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Commit | Line | Data |
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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> | |
5deb30d1 | 47 | #include <asm/fixmap.h> |
3b827c1b | 48 | #include <asm/mmu_context.h> |
f4f97b3e | 49 | #include <asm/paravirt.h> |
cbcd79c2 | 50 | #include <asm/linkage.h> |
3b827c1b JF |
51 | |
52 | #include <asm/xen/hypercall.h> | |
f4f97b3e | 53 | #include <asm/xen/hypervisor.h> |
3b827c1b JF |
54 | |
55 | #include <xen/page.h> | |
56 | #include <xen/interface/xen.h> | |
57 | ||
f4f97b3e | 58 | #include "multicalls.h" |
3b827c1b JF |
59 | #include "mmu.h" |
60 | ||
d451bb7a | 61 | #define P2M_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) |
cf0923ea | 62 | #define TOP_ENTRIES (MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE) |
d451bb7a | 63 | |
cf0923ea | 64 | /* Placeholder for holes in the address space */ |
cbcd79c2 | 65 | static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE] __page_aligned_data = |
cf0923ea JF |
66 | { [ 0 ... P2M_ENTRIES_PER_PAGE-1 ] = ~0UL }; |
67 | ||
68 | /* Array of pointers to pages containing p2m entries */ | |
cbcd79c2 | 69 | static unsigned long *p2m_top[TOP_ENTRIES] __page_aligned_data = |
cf0923ea | 70 | { [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] }; |
d451bb7a | 71 | |
d5edbc1f | 72 | /* Arrays of p2m arrays expressed in mfns used for save/restore */ |
cbcd79c2 | 73 | static unsigned long p2m_top_mfn[TOP_ENTRIES] __page_aligned_bss; |
d5edbc1f | 74 | |
cbcd79c2 JF |
75 | static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE] |
76 | __page_aligned_bss; | |
d5edbc1f | 77 | |
d451bb7a JF |
78 | static inline unsigned p2m_top_index(unsigned long pfn) |
79 | { | |
8006ec3e | 80 | BUG_ON(pfn >= MAX_DOMAIN_PAGES); |
d451bb7a JF |
81 | return pfn / P2M_ENTRIES_PER_PAGE; |
82 | } | |
83 | ||
84 | static inline unsigned p2m_index(unsigned long pfn) | |
85 | { | |
86 | return pfn % P2M_ENTRIES_PER_PAGE; | |
87 | } | |
88 | ||
d5edbc1f JF |
89 | /* Build the parallel p2m_top_mfn structures */ |
90 | void xen_setup_mfn_list_list(void) | |
91 | { | |
92 | unsigned pfn, idx; | |
93 | ||
94 | for(pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_ENTRIES_PER_PAGE) { | |
95 | unsigned topidx = p2m_top_index(pfn); | |
96 | ||
97 | p2m_top_mfn[topidx] = virt_to_mfn(p2m_top[topidx]); | |
98 | } | |
99 | ||
100 | for(idx = 0; idx < ARRAY_SIZE(p2m_top_mfn_list); idx++) { | |
101 | unsigned topidx = idx * P2M_ENTRIES_PER_PAGE; | |
102 | p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]); | |
103 | } | |
104 | ||
105 | BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); | |
106 | ||
107 | HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = | |
108 | virt_to_mfn(p2m_top_mfn_list); | |
109 | HYPERVISOR_shared_info->arch.max_pfn = xen_start_info->nr_pages; | |
110 | } | |
111 | ||
112 | /* Set up p2m_top to point to the domain-builder provided p2m pages */ | |
d451bb7a JF |
113 | void __init xen_build_dynamic_phys_to_machine(void) |
114 | { | |
d451bb7a | 115 | unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list; |
8006ec3e | 116 | unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages); |
d5edbc1f | 117 | unsigned pfn; |
d451bb7a | 118 | |
8006ec3e | 119 | for(pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) { |
d451bb7a JF |
120 | unsigned topidx = p2m_top_index(pfn); |
121 | ||
122 | p2m_top[topidx] = &mfn_list[pfn]; | |
123 | } | |
124 | } | |
125 | ||
126 | unsigned long get_phys_to_machine(unsigned long pfn) | |
127 | { | |
128 | unsigned topidx, idx; | |
129 | ||
8006ec3e JF |
130 | if (unlikely(pfn >= MAX_DOMAIN_PAGES)) |
