// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2020 - os kernal * Author: lff * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License, version 2, as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define KVM_APT_FLAG_LOGGING_ACTIVE (1UL << 1) static bool memslot_is_logging(struct kvm_memory_slot *memslot) { return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY); } /* * Return values of kvm_handle_mmio_page_fault and mmu.page_fault: * RET_AF_RETRY: let CPU fault again on the address. * RET_AF_EMULATE: mmio page fault, emulate the instruction directly. * * For kvm_handle_mmio_page_fault only: * RET_AF_INVALID: the spte is invalid, let the real page fault path update it. */ enum { RET_AF_RETRY = 0, RET_AF_EMULATE = 1, RET_AF_INVALID = 2, }; /** * apt_dissolve_pmd() - clear and flush huge PMD entry * @kvm: pointer to kvm structure. * @addr: IPA * @pmd: pmd pointer for IPA * * Function clears a PMD entry, flushes TLBs. */ static void apt_dissolve_pmd(struct kvm *kvm, phys_addr_t addr, pmd_t *pmd) { int i; if (!pmd_trans_huge(*pmd)) return; if (pmd_trans_cont(*pmd)) { for (i = 0; i < CONT_PMDS; i++, pmd++) pmd_clear(pmd); } else pmd_clear(pmd); kvm_flush_remote_tlbs(kvm); put_page(virt_to_page(pmd)); } /** * apt_dissolve_pud() - clear and flush huge PUD entry * @kvm: pointer to kvm structure. * @addr: IPA * @pud: pud pointer for IPA * * Function clears a PUD entry, flushes TLBs. */ static void apt_dissolve_pud(struct kvm *kvm, phys_addr_t addr, pud_t *pudp) { if (!pud_huge(*pudp)) return; pud_clear(pudp); kvm_flush_remote_tlbs(kvm); put_page(virt_to_page(pudp)); } static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min, int max) { void *page; BUG_ON(max > KVM_NR_MEM_OBJS); if (cache->nobjs >= min) return 0; while (cache->nobjs < max) { page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); if (!page) return -ENOMEM; cache->objects[cache->nobjs++] = page; } return 0; } static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc) { while (mc->nobjs) free_page((unsigned long)mc->objects[--mc->nobjs]); } void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu) { mmu_free_memory_cache(&vcpu->arch.mmu_page_cache); } static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc) { void *p; BUG_ON(!mc || !mc->nobjs); p = mc->objects[--mc->nobjs]; return p; } static void unmap_apt_ptes(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr, phys_addr_t end) { pte_t *pte, *start_pte; struct page *ptr_page; start_pte = pte = pte_offset_kernel(pmd, addr); do { if (!pte_none(*pte)) { /* Do we need WRITE_ONCE(pte, 0)? */ set_pte(pte, __pte(0)); put_page(virt_to_page(pte)); } } while (pte++, addr += PAGE_SIZE, addr != end); ptr_page = virt_to_page(start_pte); if (page_count(ptr_page) == 1) { pte_t *pte_table = pte_offset_kernel(pmd, 0); pmd_clear(pmd); free_page((unsigned long)pte_table); put_page(virt_to_page(pmd)); } } static void unmap_apt_pmds(struct kvm *kvm, pud_t *pud, phys_addr_t addr, phys_addr_t end) { phys_addr_t next; pmd_t *pmd, *start_pmd; struct page *ptr_page; int i; start_pmd = pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (!pmd_none(*pmd)) { if (pmd_trans_huge(*pmd)) { if (pmd_trans_cont(*pmd)) { for (i = 0; i < CONT_PMDS; i++, pmd++) pmd_clear(pmd); } else pmd_clear(pmd); /* Do we need flush tlb???? edited by lff */ kvm_flush_remote_tlbs(kvm); put_page(virt_to_page(pmd)); } else { unmap_apt_ptes(kvm, pmd, addr, next); } } } while (pmd++, addr = next, addr != end); ptr_page = virt_to_page(start_pmd); if (page_count(ptr_page) == 1) { pmd_t *pmd_table __maybe_unused = pmd_offset(pud, 0UL); pud_clear(pud); free_page((unsigned long)pmd_table); put_page(virt_to_page(pud)); } } static void unmap_apt_puds(struct kvm *kvm, p4d_t *p4d, phys_addr_t addr, phys_addr_t end) { phys_addr_t next; pud_t *pud, *start_pud; struct page *ptr_page; start_pud = pud = pud_offset(p4d, addr); do { next = pud_addr_end(addr, end); if (!pud_none(*pud)) { if (pud_huge(*pud)) { pud_clear(pud); /* Do we need flush tlb???? edited by lff */ kvm_flush_remote_tlbs(kvm); put_page(virt_to_page(pud)); } else { unmap_apt_pmds(kvm, pud, addr, next); } } } while (pud++, addr = next, addr != end); ptr_page = virt_to_page(start_pud); if (page_count(ptr_page) == 1) { pud_t *pud_table __maybe_unused = pud_offset(p4d, 0UL); p4d_clear(p4d); kvm_flush_remote_tlbs(kvm); free_page((unsigned long)pud_table); put_page(virt_to_page(p4d)); } } /** * unmap_apt_range -- Clear addtional page table entries to unmap a range * @kvm: The VM pointer * @start: The intermediate physical base address of the range to unmap * @size: The size of the area to unmap * * Clear a range of apt mappings, lowering the various