cpu(); /* make sure we don't move around */ | |
754 | drop_mm_ref(mm); | |
755 | put_cpu(); | |
3b827c1b | 756 | |
f120f13e | 757 | spin_lock(&mm->page_table_lock); |
df912ea4 JF |
758 | |
759 | /* pgd may not be pinned in the error exit path of execve */ | |
760 | if (PagePinned(virt_to_page(mm->pgd))) | |
761 | xen_pgd_unpin(mm->pgd); | |
74260714 | 762 | |
f120f13e | 763 | spin_unlock(&mm->page_table_lock); |
3b827c1b | 764 | } |