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 | } | |
15ce6005 | 139 | EXPORT_SYMBOL_GPL(get_phys_to_machine); |
d451bb7a | 140 | |
d5edbc1f | 141 | static void alloc_p2m(unsigned long **pp, unsigned long *mfnp) |
d451bb7a JF |
142 | { |
143 | unsigned long *p; | |
144 | unsigned i; | |
145 | ||
146 | p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL); | |
147 | BUG_ON(p == NULL); | |
148 | ||
149 | for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++) | |
150 | p[i] = INVALID_P2M_ENTRY; | |
151 | ||
cf0923ea | 152 | if (cmpxchg(pp, p2m_missing, p) != p2m_missing) |
d451bb7a | 153 | free_page((unsigned long)p); |
d5edbc1f JF |
154 | else |
155 | *mfnp = virt_to_mfn(p); | |
d451bb7a JF |
156 | } |
157 | ||
158 | void set_phys_to_machine(unsigned long pfn, unsigned long mfn) | |
159 | { | |
160 | unsigned topidx, idx; | |
161 | ||
162 | if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) { | |
163 | BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY); | |
8006ec3e JF |
164 | return; |
165 | } | |
166 | ||
167 | if (unlikely(pfn >= MAX_DOMAIN_PAGES)) { | |
168 | BUG_ON(mfn != INVALID_P2M_ENTRY); | |
d451bb7a JF |
169 | return; |
170 | } | |
171 | ||
172 | topidx = p2m_top_index(pfn); | |
cf0923ea | 173 | if (p2m_top[topidx] == p2m_missing) { |
d451bb7a JF |
174 | /* no need to allocate a page to store an invalid entry */ |
175 | if (mfn == INVALID_P2M_ENTRY) | |
176 | return; | |
d5edbc1f | 177 | alloc_p2m(&p2m_top[topidx], &p2m_top_mfn[topidx]); |
d451bb7a JF |
178 | } |
179 | ||
180 | idx = p2m_index(pfn); | |
181 | p2m_top[topidx][idx] = mfn; | |
182 | } | |
183 | ||
3b827c1b JF |
184 | xmaddr_t arbitrary_virt_to_machine(unsigned long address) |
185 | { | |
da7bfc50 | 186 | unsigned int level; |
f0646e43 | 187 | pte_t *pte = lookup_address(address, &level); |
de067814 | 188 | unsigned offset = address & ~PAGE_MASK; |
3b827c1b JF |
189 | |
190 | BUG_ON(pte == NULL); | |
191 | ||
192 | return XMADDR((pte_mfn(*pte) << PAGE_SHIFT) + offset); | |
193 | } | |
194 | ||
195 | void make_lowmem_page_readonly(void *vaddr) | |
196 | { | |
197 | pte_t *pte, ptev; | |
198 | unsigned long address = (unsigned long)vaddr; | |
da7bfc50 | 199 | unsigned int level; |
3b827c1b | 200 | |
f0646e43 | 201 | pte = lookup_address(address, &level); |
3b827c1b JF |
202 | BUG_ON(pte == NULL); |
203 | ||
204 | ptev = pte_wrprotect(*pte); | |
205 | ||
206 | if (HYPERVISOR_update_va_mapping(address, ptev, 0)) | |
207 | BUG(); | |
208 | } | |
209 | ||
210 | void make_lowmem_page_readwrite(void *vaddr) | |
211 | { | |
212 | pte_t *pte, ptev; | |
213 | unsigned long address = (unsigned long)vaddr; | |
da7bfc50 | 214 | unsigned int level; |
3b827c1b | 215 | |
f0646e43 | 216 | pte = lookup_address(address, &level); |
3b827c1b JF |
217 | BUG_ON(pte == NULL); |
218 | ||
219 | ptev = pte_mkwrite(*pte); | |
220 | ||
221 | if (HYPERVISOR_update_va_mapping(address, ptev, 0)) | |
222 | BUG(); | |
223 | } | |
224 | ||
225 | ||
e2426cf8 JF |
226 | static bool page_pinned(void *ptr) |
227 | { | |
228 | struct page *page = virt_to_page(ptr); | |
229 | ||
230 | return PagePinned(page); | |
231 | } | |
232 | ||
233 | void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val) | |
3b827c1b | 234 | { |
d66bf8fc JF |
235 | struct multicall_space mcs; |
236 | struct mmu_update *u; | |
