/* * Copyright 2013 Red Hat Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * 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. * * Authors: Jérôme Glisse <jglisse@redhat.com> */ /* * Refer to include/linux/hmm.h for information about heterogeneous memory * management or HMM for short. */ #include <linux/mm.h> #include <linux/hmm.h> #include <linux/init.h> #include <linux/rmap.h> #include <linux/swap.h> #include <linux/slab.h> #include <linux/sched.h> #include <linux/mmzone.h> #include <linux/pagemap.h> #include <linux/swapops.h> #include <linux/hugetlb.h> #include <linux/memremap.h> #include <linux/jump_label.h> #include <linux/mmu_notifier.h> #include <linux/memory_hotplug.h> #define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT) #if defined(CONFIG_DEVICE_PRIVATE) || defined(CONFIG_DEVICE_PUBLIC) /* * Device private memory see HMM (Documentation/vm/hmm.txt) or hmm.h */ DEFINE_STATIC_KEY_FALSE(device_private_key); EXPORT_SYMBOL(device_private_key); #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */ #if IS_ENABLED(CONFIG_HMM_MIRROR) static const struct mmu_notifier_ops hmm_mmu_notifier_ops; /* * struct hmm - HMM per mm struct * * @mm: mm struct this HMM struct is bound to * @lock: lock protecting ranges list * @sequence: we track updates to the CPU page table with a sequence number * @ranges: list of range being snapshotted * @mirrors: list of mirrors for this mm * @mmu_notifier: mmu notifier to track updates to CPU page table * @mirrors_sem: read/write semaphore protecting the mirrors list */ struct hmm { struct mm_struct *mm; spinlock_t lock; atomic_t sequence; struct list_head ranges; struct list_head mirrors; struct mmu_notifier mmu_notifier; struct rw_semaphore mirrors_sem; }; /* * hmm_register - register HMM against an mm (HMM internal) * * @mm: mm struct to attach to * * This is not intended to be used directly by device drivers. It allocates an * HMM struct if mm does not have one, and initializes it. */ static struct hmm *hmm_register(struct mm_struct *mm) { struct hmm *hmm = READ_ONCE(mm->hmm); bool cleanup = false; /* * The hmm struct can only be freed once the mm_struct goes away, * hence we should always have pre-allocated an new hmm struct * above. */ if (hmm) return hmm; hmm = kmalloc(sizeof(*hmm), GFP_KERNEL); if (!hmm) return NULL; INIT_LIST_HEAD(&hmm->mirrors); init_rwsem(&hmm->mirrors_sem); atomic_set(&hmm->sequence, 0); hmm->mmu_notifier.ops = NULL; INIT_LIST_HEAD(&hmm->ranges); spin_lock_init(&hmm->lock); hmm->mm = mm; /* * We should only get here if hold the mmap_sem in write mode ie on * registration of first mirror through hmm_mirror_register() */ hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops; if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) { kfree(hmm); return NULL; } spin_lock(&mm->page_table_lock); if (!mm->hmm) mm->hmm = hmm; else cleanup = true; spin_unlock(&mm->page_table_lock); if (cleanup) { mmu_notifier_unregister(&hmm->mmu_notifier, mm); kfree(hmm); } return mm->hmm; } void hmm_mm_destroy(struct mm_struct *mm) { kfree(mm->hmm); } static void hmm_invalidate_range(struct hmm *hmm, enum hmm_update_type action, unsigned long start, unsigned long end) { struct hmm_mirror *mirror; struct hmm_range *range; spin_lock(&hmm->lock); list_for_each_entry(range, &hmm->ranges, list) { unsigned long addr, idx, npages; if (end < range->start || start >= range->end) continue; range->valid = false; addr = max(start, range->start); idx = (addr - range->start) >> PAGE_SHIFT; npages = (min(range->end, end) - addr) >> PAGE_SHIFT; memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages); } spin_unlock(&hmm->lock); down_read(&hmm->mirrors_sem); list_for_each_entry(mirror, &hmm->mirrors, list) mirror->ops->sync_cpu_device_pagetables(mirror, action, start, end); up_read(&hmm->mirrors_sem); } static