131 | return INVALID_P2M_ENTRY; | |
132 | ||
d451bb7a | 133 | topidx = p2m_top_index(pfn); |
d451bb7a JF |
134 | idx = p2m_index(pfn); |
135 | return p2m_top[topidx][idx]; | |
136 | } | |
15ce6005 | 137 | EXPORT_SYMBOL_GPL(get_phys_to_machine); |
d451bb7a | 138 | |
d5edbc1f | 139 | static void alloc_p2m(unsigned long **pp, unsigned long *mfnp) |
d451bb7a JF |
140 | { |
141 | unsigned long *p; | |
142 | unsigned i; | |
143 | ||
144 | p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL); | |
145 | BUG_ON(p == NULL); | |
146 | ||
147 | for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++) | |
148 | p[i] = INVALID_P2M_ENTRY; | |
149 | ||
cf0923ea | 150 | if (cmpxchg(pp, p2m_missing, p) != p2m_missing) |
d451bb7a | 151 | free_page((unsigned long)p); |
d5edbc1f JF |
152 | else |
153 | *mfnp = virt_to_mfn(p); | |
d451bb7a JF |
154 | } |
155 | ||
156 | void set_phys_to_machine(unsigned long pfn, unsigned long mfn) | |
157 | { | |
158 | unsigned topidx, idx; | |
159 | ||
160 | if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) { | |
161 | BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY); | |
8006ec3e JF |
162 | return; |
163 | } | |
164 | ||
165 | if (unlikely(pfn >= MAX_DOMAIN_PAGES)) { | |
166 | BUG_ON(mfn != INVALID_P2M_ENTRY); | |
d451bb7a JF |
167 | return; |
168 | } | |
169 | ||
170 | topidx = p2m_top_index(pfn); | |
cf0923ea | 171 | if (p2m_top[topidx] == p2m_missing) { |
d451bb7a JF |
172 | /* no need to allocate a page to store an invalid entry */ |
173 | if (mfn == INVALID_P2M_ENTRY) | |
174 | return; | |
d5edbc1f | 175 | alloc_p2m(&p2m_top[topidx], &p2m_top_mfn[topidx]); |
d451bb7a JF |
176 | } |
177 | ||
178 | idx = p2m_index(pfn); | |
179 | p2m_top[topidx][idx] = mfn; | |
180 | } | |
181 | ||
ce803e70 | 182 | xmaddr_t arbitrary_virt_to_machine(void *vaddr) |
3b827c1b | 183 | { |
ce803e70 | 184 | unsigned long address = (unsigned long)vaddr; |
da7bfc50 | 185 | unsigned int level; |
f0646e43 | 186 | pte_t *pte = lookup_address(address, &level); |
de067814 | 187 | unsigned offset = address & ~PAGE_MASK; |
3b827c1b JF |
188 | |
189 | BUG_ON(pte == NULL); | |
190 | ||
ebd879e3 | 191 | return XMADDR(((phys_addr_t)pte_mfn(*pte) << PAGE_SHIFT) + offset); |
3b827c1b JF |
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 | ||
e2426cf8 JF |
225 | static bool page_pinned(void *ptr) |
226 | { | |
227 | struct page *page = virt_to_page(ptr); | |
228 | ||
229 | return PagePinned(page); | |
230 | } | |
231 | ||
400d3494 | 232 | static void extend_mmu_update(const struct mmu_update *update) |
3b827c1b | 233 | { |
d66bf8fc JF |
234 | struct multicall_space mcs; |
235 | struct mmu_update *u; | |
3b827c1b | 236 | |
400d3494 JF |
237 | mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u)); |
238 | ||
239 | if (mcs.mc != NULL) | |
240 | mcs.mc->args[1]++; | |
241 | else { | |
242 | mcs = __xen_mc_entry(sizeof(*u)); | |
243 | MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF); | |
244 | } | |
d66bf8fc | 245 | |
d66bf8fc | 246 | u = mcs.args; |
400d3494 JF |
247 | *u = *update; |
248 | } | |
249 | ||
250 | void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val) | |
251 | { | |
252 | struct mmu_update u; | |
253 | ||
254 | preempt_disable(); | |
255 | ||
256 | xen_mc_batch(); | |
257 | ||
ce803e70 JF |
258 | /* ptr may be ioremapped for 64-bit pagetable setup */ |
259 | u.ptr = arbitrary_virt_to_machine(ptr).maddr; | |
400d3494 JF |
260 | u.val = pmd_val_ma(val); |
261 | extend_mmu_update(&u); | |
d66bf8fc JF |
262 | |
263 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
264 | ||
265 | preempt_enable(); | |
3b827c1b JF |
266 | } |
267 | ||
e2426cf8 JF |
268 | void xen_set_pmd(pmd_t *ptr, pmd_t val) |