3b827c1b | 237 | |
d66bf8fc JF |
238 | preempt_disable(); |
239 | ||
240 | mcs = xen_mc_entry(sizeof(*u)); | |
241 | u = mcs.args; | |
242 | u->ptr = virt_to_machine(ptr).maddr; | |
243 | u->val = pmd_val_ma(val); | |
244 | MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); | |
245 | ||
246 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
247 | ||
248 | preempt_enable(); | |
3b827c1b JF |
249 | } |
250 | ||
e2426cf8 JF |
251 | void xen_set_pmd(pmd_t *ptr, pmd_t val) |
252 | { | |
253 | /* If page is not pinned, we can just update the entry | |
254 | directly */ | |
255 | if (!page_pinned(ptr)) { | |
256 | *ptr = val; | |
257 | return; | |
258 | } | |
259 | ||
260 | xen_set_pmd_hyper(ptr, val); | |
261 | } | |
262 | ||
3b827c1b JF |
263 | /* |
264 | * Associate a virtual page frame with a given physical page frame | |
265 | * and protection flags for that frame. | |
266 | */ | |
267 | void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) | |
268 | { | |
269 | pgd_t *pgd; | |
270 | pud_t *pud; | |
271 | pmd_t *pmd; | |
272 | pte_t *pte; | |
273 | ||
274 | pgd = swapper_pg_dir + pgd_index(vaddr); | |
275 | if (pgd_none(*pgd)) { | |
276 | BUG(); | |
277 | return; | |
278 | } | |
279 | pud = pud_offset(pgd, vaddr); | |
280 | if (pud_none(*pud)) { | |
281 | BUG(); | |
282 | return; | |
283 | } | |
284 | pmd = pmd_offset(pud, vaddr); | |
285 | if (pmd_none(*pmd)) { | |
286 | BUG(); | |
287 | return; | |
288 | } | |
289 | pte = pte_offset_kernel(pmd, vaddr); | |
290 | /* <mfn,flags> stored as-is, to permit clearing entries */ | |
291 | xen_set_pte(pte, mfn_pte(mfn, flags)); | |
292 | ||
293 | /* | |
294 | * It's enough to flush this one mapping. | |
295 | * (PGE mappings get flushed as well) | |
296 | */ | |
297 | __flush_tlb_one(vaddr); | |
298 | } | |
299 | ||
300 | void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, | |
301 | pte_t *ptep, pte_t pteval) | |
302 | { | |
2bd50036 JF |
303 | /* updates to init_mm may be done without lock */ |
304 | if (mm == &init_mm) | |
305 | preempt_disable(); | |
306 | ||
d66bf8fc | 307 | if (mm == current->mm || mm == &init_mm) { |
8965c1c0 | 308 | if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { |
d66bf8fc JF |
309 | struct multicall_space mcs; |
310 | mcs = xen_mc_entry(0); | |
311 | ||
312 | MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); | |
313 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
2bd50036 | 314 | goto out; |
d66bf8fc JF |
315 | } else |
316 | if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) | |
2bd50036 | 317 | goto out; |
d66bf8fc JF |
318 | } |
319 | xen_set_pte(ptep, pteval); | |
2bd50036 JF |
320 | |
321 | out: | |
322 | if (mm == &init_mm) | |
323 | preempt_enable(); | |
3b827c1b JF |
324 | } |
325 | ||
e57778a1 JF |
326 | pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr, pte_t *ptep) |
327 | { | |
328 | /* Just return the pte as-is. We preserve the bits on commit */ | |
329 | return *ptep; | |
330 | } | |
331 | ||
332 | void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr, | |
333 | pte_t *ptep, pte_t pte) | |
334 | { | |
335 | struct multicall_space mcs; | |
336 | struct mmu_update *u; | |
337 | ||
338 | mcs = xen_mc_entry(sizeof(*u)); | |
339 | u = mcs.args; | |
340 | u->ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD; | |
341 | u->val = pte_val_ma(pte); | |