void hmm_invalidate_range_start(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end) { struct hmm *hmm = mm->hmm; VM_BUG_ON(!hmm); atomic_inc(&hmm->sequence); } static void hmm_invalidate_range_end(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end) { struct hmm *hmm = mm->hmm; VM_BUG_ON(!hmm); hmm_invalidate_range(mm->hmm, HMM_UPDATE_INVALIDATE, start, end); } static const struct mmu_notifier_ops hmm_mmu_notifier_ops = { .invalidate_range_start = hmm_invalidate_range_start, .invalidate_range_end = hmm_invalidate_range_end, }; /* * hmm_mirror_register() - register a mirror against an mm * * @mirror: new mirror struct to register * @mm: mm to register against * * To start mirroring a process address space, the device driver must register * an HMM mirror struct. * * THE mm->mmap_sem MUST BE HELD IN WRITE MODE ! */ int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm) { /* Sanity check */ if (!mm || !mirror || !mirror->ops) return -EINVAL; mirror->hmm = hmm_register(mm); if (!mirror->hmm) return -ENOMEM; down_write(&mirror->hmm->mirrors_sem); list_add(&mirror->list, &mirror->hmm->mirrors); up_write(&mirror->hmm->mirrors_sem); return 0; } EXPORT_SYMBOL(hmm_mirror_register); /* * hmm_mirror_unregister() - unregister a mirror * * @mirror: new mirror struct to register * * Stop mirroring a process address space, and cleanup. */ void hmm_mirror_unregister(struct hmm_mirror *mirror) { struct hmm *hmm = mirror->hmm; down_write(&hmm->mirrors_sem); list_del(&mirror->list); up_write(&hmm->mirrors_sem); } EXPORT_SYMBOL(hmm_mirror_unregister); struct hmm_vma_walk { struct hmm_range *range; unsigned long last; bool fault; bool block; bool write; }; static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr, hmm_pfn_t *pfn) { unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE; struct hmm_vma_walk *hmm_vma_walk = walk->private; struct vm_area_struct *vma = walk->vma; int r; flags |= hmm_vma_walk->block ? 0 : FAULT_FLAG_ALLOW_RETRY; flags |= hmm_vma_walk->write ? FAULT_FLAG_WRITE : 0; r = handle_mm_fault(vma, addr, flags); if (r & VM_FAULT_RETRY) return -EBUSY; if (r & VM_FAULT_ERROR) { *pfn = HMM_PFN_ERROR; return -EFAULT; } return -EAGAIN; } static void hmm_pfns_special(hmm_pfn_t *pfns, unsigned long addr, unsigned long end) { for (; addr < end; addr += PAGE_SIZE, pfns++) *pfns = HMM_PFN_SPECIAL; } static int hmm_pfns_bad(unsigned long addr, unsigned long end, struct mm_walk *walk) { struct hmm_range *range = walk->private; hmm_pfn_t *pfns = range->pfns; unsigned long i; i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) pfns[i] = HMM_PFN_ERROR; return 0; } static void hmm_pfns_clear(hmm_pfn_t *pfns, unsigned long addr, unsigned long end) { for (; addr < end; addr += PAGE_SIZE, pfns++) *pfns = 0; } static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, struct mm_walk *walk) { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; hmm_pfn_t *pfns = range->pfns; unsigned long i; hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = HMM_PFN_EMPTY; if (hmm_vma_walk->fault) { int ret; ret = hmm_vma_do_fault(walk, addr, &pfns[i]); if (ret != -EAGAIN) return ret; } } return hmm_vma_walk->fault ? -EAGAIN : 0; } static int hmm_vma_walk_clear(unsigned long addr, unsigned long end, struct mm_walk *walk) { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; hmm_pfn_t *pfns = range->pfns; unsigned long i; hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = 0; if (hmm_vma_walk->fault) { int ret; ret = hmm_vma_do_fault(walk, addr, &pfns[i]); if (ret != -EAGAIN) return ret; } } return hmm_vma_walk->fault ? -EAGAIN : 0; } static int hmm_vma_walk_pmd(pmd_t *pmdp, unsigned long start, unsigned