// SPDX-License-Identifier: GPL-2.0 /* * Xen mmu operations * * This file contains the various mmu fetch and update operations. * The most important job they must perform is the mapping between the * domain's pfn and the overall machine mfns. * * Xen allows guests to directly update the pagetable, in a controlled * fashion. In other words, the guest modifies the same pagetable * that the CPU actually uses, which eliminates the overhead of having * a separate shadow pagetable. * * In order to allow this, it falls on the guest domain to map its * notion of a "physical" pfn - which is just a domain-local linear * address - into a real "machine address" which the CPU's MMU can * use. * * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be * inserted directly into the pagetable. When creating a new * pte/pmd/pgd, it converts the passed pfn into an mfn. Conversely, * when reading the content back with __(pgd|pmd|pte)_val, it converts * the mfn back into a pfn. * * The other constraint is that all pages which make up a pagetable * must be mapped read-only in the guest. This prevents uncontrolled * guest updates to the pagetable. Xen strictly enforces this, and * will disallow any pagetable update which will end up mapping a * pagetable page RW, and will disallow using any writable page as a * pagetable. * * Naively, when loading %cr3 with the base of a new pagetable, Xen * would need to validate the whole pagetable before going on. * Naturally, this is quite slow. The solution is to "pin" a * pagetable, which enforces all the constraints on the pagetable even * when it is not actively in use. This menas that Xen can be assured * that it is still valid when you do load it into %cr3, and doesn't * need to revalidate it. * * Jeremy Fitzhardinge , XenSource Inc, 2007 */ #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_KEXEC_CORE #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "multicalls.h" #include "mmu.h" #include "debugfs.h" /* l3 pud for userspace vsyscall mapping */ static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss; /* * Protects atomic reservation decrease/increase against concurrent increases. * Also protects non-atomic updates of current_pages and balloon lists. */ static DEFINE_SPINLOCK(xen_reservation_lock); /* * Note about cr3 (pagetable base) values: * * xen_cr3 contains the current logical cr3 value; it contains the * last set cr3. This may not be the current effective cr3, because * its update may be being lazily deferred. However, a vcpu looking * at its own cr3 can use this value knowing that it everything will * be self-consistent. * * xen_current_cr3 contains the actual vcpu cr3; it is set once the * hypercall to set the vcpu cr3 is complete (so it may be a little * out of date, but it will never be set early). If one vcpu is * looking at another vcpu's cr3 value, it should use this variable. */ DEFINE_PER_CPU(unsigned long, xen_cr3); /* cr3 stored as physaddr */ DEFINE_PER_CPU(unsigned long, xen_current_cr3); /* actual vcpu cr3 */ static phys_addr_t xen_pt_base, xen_pt_size __initdata; static DEFINE_STATIC_KEY_FALSE(xen_struct_pages_ready); /* * Just beyond the highest usermode address. STACK_TOP_MAX has a * redzone above it, so round it up to a PGD boundary. */ #define USER_LIMIT ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK) void make_lowmem_page_readonly(void *vaddr) { pte_t *pte, ptev; unsigned long address = (unsigned long)vaddr; unsigned int level; pte = lookup_address(address, &level); if (pte == NULL) return; /* vaddr missing */ ptev = pte_wrprotect(*pte); if (HYPERVISOR_update_va_mapping(address, ptev, 0)) BUG(); } void make_lowmem_page_readwrite(void *vaddr) { pte_t *pte, ptev; unsigned long address = (unsigned long)vaddr; unsigned int level; pte = lookup_address(address, &level); if (pte == NULL) return; /* vaddr missing */ ptev = pte_mkwrite(*pte); if (HYPERVISOR_update_va_mapping(address, ptev, 0)) BUG(); } /* * During early boot all page table pages are pinned, but we do not have struct * pages, so return true until struct pages are ready. */ static bool xen_page_pinned(void *ptr) { if (static_branch_likely(&xen_struct_pages_ready)) { struct page *page = virt_to_page(ptr); return PagePinned(page); } return true; } static void xen_extend_mmu_update(const struct mmu_update *update) { struct multicall_space mcs; struct mmu_update *u; mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u)); if (mcs.mc != NULL) { mcs.mc->args[1]++; } else { mcs = __xen_mc_entry(sizeof(*u)); MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF); } u = mcs.args; *u = *update; } static void xen_extend_mmuext_op(const struct mmuext_op *op) { struct multicall_space mcs; struct mmuext_op *u; mcs = xen_mc_extend_args(__HYPERVISOR_mmuext_op, sizeof(*u)); if (mcs.mc != NULL) { mcs.mc->args[1]++; } else { mcs = __xen_mc_entry(sizeof(*u)); MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF); } u = mcs.args; *u = *op; } static void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val) { struct mmu_update u; preempt_disable(); xen_mc_batch(); /* ptr may be ioremapped for 64-bit pagetable setup */ u.ptr = arbitrary_virt_to_machine(ptr).maddr; u.val = pmd_val_ma(val); xen_extend_mmu_update(&u); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } static void xen_set_pmd(pmd_t *ptr, pmd_t val) { trace_xen_mmu_set_pmd(ptr, val); /* If page is not pinned, we can just update the entry directly */ if (!xen_page_pinned(ptr)) { *ptr = val; return; } xen_set_pmd_hyper(ptr, val); } /* * Associate a virtual page frame with a given physical page frame * and protection flags for that frame. */ void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) { set_pte_vaddr(vaddr, mfn_pte(mfn, flags)); } static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval) { struct mmu_update u; if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU) return false; xen_mc_batch(); u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE; u.val = pte_val_ma(pteval); xen_extend_mmu_update(&u); xen_mc_issue(PARAVIRT_LAZY_MMU); return true; } static inline void __xen_set_pte(pte_t *ptep, pte_t pteval) { if (!xen_batched_set_pte(ptep, pteval)) { /* * Could call native_set_pte() here and trap and * emulate the PTE write, but a hypercall is much cheaper. */ struct mmu_update u; u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE; u.val = pte_val_ma(pteval); HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF); } } static void xen_set_pte(pte_t *ptep, pte_t pteval) { trace_xen_mmu_set_pte(ptep, pteval); __xen_set_pte(ptep, pteval); } pte_t xen_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { /* Just return the pte as-is. We preserve the bits on commit */ trace_xen_mmu_ptep_modify_prot_start(vma->vm_mm, addr, ptep, *ptep); return *ptep; } void xen_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, pte_t pte) { struct mmu_update u; trace_xen_mmu_ptep_modify_prot_commit(vma->vm_mm, addr, ptep, pte); xen_mc_batch(); u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD; u.val = pte_val_ma(pte); xen_extend_mmu_update(&u); xen_mc_issue(PARAVIRT_LAZY_MMU); } /* Assume pteval_t is equivalent to all the other *val_t types. */ static pteval_t pte_mfn_to_pfn(pteval_t