342 | MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); | |
343 | ||
344 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
345 | } | |
346 | ||
a987b16c JF |
347 | /* Assume pteval_t is equivalent to all the other *val_t types. */ |
348 | static pteval_t pte_mfn_to_pfn(pteval_t val) | |
947a69c9 | 349 | { |
a987b16c JF |
350 | if (val & _PAGE_PRESENT) { |
351 | unsigned long mfn = (val & PTE_MASK) >> PAGE_SHIFT; | |
352 | pteval_t flags = val & ~PTE_MASK; | |
353 | val = (mfn_to_pfn(mfn) << PAGE_SHIFT) | flags; | |
354 | } | |
947a69c9 | 355 | |
a987b16c JF |
356 | return val; |
357 | } | |
947a69c9 | 358 | |
a987b16c JF |
359 | static pteval_t pte_pfn_to_mfn(pteval_t val) |
360 | { | |
361 | if (val & _PAGE_PRESENT) { | |
362 | unsigned long pfn = (val & PTE_MASK) >> PAGE_SHIFT; | |
363 | pteval_t flags = val & ~PTE_MASK; | |
364 | val = (pfn_to_mfn(pfn) << PAGE_SHIFT) | flags; | |
365 | } | |
366 | ||
367 | return val; | |
368 | } | |
369 | ||
370 | pteval_t xen_pte_val(pte_t pte) | |
371 | { | |
372 | return pte_mfn_to_pfn(pte.pte); | |
947a69c9 JF |
373 | } |
374 | ||
375 | pgdval_t xen_pgd_val(pgd_t pgd) | |
376 | { | |
a987b16c | 377 | return pte_mfn_to_pfn(pgd.pgd); |
947a69c9 JF |
378 | } |
379 | ||
380 | pte_t xen_make_pte(pteval_t pte) | |
381 | { | |
a987b16c JF |
382 | pte = pte_pfn_to_mfn(pte); |
383 | return native_make_pte(pte); | |
947a69c9 JF |
384 | } |
385 | ||
386 | pgd_t xen_make_pgd(pgdval_t pgd) | |
387 | { | |
a987b16c JF |
388 | pgd = pte_pfn_to_mfn(pgd); |
389 | return native_make_pgd(pgd); | |
947a69c9 JF |
390 | } |
391 | ||
392 | pmdval_t xen_pmd_val(pmd_t pmd) | |
393 | { | |
a987b16c | 394 | return pte_mfn_to_pfn(pmd.pmd); |
947a69c9 | 395 | } |
3843fc25 | 396 | |
e2426cf8 | 397 | void xen_set_pud_hyper(pud_t *ptr, pud_t val) |
f4f97b3e | 398 | { |
d66bf8fc JF |
399 | struct multicall_space mcs; |
400 | struct mmu_update *u; | |
f4f97b3e | 401 | |
d66bf8fc JF |
402 | preempt_disable(); |
403 | ||
404 | mcs = xen_mc_entry(sizeof(*u)); | |
405 | u = mcs.args; | |
406 | u->ptr = virt_to_machine(ptr).maddr; | |
407 | u->val = pud_val_ma(val); | |
408 | MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); | |
409 | ||
410 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
411 | ||
412 | preempt_enable(); | |
f4f97b3e JF |
413 | } |
414 | ||
e2426cf8 JF |
415 | void xen_set_pud(pud_t *ptr, pud_t val) |
416 | { | |
417 | /* If page is not pinned, we can just update the entry | |
418 | directly */ | |
419 | if (!page_pinned(ptr)) { | |
420 | *ptr = val; | |
421 | return; | |
422 | } | |
423 | ||
424 | xen_set_pud_hyper(ptr, val); | |
425 | } | |
426 | ||
f4f97b3e JF |
427 | void xen_set_pte(pte_t *ptep, pte_t pte) |
428 | { | |
429 | ptep->pte_high = pte.pte_high; | |
430 | smp_wmb(); | |
431 | ptep->pte_low = pte.pte_low; | |
432 | } | |
433 | ||
3b827c1b JF |
434 | void xen_set_pte_atomic(pte_t *ptep, pte_t pte) |
435 | { | |
436 | set_64bit((u64 *)ptep, pte_val_ma(pte)); | |
437 | } | |
438 | ||
439 | void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) | |
440 | { | |
441 | ptep->pte_low = 0; | |
442 | smp_wmb(); /* make sure low gets written first */ | |
443 | ptep->pte_high = 0; | |
444 | } | |
445 | ||
446 | void xen_pmd_clear(pmd_t *pmdp) | |
447 | { | |
e2426cf8 | 448 | set_pmd(pmdp, __pmd(0)); |