269 | { | |
270 | /* If page is not pinned, we can just update the entry | |
271 | directly */ | |
272 | if (!page_pinned(ptr)) { | |
273 | *ptr = val; | |
274 | return; | |
275 | } | |
276 | ||
277 | xen_set_pmd_hyper(ptr, val); | |
278 | } | |
279 | ||
3b827c1b JF |
280 | /* |
281 | * Associate a virtual page frame with a given physical page frame | |
282 | * and protection flags for that frame. | |
283 | */ | |
284 | void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) | |
285 | { | |
836fe2f2 | 286 | set_pte_vaddr(vaddr, mfn_pte(mfn, flags)); |
3b827c1b JF |
287 | } |
288 | ||
289 | void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, | |
290 | pte_t *ptep, pte_t pteval) | |
291 | { | |
2bd50036 JF |
292 | /* updates to init_mm may be done without lock */ |
293 | if (mm == &init_mm) | |
294 | preempt_disable(); | |
295 | ||
d66bf8fc | 296 | if (mm == current->mm || mm == &init_mm) { |
8965c1c0 | 297 | if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { |
d66bf8fc JF |
298 | struct multicall_space mcs; |
299 | mcs = xen_mc_entry(0); | |
300 | ||
301 | MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); | |
302 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
2bd50036 | 303 | goto out; |
d66bf8fc JF |
304 | } else |
305 | if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) | |
2bd50036 | 306 | goto out; |
d66bf8fc JF |
307 | } |
308 | xen_set_pte(ptep, pteval); | |
2bd50036 JF |
309 | |
310 | out: | |
311 | if (mm == &init_mm) | |
312 | preempt_enable(); | |
3b827c1b JF |
313 | } |
314 | ||
e57778a1 | 315 | pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr, pte_t *ptep) |
947a69c9 | 316 | { |
e57778a1 JF |
317 | /* Just return the pte as-is. We preserve the bits on commit */ |
318 | return *ptep; | |
319 | } | |
320 | ||
321 | void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr, | |
322 | pte_t *ptep, pte_t pte) | |
323 | { | |
400d3494 | 324 | struct mmu_update u; |
e57778a1 | 325 | |
400d3494 | 326 | xen_mc_batch(); |
947a69c9 | 327 | |
400d3494 JF |
328 | u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD; |
329 | u.val = pte_val_ma(pte); | |
330 | extend_mmu_update(&u); | |
947a69c9 | 331 | |
e57778a1 | 332 | xen_mc_issue(PARAVIRT_LAZY_MMU); |
947a69c9 JF |
333 | } |
334 | ||
ebb9cfe2 JF |
335 | /* Assume pteval_t is equivalent to all the other *val_t types. */ |
336 | static pteval_t pte_mfn_to_pfn(pteval_t val) | |
947a69c9 | 337 | { |
ebb9cfe2 JF |
338 | if (val & _PAGE_PRESENT) { |
339 | unsigned long mfn = (val & PTE_MASK) >> PAGE_SHIFT; | |
340 | pteval_t flags = val & ~PTE_MASK; | |
d8355aca | 341 | val = ((pteval_t)mfn_to_pfn(mfn) << PAGE_SHIFT) | flags; |
ebb9cfe2 | 342 | } |
947a69c9 | 343 | |
ebb9cfe2 | 344 | return val; |
947a69c9 JF |
345 | } |
346 | ||
ebb9cfe2 | 347 | static pteval_t pte_pfn_to_mfn(pteval_t val) |
947a69c9 | 348 | { |
ebb9cfe2 JF |
349 | if (val & _PAGE_PRESENT) { |
350 | unsigned long pfn = (val & PTE_MASK) >> PAGE_SHIFT; | |
351 | pteval_t flags = val & ~PTE_MASK; | |
d8355aca | 352 | val = ((pteval_t)pfn_to_mfn(pfn) << PAGE_SHIFT) | flags; |
947a69c9 JF |
353 | } |
354 | ||
ebb9cfe2 | 355 | return val; |
947a69c9 JF |
356 | } |
357 | ||
ebb9cfe2 | 358 | pteval_t xen_pte_val(pte_t pte) |
947a69c9 | 359 | { |
ebb9cfe2 | 360 | return pte_mfn_to_pfn(pte.pte); |
947a69c9 | 361 | } |
947a69c9 | 362 | |
947a69c9 JF |
363 | pgdval_t xen_pgd_val(pgd_t pgd) |
364 | { | |
ebb9cfe2 | 365 | return pte_mfn_to_pfn(pgd.pgd); |
947a69c9 JF |
366 | } |
367 | ||
368 | pte_t xen_make_pte(pteval_t pte) | |
369 | { | |
ebb9cfe2 JF |
370 | pte = pte_pfn_to_mfn(pte); |
371 | return native_make_pte(pte); | |
947a69c9 JF |