ref-counts. Must * be called while holding mmu_lock (unless for freeing the apt pgd before * destroying the VM), otherwise another faulting VCPU may come in and mess * with things behind our backs. */ static void unmap_apt_range(struct kvm *kvm, phys_addr_t start, u64 size) { pgd_t *pgd; p4d_t *p4d; phys_addr_t addr = start, end = start + size; phys_addr_t next; assert_spin_locked(&kvm->mmu_lock); WARN_ON(size & ~PAGE_MASK); pgd = kvm->arch.pgd + pgd_index(addr); p4d = p4d_offset(pgd, addr); do { /* * Make sure the page table is still active, as another thread * could have possibly freed the page table, while we released * the lock. */ if (!READ_ONCE(kvm->arch.pgd)) break; next = p4d_addr_end(addr, end); if (!p4d_none(*p4d)) unmap_apt_puds(kvm, p4d, addr, next); /* * If the range is too large, release the kvm->mmu_lock * to prevent starvation and lockup detector warnings. */ if (next != end) cond_resched_lock(&kvm->mmu_lock); } while (pgd++, addr = next, addr != end); } static void apt_unmap_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot) { hva_t hva = memslot->userspace_addr; phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT; phys_addr_t size = PAGE_SIZE * memslot->npages; hva_t reg_end = hva + size; /* * A memory region could potentially cover multiple VMAs, and any holes * between them, so iterate over all of them to find out if we should * unmap any of them. * * +--------------------------------------------+ * +---------------+----------------+ +----------------+ * | : VMA 1 | VMA 2 | | VMA 3 : | * +---------------+----------------+ +----------------+ * | memory region | * +--------------------------------------------+ */ do { struct vm_area_struct *vma = find_vma(current->mm, hva); hva_t vm_start, vm_end; if (!vma || vma->vm_start >= reg_end) break; /* * Take the intersection of this VMA with the memory region */ vm_start = max(hva, vma->vm_start); vm_end = min(reg_end, vma->vm_end); if (!(vma->vm_flags & VM_PFNMAP)) { gpa_t gpa = addr + (vm_start - memslot->userspace_addr); unmap_apt_range(kvm, gpa, vm_end - vm_start); } hva = vm_end; } while (hva < reg_end); } /** * apt_unmap_vm - Unmap Additional Stage RAM mappings * @kvm: The struct kvm pointer * * Go through the memregions and unmap any reguler RAM * backing memory already mapped to the VM. */ void apt_unmap_vm(struct kvm *kvm) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; int idx; idx = srcu_read_lock(&kvm->srcu); down_read(¤t->mm->mmap_lock); spin_lock(&kvm->mmu_lock); slots = kvm_memslots(kvm); kvm_for_each_memslot(memslot, slots) apt_unmap_memslot(kvm, memslot); spin_unlock(&kvm->mmu_lock); up_read(¤t->mm->mmap_lock); srcu_read_unlock(&kvm->srcu, idx); } static pud_t *apt_get_pud(pgd_t *pgd, struct kvm_mmu_memory_cache *cache, phys_addr_t addr) { p4d_t *p4d; pud_t *pud; pgd += pgd_index(addr); if (pgd_none(*pgd)) { /* Not used on SW64 yet */ VM_BUG_ON(pgd); return NULL; } p4d = p4d_offset(pgd, addr); if (p4d_none(*p4d)) { if (!cache) return NULL; pud = mmu_memory_cache_alloc(cache); p4d_populate(NULL, p4d, pud); get_page(virt_to_page(p4d)); } return pud_offset(p4d, addr); } static pmd_t *apt_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, phys_addr_t addr, unsigned long sz) { pud_t *pud; pmd_t *pmd; pud = apt_get_pud(kvm->arch.pgd, cache, addr); if (!pud || pud_huge(*pud)) return NULL; if (pud_none(*pud)) { if (!cache) return NULL; pmd = mmu_memory_cache_alloc(cache); pud_populate(NULL, pud, pmd); get_page(virt_to_page(pud)); } if (sz == CONT_PMD_SIZE) addr &= CONT_PMD_MASK; return pmd_offset(pud, addr); } static bool kvm_is_write_fault(unsigned long access_type) { if (access_type == AF_WRITE_ACCESS_TYPE) return true; return false; } static bool kvm_is_exec_fault(unsigned long access_type) { if (access_type == AF_EXEC_ACCESS_TYPE) return true; return false; } /** * apt_wp_ptes - write protect PMD range * @pmd: pointer to pmd entry * @addr: range start address * @end: range end address */ static void apt_wp_ptes(pmd_t *pmd, phys_addr_t addr, phys_addr_t end) { pte_t *pte; pte = pte_offset_kernel(pmd, addr); do { if (!pte_none(*pte)) { if (!kvm_aptpte_readonly(pte)) kvm_set_aptpte_readonly(pte); } } while (pte++, addr += PAGE_SIZE, addr != end); } /** * apt_wp_pmds - write protect PUD range * @pud: pointer to pud entry * @addr: range start address * @end: range end address */ static void apt_wp_pmds(pud_t *pud, phys_addr_t addr, phys_addr_t end) { pmd_t *pmd; phys_addr_t next; pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (!pmd_none(*pmd)) { if (pmd_trans_huge(*pmd)) { if (!kvm_aptpmd_readonly(pmd)) kvm_set_aptpmd_readonly(pmd); } else { apt_wp_ptes(pmd, addr, next); } } } while (pmd++, addr = next, addr != end); } /** * apt_wp_puds - write protect PGD range * @pgd: pointer to pgd entry * @addr: range start address * @end: range end address * * Process PUD entries, for a huge PUD we cause a panic. */ static void apt_wp_puds(p4d_t *p4d, phys_addr_t addr, phys_addr_t end) { pud_t *pud; phys_addr_t next; pud = pud_offset(p4d, addr); do { next = pud_addr_end(addr, end); if (!pud_none(*pud)) { if (pud_huge(*pud)) { if (!kvm_aptpud_readonly(pud)) kvm_set_aptpud_readonly(pud); } else { /* TODO:PUD not supported, revisit later if supported */ // BUG_ON(pud_trans_huge(*pud)); apt_wp_pmds(pud, addr, next); } } } while (pud++, addr = next, addr != end); } /** * apt_wp_range() - write protect apt memory region range * @kvm: The KVM pointer * @addr: Start address of range * @end: End address of range */ static void apt_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end) { pgd_t *pgd; p4d_t *p4d; phys_addr_t next; pgd = kvm->arch.pgd + pgd_index(addr); p4d = p4d_offset(pgd, addr); do { /* * Release kvm_mmu_lock periodically if the memory region is * large. Otherwise, we may see kernel panics with * CONFIG_DETECT_HUNG_TASK, CONFIG_LOCKUP_DETECTOR, * CONFIG_LOCKDEP. Additionally, holding the lock too long * will also starve other vCPUs. We have to also make sure * that the page tables are not freed while we released * the lock. */ cond_resched_lock(&kvm->mmu_lock); if (!READ_ONCE(kvm->arch.pgd)) break; next = p4d_addr_end(addr, end); if (p4d_present(*p4d)) apt_wp_puds(p4d, addr, next); } while (p4d++, addr = next, addr != end); } /** * kvm_mmu_wp_memory_region() - write protect apt entries for memory slot * @kvm: The KVM pointer * @slot: The memory slot to write protect * * Called to start logging dirty pages after memory region * KVM_MEM_LOG_DIRTY_PAGES operation is called. After this function returns * all present PMD and PTEs are write protected in the memory region. * Afterwards read of dirty page log can be called. * * Acquires kvm_mmu_lock. Called with kvm->slots_lock mutex acquired, * serializing operations for VM memory regions. */ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot) { struct kvm_memslots *slots = kvm_memslots(kvm); struct kvm_memory_slot *memslot = id_to_memslot(slots, slot); phys_addr_t start = memslot->base_gfn << PAGE_SHIFT; phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT; spin_lock(&kvm->mmu_lock); apt_wp_range(kvm, start, end); spin_unlock(&kvm->mmu_lock); kvm_flush_remote_tlbs(kvm); // 需要通知其他vcpu进行tlb刷新，利用request机制 } void kvm_mark_migration(struct kvm *kvm, int mark) { struct kvm_vcpu *vcpu; unsigned long cpu; kvm_for_each_vcpu(cpu, vcpu, kvm) vcpu->arch.migration_mark = mark; } void kvm_arch_commit_memory_region(struct kvm *kvm, struct kvm_memory_slot *old, const struct kvm_memory_slot *new, enum kvm_mr_change change) { /* * At this point memslot has been committed and there is an * allocated dirty_bitmap[], dirty pages will be tracked while the * memory slot is write protected. */ if (change == KVM_MR_FLAGS_ONLY && (!(old->flags & KVM_MEM_LOG_DIRTY_PAGES) && new->flags & KVM_MEM_LOG_DIRTY_PAGES)) { kvm_mark_migration(kvm, 1); kvm_mmu_wp_memory_region(kvm, new->id); } /* If dirty logging has been stopped, do nothing for now. */ if ((change != KVM_MR_DELETE) && (old->flags & KVM_MEM_LOG_DIRTY_PAGES) && (!(new->flags & KVM_MEM_LOG_DIRTY_PAGES))) { kvm_mark_migration(kvm, 0); return; } } void kvm_arch_flush_shadow_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) { gpa_t gpa = slot->base_gfn << PAGE_SHIFT; phys_addr_t size = slot->npages << PAGE_SHIFT; spin_lock(&kvm->mmu_lock); // flush_apt_tlbs(kvm); unmap_apt_range(kvm, gpa, size); spin_unlock(&kvm->mmu_lock); } /** * kvm_alloc_addtional_stage_pgd - allocate level-1 table for addtional stage translation. * @kvm: The KVM struct pointer for the VM. * * Allocates only the addtional stage HW PGD level table(s) (can support full * 48-bit input addresses). Clears the allocated pages. * * Note we don't need locking here as this is only called when the VM is * created, which can only be done once. */ int kvm_alloc_addtional_stage_pgd(struct kvm *kvm) { pgd_t *pgd; if (kvm->arch.pgd != NULL) { kvm_err("kvm_arch already initialized?