3b827c1b JF |
449 | } |
450 | ||
abf33038 | 451 | pmd_t xen_make_pmd(pmdval_t pmd) |
3b827c1b | 452 | { |
a987b16c | 453 | pmd = pte_pfn_to_mfn(pmd); |
947a69c9 | 454 | return native_make_pmd(pmd); |
3b827c1b | 455 | } |
3b827c1b | 456 | |
f4f97b3e JF |
457 | /* |
458 | (Yet another) pagetable walker. This one is intended for pinning a | |
459 | pagetable. This means that it walks a pagetable and calls the | |
460 | callback function on each page it finds making up the page table, | |
461 | at every level. It walks the entire pagetable, but it only bothers | |
462 | pinning pte pages which are below pte_limit. In the normal case | |
463 | this will be TASK_SIZE, but at boot we need to pin up to | |
464 | FIXADDR_TOP. But the important bit is that we don't pin beyond | |
465 | there, because then we start getting into Xen's ptes. | |
466 | */ | |
74260714 | 467 | static int pgd_walk(pgd_t *pgd_base, int (*func)(struct page *, enum pt_level), |
f4f97b3e | 468 | unsigned long limit) |
3b827c1b JF |
469 | { |
470 | pgd_t *pgd = pgd_base; | |
f4f97b3e JF |
471 | int flush = 0; |
472 | unsigned long addr = 0; | |
473 | unsigned long pgd_next; | |
474 | ||
475 | BUG_ON(limit > FIXADDR_TOP); | |
3b827c1b JF |
476 | |
477 | if (xen_feature(XENFEAT_auto_translated_physmap)) | |
f4f97b3e JF |
478 | return 0; |
479 | ||
480 | for (; addr != FIXADDR_TOP; pgd++, addr = pgd_next) { | |
481 | pud_t *pud; | |
482 | unsigned long pud_limit, pud_next; | |
3b827c1b | 483 | |
f4f97b3e JF |
484 | pgd_next = pud_limit = pgd_addr_end(addr, FIXADDR_TOP); |
485 | ||
486 | if (!pgd_val(*pgd)) | |
3b827c1b | 487 | continue; |
f4f97b3e | 488 | |
3b827c1b JF |
489 | pud = pud_offset(pgd, 0); |
490 | ||
491 | if (PTRS_PER_PUD > 1) /* not folded */ | |
74260714 | 492 | flush |= (*func)(virt_to_page(pud), PT_PUD); |
f4f97b3e JF |
493 | |
494 | for (; addr != pud_limit; pud++, addr = pud_next) { | |
495 | pmd_t *pmd; | |
496 | unsigned long pmd_limit; | |
497 | ||
498 | pud_next = pud_addr_end(addr, pud_limit); | |
499 | ||
500 | if (pud_next < limit) | |
501 | pmd_limit = pud_next; | |
502 | else | |
503 | pmd_limit = limit; | |
3b827c1b | 504 | |
3b827c1b JF |
505 | if (pud_none(*pud)) |
506 | continue; | |
f4f97b3e | 507 | |
3b827c1b JF |
508 | pmd = pmd_offset(pud, 0); |
509 | ||
510 | if (PTRS_PER_PMD > 1) /* not folded */ | |
74260714 | 511 | flush |= (*func)(virt_to_page(pmd), PT_PMD); |
f4f97b3e JF |
512 | |
513 | for (; addr != pmd_limit; pmd++) { | |
514 | addr += (PAGE_SIZE * PTRS_PER_PTE); | |
515 | if ((pmd_limit-1) < (addr-1)) { | |
516 | addr = pmd_limit; | |
517 | break; | |
518 | } | |
3b827c1b | 519 | |
3b827c1b JF |
520 | if (pmd_none(*pmd)) |
521 | continue; | |
522 | ||
74260714 | 523 | flush |= (*func)(pmd_page(*pmd), PT_PTE); |
3b827c1b JF |
524 | } |
525 | } | |
526 | } | |
527 | ||
74260714 | 528 | flush |= (*func)(virt_to_page(pgd_base), PT_PGD); |
f4f97b3e JF |
529 | |
530 | return flush; | |
3b827c1b JF |
531 | } |
532 | ||
74260714 JF |
533 | static spinlock_t *lock_pte(struct page *page) |
534 | { | |
535 | spinlock_t *ptl = NULL; | |
536 | ||
537 | #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS | |
538 | ptl = __pte_lockptr(page); | |
539 | spin_lock(ptl); | |
540 | #endif | |
541 | ||
542 | return ptl; | |
543 | } | |
544 | ||
545 | static void do_unlock(void *v) | |