val) { if (val & _PAGE_PRESENT) { unsigned long mfn = (val & XEN_PTE_MFN_MASK) >> PAGE_SHIFT; unsigned long pfn = mfn_to_pfn(mfn); pteval_t flags = val & PTE_FLAGS_MASK; if (unlikely(pfn == ~0)) val = flags & ~_PAGE_PRESENT; else val = ((pteval_t)pfn << PAGE_SHIFT) | flags; } return val; } static pteval_t pte_pfn_to_mfn(pteval_t val) { if (val & _PAGE_PRESENT) { unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; pteval_t flags = val & PTE_FLAGS_MASK; unsigned long mfn; mfn = __pfn_to_mfn(pfn); /* * If there's no mfn for the pfn, then just create an * empty non-present pte. Unfortunately this loses * information about the original pfn, so * pte_mfn_to_pfn is asymmetric. */ if (unlikely(mfn == INVALID_P2M_ENTRY)) { mfn = 0; flags = 0; } else mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT); val = ((pteval_t)mfn << PAGE_SHIFT) | flags; } return val; } __visible pteval_t xen_pte_val(pte_t pte) { pteval_t pteval = pte.pte; return pte_mfn_to_pfn(pteval); } PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val); __visible pgdval_t xen_pgd_val(pgd_t pgd) { return pte_mfn_to_pfn(pgd.pgd); } PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val); __visible pte_t xen_make_pte(pteval_t pte) { pte = pte_pfn_to_mfn(pte); return native_make_pte(pte); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte); __visible pgd_t xen_make_pgd(pgdval_t pgd) { pgd = pte_pfn_to_mfn(pgd); return native_make_pgd(pgd); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_pgd); __visible pmdval_t xen_pmd_val(pmd_t pmd) { return pte_mfn_to_pfn(pmd.pmd); } PV_CALLEE_SAVE_REGS_THUNK(xen_pmd_val); static void xen_set_pud_hyper(pud_t *ptr, pud_t val) { struct mmu_update u; preempt_disable(); xen_mc_batch(); /* ptr may be ioremapped for 64-bit pagetable setup */ u.ptr = arbitrary_virt_to_machine(ptr).maddr; u.val = pud_val_ma(val); xen_extend_mmu_update(&u); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } static void xen_set_pud(pud_t *ptr, pud_t val) { trace_xen_mmu_set_pud(ptr, val); /* If page is not pinned, we can just update the entry directly */ if (!xen_page_pinned(ptr)) { *ptr = val; return; } xen_set_pud_hyper(ptr, val); } __visible pmd_t xen_make_pmd(pmdval_t pmd) { pmd = pte_pfn_to_mfn(pmd); return native_make_pmd(pmd); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd); __visible pudval_t xen_pud_val(pud_t pud) { return pte_mfn_to_pfn(pud.pud); } PV_CALLEE_SAVE_REGS_THUNK(xen_pud_val); __visible pud_t xen_make_pud(pudval_t pud) { pud = pte_pfn_to_mfn(pud); return native_make_pud(pud); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_pud); static pgd_t *xen_get_user_pgd(pgd_t *pgd) { pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK); unsigned offset = pgd - pgd_page; pgd_t *user_ptr = NULL; if (offset < pgd_index(USER_LIMIT)) { struct page *page = virt_to_page(pgd_page); user_ptr = (pgd_t *)page->private; if (user_ptr) user_ptr += offset; } return user_ptr; } static void __xen_set_p4d_hyper(p4d_t *ptr, p4d_t val) { struct mmu_update u; u.ptr = virt_to_machine(ptr).maddr; u.val = p4d_val_ma(val); xen_extend_mmu_update(&u); } /* * Raw hypercall-based set_p4d, intended for in early boot before * there's a page structure. This implies: * 1. The only existing pagetable is the kernel's * 2. It is always pinned * 3. It has no user pagetable attached to it */ static void __init xen_set_p4d_hyper(p4d_t *ptr, p4d_t val) { preempt_disable(); xen_mc_batch(); __xen_set_p4d_hyper(ptr, val); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } static void xen_set_p4d(p4d_t *ptr, p4d_t val) { pgd_t *user_ptr = xen_get_user_pgd((pgd_t *)ptr); pgd_t pgd_val; trace_xen_mmu_set_p4d(ptr, (p4d_t *)user_ptr, val); /* If page is not pinned, we can just update the entry directly */ if (!xen_page_pinned(ptr)) { *ptr = val; if (user_ptr) { WARN_ON(xen_page_pinned(user_ptr)); pgd_val.pgd = p4d_val_ma(val); *user_ptr = pgd_val; } return; } /* If it's pinned, then we can at least batch the kernel and user updates together. */ xen_mc_batch(); __xen_set_p4d_hyper(ptr, val); if (user_ptr) __xen_set_p4d_hyper((p4d_t *)user_ptr, val); xen_mc_issue(PARAVIRT_LAZY_MMU); } #if CONFIG_PGTABLE_LEVELS >= 5 __visible p4dval_t xen_p4d_val(p4d_t p4d) { return pte_mfn_to_pfn(p4d.p4d); } PV_CALLEE_SAVE_REGS_THUNK(xen_p4d_val); __visible p4d_t xen_make_p4d(p4dval_t p4d) { p4d = pte_pfn_to_mfn(p4d); return native_make_p4d(p4d); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d); #endif /* CONFIG_PGTABLE_LEVELS >= 5 */ static void xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd, void (*func)(struct mm_struct *mm, struct page *, enum pt_level), bool last, unsigned long limit) { int i, nr; nr = last ? pmd_index(limit) + 1 : PTRS_PER_PMD; for (i = 0; i < nr; i++) { if (!pmd_none(pmd[i])) (*func)(mm, pmd_page(pmd[i]), PT_PTE); } } static void xen_pud_walk(struct mm_struct *mm, pud_t *pud, void (*func)(struct mm_struct *mm, struct page *, enum pt_level), bool last, unsigned long limit) { int i, nr; nr = last ? pud_index(limit) + 1 : PTRS_PER_PUD; for (i = 0; i < nr; i++) { pmd_t *pmd; if (pud_none(pud[i])) continue; pmd = pmd_offset(&pud[i], 0); if (PTRS_PER_PMD > 1) (*func)(mm, virt_to_page(pmd), PT_PMD); xen_pmd_walk(mm, pmd, func, last && i == nr - 1, limit); } } static void xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d, void (*func)(struct mm_struct *mm, struct page *, enum pt_level), bool last, unsigned long limit) { pud_t *pud; if (p4d_none(*p4d)) return; pud = pud_offset(p4d, 0); if (PTRS_PER_PUD > 1) (*func)(mm, virt_to_page(pud), PT_PUD); xen_pud_walk(mm, pud, func, last, limit); } /* * (Yet another) pagetable walker. This one is intended for pinning a * pagetable. This means that it walks a pagetable and calls the * callback function on each page it finds making up the page table, * at every level. It walks the entire pagetable, but it only bothers * pinning pte pages which are below limit. In the normal case this * will be STACK_TOP_MAX, but at boot we need to pin up to * FIXADDR_TOP. * * We must skip the Xen hole in the middle of the address space, just after * the big x86-64 virtual hole. */ static void __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd, void (*func)(struct mm_struct *mm, struct page *, enum pt_level), unsigned long limit) { int i, nr; unsigned hole_low = 0, hole_high = 0; /* The limit is the last byte to be touched */ limit--; BUG_ON(limit >= FIXADDR_TOP); /* * 64-bit has a great big hole in the middle of the address * space, which contains the Xen mappings. */ hole_low = pgd_index(GUARD_HOLE_BASE_ADDR); hole_high = pgd_index(GUARD_HOLE_END_ADDR); nr = pgd_index(limit) + 1; for (i = 0; i < nr; i++) { p4d_t *p4d; if (i >= hole_low && i < hole_high) continue; if (pgd_none(pgd[i])) continue; p4d = p4d_offset(&pgd[i], 0); xen_p4d_walk(mm, p4d, func, i == nr - 1, limit); } /* Do the top level last, so that the callbacks can use it as a cue to do final things like tlb flushes. */ (*func)(mm, virt_to_page(pgd), PT_PGD); } static void xen_pgd_walk(struct mm_struct *mm, void (*func)(struct mm_struct *mm, struct page *, enum pt_level), unsigned long limit) { __xen_pgd_walk(mm, mm->pgd, func, limit); } /* If we're using split pte locks, then take the page's lock and