372 | } |
373 | ||
374 | pgd_t xen_make_pgd(pgdval_t pgd) | |
375 | { | |
ebb9cfe2 JF |
376 | pgd = pte_pfn_to_mfn(pgd); |
377 | return native_make_pgd(pgd); | |
947a69c9 JF |
378 | } |
379 | ||
380 | pmdval_t xen_pmd_val(pmd_t pmd) | |
381 | { | |
ebb9cfe2 | 382 | return pte_mfn_to_pfn(pmd.pmd); |
947a69c9 | 383 | } |
28499143 | 384 | |
e2426cf8 | 385 | void xen_set_pud_hyper(pud_t *ptr, pud_t val) |
f4f97b3e | 386 | { |
400d3494 | 387 | struct mmu_update u; |
f4f97b3e | 388 | |
d66bf8fc JF |
389 | preempt_disable(); |
390 | ||
400d3494 JF |
391 | xen_mc_batch(); |
392 | ||
ce803e70 JF |
393 | /* ptr may be ioremapped for 64-bit pagetable setup */ |
394 | u.ptr = arbitrary_virt_to_machine(ptr).maddr; | |
400d3494 JF |
395 | u.val = pud_val_ma(val); |
396 | extend_mmu_update(&u); | |
d66bf8fc JF |
397 | |
398 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
399 | ||
400 | preempt_enable(); | |
f4f97b3e JF |
401 | } |
402 | ||
e2426cf8 JF |
403 | void xen_set_pud(pud_t *ptr, pud_t val) |
404 | { | |
405 | /* If page is not pinned, we can just update the entry | |
406 | directly */ | |
407 | if (!page_pinned(ptr)) { | |
408 | *ptr = val; | |
409 | return; | |
410 | } | |
411 | ||
412 | xen_set_pud_hyper(ptr, val); | |
413 | } | |
414 | ||
f4f97b3e JF |
415 | void xen_set_pte(pte_t *ptep, pte_t pte) |
416 | { | |
f6e58732 | 417 | #ifdef CONFIG_X86_PAE |
f4f97b3e JF |
418 | ptep->pte_high = pte.pte_high; |
419 | smp_wmb(); | |
420 | ptep->pte_low = pte.pte_low; | |
f6e58732 JF |
421 | #else |
422 | *ptep = pte; | |
423 | #endif | |
f4f97b3e JF |
424 | } |
425 | ||
f6e58732 | 426 | #ifdef CONFIG_X86_PAE |
3b827c1b JF |
427 | void xen_set_pte_atomic(pte_t *ptep, pte_t pte) |
428 | { | |
f6e58732 | 429 | set_64bit((u64 *)ptep, native_pte_val(pte)); |
3b827c1b JF |
430 | } |
431 | ||
432 | void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) | |
433 | { | |
434 | ptep->pte_low = 0; | |
435 | smp_wmb(); /* make sure low gets written first */ | |
436 | ptep->pte_high = 0; | |
437 | } | |
438 | ||
439 | void xen_pmd_clear(pmd_t *pmdp) | |
440 | { | |
e2426cf8 | 441 | set_pmd(pmdp, __pmd(0)); |
3b827c1b | 442 | } |
f6e58732 | 443 | #endif /* CONFIG_X86_PAE */ |
3b827c1b | 444 | |
abf33038 | 445 | pmd_t xen_make_pmd(pmdval_t pmd) |
3b827c1b | 446 | { |
ebb9cfe2 | 447 | pmd = pte_pfn_to_mfn(pmd); |
947a69c9 | 448 | return native_make_pmd(pmd); |
3b827c1b | 449 | } |
3b827c1b | 450 | |
f6e58732 JF |
451 | #if PAGETABLE_LEVELS == 4 |
452 | pudval_t xen_pud_val(pud_t pud) | |
453 | { | |
454 | return pte_mfn_to_pfn(pud.pud); | |
455 | } | |
456 | ||
457 | pud_t xen_make_pud(pudval_t pud) | |
458 | { | |
459 | pud = pte_pfn_to_mfn(pud); | |
460 | ||
461 | return native_make_pud(pud); | |
462 | } | |
463 | ||
464 | void xen_set_pgd_hyper(pgd_t *ptr, pgd_t val) | |
465 | { | |
466 | struct mmu_update u; | |
467 | ||
468 | preempt_disable(); | |
469 | ||
470 | xen_mc_batch(); | |
471 | ||
472 | u.ptr = virt_to_machine(ptr).maddr; | |
473 | u.val = pgd_val_ma(val); | |
474 | extend_mmu_update(&u); | |
475 | ||
476 | xen_mc_issue(PARAVIRT_LAZY_MMU); | |
477 | ||
478 | preempt_enable(); | |
479 | } | |
480 | ||
481 | void xen_set_pgd(pgd_t *ptr, pgd_t val) | |
482 | { | |
483 | /* If page is not pinned, we can just update the entry | |
484 | directly */ | |
485 | if (!page_pinned(ptr)) { | |
486 | *ptr = val; | |
487 | return; | |
488 | } | |
489 | ||
490 | xen_set_pgd_hyper(ptr, val); | |
491 | } | |
492 | #endif /* PAGETABLE_LEVELS == 4 */ | |
493 | ||
f4f97b3e | 494 | /* |
5deb30d1 JF |
495 | * (Yet another) pagetable walker. This one is intended for pinning a |
496 | * pagetable. This means that it walks a pagetable and calls the | |