546 | { | |
547 | spinlock_t *ptl = v; | |
548 | spin_unlock(ptl); | |
549 | } | |
550 | ||
551 | static void xen_do_pin(unsigned level, unsigned long pfn) | |
552 | { | |
553 | struct mmuext_op *op; | |
554 | struct multicall_space mcs; | |
555 | ||
556 | mcs = __xen_mc_entry(sizeof(*op)); | |
557 | op = mcs.args; | |
558 | op->cmd = level; | |
559 | op->arg1.mfn = pfn_to_mfn(pfn); | |
560 | MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); | |
561 | } | |
562 | ||
563 | static int pin_page(struct page *page, enum pt_level level) | |
f4f97b3e | 564 | { |
d60cd46b | 565 | unsigned pgfl = TestSetPagePinned(page); |
f4f97b3e JF |
566 | int flush; |
567 | ||
568 | if (pgfl) | |
569 | flush = 0; /* already pinned */ | |
570 | else if (PageHighMem(page)) | |
571 | /* kmaps need flushing if we found an unpinned | |
572 | highpage */ | |
573 | flush = 1; | |
574 | else { | |
575 | void *pt = lowmem_page_address(page); | |
576 | unsigned long pfn = page_to_pfn(page); | |
577 | struct multicall_space mcs = __xen_mc_entry(0); | |
74260714 | 578 | spinlock_t *ptl; |
f4f97b3e JF |
579 | |
580 | flush = 0; | |
581 | ||
74260714 JF |
582 | ptl = NULL; |
583 | if (level == PT_PTE) | |
584 | ptl = lock_pte(page); | |
585 | ||
f4f97b3e JF |
586 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, |
587 | pfn_pte(pfn, PAGE_KERNEL_RO), | |
74260714 JF |
588 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
589 | ||
590 | if (level == PT_PTE) | |
591 | xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn); | |
592 | ||
593 | if (ptl) { | |
594 | /* Queue a deferred unlock for when this batch | |
595 | is completed. */ | |
596 | xen_mc_callback(do_unlock, ptl); | |
597 | } | |
f4f97b3e JF |
598 | } |
599 | ||
600 | return flush; | |
601 | } | |
3b827c1b | 602 | |
f4f97b3e JF |
603 | /* This is called just after a mm has been created, but it has not |
604 | been used yet. We need to make sure that its pagetable is all | |
605 | read-only, and can be pinned. */ | |
3b827c1b JF |
606 | void xen_pgd_pin(pgd_t *pgd) |
607 | { | |
f4f97b3e | 608 | xen_mc_batch(); |
3b827c1b | 609 | |
f87e4cac JF |
610 | if (pgd_walk(pgd, pin_page, TASK_SIZE)) { |
611 | /* re-enable interrupts for kmap_flush_unused */ | |
612 | xen_mc_issue(0); | |
f4f97b3e | 613 | kmap_flush_unused(); |
f87e4cac JF |
614 | xen_mc_batch(); |
615 | } | |
f4f97b3e | 616 | |
3843fc25 | 617 | xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e | 618 | xen_mc_issue(0); |
3b827c1b JF |
619 | } |
620 | ||
0e91398f JF |
621 | /* |
622 | * On save, we need to pin all pagetables to make sure they get their | |
623 | * mfns turned into pfns. Search the list for any unpinned pgds and pin | |
624 | * them (unpinned pgds are not currently in use, probably because the | |
625 | * process is under construction or destruction). | |
626 | */ | |
627 | void xen_mm_pin_all(void) | |
628 | { | |
629 | unsigned long flags; | |
630 | struct page *page; | |
631 | ||
632 | spin_lock_irqsave(&pgd_lock, flags); | |
633 | ||
634 | list_for_each_entry(page, &pgd_list, lru) { | |
635 | if (!PagePinned(page)) { | |
636 | xen_pgd_pin((pgd_t *)page_address(page)); | |
637 | SetPageSavePinned(page); | |
638 | } | |
639 | } | |
640 | ||
641 | spin_unlock_irqrestore(&pgd_lock, flags); | |
642 | } | |
643 | ||
f4f97b3e JF |