return a pointer to it. Otherwise return NULL. */ static spinlock_t *xen_pte_lock(struct page *page, struct mm_struct *mm) { spinlock_t *ptl = NULL; #if USE_SPLIT_PTE_PTLOCKS ptl = ptlock_ptr(page); spin_lock_nest_lock(ptl, &mm->page_table_lock); #endif return ptl; } static void xen_pte_unlock(void *v) { spinlock_t *ptl = v; spin_unlock(ptl); } static void xen_do_pin(unsigned level, unsigned long pfn) { struct mmuext_op op; op.cmd = level; op.arg1.mfn = pfn_to_mfn(pfn); xen_extend_mmuext_op(&op); } static void xen_pin_page(struct mm_struct *mm, struct page *page, enum pt_level level) { unsigned pgfl = TestSetPagePinned(page); if (!pgfl) { void *pt = lowmem_page_address(page); unsigned long pfn = page_to_pfn(page); struct multicall_space mcs = __xen_mc_entry(0); spinlock_t *ptl; /* * We need to hold the pagetable lock between the time * we make the pagetable RO and when we actually pin * it. If we don't, then other users may come in and * attempt to update the pagetable by writing it, * which will fail because the memory is RO but not * pinned, so Xen won't do the trap'n'emulate. * * If we're using split pte locks, we can't hold the * entire pagetable's worth of locks during the * traverse, because we may wrap the preempt count (8 * bits). The solution is to mark RO and pin each PTE * page while holding the lock. This means the number * of locks we end up holding is never more than a * batch size (~32 entries, at present). * * If we're not using split pte locks, we needn't pin * the PTE pages independently, because we're * protected by the overall pagetable lock. */ ptl = NULL; if (level == PT_PTE) ptl = xen_pte_lock(page, mm); MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, pfn_pte(pfn, PAGE_KERNEL_RO), level == PT_PGD ? UVMF_TLB_FLUSH : 0); if (ptl) { xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn); /* Queue a deferred unlock for when this batch is completed. */ xen_mc_callback(xen_pte_unlock, ptl); } } } /* This is called just after a mm has been created, but it has not been used yet. We need to make sure that its pagetable is all read-only, and can be pinned. */ static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd) { pgd_t *user_pgd = xen_get_user_pgd(pgd); trace_xen_mmu_pgd_pin(mm, pgd); xen_mc_batch(); __xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT); xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd))); if (user_pgd) { xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD); xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(user_pgd))); } xen_mc_issue(0); } static void xen_pgd_pin(struct mm_struct *mm) { __xen_pgd_pin(mm, mm->pgd); } /* * On save, we need to pin all pagetables to make sure they get their * mfns turned into pfns. Search the list for any unpinned pgds and pin * them (unpinned pgds are not currently in use, probably because the * process is under construction or destruction). * * Expected to be called in stop_machine() ("equivalent to taking * every spinlock in the system"), so the locking doesn't really * matter all that much. */ void xen_mm_pin_all(void) { struct page *page; spin_lock(&pgd_lock); list_for_each_entry(page, &pgd_list, lru) { if (!PagePinned(page)) { __xen_pgd_pin(&init_mm, (pgd_t *)page_address(page)); SetPageSavePinned(page); } } spin_unlock(&pgd_lock); } static void __init xen_mark_pinned(struct mm_struct *mm, struct page *page, enum pt_level level) { SetPagePinned(page); } /* * The init_mm pagetable is really pinned as soon as its created, but * that's before we have page structures to store the bits. So do all * the book-keeping now once struct pages for allocated pages are * initialized. This happens only after memblock_free_all() is called. */ static void __init xen_after_bootmem(void) { static_branch_enable(&xen_struct_pages_ready); SetPagePinned(virt_to_page(level3_user_vsyscall)); xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP); } static void xen_unpin_page(struct mm_struct *mm, struct page *page, enum pt_level level) { unsigned pgfl = TestClearPagePinned(page); if (pgfl) { void *pt = lowmem_page_address(page); unsigned long pfn = page_to_pfn(page); spinlock_t *ptl = NULL; struct multicall_space mcs; /* * Do the converse to pin_page. If we're using split * pte locks, we must be holding the lock for while * the pte page is unpinned but still RO to prevent * concurrent updates from seeing it in this * partially-pinned state. */ if (level == PT_PTE) { ptl = xen_pte_lock(page, mm); if (ptl) xen_do_pin(MMUEXT_UNPIN_TABLE, pfn); } mcs = __xen_mc_entry(0); MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, pfn_pte(pfn, PAGE_KERNEL), level == PT_PGD ? UVMF_TLB_FLUSH : 0); if (ptl) { /* unlock when batch completed */ xen_mc_callback(xen_pte_unlock, ptl); } } } /* Release a pagetables pages back as normal RW */ static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd) { pgd_t *user_pgd = xen_get_user_pgd(pgd); trace_xen_mmu_pgd_unpin(mm, pgd); xen_mc_batch(); xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); if (user_pgd) { xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(user_pgd))); xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD); } __xen_pgd_walk(mm, pgd, xen_unpin_page, USER_LIMIT); xen_mc_issue(0); } static void xen_pgd_unpin(struct mm_struct *mm) { __xen_pgd_unpin(mm, mm->pgd); } /* * On resume, undo any pinning done at save, so that the rest of the * kernel doesn't see any unexpected pinned pagetables. */ void xen_mm_unpin_all(void) { struct page *page; spin_lock(&pgd_lock); list_for_each_entry(page, &pgd_list, lru) { if (PageSavePinned(page)) { BUG_ON(!PagePinned(page)); __xen_pgd_unpin(&init_mm, (pgd_t *)page_address(page)); ClearPageSavePinned(page); } } spin_unlock(&pgd_lock); } static void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) { spin_lock(&next->page_table_lock); xen_pgd_pin(next); spin_unlock(&next->page_table_lock); } static void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) { spin_lock(&mm->page_table_lock); xen_pgd_pin(mm); spin_unlock(&mm->page_table_lock); } static void drop_mm_ref_this_cpu(void *info) { struct mm_struct *mm = info; if (this_cpu_read(cpu_tlbstate.loaded_mm) == mm) leave_mm(smp_processor_id()); /* * If this cpu still has a stale cr3 reference, then make sure * it has been flushed. */ if (this_cpu_read(xen_current_cr3) == __pa(mm->pgd)) xen_mc_flush(); } #ifdef CONFIG_SMP /* * Another cpu may still have their %cr3 pointing at the pagetable, so * we need to repoint it somewhere else before we can unpin it. */ static void xen_drop_mm_ref(struct mm_struct *mm) { cpumask_var_t mask; unsigned cpu; drop_mm_ref_this_cpu(mm); /* Get the "official" set of cpus referring to our pagetable. */ if (!alloc_cpumask_var(&mask, GFP_ATOMIC)) { for_each_online_cpu(cpu) { if (per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd)) continue; smp_call_function_single(cpu, drop_mm_ref_this_cpu, mm, 1); } return; } /* * It's possible that a vcpu may have a stale reference to our * cr3, because its in lazy mode, and it hasn't yet flushed * its set of pending hypercalls yet. In this case, we can * look at its actual current cr3 value, and force it to flush * if needed. */ cpumask_clear(mask); for_each_online_cpu(cpu) { if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd)) cpumask_set_cpu(cpu, mask); } smp_call_function_many(mask, drop_mm_ref_this_cpu, mm, 1); free_cpumask_var(mask); } #else static void xen_drop_mm_ref(struct mm_struct *mm) { drop_mm_ref_this_cpu(mm); } #endif /* * While a process runs, Xen pins its pagetables, which means that the * hypervisor forces it to be read-only, and it controls all updates * to it. This means that all pagetable updates have to go via the * hypervisor, which is moderately expensive. * * Since we're pulling the pagetable down, we switch to use init_mm, * unpin old process pagetable and mark it all read-write, which * allows further operations on it to be simple memory accesses. * * The only subtle point is that another CPU may be still using the * pagetable because of lazy tlb flushing. This means we need need to * switch all CPUs off this pagetable before we can unpin it. */ static void xen_exit_mmap(struct mm_struct *mm) { get_cpu(); /* make sure we don't move around */ xen_drop_mm_ref(mm); put_cpu(); spin_lock(&mm->page_table_lock); /* pgd may not be pinned in the error exit path of execve */ if (xen_page_pinned(mm->pgd)) xen_pgd_unpin(mm); spin_unlock(&mm->page_table_lock); } static void xen_post_allocator_init(void); static void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn) { struct mmuext_op op; op.cmd = cmd; op.arg1.mfn = pfn_to_mfn(pfn); if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF)) BUG(); } static void __init xen_cleanhighmap(unsigned long vaddr, unsigned long vaddr_end) { unsigned long kernel_end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1; pmd_t *pmd = level2_kernel_pgt + pmd_index(vaddr); /* NOTE: The loop is more greedy than the cleanup_highmap variant. * We include the PMD passed in on _both_ boundaries. */ for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PTRS_PER_PMD)); pmd++, vaddr += PMD_SIZE) { if (pmd_none(*pmd)) continue; if (vaddr < (unsigned long) _text || vaddr > kernel_end) set_pmd(pmd, __pmd(0)); } /* In case we did something silly, we should crash in this function * instead of somewhere later and be confusing. */ xen_mc_flush(); } /* * Make a page range writeable and free it. */ static void __init xen_free_ro_pages(unsigned long paddr, unsigned long size) { void *vaddr = __va(paddr); void *vaddr_end = vaddr + size; for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) make_lowmem_page_readwrite(vaddr); memblock_phys_free(paddr, size); } static void __init xen_cleanmfnmap_free_pgtbl(void *pgtbl, bool unpin) { unsigned long pa = __pa(pgtbl) & PHYSICAL_PAGE_MASK; if (unpin) pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(pa)); ClearPagePinned(virt_to_page(__va(pa))); xen_free_ro_pages(pa, PAGE_SIZE); } static void __init xen_cleanmfnmap_pmd(pmd_t *pmd, bool unpin) { unsigned long pa; pte_t *pte_tbl; int i; if (pmd_large(*pmd)) { pa = pmd_val(*pmd) & PHYSICAL_PAGE_MASK; xen_free_ro_pages(pa, PMD_SIZE); return; } pte_tbl = pte_offset_kernel(pmd, 0); for (i = 0; i < PTRS_PER_PTE; i++) { if (pte_none(pte_tbl[i])) continue; pa = pte_pfn(pte_tbl[i]) << PAGE_SHIFT; xen_free_ro_pages(pa, PAGE_SIZE); } set_pmd(pmd, __pmd(0)); xen_cleanmfnmap_free_pgtbl(pte_tbl, unpin); } static void __init xen_cleanmfnmap_pud(pud_t *pud, bool unpin) { unsigned long pa; pmd_t *pmd_tbl; int i; if (pud_large(*pud)) { pa = pud_val(*pud) & PHYSICAL_PAGE_MASK; xen_free_ro_pages(pa, PUD_SIZE); return; } pmd_tbl = pmd_offset(pud, 0); for (i = 0; i < PTRS_PER_PMD; i++) { if (pmd_none(pmd_tbl[i])) continue; xen_cleanmfnmap_pmd(pmd_tbl + i, unpin); } set_pud(pud, __pud(0)); xen_cleanmfnmap_free_pgtbl(pmd_tbl, unpin); } static void __init xen_cleanmfnmap_p4d(p4d_t *p4d, bool unpin) { unsigned long pa; pud_t *pud_tbl; int i; if (p4d_large(*p4d)) { pa = p4d_val(*p4d) & PHYSICAL_PAGE_MASK; xen_free_ro_pages(pa, P4D_SIZE); return; } pud_tbl = pud_offset(p4d, 0); for (i = 0; i < PTRS_PER_PUD; i++) { if (pud_none(pud_tbl[i])) continue; xen_cleanmfnmap_pud(pud_tbl + i, unpin); } set_p4d(p4d, __p4d(0)); xen_cleanmfnmap_free_pgtbl(pud_tbl, unpin); } /* * Since it is well isolated we can (and since it is perhaps large we should) * also free the page tables mapping the initial P->M table. */ static void __init xen_cleanmfnmap(unsigned long vaddr) { pgd_t *pgd; p4d_t *p4d; bool unpin; unpin = (vaddr == 2 * PGDIR_SIZE); vaddr &= PMD_MASK; pgd = pgd_offset_k(vaddr); p4d = p4d_offset(pgd, 0); if (!p4d_none(*p4d)) xen_cleanmfnmap_p4d(p4d, unpin); } static void __init xen_pagetable_p2m_free(void) { unsigned long size; unsigned long addr; size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long)); /* No memory or already called. */ if ((unsigned long)xen_p2m_addr == xen_start_info->mfn_list) return; /* using __ka address and sticking INVALID_P2M_ENTRY! */ memset((void *)xen_start_info->mfn_list, 0xff, size); addr = xen_start_info->mfn_list; /* * We could be in __ka space. * We roundup to the PMD, which means that if anybody at this stage is * using the __ka address of xen_start_info or * xen_start_info->shared_info they are in going to crash. Fortunately * we have already revectored in xen_setup_kernel_pagetable. */ size = roundup(size, PMD_SIZE); if (addr >= __START_KERNEL_map) { xen_cleanhighmap(addr, addr + size); size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long)); memblock_phys_free(__pa(addr), size); } else { xen_cleanmfnmap(addr); } } static void __init xen_pagetable_cleanhighmap(void) { unsigned long size; unsigned long addr; /* At this stage, cleanup_highmap has already cleaned __ka space * from _brk_limit way up to the max_pfn_mapped (which is the end of * the ramdisk). We continue on, erasing PMD entries that point to page * tables - do note that they are accessible at this stage via __va. * As Xen is aligning the memory end to a 4MB boundary, for good * measure we also round up to PMD_SIZE * 2 - which means that if * anybody is using __ka address to the initial boot-stack - and try * to use it - they are going to crash. The xen_start_info has been * taken care of already in xen_setup_kernel_pagetable. */ addr = xen_start_info->pt_base; size = xen_start_info->nr_pt_frames * PAGE_SIZE; xen_cleanhighmap(addr, roundup(addr + size, PMD_SIZE * 2)); xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base)); } static void __init xen_pagetable_p2m_setup(void) { xen_vmalloc_p2m_tree(); xen_pagetable_p2m_free(); xen_pagetable_cleanhighmap(); /* And revector! Bye bye old array */ xen_start_info->mfn_list = (unsigned long)xen_p2m_addr; } static void __init xen_pagetable_init(void) { paging_init(); xen_post_allocator_init(); xen_pagetable_p2m_setup(); /* Allocate and initialize top and mid mfn levels for p2m structure */ xen_build_mfn_list_list(); /* Remap memory freed due to conflicts with E820 map */ xen_remap_memory(); xen_setup_mfn_list_list(); } static void xen_write_cr2(unsigned long cr2) { this_cpu_read(xen_vcpu)->arch.cr2 = cr2; } static noinline void xen_flush_tlb(void) { struct mmuext_op *op; struct multicall_space mcs; preempt_disable(); mcs = xen_mc_entry(sizeof(*op)); op = mcs.args; op->cmd = MMUEXT_TLB_FLUSH_LOCAL; MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } static void xen_flush_tlb_one_user(unsigned