long end, struct mm_walk *walk) { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; struct vm_area_struct *vma = walk->vma; hmm_pfn_t *pfns = range->pfns; unsigned long addr = start, i; bool write_fault; hmm_pfn_t flag; pte_t *ptep; i = (addr - range->start) >> PAGE_SHIFT; flag = vma->vm_flags & VM_READ ? HMM_PFN_READ : 0; write_fault = hmm_vma_walk->fault & hmm_vma_walk->write; again: if (pmd_none(*pmdp)) return hmm_vma_walk_hole(start, end, walk); if (pmd_huge(*pmdp) && vma->vm_flags & VM_HUGETLB) return hmm_pfns_bad(start, end, walk); if (pmd_devmap(*pmdp) || pmd_trans_huge(*pmdp)) { unsigned long pfn; pmd_t pmd; /* * No need to take pmd_lock here, even if some other threads * is splitting the huge pmd we will get that event through * mmu_notifier callback. * * So just read pmd value and check again its a transparent * huge or device mapping one and compute corresponding pfn * values. */ pmd = pmd_read_atomic(pmdp); barrier(); if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd)) goto again; if (pmd_protnone(pmd)) return hmm_vma_walk_clear(start, end, walk); if (write_fault && !pmd_write(pmd)) return hmm_vma_walk_clear(start, end, walk); pfn = pmd_pfn(pmd) + pte_index(addr); flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0; for (; addr < end; addr += PAGE_SIZE, i++, pfn++) pfns[i] = hmm_pfn_t_from_pfn(pfn) | flag; return 0; } if (pmd_bad(*pmdp)) return hmm_pfns_bad(start, end, walk); ptep = pte_offset_map(pmdp, addr); for (; addr < end; addr += PAGE_SIZE, ptep++, i++) { pte_t pte = *ptep; pfns[i] = 0; if (pte_none(pte)) { pfns[i] = HMM_PFN_EMPTY; if (hmm_vma_walk->fault) goto fault; continue; } if (!pte_present(pte)) { swp_entry_t entry; if (!non_swap_entry(entry)) { if (hmm_vma_walk->fault) goto fault; continue; } entry = pte_to_swp_entry(pte); /* * This is a special swap entry, ignore migration, use * device and report anything else as error. */ if (is_device_private_entry(entry)) { pfns[i] = hmm_pfn_t_from_pfn(swp_offset(entry)); if (is_write_device_private_entry(entry)) { pfns[i] |= HMM_PFN_WRITE; } else if (write_fault) goto fault; pfns[i] |= HMM_PFN_DEVICE_UNADDRESSABLE; pfns[i] |= flag; } else if (is_migration_entry(entry)) { if (hmm_vma_walk->fault) { pte_unmap(ptep); hmm_vma_walk->last = addr; migration_entry_wait(vma->vm_mm, pmdp, addr); return -EAGAIN; } continue; } else { /* Report error for everything else */ pfns[i] = HMM_PFN_ERROR; } continue; } if (write_fault && !pte_write(pte)) goto fault; pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)) | flag; pfns[i] |= pte_write(pte) ? HMM_PFN_WRITE : 0; continue; fault: pte_unmap(ptep); /* Fault all pages in range */ return hmm_vma_walk_clear(start, end, walk); } pte_unmap(ptep - 1); return 0; } /* * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses * @vma: virtual memory area containing the virtual address range * @range: used to track snapshot validity * @start: range virtual start address (inclusive) * @end: range virtual end address (exclusive) * @entries: array of hmm_pfn_t: provided by the caller, filled in by function * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, 0 success * * This snapshots the CPU page table for a range of virtual addresses. Snapshot * validity is tracked by range struct. See hmm_vma_range_done() for further * information. * * The range struct is initialized here. It tracks the CPU page table, but only * if the function returns success (0), in which case the caller must then call * hmm_vma_range_done() to stop CPU page table update tracking on this range. * * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED ! */ int hmm_vma_get_pfns(struct vm_area_struct *vma, struct hmm_range *range, unsigned long start, unsigned long end, hmm_pfn_t *pfns) { struct hmm_vma_walk hmm_vma_walk; struct mm_walk mm_walk; struct hmm *hmm; /* FIXME support hugetlb fs */ if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { hmm_pfns_special(pfns, start, end); return -EINVAL; } /* Sanity check, this really should not happen ! */ if (start < vma->vm_start || start >= vma->vm_end) return -EINVAL; if (end < vma->vm_start || end > vma->vm_end) return -EINVAL; hmm = hmm_register(vma->vm_mm); if (!hmm) return -ENOMEM; /* Caller must have registered a mirror, via hmm_mirror_register() ! */ if (!hmm->mmu_notifier.ops) return -EINVAL; /* Initialize range to track CPU page table update */ range->start = start; range->pfns = pfns; range->end = end; spin_lock(&hmm->lock); range->valid = true; list_add_rcu(&range->list, &hmm->ranges); spin_unlock(&hmm->lock); hmm_vma_walk.fault = false; hmm_vma_walk.range = range; mm_walk.private = &hmm_vma_walk; mm_walk.vma = vma; mm_walk.mm = vma->vm_mm; mm_walk.pte_entry = NULL; mm_walk.test_walk = NULL; mm_walk.hugetlb_entry = NULL; mm_walk.pmd_entry = hmm_vma_walk_pmd; mm_walk.pte_hole = hmm_vma_walk_hole; walk_page_range(start, end, &mm_walk); return 0; } EXPORT_SYMBOL(hmm_vma_get_pfns); /* * hmm_vma_range_done() - stop tracking change to CPU page table over a range * @vma: virtual memory area containing the virtual address range * @range: range being tracked * Returns: false if range data has been invalidated, true otherwise * * Range struct is used to track updates to the CPU page table after a call to * either hmm_vma_get_pfns() or hmm_vma_fault(). Once the device driver is done * using the data, or wants to lock updates to the data it got from those * functions, it must call the hmm_vma_range_done() function, which will then * stop tracking CPU page table updates. * * Note that device driver must still implement general CPU page table update * tracking either by using hmm_mirror (see hmm_mirror_register()) or by using * the mmu_notifier API directly. * * CPU page table update tracking done through hmm_range is only temporary and * to be used while trying to duplicate CPU page table contents for a range of * virtual addresses. * * There are two ways to use this : * again: * hmm_vma_get_pfns(vma, range, start, end, pfns); or hmm_vma_fault(...); * trans = device_build_page_table_update_transaction(pfns); * device_page_table_lock(); * if (!hmm_vma_range_done(vma, range)) { * device_page_table_unlock(); * goto again; * } * device_commit_transaction(trans); * device_page_table_unlock(); * * Or: * hmm_vma_get_pfns(vma, range, start, end, pfns); or hmm_vma_fault(...); * device_page_table_lock(); * hmm_vma_range_done(vma, range); * device_update_page_table(pfns); * device_page_table_unlock(); */ bool hmm_vma_range_done(struct vm_area_struct *vma, struct hmm_range *range) { unsigned long npages = (range->end - range->start) >> PAGE_SHIFT; struct hmm *hmm; if (range->end <= range->start) { BUG(); return false; } hmm = hmm_register(vma->vm_mm); if (!hmm) { memset(range->pfns, 0, sizeof(*range->pfns) * npages); return false; } spin_lock(&hmm->lock); list_del_rcu(&range->list); spin_unlock(&hmm->lock); return range->valid; } EXPORT_SYMBOL(hmm_vma_range_done); /* * hmm_vma_fault() - try to fault some address in a virtual address range * @vma: virtual memory area containing the virtual address range * @range: use to track pfns array content validity * @start: fault range virtual start address (inclusive) * @end: fault range virtual end address (exclusive) * @pfns: array of hmm_pfn_t, only entry with fault flag set will be faulted * @write: is it a write fault * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem) * Returns: 0 success, error otherwise (-EAGAIN means mmap_sem have been drop) * * This is similar