644 | /* The init_mm pagetable is really pinned as soon as its created, but |
645 | that's before we have page structures to store the bits. So do all | |
646 | the book-keeping now. */ | |
74260714 | 647 | static __init int mark_pinned(struct page *page, enum pt_level level) |
3b827c1b | 648 | { |
f4f97b3e JF |
649 | SetPagePinned(page); |
650 | return 0; | |
651 | } | |
3b827c1b | 652 | |
f4f97b3e JF |
653 | void __init xen_mark_init_mm_pinned(void) |
654 | { | |
655 | pgd_walk(init_mm.pgd, mark_pinned, FIXADDR_TOP); | |
656 | } | |
3b827c1b | 657 | |
74260714 | 658 | static int unpin_page(struct page *page, enum pt_level level) |
f4f97b3e | 659 | { |
d60cd46b | 660 | unsigned pgfl = TestClearPagePinned(page); |
3b827c1b | 661 | |
f4f97b3e JF |
662 | if (pgfl && !PageHighMem(page)) { |
663 | void *pt = lowmem_page_address(page); | |
664 | unsigned long pfn = page_to_pfn(page); | |
74260714 JF |
665 | spinlock_t *ptl = NULL; |
666 | struct multicall_space mcs; | |
667 | ||
668 | if (level == PT_PTE) { | |
669 | ptl = lock_pte(page); | |
670 | ||
671 | xen_do_pin(MMUEXT_UNPIN_TABLE, pfn); | |
672 | } | |
673 | ||
674 | mcs = __xen_mc_entry(0); | |
f4f97b3e JF |
675 | |
676 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, | |
677 | pfn_pte(pfn, PAGE_KERNEL), | |
74260714 JF |
678 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
679 | ||
680 | if (ptl) { | |
681 | /* unlock when batch completed */ | |
682 | xen_mc_callback(do_unlock, ptl); | |
683 | } | |
f4f97b3e JF |
684 | } |
685 | ||
686 | return 0; /* never need to flush on unpin */ | |
3b827c1b JF |
687 | } |
688 | ||
f4f97b3e JF |
689 | /* Release a pagetables pages back as normal RW */ |
690 | static void xen_pgd_unpin(pgd_t *pgd) | |
691 | { | |
f4f97b3e JF |
692 | xen_mc_batch(); |
693 | ||
74260714 | 694 | xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e JF |
695 | |
696 | pgd_walk(pgd, unpin_page, TASK_SIZE); | |
697 | ||
698 | xen_mc_issue(0); | |
699 | } | |
3b827c1b | 700 | |
0e91398f JF |
701 | /* |
702 | * On resume, undo any pinning done at save, so that the rest of the | |
703 | * kernel doesn't see any unexpected pinned pagetables. | |
704 | */ | |
705 | void xen_mm_unpin_all(void) | |
706 | { | |
707 | unsigned long flags; | |
708 | struct page *page; | |
709 | ||
710 | spin_lock_irqsave(&pgd_lock, flags); | |
711 | ||
712 | list_for_each_entry(page, &pgd_list, lru) { | |
713 | if (PageSavePinned(page)) { | |
714 | BUG_ON(!PagePinned(page)); | |
715 | printk("unpinning pinned %p\n", page_address(page)); | |
716 | xen_pgd_unpin((pgd_t *)page_address(page)); | |
717 | ClearPageSavePinned(page); | |
718 | } | |
719 | } | |
720 | ||
721 | spin_unlock_irqrestore(&pgd_lock, flags); | |
722 | } | |
723 | ||
3b827c1b JF |
724 | void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) |
725 | { | |
f4f97b3e | 726 | spin_lock(&next->page_table_lock); |
3b827c1b | 727 | xen_pgd_pin(next->pgd); |
f4f97b3e | 728 | spin_unlock(&next->page_table_lock); |
3b827c1b JF |
729 | } |
730 | ||
731 | void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) | |
732 | { | |
f4f97b3e | 733 | spin_lock(&mm->page_table_lock); |
3b827c1b | 734 | xen_pgd_pin(mm->pgd); |
f4f97b3e | 735 | spin_unlock(&mm->page_table_lock); |
3b827c1b JF |
736 | } |
737 | ||
3b827c1b | 738 | |
f87e4cac JF |
739 | #ifdef CONFIG_SMP |