long addr) { struct mmuext_op *op; struct multicall_space mcs; trace_xen_mmu_flush_tlb_one_user(addr); preempt_disable(); mcs = xen_mc_entry(sizeof(*op)); op = mcs.args; op->cmd = MMUEXT_INVLPG_LOCAL; op->arg1.linear_addr = addr & PAGE_MASK; MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } static void xen_flush_tlb_multi(const struct cpumask *cpus, const struct flush_tlb_info *info) { struct { struct mmuext_op op; DECLARE_BITMAP(mask, NR_CPUS); } *args; struct multicall_space mcs; const size_t mc_entry_size = sizeof(args->op) + sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus()); trace_xen_mmu_flush_tlb_multi(cpus, info->mm, info->start, info->end); if (cpumask_empty(cpus)) return; /* nothing to do */ mcs = xen_mc_entry(mc_entry_size); args = mcs.args; args->op.arg2.vcpumask = to_cpumask(args->mask); /* Remove any offline CPUs */ cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask); args->op.cmd = MMUEXT_TLB_FLUSH_MULTI; if (info->end != TLB_FLUSH_ALL && (info->end - info->start) <= PAGE_SIZE) { args->op.cmd = MMUEXT_INVLPG_MULTI; args->op.arg1.linear_addr = info->start; } MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_MMU); } static unsigned long xen_read_cr3(void) { return this_cpu_read(xen_cr3); } static void set_current_cr3(void *v) { this_cpu_write(xen_current_cr3, (unsigned long)v); } static void __xen_write_cr3(bool kernel, unsigned long cr3) { struct mmuext_op op; unsigned long mfn; trace_xen_mmu_write_cr3(kernel, cr3); if (cr3) mfn = pfn_to_mfn(PFN_DOWN(cr3)); else mfn = 0; WARN_ON(mfn == 0 && kernel); op.cmd = kernel ? MMUEXT_NEW_BASEPTR : MMUEXT_NEW_USER_BASEPTR; op.arg1.mfn = mfn; xen_extend_mmuext_op(&op); if (kernel) { this_cpu_write(xen_cr3, cr3); /* Update xen_current_cr3 once the batch has actually been submitted. */ xen_mc_callback(set_current_cr3, (void *)cr3); } } static void xen_write_cr3(unsigned long cr3) { pgd_t *user_pgd = xen_get_user_pgd(__va(cr3)); BUG_ON(preemptible()); xen_mc_batch(); /* disables interrupts */ /* Update while interrupts are disabled, so its atomic with respect to ipis */ this_cpu_write(xen_cr3, cr3); __xen_write_cr3(true, cr3); if (user_pgd) __xen_write_cr3(false, __pa(user_pgd)); else __xen_write_cr3(false, 0); xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ } /* * At the start of the day - when Xen launches a guest, it has already * built pagetables for the guest. We diligently look over them * in xen_setup_kernel_pagetable and graft as appropriate them in the * init_top_pgt and its friends. Then when we are happy we load * the new init_top_pgt - and continue on. * * The generic code starts (start_kernel) and 'init_mem_mapping' sets * up the rest of the pagetables. When it has completed it loads the cr3. * N.B. that baremetal would start at 'start_kernel' (and the early * #PF handler would create bootstrap pagetables) - so we are running * with the same assumptions as what to do when write_cr3 is executed * at this point. * * Since there are no user-page tables at all, we have two variants * of xen_write_cr3 - the early bootup (this one), and the late one * (xen_write_cr3). The reason we have to do that is that in 64-bit * the Linux kernel and user-space are both in ring 3 while the * hypervisor is in ring 0. */ static void __init xen_write_cr3_init(unsigned long cr3) { BUG_ON(preemptible()); xen_mc_batch(); /* disables interrupts */ /* Update while interrupts are disabled, so its atomic with respect to ipis */ this_cpu_write(xen_cr3, cr3); __xen_write_cr3(true, cr3); xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ } static int xen_pgd_alloc(struct mm_struct *mm) { pgd_t *pgd = mm->pgd; struct page *page = virt_to_page(pgd); pgd_t *user_pgd; int ret = -ENOMEM; BUG_ON(PagePinned(virt_to_page(pgd))); BUG_ON(page->private != 0); user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); page->private = (unsigned long)user_pgd; if (user_pgd != NULL) { #ifdef CONFIG_X86_VSYSCALL_EMULATION user_pgd[pgd_index(VSYSCALL_ADDR)] = __pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE); #endif ret = 0; } BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd)))); return ret; } static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd) { pgd_t *user_pgd = xen_get_user_pgd(pgd); if (user_pgd) free_page((unsigned long)user_pgd); } /* * Init-time set_pte while constructing initial pagetables, which * doesn't allow RO page table pages to be remapped RW. * * If there is no MFN for this PFN then this page is initially * ballooned out so clear the PTE (as in decrease_reservation() in * drivers/xen/balloon.c). * * Many of these PTE updates are done on unpinned and writable pages * and doing a hypercall for these is unnecessary and expensive. At * this point it is not possible to tell if a page is pinned or not, * so always write the PTE directly and rely on Xen trapping and * emulating any updates as necessary. */ __visible pte_t xen_make_pte_init(pteval_t pte) { unsigned long pfn; /* * Pages belonging to the initial p2m list mapped outside the default * address range must be mapped read-only. This region contains the * page tables for mapping the p2m list, too, and page tables MUST be * mapped read-only. */ pfn = (pte & PTE_PFN_MASK) >> PAGE_SHIFT; if (xen_start_info->mfn_list < __START_KERNEL_map && pfn >= xen_start_info->first_p2m_pfn && pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames) pte &= ~_PAGE_RW; pte = pte_pfn_to_mfn(pte); return native_make_pte(pte); } PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init); static void __init xen_set_pte_init(pte_t *ptep, pte_t pte) { __xen_set_pte(ptep, pte); } /* Early in boot, while setting up the initial pagetable, assume everything is pinned. */ static void __init xen_alloc_pte_init(struct mm_struct *mm, unsigned long pfn) { #ifdef CONFIG_FLATMEM BUG_ON(mem_map); /* should only be used early */ #endif make_lowmem_page_readonly(__va(PFN_PHYS(pfn))); pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn); } /* Used for pmd and pud */ static void __init xen_alloc_pmd_init(struct mm_struct *mm, unsigned long pfn) { #ifdef CONFIG_FLATMEM BUG_ON(mem_map); /* should only be used early */ #endif make_lowmem_page_readonly(__va(PFN_PHYS(pfn))); } /* Early release_pte assumes that all pts are pinned, since there's only init_mm and anything attached to that is pinned. */ static void __init xen_release_pte_init(unsigned long pfn) { pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); } static void __init xen_release_pmd_init(unsigned long pfn) { make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); } static inline void __pin_pagetable_pfn(unsigned cmd, unsigned long pfn) { struct multicall_space mcs; struct mmuext_op *op; mcs = __xen_mc_entry(sizeof(*op)); op = mcs.args; op->cmd = cmd; op->arg1.mfn = pfn_to_mfn(pfn); MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF); } static inline void __set_pfn_prot(unsigned long pfn, pgprot_t prot) { struct multicall_space mcs; unsigned long addr = (unsigned long)__va(pfn << PAGE_SHIFT); mcs = __xen_mc_entry(0); MULTI_update_va_mapping(mcs.mc, (unsigned long)addr, pfn_pte(pfn, prot), 0); } /* This needs to make sure the new pte page is pinned iff its being attached to a pinned pagetable. */ static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn, unsigned level) { bool pinned = xen_page_pinned(mm->pgd); trace_xen_mmu_alloc_ptpage(mm, pfn, level, pinned); if (pinned) { struct page *page = pfn_to_page(pfn); pinned = false; if (static_branch_likely(&xen_struct_pages_ready)) { pinned = PagePinned(page); SetPagePinned(page); } xen_mc_batch(); __set_pfn_prot(pfn, PAGE_KERNEL_RO); if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS && !pinned) __pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn); xen_mc_issue(PARAVIRT_LAZY_MMU); } } static void xen_alloc_pte(struct mm_struct *mm, unsigned long pfn) { xen_alloc_ptpage(mm, pfn, PT_PTE); } static void xen_alloc_pmd(struct mm_struct *mm, unsigned long pfn) { xen_alloc_ptpage(mm, pfn, PT_PMD); } /* This should never happen until we're OK to use struct page */ static inline void xen_release_ptpage(unsigned long pfn, unsigned level) { struct page *page = pfn_to_page(pfn); bool pinned = PagePinned(page); trace_xen_mmu_release_ptpage(pfn, level, pinned); if (pinned) { xen_mc_batch(); if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS) __pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); __set_pfn_prot(pfn, PAGE_KERNEL); xen_mc_issue(PARAVIRT_LAZY_MMU); ClearPagePinned(page); } } static void xen_release_pte(unsigned long pfn) { xen_release_ptpage(pfn, PT_PTE); } static void xen_release_pmd(unsigned long pfn) { xen_release_ptpage(pfn, PT_PMD); } static void xen_alloc_pud(struct mm_struct *mm, unsigned long pfn) { xen_alloc_ptpage(mm, pfn, PT_PUD); } static void xen_release_pud(unsigned long pfn) { xen_release_ptpage(pfn, PT_PUD); } /* * Like __va(), but returns address in the kernel mapping (which is * all we have until the physical memory mapping has been set up. */ static void * __init __ka(phys_addr_t paddr) { return (void *)(paddr + __START_KERNEL_map); } /* Convert a machine address to physical address */ static unsigned long __init m2p(phys_addr_t maddr) { phys_addr_t paddr; maddr &= XEN_PTE_MFN_MASK; paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT; return paddr; } /* Convert a machine address to kernel virtual */ static void * __init m2v(phys_addr_t maddr) { return __ka(m2p(maddr)); } /* Set the page permissions on an identity-mapped pages */ static void __init set_page_prot_flags(void *addr, pgprot_t prot, unsigned long flags) { unsigned long pfn = __pa(addr) >> PAGE_SHIFT; pte_t pte = pfn_pte(pfn, prot); if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, flags)) BUG(); } static void __init set_page_prot(void *addr, pgprot_t prot) { return set_page_prot_flags(addr, prot, UVMF_NONE); } void __init xen_setup_machphys_mapping(void) { struct xen_machphys_mapping mapping; if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) { machine_to_phys_mapping = (unsigned long *)mapping.v_start; machine_to_phys_nr = mapping.max_mfn + 1; } else { machine_to_phys_nr = MACH2PHYS_NR_ENTRIES; } } static void __init convert_pfn_mfn(void *v) { pte_t *pte = v; int i; /* All levels are converted the same way, so just treat them as ptes. */ for (i = 0; i < PTRS_PER_PTE; i++) pte[i] = xen_make_pte(pte[i].pte); } static void __init check_pt_base(unsigned long *pt_base, unsigned long *pt_end, unsigned long addr) { if (*pt_base == PFN_DOWN(__pa(addr))) { set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG); clear_page((void *)addr); (*pt_base)++; } if (*pt_end == PFN_DOWN(__pa(addr))) { set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG); clear_page((void *)addr); (*pt_end)--; } } /* * Set up the initial kernel pagetable. * * We can construct this by grafting the Xen provided pagetable into * head_64.S's preconstructed pagetables. We copy the Xen L2's into * level2_ident_pgt, and level2_kernel_pgt. This means that only the * kernel has a physical mapping to start with - but that's enough to * get __va working. We need to fill in the rest of the physical * mapping once some sort of allocator has been set up. */ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) { pud_t *l3; pmd_t *l2; unsigned long addr[3]; unsigned long pt_base, pt_end; unsigned i; /* max_pfn_mapped is the last pfn mapped in the initial memory * mappings. Considering that on Xen after the kernel mappings we * have the mappings of some pages that don't exist in pfn space, we * set max_pfn_mapped to the last real pfn mapped. */ if (xen_start_info->mfn_list < __START_KERNEL_map) max_pfn_mapped = xen_start_info->first_p2m_pfn; else max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list)); pt_base = PFN_DOWN(__pa(xen_start_info->pt_base)); pt_end = pt_base + xen_start_info->nr_pt_frames; /* Zap identity mapping */ init_top_pgt[0] = __pgd(0); /* Pre-constructed entries are in pfn, so convert to mfn */ /* L4[273] -> level3_ident_pgt */ /* L4[511] -> level3_kernel_pgt */ convert_pfn_mfn(init_top_pgt); /* L3_i[0] -> level2_ident_pgt */ convert_pfn_mfn(level3_ident_pgt); /* L3_k[510] -> level2_kernel_pgt */ /* L3_k[511] -> level2_fixmap_pgt */ convert_pfn_mfn(level3_kernel_pgt); /* L3_k[511][508-FIXMAP_PMD_NUM ... 507] -> level1_fixmap_pgt */ convert_pfn_mfn(level2_fixmap_pgt); /* We get [511][511] and have Xen's version of level2_kernel_pgt */ l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd); l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud); addr[0] = (unsigned long)pgd; addr[1] = (unsigned long)l3; addr[2] = (unsigned long)l2; /* Graft it onto L4[273][0]. Note that we creating an aliasing problem: * Both L4[273][0] and L4[511][510] have entries that point to the same * L2 (PMD) tables. Meaning that if you modify it in __va space * it will be also modified in the __ka space! (But if you just * modify the PMD table to point to other PTE's or none, then you * are OK - which is what cleanup_highmap does) */ copy_page(level2_ident_pgt, l2); /* Graft it onto L4[511][510] */ copy_page(level2_kernel_pgt, l2); /* * Zap execute permission from the ident map. Due to the sharing of * L1 entries we need to do this in the L2. */ if (__supported_pte_mask & _PAGE_NX) { for (i = 0; i < PTRS_PER_PMD; ++i) { if (pmd_none(level2_ident_pgt[i])) continue; level2_ident_pgt[i] = pmd_set_flags(level2_ident_pgt[i], _PAGE_NX); } } /* Copy the initial P->M table mappings if necessary. */ i = pgd_index(xen_start_info->mfn_list); if (i && i < pgd_index(__START_KERNEL_map)) init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i]; /* Make pagetable pieces RO */ set_page_prot(init_top_pgt, PAGE_KERNEL_RO); set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO); set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO); set_page_prot(level3_user_vsyscall, PAGE_KERNEL_RO); set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO); set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO); set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO); for (i = 0; i < FIXMAP_PMD_NUM; i++) { set_page_prot(level1_fixmap_pgt + i * PTRS_PER_PTE, PAGE_KERNEL_RO); } /* Pin down new L4 */ pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa_symbol(init_top_pgt))); /* Unpin Xen-provided one */ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); /* * At this stage there can be no user pgd, and no page structure to * attach it to, so make