\n"); return -EINVAL; } /* Allocate the HW PGD, making sure that each page gets its own refcount */ pgd = alloc_pages_exact(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO); if (!pgd) return -ENOMEM; kvm->arch.pgd = pgd; return 0; } /** * kvm_free_apt_pgd - free all apt tables * @kvm: The KVM struct pointer for the VM. * * Walks the level-1 page table pointed to by kvm->arch.pgd and frees all * underlying level-2 and level-3 tables before freeing the actual level-1 table * and setting the struct pointer to NULL. */ void kvm_free_apt_pgd(struct kvm *kvm) { void *pgd = NULL; spin_lock(&kvm->mmu_lock); if (kvm->arch.pgd) { unmap_apt_range(kvm, 0, KVM_PHYS_SIZE); pgd = READ_ONCE(kvm->arch.pgd); kvm->arch.pgd = NULL; } spin_unlock(&kvm->mmu_lock); /* Free the HW pgd, one page at a time */ if (pgd) free_pages_exact(pgd, PAGE_SIZE); } void kvm_arch_flush_shadow_all(struct kvm *kvm) { kvm_free_apt_pgd(kvm); } static void kvm_send_hwpoison_signal(unsigned long address, struct vm_area_struct *vma) { kernel_siginfo_t info; clear_siginfo(&info); info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_MCEERR_AR; info.si_addr = (void __user *)address; if (is_vm_hugetlb_page(vma)) info.si_addr_lsb = huge_page_shift(hstate_vma(vma)); else info.si_addr_lsb = PAGE_SHIFT; send_sig_info(SIGBUS, &info, current); } static bool fault_supports_apt_huge_mapping(struct kvm_memory_slot *memslot, unsigned long hva, unsigned long map_size) { gpa_t gpa_start; hva_t uaddr_start, uaddr_end; size_t size; /* The memslot and the VMA are guaranteed to be aligned to PAGE_SIZE */ if (map_size == PAGE_SIZE) return true; size = memslot->npages * PAGE_SIZE; gpa_start = memslot->base_gfn << PAGE_SHIFT; uaddr_start = memslot->userspace_addr; uaddr_end = uaddr_start + size; /* * Pages belonging to memslots that don't have the same alignment * within a PMD/PUD for userspace and IPA cannot be mapped with stage-2 * PMD/PUD entries, because we'll end up mapping the wrong pages. * * Consider a layout like the following: * * memslot->userspace_addr: * +-----+--------------------+--------------------+---+ * |abcde|fgh Stage-1 block | Stage-1 block tv|xyz| * +-----+--------------------+--------------------+---+ * * memslot->base_gfn << PAGE_SHIFT: * +---+--------------------+--------------------+-----+ * |abc|def Stage-2 block | Stage-2 block |tvxyz| * +---+--------------------+--------------------+-----+ * * If we create those stage-2 blocks, we'll end up with this incorrect * mapping: * d -> f * e -> g * f -> h */ if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1))) return false; /* * Next, let's make sure we're not trying to map anything not covered * by the memslot. This means we have to prohibit block size mappings * for the beginning and end of a non-block aligned and non-block sized * memory slot (illustrated by the head and tail parts of the * userspace view above containing pages 'abcde' and 'xyz', * respectively). * * Note that it doesn't matter if we do the check using the * userspace_addr or the base_gfn, as both are equally aligned (per * the check above) and equally sized. */ return (hva & ~(map_size - 1)) >= uaddr_start && (hva & ~(map_size - 1)) + map_size <= uaddr_end; } /* * apt_get_leaf_entry - walk the stage2 VM page tables and return * true if a valid and present leaf-entry is found. A pointer to the * leaf-entry is returned in the appropriate level variable - pudpp, * pmdpp, ptepp. */ static bool apt_get_leaf_entry(struct kvm *kvm, phys_addr_t addr, pud_t **pudpp, pmd_t **pmdpp, pte_t **ptepp) { pud_t *pudp; pmd_t *pmdp; pte_t *ptep; *pudpp = NULL; *pmdpp = NULL; *ptepp = NULL; pudp = apt_get_pud(kvm->arch.pgd, NULL, addr); if (!pudp || pud_none(*pudp) || !pud_present(*pudp)) return false; if (pud_huge(*pudp)) { *pudpp = pudp; return true; } pmdp = pmd_offset(pudp, addr); if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp)) return false; if (pmd_trans_huge(*pmdp)) { *pmdpp = pmdp; return true; } ptep = pte_offset_kernel(pmdp, addr); if (!ptep || pte_none(*ptep) || !pte_present(*ptep)) return false; *ptepp = ptep; return true; } static bool apt_is_exec(struct kvm *kvm, phys_addr_t addr) { pud_t *pudp; pmd_t *pmdp; pte_t *ptep; bool found; found = apt_get_leaf_entry(kvm, addr, &pudp, &pmdp, &ptep); if (!found) return false; if (pudp) return kvm_pud_exec(pudp); else if (pmdp) return kvm_pmd_exec(pmdp); else return kvm_pte_exec(ptep); } static int apt_set_pte_fast(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, phys_addr_t addr, const pte_t *new_pte, unsigned long flags) { pud_t *pud; pmd_t *pmd; pte_t *pte, old_pte; bool logging_active = flags & KVM_APT_FLAG_LOGGING_ACTIVE; int inv_level = ((read_csr(CSR_AS_INFO)) >> AF_INV_LEVEL_SHIFT) & AF_INV_LEVEL_MASK; unsigned long inv_hpa = read_csr(CSR_AS_INFO) & AF_ENTRY_ADDR_MASK; VM_BUG_ON(logging_active && !cache); if (inv_level == 1) { pud = (pud_t *)(inv_hpa | PAGE_OFFSET); goto find_pud; } else if (inv_level == 2) { pmd = (pmd_t *)(inv_hpa | PAGE_OFFSET); goto find_pmd; } else if (inv_level == 3) { pte = (pte_t *)(inv_hpa | PAGE_OFFSET); goto find_pte; } /* Create addtional page table mapping - Levels 0 and 1 */ pud = apt_get_pud(kvm->arch.pgd, cache, addr); if (!pud) { /* * Ignore calls from kvm_set_spte_hva for unallocated * address ranges. */ return 0; } /* * While dirty page logging - dissolve huge PUD, then continue * on to allocate page. */ if (logging_active) apt_dissolve_pud(kvm, addr, pud); find_pud: if (pud_none(*pud)) { if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ pmd = mmu_memory_cache_alloc(cache); pud_populate(NULL, pud, pmd); get_page(virt_to_page(pud)); } pmd = pmd_offset(pud, addr); if (!pmd) { /* * Ignore calls from kvm_set_spte_hva for unallocated * address ranges. */ return 0; } /* * While dirty page logging - dissolve huge PMD, then continue on to * allocate page. */ if (logging_active) apt_dissolve_pmd(kvm, addr, pmd); find_pmd: /* Create stage-2 page mappings - Level 2 */ if (pmd_none(*pmd)) { if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ pte = mmu_memory_cache_alloc(cache); pmd_populate_kernel(NULL, pmd, pte); get_page(virt_to_page(pmd)); } pte = pte_offset_kernel(pmd, addr); find_pte: /* Create 2nd stage page table mapping - Level 3 */ old_pte = *pte; /* new pte should be readonly? */ // *new_pte = pte_wrprotect(*new_pte); if (pte_present(old_pte)) { /* Skip page table update if there is no change */ if (pte_val(old_pte) == pte_val(*new_pte)) return 0; /* Do we need WRITE_ONCE(pte, 0)? */ set_pte(pte, __pte(0)); kvm_flush_remote_tlbs(kvm); } else { get_page(virt_to_page(pte)); } /* Do we need WRITE_ONCE(pte, new_pte)? */ set_pte(pte, *new_pte); return 0; } static int apt_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, phys_addr_t addr, const pte_t *new_pte, unsigned long flags) { pud_t *pud; pmd_t *pmd; pte_t *pte, old_pte; bool logging_active = flags & KVM_APT_FLAG_LOGGING_ACTIVE; VM_BUG_ON(logging_active && !cache); /* Create addtional page table mapping - Levels 0 and 1 */ pud = apt_get_pud(kvm->arch.pgd, cache, addr); if (!pud) { /* * Ignore calls from kvm_set_spte_hva for unallocated * address ranges. */ return 0; } /* * While dirty page logging - dissolve huge PUD, then continue * on to allocate page. */ if (logging_active) apt_dissolve_pud(kvm, addr, pud); if (pud_none(*pud)) { if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ pmd = mmu_memory_cache_alloc(cache); pud_populate(NULL, pud, pmd); get_page(virt_to_page(pud)); } pmd = pmd_offset(pud, addr); if (!pmd) { /* * Ignore calls from kvm_set_spte_hva for unallocated * address ranges. */ return 0; } /* * While dirty page logging - dissolve huge PMD, then continue on to * allocate page. */ if (logging_active) apt_dissolve_pmd(kvm, addr, pmd); /* Create stage-2 page mappings - Level 2 */ if (pmd_none(*pmd)) { if (!cache) return 0; /* ignore calls from kvm_set_spte_hva */ pte = mmu_memory_cache_alloc(cache); pmd_populate_kernel(NULL, pmd, pte); get_page(virt_to_page(pmd)); } pte = pte_offset_kernel(pmd, addr); /* Create 2nd stage page table mapping - Level 3 */ old_pte = *pte; /* new pte should be readonly? */ // *new_pte = pte_wrprotect(*new_pte); if (pte_present(old_pte)) { /* Skip page table update if there is no change */ if (pte_val(old_pte) == pte_val(*new_pte)) return 0; /* Do we need WRITE_ONCE(pte, 0)? */ set_pte(pte, __pte(0)); kvm_flush_remote_tlbs(kvm); } else { get_page(virt_to_page(pte)); } /* Do we need WRITE_ONCE(pte, new_pte)? */ set_pte(pte, *new_pte); return 0; } static int apt_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, phys_addr_t addr, const pmd_t *new_pmd, unsigned long sz) { pmd_t *pmd, old_pmd, *ori_pmd; int i; retry: pmd = apt_get_pmd(kvm, cache, addr, sz); VM_BUG_ON(!pmd); ori_pmd = pmd; old_pmd = *pmd; if (pmd_present(old_pmd)) { /* * If we already have PTE level mapping for this block, * we must unmap it to avoid inconsistent TLB state and * leaking the table page. We could end up in this situation * if the memory slot was marked for dirty logging and was * reverted, leaving PTE level mappings for the pages accessed * during the period. So, unmap the PTE level mapping for this * block and retry, as we could have released the upper level * table in the process. * * Normal THP split/merge follows mmu_notifier callbacks and do * get handled accordingly. */ if (!pmd_trans_huge(old_pmd)) { unmap_apt_range(kvm, addr & PMD_MASK, PMD_SIZE); goto retry; } /* * Multiple vcpus faulting on the same PMD entry, can * lead to them sequentially updating the PMD with the * same value. Following the break-before-make * (pmd_clear() followed by tlb_flush()) process can * hinder forward progress due to refaults generated * on missing translations. * * Skip updating the page table if the entry is * unchanged. */ if (pmd_val(old_pmd) == pmd_val(*new_pmd)) return 0; /* * Mapping in huge pages should only happen