740 | /* Another cpu may still have their %cr3 pointing at the pagetable, so | |
741 | we need to repoint it somewhere else before we can unpin it. */ | |
742 | static void drop_other_mm_ref(void *info) | |
743 | { | |
744 | struct mm_struct *mm = info; | |
3b827c1b | 745 | |
f87e4cac JF |
746 | if (__get_cpu_var(cpu_tlbstate).active_mm == mm) |
747 | leave_mm(smp_processor_id()); | |
9f79991d JF |
748 | |
749 | /* If this cpu still has a stale cr3 reference, then make sure | |
750 | it has been flushed. */ | |
751 | if (x86_read_percpu(xen_current_cr3) == __pa(mm->pgd)) { | |
752 | load_cr3(swapper_pg_dir); | |
753 | arch_flush_lazy_cpu_mode(); | |
754 | } | |
f87e4cac | 755 | } |
3b827c1b | 756 | |
f87e4cac JF |
757 | static void drop_mm_ref(struct mm_struct *mm) |
758 | { | |
9f79991d JF |
759 | cpumask_t mask; |
760 | unsigned cpu; | |
761 | ||
f87e4cac JF |
762 | if (current->active_mm == mm) { |
763 | if (current->mm == mm) | |
764 | load_cr3(swapper_pg_dir); | |
765 | else | |
766 | leave_mm(smp_processor_id()); | |
9f79991d JF |
767 | arch_flush_lazy_cpu_mode(); |
768 | } | |
769 | ||
770 | /* Get the "official" set of cpus referring to our pagetable. */ | |
771 | mask = mm->cpu_vm_mask; | |
772 | ||
773 | /* It's possible that a vcpu may have a stale reference to our | |
774 | cr3, because its in lazy mode, and it hasn't yet flushed | |
775 | its set of pending hypercalls yet. In this case, we can | |
776 | look at its actual current cr3 value, and force it to flush | |
777 | if needed. */ | |
778 | for_each_online_cpu(cpu) { | |
779 | if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd)) | |
780 | cpu_set(cpu, mask); | |
3b827c1b JF |
781 | } |
782 | ||
9f79991d JF |
783 | if (!cpus_empty(mask)) |
784 | xen_smp_call_function_mask(mask, drop_other_mm_ref, mm, 1); | |
f87e4cac JF |
785 | } |
786 | #else | |
787 | static void drop_mm_ref(struct mm_struct *mm) | |
788 | { | |
789 | if (current->active_mm == mm) | |
790 | load_cr3(swapper_pg_dir); | |
791 | } | |
792 | #endif | |
793 | ||
794 | /* | |
795 | * While a process runs, Xen pins its pagetables, which means that the | |
796 | * hypervisor forces it to be read-only, and it controls all updates | |
797 | * to it. This means that all pagetable updates have to go via the | |
798 | * hypervisor, which is moderately expensive. | |
799 | * | |
800 | * Since we're pulling the pagetable down, we switch to use init_mm, | |
801 | * unpin old process pagetable and mark it all read-write, which | |
802 | * allows further operations on it to be simple memory accesses. | |
803 | * | |
804 | * The only subtle point is that another CPU may be still using the | |
805 | * pagetable because of lazy tlb flushing. This means we need need to | |
806 | * switch all CPUs off this pagetable before we can unpin it. | |
807 | */ | |
808 | void xen_exit_mmap(struct mm_struct *mm) | |
809 | { | |
810 | get_cpu(); /* make sure we don't move around */ | |
811 | drop_mm_ref(mm); | |
812 | put_cpu(); | |
3b827c1b | 813 | |
f120f13e | 814 | spin_lock(&mm->page_table_lock); |
df912ea4 JF |
815 | |
816 | /* pgd may not be pinned in the error exit path of execve */ | |
e2426cf8 | 817 | if (page_pinned(mm->pgd)) |
df912ea4 | 818 | xen_pgd_unpin(mm->pgd); |
74260714 | 819 | |
f120f13e | 820 | spin_unlock(&mm->page_table_lock); |
3b827c1b | 821 | } |