sure we just set kernel pgd. */ xen_mc_batch(); __xen_write_cr3(true, __pa(init_top_pgt)); xen_mc_issue(PARAVIRT_LAZY_CPU); /* We can't that easily rip out L3 and L2, as the Xen pagetables are * set out this way: [L4], [L1], [L2], [L3], [L1], [L1] ... for * the initial domain. For guests using the toolstack, they are in: * [L4], [L3], [L2], [L1], [L1], order .. So for dom0 we can only * rip out the [L4] (pgd), but for guests we shave off three pages. */ for (i = 0; i < ARRAY_SIZE(addr); i++) check_pt_base(&pt_base, &pt_end, addr[i]); /* Our (by three pages) smaller Xen pagetable that we are using */ xen_pt_base = PFN_PHYS(pt_base); xen_pt_size = (pt_end - pt_base) * PAGE_SIZE; memblock_reserve(xen_pt_base, xen_pt_size); /* Revector the xen_start_info */ xen_start_info = (struct start_info *)__va(__pa(xen_start_info)); } /* * Read a value from a physical address. */ static unsigned long __init xen_read_phys_ulong(phys_addr_t addr) { unsigned long *vaddr; unsigned long val; vaddr = early_memremap_ro(addr, sizeof(val)); val = *vaddr; early_memunmap(vaddr, sizeof(val)); return val; } /* * Translate a virtual address to a physical one without relying on mapped * page tables. Don't rely on big pages being aligned in (guest) physical * space! */ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr) { phys_addr_t pa; pgd_t pgd; pud_t pud; pmd_t pmd; pte_t pte; pa = read_cr3_pa(); pgd = native_make_pgd(xen_read_phys_ulong(pa + pgd_index(vaddr) * sizeof(pgd))); if (!pgd_present(pgd)) return 0; pa = pgd_val(pgd) & PTE_PFN_MASK; pud = native_make_pud(xen_read_phys_ulong(pa + pud_index(vaddr) * sizeof(pud))); if (!pud_present(pud)) return 0; pa = pud_val(pud) & PTE_PFN_MASK; if (pud_large(pud)) return pa + (vaddr & ~PUD_MASK); pmd = native_make_pmd(xen_read_phys_ulong(pa + pmd_index(vaddr) * sizeof(pmd))); if (!pmd_present(pmd)) return 0; pa = pmd_val(pmd) & PTE_PFN_MASK; if (pmd_large(pmd)) return pa + (vaddr & ~PMD_MASK); pte = native_make_pte(xen_read_phys_ulong(pa + pte_index(vaddr) * sizeof(pte))); if (!pte_present(pte)) return 0; pa = pte_pfn(pte) << PAGE_SHIFT; return pa | (vaddr & ~PAGE_MASK); } /* * Find a new area for the hypervisor supplied p2m list and relocate the p2m to * this area. */ void __init xen_relocate_p2m(void) { phys_addr_t size, new_area, pt_phys, pmd_phys, pud_phys; unsigned long p2m_pfn, p2m_pfn_end, n_frames, pfn, pfn_end; int n_pte, n_pt, n_pmd, n_pud, idx_pte, idx_pt, idx_pmd, idx_pud; pte_t *pt; pmd_t *pmd; pud_t *pud; pgd_t *pgd; unsigned long *new_p2m; size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long)); n_pte = roundup(size, PAGE_SIZE) >> PAGE_SHIFT; n_pt = roundup(size, PMD_SIZE) >> PMD_SHIFT; n_pmd = roundup(size, PUD_SIZE) >> PUD_SHIFT; n_pud = roundup(size, P4D_SIZE) >> P4D_SHIFT; n_frames = n_pte + n_pt + n_pmd + n_pud; new_area = xen_find_free_area(PFN_PHYS(n_frames)); if (!new_area) { xen_raw_console_write("Can't find new memory area for p2m needed due to E820 map conflict\n"); BUG(); } /* * Setup the page tables for addressing the new p2m list. * We have asked the hypervisor to map the p2m list at the user address * PUD_SIZE. It may have done so, or it may have used a kernel space * address depending on the Xen version. * To avoid any possible virtual address collision, just use * 2 * PUD_SIZE for the new area. */ pud_phys = new_area; pmd_phys = pud_phys + PFN_PHYS(n_pud); pt_phys = pmd_phys + PFN_PHYS(n_pmd); p2m_pfn = PFN_DOWN(pt_phys) + n_pt; pgd = __va(read_cr3_pa()); new_p2m = (unsigned long *)(2 * PGDIR_SIZE); for (idx_pud = 0; idx_pud < n_pud; idx_pud++) { pud = early_memremap(pud_phys, PAGE_SIZE); clear_page(pud); for (idx_pmd = 0; idx_pmd < min(n_pmd, PTRS_PER_PUD); idx_pmd++) { pmd = early_memremap(pmd_phys, PAGE_SIZE); clear_page(pmd); for (idx_pt = 0; idx_pt < min(n_pt, PTRS_PER_PMD); idx_pt++) { pt = early_memremap(pt_phys, PAGE_SIZE); clear_page(pt); for (idx_pte = 0; idx_pte < min(n_pte, PTRS_PER_PTE); idx_pte++) { pt[idx_pte] = pfn_pte(p2m_pfn, PAGE_KERNEL); p2m_pfn++; } n_pte -= PTRS_PER_PTE; early_memunmap(pt, PAGE_SIZE); make_lowmem_page_readonly(__va(pt_phys)); pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, PFN_DOWN(pt_phys)); pmd[idx_pt] = __pmd(_PAGE_TABLE | pt_phys); pt_phys += PAGE_SIZE; } n_pt -= PTRS_PER_PMD; early_memunmap(pmd, PAGE_SIZE); make_lowmem_page_readonly(__va(pmd_phys)); pin_pagetable_pfn(MMUEXT_PIN_L2_TABLE, PFN_DOWN(pmd_phys)); pud[idx_pmd] = __pud(_PAGE_TABLE | pmd_phys); pmd_phys += PAGE_SIZE; } n_pmd -= PTRS_PER_PUD; early_memunmap(pud, PAGE_SIZE); make_lowmem_page_readonly(__va(pud_phys)); pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(pud_phys)); set_pgd(pgd + 2 + idx_pud, __pgd(_PAGE_TABLE | pud_phys)); pud_phys += PAGE_SIZE; } /* Now copy the old p2m info to the new area. */ memcpy(new_p2m, xen_p2m_addr, size); xen_p2m_addr = new_p2m; /* Release the old p2m list and set new list info. */ p2m_pfn = PFN_DOWN(xen_early_virt_to_phys(xen_start_info->mfn_list)); BUG_ON(!p2m_pfn); p2m_pfn_end = p2m_pfn + PFN_DOWN(size); if (xen_start_info->mfn_list < __START_KERNEL_map) { pfn = xen_start_info->first_p2m_pfn; pfn_end = xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames; set_pgd(pgd + 1, __pgd(0)); } else { pfn = p2m_pfn; pfn_end = p2m_pfn_end; } memblock_phys_free(PFN_PHYS(pfn), PAGE_SIZE * (pfn_end - pfn)); while (pfn < pfn_end) { if (pfn == p2m_pfn) { pfn = p2m_pfn_end; continue; } make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); pfn++; } xen_start_info->mfn_list = (unsigned long)xen_p2m_addr; xen_start_info->first_p2m_pfn = PFN_DOWN(new_area); xen_start_info->nr_p2m_frames = n_frames; } void __init xen_reserve_special_pages(void) { phys_addr_t paddr; memblock_reserve(__pa(xen_start_info), PAGE_SIZE); if (xen_start_info->store_mfn) { paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->store_mfn)); memblock_reserve(paddr, PAGE_SIZE); } if (!xen_initial_domain()) { paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->console.domU.mfn)); memblock_reserve(paddr, PAGE_SIZE); } } void __init xen_pt_check_e820(void) { if (xen_is_e820_reserved(xen_pt_base, xen_pt_size)) { xen_raw_console_write("Xen hypervisor allocated page table memory conflicts with E820 map\n"); BUG(); } } static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss; static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) { pte_t pte; phys >>= PAGE_SHIFT; switch (idx) { case FIX_BTMAP_END ... FIX_BTMAP_BEGIN: #ifdef CONFIG_X86_VSYSCALL_EMULATION case VSYSCALL_PAGE: #endif /* All local page mappings */ pte = pfn_pte(phys, prot); break; #ifdef CONFIG_X86_LOCAL_APIC case FIX_APIC_BASE: /* maps dummy local APIC */ pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL); break; #endif #ifdef CONFIG_X86_IO_APIC case FIX_IO_APIC_BASE_0 ... FIX_IO_APIC_BASE_END: /* * We just don't map the IO APIC - all access is via * hypercalls. Keep the address in the pte for reference. */ pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL); break; #endif case FIX_PARAVIRT_BOOTMAP: /* This is an MFN, but it isn't an IO mapping from the IO domain */ pte = mfn_pte(phys, prot); break; default: /* By default, set_fixmap is used for hardware mappings */ pte = mfn_pte(phys, prot); break; } __native_set_fixmap(idx, pte); #ifdef