through a * fault. If a page is merged into a transparent huge * page, the individual subpages of that huge page * should be unmapped through MMU notifiers before we * get here. * * Merging of CompoundPages is not supported; they * should become splitting first, unmapped, merged, * and mapped back in on-demand. */ VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd)); if (sz == CONT_PMD_SIZE) { for (i = 0; i < CONT_PMDS; i++, pmd++) pmd_clear(pmd); } else pmd_clear(pmd); kvm_flush_remote_tlbs(kvm); } else { get_page(virt_to_page(pmd)); } /* Do we need WRITE_ONCE(pmd, new_pmd)? */ if (sz == CONT_PMD_SIZE) { for (i = 0; i < CONT_PMDS; i++, ori_pmd++) set_pmd(ori_pmd, *new_pmd); } else set_pmd(pmd, *new_pmd); return 0; } static int apt_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, phys_addr_t addr, const pud_t *new_pudp) { pud_t *pudp, old_pud; retry: pudp = apt_get_pud(kvm->arch.pgd, cache, addr); VM_BUG_ON(!pudp); old_pud = *pudp; /* * A large number of vcpus faulting on the same stage 2 entry, * can lead to a refault due to the stage2_pud_clear()/tlb_flush(). * Skip updating the page tables if there is no change. */ if (pud_val(old_pud) == pud_val(*new_pudp)) return 0; if (pud_present(old_pud)) { /* * If we already have table level mapping for this block, unmap * the range for this block and retry. */ if (!pud_huge(old_pud)) { unmap_apt_range(kvm, addr & PUD_MASK, PUD_SIZE); goto retry; } // WARN_ON_ONCE(kvm_pud_pfn(old_pud) != kvm_pud_pfn(*new_pudp)); pud_clear(pudp); kvm_flush_remote_tlbs(kvm); } else { get_page(virt_to_page(pudp)); } set_pud(pudp, *new_pudp); return 0; } static unsigned long transparent_hugepage_adjust(struct kvm_memory_slot *memslot, unsigned long hva, kvm_pfn_t *pfnp, phys_addr_t *gpap) { kvm_pfn_t pfn = *pfnp; struct page *page = pfn_to_page(pfn); /* * Make sure the adjustment is done only for THP pages. Also make * sure that the HVA and IPA are sufficiently aligned and that the * block map is contained within the memslot. */ if (!PageHuge(page) && PageTransCompoundMap(page) && fault_supports_apt_huge_mapping(memslot, hva, PMD_SIZE)) { /* * The address we faulted on is backed by a transparent huge * page. However, because we map the compound huge page and * not the individual tail page, we need to transfer the * refcount to the head page. We have to be careful that the * THP doesn't start to split while we are adjusting the * refcounts. * * We are sure this doesn't happen, because mmu_notifier_retry * was successful and we are holding the mmu_lock, so if this * THP is trying to split, it will be blocked in the mmu * notifier before touching any of the pages, specifically * before being able to call __split_huge_page_refcount(). * * We can therefore safely transfer the refcount from PG_tail * to PG_head and switch the pfn from a tail page to the head * page accordingly. */ *gpap &= PMD_MASK; kvm_release_pfn_clean(pfn); pfn &= ~(PTRS_PER_PMD - 1); kvm_get_pfn(pfn); *pfnp = pfn; return PMD_SIZE; } return PAGE_SIZE; } static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_gpa, struct kvm_memory_slot *memslot, unsigned long hva, unsigned long fault_status) { int ret; bool write_fault, exec_fault, writable, force_pte = false; unsigned long mmu_seq; gfn_t gfn = fault_gpa >> PAGE_SHIFT; struct kvm *kvm = vcpu->kvm; struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; struct vm_area_struct *vma; kvm_pfn_t pfn; pgprot_t mem_type = PAGE_READONLY; bool logging_active = memslot_is_logging(memslot); unsigned long vma_pagesize, flags = 0; unsigned long as_info, access_type; unsigned int vma_shift; as_info = read_csr(CSR_AS_INFO); access_type = (as_info >> AF_ACCESS_TYPE_SHIFT) & AF_ACCESS_TYPE_MASK; write_fault = kvm_is_write_fault(access_type); exec_fault = kvm_is_exec_fault(access_type); VM_BUG_ON(write_fault && exec_fault); if (fault_status == AF_STATUS_FOR) { kvm_err("Unexpected APT read permission error\n"); return -EFAULT; } /* Let's check if we will get back a huge page backed by hugetlbfs */ down_read(¤t->mm->mmap_lock); vma = find_vma_intersection(current->mm, hva, hva + 1); if (unlikely(!vma)) { kvm_err("Failed to find VMA for hva 0x%lx\n", hva); up_read(¤t->mm->mmap_lock); return -EFAULT; } if (is_vm_hugetlb_page(vma)) vma_shift = huge_page_shift(hstate_vma(vma)); else vma_shift = PAGE_SHIFT; vma_pagesize = 1ULL << vma_shift; if (logging_active || (vma->vm_flags & VM_PFNMAP) || !fault_supports_apt_huge_mapping(memslot, hva, vma_pagesize)) { force_pte = true; vma_pagesize = PAGE_SIZE; } if (vma_pagesize == PMD_SIZE || vma_pagesize == CONT_PMD_SIZE || vma_pagesize == PUD_SIZE) gfn = (fault_gpa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT; up_read(¤t->mm->mmap_lock); /* We