497 | * callback function on each page it finds making up the page table, | |
498 | * at every level. It walks the entire pagetable, but it only bothers | |
499 | * pinning pte pages which are below limit. In the normal case this | |
500 | * will be STACK_TOP_MAX, but at boot we need to pin up to | |
501 | * FIXADDR_TOP. | |
502 | * | |
503 | * For 32-bit the important bit is that we don't pin beyond there, | |
504 | * because then we start getting into Xen's ptes. | |
505 | * | |
506 | * For 64-bit, we must skip the Xen hole in the middle of the address | |
507 | * space, just after the big x86-64 virtual hole. | |
508 | */ | |
509 | static int pgd_walk(pgd_t *pgd, int (*func)(struct page *, enum pt_level), | |
f4f97b3e | 510 | unsigned long limit) |
3b827c1b | 511 | { |
f4f97b3e | 512 | int flush = 0; |
5deb30d1 JF |
513 | unsigned hole_low, hole_high; |
514 | unsigned pgdidx_limit, pudidx_limit, pmdidx_limit; | |
515 | unsigned pgdidx, pudidx, pmdidx; | |
f4f97b3e | 516 | |
5deb30d1 JF |
517 | /* The limit is the last byte to be touched */ |
518 | limit--; | |
519 | BUG_ON(limit >= FIXADDR_TOP); | |
3b827c1b JF |
520 | |
521 | if (xen_feature(XENFEAT_auto_translated_physmap)) | |
f4f97b3e JF |
522 | return 0; |
523 | ||
5deb30d1 JF |
524 | /* |
525 | * 64-bit has a great big hole in the middle of the address | |
526 | * space, which contains the Xen mappings. On 32-bit these | |
527 | * will end up making a zero-sized hole and so is a no-op. | |
528 | */ | |
529 | hole_low = pgd_index(STACK_TOP_MAX + PGDIR_SIZE - 1); | |
530 | hole_high = pgd_index(PAGE_OFFSET); | |
531 | ||
532 | pgdidx_limit = pgd_index(limit); | |
533 | #if PTRS_PER_PUD > 1 | |
534 | pudidx_limit = pud_index(limit); | |
535 | #else | |
536 | pudidx_limit = 0; | |
537 | #endif | |
538 | #if PTRS_PER_PMD > 1 | |
539 | pmdidx_limit = pmd_index(limit); | |
540 | #else | |
541 | pmdidx_limit = 0; | |
542 | #endif | |
543 | ||
544 | flush |= (*func)(virt_to_page(pgd), PT_PGD); | |
545 | ||
546 | for (pgdidx = 0; pgdidx <= pgdidx_limit; pgdidx++) { | |
f4f97b3e | 547 | pud_t *pud; |
3b827c1b | 548 | |
5deb30d1 JF |
549 | if (pgdidx >= hole_low && pgdidx < hole_high) |
550 | continue; | |
f4f97b3e | 551 | |
5deb30d1 | 552 | if (!pgd_val(pgd[pgdidx])) |
3b827c1b | 553 | continue; |
f4f97b3e | 554 | |
5deb30d1 | 555 | pud = pud_offset(&pgd[pgdidx], 0); |
3b827c1b JF |
556 | |
557 | if (PTRS_PER_PUD > 1) /* not folded */ | |
74260714 | 558 | flush |= (*func)(virt_to_page(pud), PT_PUD); |
f4f97b3e | 559 | |
5deb30d1 | 560 | for (pudidx = 0; pudidx < PTRS_PER_PUD; pudidx++) { |
f4f97b3e | 561 | pmd_t *pmd; |
f4f97b3e | 562 | |
5deb30d1 JF |
563 | if (pgdidx == pgdidx_limit && |
564 | pudidx > pudidx_limit) | |
565 | goto out; | |
3b827c1b | 566 | |
5deb30d1 | 567 | if (pud_none(pud[pudidx])) |
3b827c1b | 568 | continue; |
f4f97b3e | 569 | |
5deb30d1 | 570 | pmd = pmd_offset(&pud[pudidx], 0); |
3b827c1b JF |
571 | |
572 | if (PTRS_PER_PMD > 1) /* not folded */ | |
74260714 | 573 | flush |= (*func)(virt_to_page(pmd), PT_PMD); |
f4f97b3e | 574 | |
5deb30d1 JF |
575 | for (pmdidx = 0; pmdidx < PTRS_PER_PMD; pmdidx++) { |
576 | struct page *pte; | |
577 | ||
578 | if (pgdidx == pgdidx_limit && | |
579 | pudidx == pudidx_limit && | |
580 | pmdidx > pmdidx_limit) | |
581 | goto out; | |
3b827c1b | 582 | |
5deb30d1 | 583 | if (pmd_none(pmd[pmdidx])) |
3b827c1b JF |
584 | continue; |
585 | ||
5deb30d1 JF |
586 | pte = pmd_page(pmd[pmdidx]); |
587 | flush |= (*func)(pte, PT_PTE); | |
3b827c1b JF |
588 | } |
589 | } | |
590 | } | |
5deb30d1 | 591 | out: |
f4f97b3e JF |
592 | |
593 | return flush; | |
3b827c1b JF |
594 | } |
595 | ||
74260714 JF |