CONFIG_X86_VSYSCALL_EMULATION /* Replicate changes to map the vsyscall page into the user pagetable vsyscall mapping. */ if (idx == VSYSCALL_PAGE) { unsigned long vaddr = __fix_to_virt(idx); set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte); } #endif } static void __init xen_post_allocator_init(void) { pv_ops.mmu.set_pte = xen_set_pte; pv_ops.mmu.set_pmd = xen_set_pmd; pv_ops.mmu.set_pud = xen_set_pud; pv_ops.mmu.set_p4d = xen_set_p4d; /* This will work as long as patching hasn't happened yet (which it hasn't) */ pv_ops.mmu.alloc_pte = xen_alloc_pte; pv_ops.mmu.alloc_pmd = xen_alloc_pmd; pv_ops.mmu.release_pte = xen_release_pte; pv_ops.mmu.release_pmd = xen_release_pmd; pv_ops.mmu.alloc_pud = xen_alloc_pud; pv_ops.mmu.release_pud = xen_release_pud; pv_ops.mmu.make_pte = PV_CALLEE_SAVE(xen_make_pte); pv_ops.mmu.write_cr3 = &xen_write_cr3; } static void xen_leave_lazy_mmu(void) { preempt_disable(); xen_mc_flush(); paravirt_leave_lazy_mmu(); preempt_enable(); } static const struct pv_mmu_ops xen_mmu_ops __initconst = { .read_cr2 = __PV_IS_CALLEE_SAVE(xen_read_cr2), .write_cr2 = xen_write_cr2, .read_cr3 = xen_read_cr3, .write_cr3 = xen_write_cr3_init, .flush_tlb_user = xen_flush_tlb, .flush_tlb_kernel = xen_flush_tlb, .flush_tlb_one_user = xen_flush_tlb_one_user, .flush_tlb_multi = xen_flush_tlb_multi, .tlb_remove_table = tlb_remove_table, .pgd_alloc = xen_pgd_alloc, .pgd_free = xen_pgd_free, .alloc_pte = xen_alloc_pte_init, .release_pte = xen_release_pte_init, .alloc_pmd = xen_alloc_pmd_init, .release_pmd = xen_release_pmd_init, .set_pte = xen_set_pte_init, .set_pmd = xen_set_pmd_hyper, .ptep_modify_prot_start = xen_ptep_modify_prot_start, .ptep_modify_prot_commit = xen_ptep_modify_prot_commit, .pte_val = PV_CALLEE_SAVE(xen_pte_val), .pgd_val = PV_CALLEE_SAVE(xen_pgd_val), .make_pte = PV_CALLEE_SAVE(xen_make_pte_init), .make_pgd = PV_CALLEE_SAVE(xen_make_pgd), .set_pud = xen_set_pud_hyper, .make_pmd = PV_CALLEE_SAVE(xen_make_pmd), .pmd_val = PV_CALLEE_SAVE(xen_pmd_val), .pud_val = PV_CALLEE_SAVE(xen_pud_val), .make_pud = PV_CALLEE_SAVE(xen_make_pud), .set_p4d = xen_set_p4d_hyper, .alloc_pud = xen_alloc_pmd_init, .release_pud = xen_release_pmd_init, #if CONFIG_PGTABLE_LEVELS >= 5 .p4d_val = PV_CALLEE_SAVE(xen_p4d_val), .make_p4d = PV_CALLEE_SAVE(xen_make_p4d), #endif .activate_mm = xen_activate_mm, .dup_mmap = xen_dup_mmap, .exit_mmap = xen_exit_mmap, .lazy_mode = { .enter = paravirt_enter_lazy_mmu, .leave = xen_leave_lazy_mmu, .flush = paravirt_flush_lazy_mmu, }, .set_fixmap = xen_set_fixmap, }; void __init xen_init_mmu_ops(void) { x86_init.paging.pagetable_init = xen_pagetable_init; x86_init.hyper.init_after_bootmem = xen_after_bootmem; pv_ops.mmu = xen_mmu_ops; memset(dummy_mapping, 0xff, PAGE_SIZE); } /* Protected by xen_reservation_lock. */ #define MAX_CONTIG_ORDER 9 /* 2MB */ static unsigned long discontig_frames[1< MAX_CONTIG_ORDER)) return -ENOMEM; memset((void *) vstart, 0, PAGE_SIZE << order); spin_lock_irqsave(&xen_reservation_lock, flags); /* 1. Zap current PTEs, remembering MFNs. */ xen_zap_pfn_range(vstart, order, in_frames, NULL); /* 2. Get a new contiguous memory extent. */ out_frame = virt_to_pfn(vstart); success = xen_exchange_memory(1UL << order, 0, in_frames, 1, order, &out_frame, address_bits); /* 3. Map the new extent in place of old pages. */ if (success) xen_remap_exchanged_ptes(vstart, order, NULL, out_frame); else xen_remap_exchanged_ptes(vstart, order, in_frames, 0); spin_unlock_irqrestore(&xen_reservation_lock, flags); *dma_handle = virt_to_machine(vstart).maddr; return success ? 0 : -ENOMEM; } void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) { unsigned long *out_frames = discontig_frames, in_frame; unsigned long flags; int success; unsigned long vstart; if (unlikely(order > MAX_CONTIG_ORDER)) return; vstart = (unsigned long)phys_to_virt(pstart); memset((void *) vstart, 0, PAGE_SIZE << order); spin_lock_irqsave(&xen_reservation_lock, flags); /* 1. Find start MFN of contiguous extent. */ in_frame = virt_to_mfn(vstart); /* 2. Zap current PTEs. */ xen_zap_pfn_range(vstart, order, NULL, out_frames); /* 3. Do the exchange for non-contiguous MFNs. */ success = xen_exchange_memory(1, order, &in_frame, 1UL << order, 0, out_frames, 0); /* 4. Map new pages in place of old pages. */ if (success) xen_remap_exchanged_ptes(vstart, order, out_frames, 0); else xen_remap_exchanged_ptes(vstart, order, NULL, in_frame); spin_unlock_irqrestore(&xen_reservation_lock, flags); } static noinline void xen_flush_tlb_all(void) { struct mmuext_op *op; struct multicall_space mcs; preempt_disable(); mcs = xen_mc_entry(sizeof(*op)); op = mcs.args; op->cmd = MMUEXT_TLB_FLUSH_ALL; MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_MMU); preempt_enable(); } #define REMAP_BATCH_SIZE 16 struct remap_data { xen_pfn_t *pfn; bool contiguous; bool no_translate; pgprot_t prot; struct mmu_update *mmu_update; }; static int remap_area_pfn_pte_fn(pte_t *ptep, unsigned long addr, void *data) { struct remap_data *rmd = data; pte_t pte = pte_mkspecial(mfn_pte(*rmd->pfn, rmd->prot)); /* * If we have a contiguous range, just update the pfn itself, * else update pointer to be "next pfn". */ if (rmd->contiguous) (*rmd->pfn)++; else rmd->pfn++; rmd->mmu_update->ptr = virt_to_machine(ptep).maddr; rmd->mmu_update->ptr |= rmd->no_translate ? MMU_PT_UPDATE_NO_TRANSLATE : MMU_NORMAL_PT_UPDATE; rmd->mmu_update->val = pte_val_ma(pte); rmd->mmu_update++; return 0; } int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr, xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot, unsigned int domid, bool no_translate) { int err = 0; struct remap_data rmd; struct mmu_update mmu_update[REMAP_BATCH_SIZE]; unsigned long range; int mapped = 0; BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO))); rmd.pfn = pfn; rmd.prot = prot; /* * We use the err_ptr to indicate if there we are doing a contiguous * mapping or a discontiguous mapping. */ rmd.contiguous = !err_ptr; rmd.no_translate = no_translate; while (nr) { int index = 0; int done = 0; int batch = min(REMAP_BATCH_SIZE, nr); int batch_left = batch; range = (unsigned long)batch << PAGE_SHIFT; rmd.mmu_update = mmu_update; err = apply_to_page_range(vma->vm_mm, addr, range, remap_area_pfn_pte_fn, &rmd); if (err) goto out; /* * We record the error for each page that gives an error, but * continue mapping until the whole set is done */ do { int i; err = HYPERVISOR_mmu_update(&mmu_update[index], batch_left, &done, domid); /* * @err_ptr may be the same buffer as @gfn, so * only clear it after each chunk of @gfn is * used. */ if (err_ptr) { for (i = index; i < index + done; i++) err_ptr[i] = 0; } if (err < 0) { if (!err_ptr) goto out; err_ptr[i] = err; done++; /* Skip failed frame. */ } else mapped += done; batch_left -= done; index += done; } while (batch_left); nr -= batch; addr += range; if (err_ptr) err_ptr += batch; cond_resched(); } out: xen_flush_tlb_all(); return err < 0 ? err : mapped; } EXPORT_SYMBOL_GPL(xen_remap_pfn); #ifdef CONFIG_KEXEC_CORE phys_addr_t paddr_vmcoreinfo_note(void) { if (xen_pv_domain()) return virt_to_machine(vmcoreinfo_note).maddr; else return __pa(vmcoreinfo_note); } #endif /* CONFIG_KEXEC_CORE */