to a regular CPU page fault except that it will not trigger * any memory migration if the memory being faulted is not accessible by CPUs. * * On error, for one virtual address in the range, the function will set the * hmm_pfn_t error flag for the corresponding pfn entry. * * Expected use pattern: * retry: * down_read(&mm->mmap_sem); * // Find vma and address device wants to fault, initialize hmm_pfn_t * // array accordingly * ret = hmm_vma_fault(vma, start, end, pfns, allow_retry); * switch (ret) { * case -EAGAIN: * hmm_vma_range_done(vma, range); * // You might want to rate limit or yield to play nicely, you may * // also commit any valid pfn in the array assuming that you are * // getting true from hmm_vma_range_monitor_end() * goto retry; * case 0: * break; * default: * // Handle error ! * up_read(&mm->mmap_sem) * return; * } * // Take device driver lock that serialize device page table update * driver_lock_device_page_table_update(); * hmm_vma_range_done(vma, range); * // Commit pfns we got from hmm_vma_fault() * driver_unlock_device_page_table_update(); * up_read(&mm->mmap_sem) * * YOU MUST CALL hmm_vma_range_done() AFTER THIS FUNCTION RETURN SUCCESS (0) * BEFORE FREEING THE range struct OR YOU WILL HAVE SERIOUS MEMORY CORRUPTION ! * * YOU HAVE BEEN WARNED ! */ int hmm_vma_fault(struct vm_area_struct *vma, struct hmm_range *range, unsigned long start, unsigned long end, hmm_pfn_t *pfns, bool write, bool block) { struct hmm_vma_walk hmm_vma_walk; struct mm_walk mm_walk; struct hmm *hmm; int ret; /* Sanity check, this really should not happen ! */ if (start < vma->vm_start || start >= vma->vm_end) return -EINVAL; if (end < vma->vm_start || end > vma->vm_end) return -EINVAL; hmm = hmm_register(vma->vm_mm); if (!hmm) { hmm_pfns_clear(pfns, start, end); return -ENOMEM; } /* Caller must have registered a mirror using hmm_mirror_register() */ if (!hmm->mmu_notifier.ops) return -EINVAL; /* Initialize range to track CPU page table update */ range->start = start; range->pfns = pfns; range->end = end; spin_lock(&hmm->lock); range->valid = true; list_add_rcu(&range->list, &hmm->ranges); spin_unlock(&hmm->lock); /* FIXME support hugetlb fs */ if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { hmm_pfns_special(pfns, start, end); return 0; } hmm_vma_walk.fault = true; hmm_vma_walk.write = write; hmm_vma_walk.block = block; hmm_vma_walk.range = range; mm_walk.private = &hmm_vma_walk; hmm_vma_walk.last = range->start; mm_walk.vma = vma; mm_walk.mm = vma->vm_mm; mm_walk.pte_entry = NULL; mm_walk.test_walk = NULL; mm_walk.hugetlb_entry = NULL; mm_walk.pmd_entry = hmm_vma_walk_pmd; mm_walk.pte_hole = hmm_vma_walk_hole; do { ret = walk_page_range(start, end, &mm_walk); start = hmm_vma_walk.last; } while (ret == -EAGAIN); if (ret) { unsigned long i; i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT; hmm_pfns_clear(&pfns[i], hmm_vma_walk.last, end); hmm_vma_range_done(vma, range); } return ret; } EXPORT_SYMBOL(hmm_vma_fault); #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */ #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC) struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma, unsigned long addr) { struct page *page; page = alloc_page_vma(GFP_HIGHUSER, vma, addr); if (!page) return NULL; lock_page(page); return page; } EXPORT_SYMBOL(hmm_vma_alloc_locked_page); static void hmm_devmem_ref_release(struct percpu_ref *ref) { struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); complete(&devmem->completion); } static void hmm_devmem_ref_exit(void *data) { struct percpu_ref *ref = data; struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); percpu_ref_exit(ref); devm_remove_action(devmem->device, &hmm_devmem_ref_exit, data); } static void hmm_devmem_ref_kill(void *data) { struct percpu_ref *ref = data; struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); percpu_ref_kill(ref); wait_for_completion(&devmem->completion); devm_remove_action(devmem->device, &hmm_devmem_ref_kill, data); } static int hmm_devmem_fault(struct vm_area_struct *vma, unsigned long addr, const struct page *page, unsigned int flags, pmd_t *pmdp) { struct hmm_devmem *devmem = page->pgmap->data; return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp); } static void hmm_devmem_free(struct page *page, void *data) { struct hmm_devmem *devmem = data; devmem->ops->free(devmem, page); } static DEFINE_MUTEX(hmm_devmem_lock); static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL); static void hmm_devmem_radix_release(struct resource *resource) { resource_size_t key, align_start, align_size, align_end; align_start = resource->start & ~(PA_SECTION_SIZE - 1); align_size = ALIGN(resource_size(resource), PA_SECTION_SIZE); align_end = align_start + align_size - 1; mutex_lock(&hmm_devmem_lock); for (key = resource->start; key <= resource->end; key += PA_SECTION_SIZE) radix_tree_delete(&hmm_devmem_radix, key >> PA_SECTION_SHIFT); mutex_unlock(&hmm_devmem_lock); } static void hmm_devmem_release(struct device *dev, void *data) { struct hmm_devmem *devmem = data; struct resource *resource = devmem->resource; unsigned long start_pfn, npages; struct zone *zone; struct page *page; if (percpu_ref_tryget_live(&devmem->ref)) { dev_WARN(dev, "%s: page mapping is still live!\n", __func__); percpu_ref_put(&devmem->ref); } /* pages are dead and unused, undo the arch mapping */ start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT; npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT; page = pfn_to_page(start_pfn); zone = page_zone(page); mem_hotplug_begin(); if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) __remove_pages(zone, start_pfn, npages); else arch_remove_memory(start_pfn << PAGE_SHIFT, npages << PAGE_SHIFT); mem_hotplug_done(); hmm_devmem_radix_release(resource); } static struct hmm_devmem *hmm_devmem_find(resource_size_t phys) { WARN_ON_ONCE(!rcu_read_lock_held()); return radix_tree_lookup(&hmm_devmem_radix, phys >> PA_SECTION_SHIFT); } static int hmm_devmem_pages_create(struct hmm_devmem *devmem) { resource_size_t key, align_start, align_size, align_end; struct device *device = devmem->device; int ret, nid, is_ram; unsigned long pfn; align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1); align_size = ALIGN(devmem->resource->start + resource_size(devmem->resource), PA_SECTION_SIZE) - align_start; is_ram = region_intersects(align_start, align_size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); if (is_ram == REGION_MIXED) { WARN_ONCE(1, "%s attempted on mixed region %pr\n", __func__, devmem->resource); return -ENXIO; } if (is_ram == REGION_INTERSECTS) return -ENXIO; if (devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY) devmem->pagemap.type = MEMORY_DEVICE_PUBLIC; else devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; devmem->pagemap.res = devmem->resource; devmem->pagemap.page_fault = hmm_devmem_fault; devmem->pagemap.page_free = hmm_devmem_free; devmem->pagemap.dev = devmem->device; devmem->pagemap.ref = &devmem->ref; devmem->pagemap.data = devmem; mutex_lock(&hmm_devmem_lock); align_end = align_start + align_size - 1; for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) { struct hmm_devmem *dup; rcu_read_lock(); dup = hmm_devmem_find(key); rcu_read_unlock(); if (dup) { dev_err(device, "%s: collides with mapping for %s\n", __func__, dev_name(dup->device)); mutex_unlock(&hmm_devmem_lock); ret = -EBUSY; goto error; } ret = radix_tree_insert(&hmm_devmem_radix, key >> PA_SECTION_SHIFT, devmem); if (ret) { dev_err(device, "%s: failed: %d\n", __func__, ret); mutex_unlock(&hmm_devmem_lock); goto error_radix; } } mutex_unlock(&hmm_devmem_lock); nid = dev_to_node(device); if (nid < 0) nid = numa_mem_id(); mem_hotplug_begin(); /* * For device private memory we call add_pages() as we only need to * allocate and initialize struct page for the device memory. More- * over the device memory is un-accessible thus we do not want to * create a linear mapping for the memory like arch_add_memory() * would do. * * For device public memory, which is accesible by the CPU, we do * want the linear mapping and thus use arch_add_memory(). */ if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC) ret = arch_add_memory(nid, align_start, align_size, false); else ret = add_pages(nid, align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT, false); if (ret) { mem_hotplug_done(); goto error_add_memory; } move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT); mem_hotplug_done(); for (pfn = devmem->pfn_first; pfn < devmem->pfn_last; pfn++) { struct page *page = pfn_to_page(pfn); page->pgmap = &devmem->pagemap; } return 0; error_add_memory: untrack_pfn(NULL, PHYS_PFN(align_start), align_size); error_radix: hmm_devmem_radix_release(devmem->resource); error: return ret; } static int hmm_devmem_match(struct device *dev, void *data, void *match_data) { struct hmm_devmem *devmem = data; return devmem->resource == match_data; } static void hmm_devmem_pages_remove(struct hmm_devmem *devmem) { devres_release(devmem->device, &hmm_devmem_release, &hmm_devmem_match, devmem->resource); } /* * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory * * @ops: memory event device driver callback (see struct hmm_devmem_ops) * @device: device struct to bind the resource too * @size: size in bytes of the device memory to add * Returns: pointer to new hmm_devmem struct ERR_PTR otherwise * * This function first finds an empty range of physical address big enough to * contain the new resource, and then hotplugs it as ZONE_DEVICE memory, which * in turn allocates struct pages. It does not do anything beyond that; all * events affecting the memory will go through the various callbacks provided * by hmm_devmem_ops struct. * * Device driver should call this function during device initialization and * is then responsible of memory management. HMM only provides helpers. */ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, struct device *device, unsigned long size) { struct hmm_devmem *devmem; resource_size_t addr; int ret; static_branch_enable(&device_private_key); devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), GFP_KERNEL, dev_to_node(device)); if (!devmem) return ERR_PTR(-ENOMEM); init_completion(&devmem->completion); devmem->pfn_first = -1UL; devmem->pfn_last = -1UL; devmem->resource = NULL; devmem->device = device; devmem->ops = ops; ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release, 0, GFP_KERNEL); if (ret) goto error_percpu_ref; ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref); if (ret) goto error_devm_add_action; size = ALIGN(size, PA_SECTION_SIZE); addr = min((unsigned long)iomem_resource.end, (1UL << MAX_PHYSMEM_BITS) - 1); addr = addr - size + 1UL; /* * FIXME add a new helper to quickly walk resource tree and find free * range * * FIXME what about ioport_resource resource ? */ for (; addr > size && addr >= iomem_resource.start; addr -= size) { ret = region_intersects(addr, size, 0, IORES_DESC_NONE); if (ret != REGION_DISJOINT) continue; devmem->resource = devm_request_mem_region(device, addr, size, dev_name(device)); if (!devmem->resource) { ret = -ENOMEM; goto error_no_resource; } break; } if (!devmem->resource) { ret = -ERANGE; goto