596 | static spinlock_t *lock_pte(struct page *page) |
597 | { | |
598 | spinlock_t *ptl = NULL; | |
599 | ||
600 | #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS | |
601 | ptl = __pte_lockptr(page); | |
602 | spin_lock(ptl); | |
603 | #endif | |
604 | ||
605 | return ptl; | |
606 | } | |
607 | ||
608 | static void do_unlock(void *v) | |
609 | { | |
610 | spinlock_t *ptl = v; | |
611 | spin_unlock(ptl); | |
612 | } | |
613 | ||
614 | static void xen_do_pin(unsigned level, unsigned long pfn) | |
615 | { | |
616 | struct mmuext_op *op; | |
617 | struct multicall_space mcs; | |
618 | ||
619 | mcs = __xen_mc_entry(sizeof(*op)); | |
620 | op = mcs.args; | |
621 | op->cmd = level; | |
622 | op->arg1.mfn = pfn_to_mfn(pfn); | |
623 | MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); | |
624 | } | |
625 | ||
626 | static int pin_page(struct page *page, enum pt_level level) | |
f4f97b3e | 627 | { |
d60cd46b | 628 | unsigned pgfl = TestSetPagePinned(page); |
f4f97b3e JF |
629 | int flush; |
630 | ||
631 | if (pgfl) | |
632 | flush = 0; /* already pinned */ | |
633 | else if (PageHighMem(page)) | |
634 | /* kmaps need flushing if we found an unpinned | |
635 | highpage */ | |
636 | flush = 1; | |
637 | else { | |
638 | void *pt = lowmem_page_address(page); | |
639 | unsigned long pfn = page_to_pfn(page); | |
640 | struct multicall_space mcs = __xen_mc_entry(0); | |
74260714 | 641 | spinlock_t *ptl; |
f4f97b3e JF |
642 | |
643 | flush = 0; | |
644 | ||
74260714 JF |
645 | ptl = NULL; |
646 | if (level == PT_PTE) | |
647 | ptl = lock_pte(page); | |
648 | ||
f4f97b3e JF |
649 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, |
650 | pfn_pte(pfn, PAGE_KERNEL_RO), | |
74260714 JF |
651 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
652 | ||
653 | if (level == PT_PTE) | |
654 | xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn); | |
655 | ||
656 | if (ptl) { | |
657 | /* Queue a deferred unlock for when this batch | |
658 | is completed. */ | |
659 | xen_mc_callback(do_unlock, ptl); | |
660 | } | |
f4f97b3e JF |
661 | } |
662 | ||
663 | return flush; | |
664 | } | |
3b827c1b | 665 | |
f4f97b3e JF |
666 | /* This is called just after a mm has been created, but it has not |
667 | been used yet. We need to make sure that its pagetable is all | |
668 | read-only, and can be pinned. */ | |
3b827c1b JF |
669 | void xen_pgd_pin(pgd_t *pgd) |
670 | { | |
f4f97b3e | 671 | xen_mc_batch(); |
3b827c1b | 672 | |
f87e4cac JF |
673 | if (pgd_walk(pgd, pin_page, TASK_SIZE)) { |
674 | /* re-enable interrupts for kmap_flush_unused */ | |
675 | xen_mc_issue(0); | |
f4f97b3e | 676 | kmap_flush_unused(); |
f87e4cac JF |
677 | xen_mc_batch(); |
678 | } | |
f4f97b3e | 679 | |
5deb30d1 JF |
680 | #ifdef CONFIG_X86_PAE |
681 | /* Need to make sure unshared kernel PMD is pinnable */ | |
682 | pin_page(virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])), PT_PMD); | |
683 | #endif | |
684 | ||
28499143 | 685 | xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e | 686 | xen_mc_issue(0); |
3b827c1b JF |
687 | } |
688 | ||
0e91398f JF |
689 | /* |
690 | * On save, we need to pin all pagetables to make sure they get their | |
691 | * mfns turned into pfns. Search the list for any unpinned pgds and pin | |
692 | * them (unpinned pgds are not currently in use, probably because the | |
693 | * process is under construction or destruction). | |
694 | */ | |
695 | void xen_mm_pin_all(void) | |
696 | { | |
697 | unsigned long flags; | |
698 | struct page *page; | |
74260714 | 699 | |
0e91398f | 700 | spin_lock_irqsave(&pgd_lock, flags); |
f4f97b3e | 701 | |
0e91398f JF |
702 | list_for_each_entry(page, &pgd_list, lru) { |