need minimum second+third level pages */ ret = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES, KVM_NR_MEM_OBJS); if (ret) return ret; mmu_seq = vcpu->kvm->mmu_notifier_seq; /* * Ensure the read of mmu_notifier_seq happens before we call * gfn_to_pfn_prot (which calls get_user_pages), so that we don't risk * the page we just got a reference to gets unmapped before we have a * chance to grab the mmu_lock, which ensure that if the page gets * unmapped afterwards, the call to kvm_unmap_hva will take it away * from us again properly. This smp_rmb() interacts with the smp_wmb() * in kvm_mmu_notifier_invalidate_. */ smp_rmb(); pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable); if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(hva, vma); return 0; } if (is_error_noslot_pfn(pfn)) return -EFAULT; if (logging_active) { /* * Faults on pages in a memslot with logging enabled * should not be mapped with huge pages (it introduces churn * and performance degradation), so force a pte mapping. */ flags |= KVM_APT_FLAG_LOGGING_ACTIVE; /* * Only actually map the page as writable if this was a write * fault. */ if (!write_fault) writable = false; } spin_lock(&kvm->mmu_lock); if (mmu_notifier_retry(kvm, mmu_seq)) goto out_unlock; /* * If we are not forced to use page mapping, check if we are * backed by a THP and thus use block mapping if possible. */ if (vma_pagesize == PAGE_SIZE && !force_pte) { vma_pagesize = transparent_hugepage_adjust(memslot, hva, &pfn, &fault_gpa); } if (vma_pagesize == PUD_SIZE) { pud_t new_pud = pfn_pud(pfn, mem_type); new_pud = pud_mkhuge(new_pud); if (writable) { new_pud = kvm_pud_mkwrite(new_pud); kvm_set_pfn_dirty(pfn); } if (exec_fault && fault_status == AF_STATUS_INV) { new_pud = kvm_pud_mkexec(new_pud); } else if (fault_status == AF_STATUS_FOE) { /* Preserve execute if FOE was already cleared */ if (apt_is_exec(kvm, fault_gpa)) new_pud = kvm_pud_mkexec(new_pud); } ret = apt_set_pud_huge(kvm, memcache, fault_gpa, &new_pud); } else if (vma_pagesize == CONT_PMD_SIZE) { pmd_t new_pmd = pfn_pmd(pfn, mem_type); new_pmd = pmd_mkhuge(new_pmd); new_pmd = pmd_mkcont(new_pmd); if (writable) { new_pmd = kvm_pmd_mkwrite(new_pmd); kvm_set_pfn_dirty(pfn); } if (exec_fault && fault_status == AF_STATUS_INV) { new_pmd = kvm_pmd_mkexec(new_pmd); } else if (fault_status == AF_STATUS_FOE) { /* Preserve execute if FOE was already cleared */ if (apt_is_exec(kvm, fault_gpa)) new_pmd = kvm_pmd_mkexec(new_pmd); } ret = apt_set_pmd_huge(kvm, memcache, fault_gpa, &new_pmd, vma_pagesize); } else if (vma_pagesize == PMD_SIZE) { pmd_t new_pmd = pfn_pmd(pfn, mem_type); new_pmd = pmd_mkhuge(new_pmd); if (writable) { new_pmd = kvm_pmd_mkwrite(new_pmd); kvm_set_pfn_dirty(pfn); } if (exec_fault && fault_status == AF_STATUS_INV) { new_pmd = kvm_pmd_mkexec(new_pmd); } else if (fault_status == AF_STATUS_FOE) { /* Preserve execute if FOE was already cleared */ if (apt_is_exec(kvm, fault_gpa)) new_pmd = kvm_pmd_mkexec(new_pmd); } ret = apt_set_pmd_huge(kvm, memcache, fault_gpa, &new_pmd, vma_pagesize); } else { pte_t new_pte = pfn_pte(pfn, mem_type); if (writable) { new_pte = kvm_pte_mkwrite(new_pte); kvm_set_pfn_dirty(pfn); mark_page_dirty(kvm, gfn); } if (exec_fault && fault_status == AF_STATUS_INV) { new_pte = kvm_pte_mkexec(new_pte); } else if (fault_status == AF_STATUS_FOE) { /* Preserve execute if FOE was already cleared */ if (apt_is_exec(kvm, fault_gpa)) new_pte = kvm_pte_mkexec(new_pte); } ret = apt_set_pte_fast(kvm, memcache, fault_gpa, &new_pte, flags); if (!ret) goto out_unlock; } out_unlock: spin_unlock(&kvm->mmu_lock); kvm_set_pfn_accessed(pfn); kvm_release_pfn_clean(pfn); return ret; } /** * kvm_handle_guest_abort - handles all 2nd stage aborts * @vcpu: the VCPU pointer * @run: the kvm_run structure * * Any abort that gets to the host is almost guaranteed to be caused by a * missing second stage translation table entry, which can mean that either the * guest simply needs more memory and we must allocate an appropriate page or it * can mean that the guest tried to access I/O memory, which is emulated by user * space. The distinction is based on the IPA causing the fault and whether this * memory region has been registered as standard RAM by user space. */ #ifdef CONFIG_SUBARCH_C4 int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) { unsigned long as_info; /* the value of CSR: AS_INFO */ unsigned int access_type, inv_level; unsigned int fault_status; unsigned long fault_entry_addr; phys_addr_t fault_gpa; struct kvm_memory_slot *memslot; unsigned long hva; bool write_fault, writable; gfn_t gfn; int ret, idx; as_info = read_csr(CSR_AS_INFO); access_type = (as_info >> AF_ACCESS_TYPE_SHIFT) & AF_ACCESS_TYPE_MASK; inv_level = (as_info >> AF_INV_LEVEL_SHIFT) & AF_INV_LEVEL_MASK; fault_status = (as_info >> AF_FAULT_STATUS_SHIFT) & AF_FAULT_STATUS_MASK; fault_entry_addr = (as_info & AF_ENTRY_ADDR_MASK) >> 3; fault_gpa = read_csr(CSR_EXC_GPA); idx = srcu_read_lock(&vcpu->kvm->srcu); gfn = fault_gpa >> PAGE_SHIFT; memslot = gfn_to_memslot(vcpu->kvm, gfn); hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable); write_fault = kvm_is_write_fault(access_type); /* The memory slot for IO doesn't register in memory region * with kvm, if hva == KVM_HVA_ERR_BAD, the gpa used for MMIO * needs emulation. */ if (hva == KVM_HVA_ERR_BAD) { ret = io_mem_abort(vcpu, run, NULL); goto out_unlock; } /* Userspace should not be able to register out-of-bounds IPAs */ VM_BUG_ON(fault_gpa >= KVM_PHYS_SIZE); ret = user_mem_abort(vcpu, fault_gpa, memslot, hva, fault_status); if (ret == 0) ret = 1; out_unlock: srcu_read_unlock(&vcpu->kvm->srcu, idx); return ret; } #endif static int handle_hva_to_gpa(struct kvm *kvm, unsigned long start, unsigned long end, int (*handler)(struct kvm *kvm, gpa_t gpa, u64 size, void *data), void *data) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; int ret = 0; slots = kvm_memslots(kvm); /* we only care about the pages that the guest sees */ kvm_for_each_memslot(memslot, slots) { unsigned long hva_start, hva_end; gfn_t gpa; hva_start = max(start, memslot->userspace_addr); hva_end = min(end, memslot->userspace_addr + (memslot->npages << PAGE_SHIFT)); if (hva_start >= hva_end) continue; gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT; ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data); } return ret; } static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { unmap_apt_range(kvm, gpa, size); return 0; } int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end, bool blockable) { if (!kvm->arch.pgd) return 0; handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL); return 1; } static int apt_ptep_test_and_clear_young(pte_t *pte) { if (pte_young(*pte)) { *pte = pte_mkold(*pte); return 1; } return 0; } static int apt_pmdp_test_and_clear_young(pmd_t *pmd) { return apt_ptep_test_and_clear_young((pte_t *)pmd); } static int apt_pudp_test_and_clear_young(pud_t *pud) { return apt_ptep_test_and_clear_young((pte_t *)pud); } static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pud_t *pud; pmd_t *pmd; pte_t *pte; WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE); if (!apt_get_leaf_entry(kvm, gpa, &pud, &pmd, &pte)) return 0; if (pud) return apt_pudp_test_and_clear_young(pud); else if (pmd) return apt_pmdp_test_and_clear_young(pmd); else return apt_ptep_test_and_clear_young(pte); } static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pud_t *pud; pmd_t *pmd; pte_t *pte; WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE); if (!apt_get_leaf_entry(kvm, gpa, &pud, &pmd, &pte)) return 0; if (pud) return apt_pudp_test_and_clear_young(pud); else if (pmd) return apt_pmdp_test_and_clear_young(pmd); else return apt_ptep_test_and_clear_young(pte); } int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end) { if (!kvm->arch.pgd) return 0; return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL); } int kvm_test_age_hva(struct kvm *kvm, unsigned long hva) { if (!kvm->arch.pgd) return 0; return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL); } static int kvm_set_apte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pte_t *pte = (pte_t *)data; WARN_ON(size != PAGE_SIZE); apt_set_pte(kvm, NULL, gpa, pte, 0); return 0; } int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) { unsigned long end = hva + PAGE_SIZE; pte_t apt_pte; if (!kvm->arch.pgd) return 0; apt_pte = pte_wrprotect(pte); handle_hva_to_gpa(kvm, hva, end, &kvm_set_apte_handler, &apt_pte); return 0; } /** * kvm_mmu_write_protect_pt_masked() - write protect dirty pages * @kvm: The KVM pointer * @slot: The memory slot associated with mask * @gfn_offset: The gfn offset in memory slot * @mask: The mask of dirty pages at offset 'gfn_offset' in this memory * slot to be write protected * * Walks bits set in mask write protects the associated pte's. Caller must * acquire kvm_mmu_lock. */ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { phys_addr_t base_gfn = slot->base_gfn + gfn_offset; phys_addr_t start = (base_gfn + __ffs(mask)) << PAGE_SHIFT; phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT; apt_wp_range(kvm, start, end); } /* * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected * dirty pages. * * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to * enable dirty logging for them. */ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); }