703 | if (!PagePinned(page)) { | |
704 | xen_pgd_pin((pgd_t *)page_address(page)); | |
705 | SetPageSavePinned(page); | |
706 | } | |
707 | } | |
708 | ||
709 | spin_unlock_irqrestore(&pgd_lock, flags); | |
3b827c1b JF |
710 | } |
711 | ||
c1f2f09e EH |
712 | /* |
713 | * The init_mm pagetable is really pinned as soon as its created, but | |
714 | * that's before we have page structures to store the bits. So do all | |
715 | * the book-keeping now. | |
716 | */ | |
74260714 | 717 | static __init int mark_pinned(struct page *page, enum pt_level level) |
3b827c1b | 718 | { |
f4f97b3e JF |
719 | SetPagePinned(page); |
720 | return 0; | |
721 | } | |
3b827c1b | 722 | |
f4f97b3e JF |
723 | void __init xen_mark_init_mm_pinned(void) |
724 | { | |
725 | pgd_walk(init_mm.pgd, mark_pinned, FIXADDR_TOP); | |
726 | } | |
3b827c1b | 727 | |
74260714 | 728 | static int unpin_page(struct page *page, enum pt_level level) |
f4f97b3e | 729 | { |
d60cd46b | 730 | unsigned pgfl = TestClearPagePinned(page); |
3b827c1b | 731 | |
f4f97b3e JF |
732 | if (pgfl && !PageHighMem(page)) { |
733 | void *pt = lowmem_page_address(page); | |
734 | unsigned long pfn = page_to_pfn(page); | |
74260714 JF |
735 | spinlock_t *ptl = NULL; |
736 | struct multicall_space mcs; | |
737 | ||
738 | if (level == PT_PTE) { | |
739 | ptl = lock_pte(page); | |
740 | ||
741 | xen_do_pin(MMUEXT_UNPIN_TABLE, pfn); | |
742 | } | |
743 | ||
744 | mcs = __xen_mc_entry(0); | |
f4f97b3e JF |
745 | |
746 | MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, | |
747 | pfn_pte(pfn, PAGE_KERNEL), | |
74260714 JF |
748 | level == PT_PGD ? UVMF_TLB_FLUSH : 0); |
749 | ||
750 | if (ptl) { | |
751 | /* unlock when batch completed */ | |
752 | xen_mc_callback(do_unlock, ptl); | |
753 | } | |
f4f97b3e JF |
754 | } |
755 | ||
756 | return 0; /* never need to flush on unpin */ | |
3b827c1b JF |
757 | } |
758 | ||
f4f97b3e JF |
759 | /* Release a pagetables pages back as normal RW */ |
760 | static void xen_pgd_unpin(pgd_t *pgd) | |
761 | { | |
f4f97b3e JF |
762 | xen_mc_batch(); |
763 | ||
74260714 | 764 | xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); |
f4f97b3e | 765 | |
5deb30d1 JF |
766 | #ifdef CONFIG_X86_PAE |
767 | /* Need to make sure unshared kernel PMD is unpinned */ | |
768 | pin_page(virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])), PT_PMD); | |
769 | #endif | |
f4f97b3e JF |
770 | pgd_walk(pgd, unpin_page, TASK_SIZE); |
771 | ||
772 | xen_mc_issue(0); | |
773 | } | |
3b827c1b | 774 | |
0e91398f JF |
775 | /* |
776 | * On resume, undo any pinning done at save, so that the rest of the | |
777 | * kernel doesn't see any unexpected pinned pagetables. | |
778 | */ | |
779 | void xen_mm_unpin_all(void) | |
780 | { | |
781 | unsigned long flags; | |
782 | struct page *page; | |
783 | ||
784 | spin_lock_irqsave(&pgd_lock, flags); | |
785 | ||
786 | list_for_each_entry(page, &pgd_list, lru) { | |
787 | if (PageSavePinned(page)) { | |
788 | BUG_ON(!PagePinned(page)); | |
0e91398f JF |
789 | xen_pgd_unpin((pgd_t *)page_address(page)); |
790 | ClearPageSavePinned(page); | |
791 | } | |
792 | } | |
793 | ||
794 | spin_unlock_irqrestore(&pgd_lock, flags); | |
795 | } | |
796 | ||
3b827c1b JF |
797 | void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) |
798 | { | |
f4f97b3e | 799 | spin_lock(&next->page_table_lock); |
3b827c1b | 800 | xen_pgd_pin(next->pgd); |
f4f97b3e | 801 | spin_unlock(&next->page_table_lock); |
3b827c1b JF |
802 | } |
803 | ||
804 | void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) | |
805 | { | |
f4f97b3e | 806 | spin_lock(&mm->page_table_lock); |
3b827c1b | 807 | xen_pgd_pin(mm->pgd); |
f4f97b3e | 808 | spin_unlock(&mm->page_table_lock); |
3b827c1b JF |
809 | } |
810 | ||
3b827c1b | 811 | |
f87e4cac JF |
812 | #ifdef CONFIG_SMP |
813 | /* Another cpu may still have their %cr3 pointing at the pagetable, so | |
814 | we need to repoint it somewhere else before we can unpin it. */ | |
815 | static void drop_other_mm_ref(void *info) | |
816 | { | |
817 | struct mm_struct *mm = info; | |
ce87b3d3 | 818 | struct mm_struct *active_mm; |
3b827c1b | 819 | |
ce87b3d3 JF |
820 | #ifdef CONFIG_X86_64 |
821 | active_mm = read_pda(active_mm); | |
822 | #else | |
823 | active_mm = __get_cpu_var(cpu_tlbstate).active_mm; | |
824 | #endif | |
825 | ||
826 | if (active_mm == mm) | |
f87e4cac | 827 | leave_mm(smp_processor_id()); |
9f79991d JF |
828 | |
829 | /* If this cpu still has a stale cr3 reference, then make sure | |
830 | it has been flushed. */ | |
831 | if (x86_read_percpu(xen_current_cr3) == __pa(mm->pgd)) { | |
832 | load_cr3(swapper_pg_dir); | |
833 | arch_flush_lazy_cpu_mode(); | |
834 | } | |
f87e4cac | 835 | } |
3b827c1b | 836 | |
f87e4cac JF |
837 | static void drop_mm_ref(struct mm_struct *mm) |
838 | { | |
9f79991d JF |
839 | cpumask_t mask; |
840 | unsigned cpu; | |
841 | ||
f87e4cac JF |
842 | if (current->active_mm == mm) { |
843 | if (current->mm == mm) | |
844 | load_cr3(swapper_pg_dir); | |
845 | else | |
846 | leave_mm(smp_processor_id()); | |
9f79991d JF |
847 | arch_flush_lazy_cpu_mode(); |
848 | } | |
849 | ||
850 | /* Get the "official" set of cpus referring to our pagetable. */ | |
851 | mask = mm->cpu_vm_mask; | |
852 | ||
853 | /* It's possible that a vcpu may have a stale reference to our | |
854 | cr3, because its in lazy mode, and it hasn't yet flushed | |
855 | its set of pending hypercalls yet. In this case, we can | |
856 | look at its actual current cr3 value, and force it to flush | |
857 | if needed. */ | |
858 | for_each_online_cpu(cpu) { | |
859 | if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd)) | |
860 | cpu_set(cpu, mask); | |
3b827c1b JF |
861 | } |
862 | ||
9f79991d | 863 | if (!cpus_empty(mask)) |
3b16cf87 | 864 | smp_call_function_mask(mask, drop_other_mm_ref, mm, 1); |
f87e4cac JF |
865 | } |
866 | #else | |
867 | static void drop_mm_ref(struct mm_struct *mm) | |
868 | { | |
869 | if (current->active_mm == mm) | |
870 | load_cr3(swapper_pg_dir); | |
871 | } | |
872 | #endif | |
873 | ||
874 | /* | |
875 | * While a process runs, Xen pins its pagetables, which means that the | |
876 | * hypervisor forces it to be read-only, and it controls all updates | |
877 | * to it. This means that all pagetable updates have to go via the | |
878 | * hypervisor, which is moderately expensive. | |
879 | * | |
880 | * Since we're pulling the pagetable down, we switch to use init_mm, | |
881 | * unpin old process pagetable and mark it all read-write, which | |
882 | * allows further operations on it to be simple memory accesses. | |
883 | * | |
884 | * The only subtle point is that another CPU may be still using the | |
885 | * pagetable because of lazy tlb flushing. This means we need need to | |
886 | * switch all CPUs off this pagetable before we can unpin it. | |
887 | */ | |
888 | void xen_exit_mmap(struct mm_struct *mm) | |
889 | { | |
890 | get_cpu(); /* make sure we don't move around */ | |
891 | drop_mm_ref(mm); | |
892 | put_cpu(); | |
3b827c1b | 893 | |
f120f13e | 894 | spin_lock(&mm->page_table_lock); |
df912ea4 JF |
895 | |
896 | /* pgd may not be pinned in the error exit path of execve */ | |
e2426cf8 | 897 | if (page_pinned(mm->pgd)) |
df912ea4 | 898 | xen_pgd_unpin(mm->pgd); |
74260714 | 899 | |
f120f13e | 900 | spin_unlock(&mm->page_table_lock); |
3b827c1b | 901 | } |