error_no_resource; } devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY; devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; devmem->pfn_last = devmem->pfn_first + (resource_size(devmem->resource) >> PAGE_SHIFT); ret = hmm_devmem_pages_create(devmem); if (ret) goto error_pages; devres_add(device, devmem); ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref); if (ret) { hmm_devmem_remove(devmem); return ERR_PTR(ret); } return devmem; error_pages: devm_release_mem_region(device, devmem->resource->start, resource_size(devmem->resource)); error_no_resource: error_devm_add_action: hmm_devmem_ref_kill(&devmem->ref); hmm_devmem_ref_exit(&devmem->ref); error_percpu_ref: devres_free(devmem); return ERR_PTR(ret); } EXPORT_SYMBOL(hmm_devmem_add); struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, struct device *device, struct resource *res) { struct hmm_devmem *devmem; int ret; if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY) return ERR_PTR(-EINVAL); static_branch_enable(&device_private_key); devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), GFP_KERNEL, dev_to_node(device)); if (!devmem) return ERR_PTR(-ENOMEM); init_completion(&devmem->completion); devmem->pfn_first = -1UL; devmem->pfn_last = -1UL; devmem->resource = res; devmem->device = device; devmem->ops = ops; ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release, 0, GFP_KERNEL); if (ret) goto error_percpu_ref; ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref); if (ret) goto error_devm_add_action; devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; devmem->pfn_last = devmem->pfn_first + (resource_size(devmem->resource) >> PAGE_SHIFT); ret = hmm_devmem_pages_create(devmem); if (ret) goto error_devm_add_action; devres_add(device, devmem); ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref); if (ret) { hmm_devmem_remove(devmem); return ERR_PTR(ret); } return devmem; error_devm_add_action: hmm_devmem_ref_kill(&devmem->ref); hmm_devmem_ref_exit(&devmem->ref); error_percpu_ref: devres_free(devmem); return ERR_PTR(ret); } EXPORT_SYMBOL(hmm_devmem_add_resource); /* * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE) * * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory * * This will hot-unplug memory that was hotplugged by hmm_devmem_add on behalf * of the device driver. It will free struct page and remove the resource that * reserved the physical address range for this device memory. */ void hmm_devmem_remove(struct hmm_devmem *devmem) { resource_size_t start, size; struct device *device; bool cdm = false; if (!devmem) return; device = devmem->device; start = devmem->resource->start; size = resource_size(devmem->resource); cdm = devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY; hmm_devmem_ref_kill(&devmem->ref); hmm_devmem_ref_exit(&devmem->ref); hmm_devmem_pages_remove(devmem); if (!cdm) devm_release_mem_region(device, start, size); } EXPORT_SYMBOL(hmm_devmem_remove); /* * A device driver that wants to handle multiple devices memory through a * single fake device can use hmm_device to do so. This is purely a helper * and it is not needed to make use of any HMM functionality. */ #define HMM_DEVICE_MAX 256 static DECLARE_BITMAP(hmm_device_mask, HMM_DEVICE_MAX); static DEFINE_SPINLOCK(hmm_device_lock); static struct class *hmm_device_class; static dev_t hmm_device_devt; static void hmm_device_release(struct device *device) { struct hmm_device *hmm_device; hmm_device = container_of(device, struct hmm_device, device); spin_lock(&hmm_device_lock); clear_bit(hmm_device->minor, hmm_device_mask); spin_unlock(&hmm_device_lock); kfree(hmm_device); } struct hmm_device *hmm_device_new(void *drvdata) { struct hmm_device *hmm_device; hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL); if (!hmm_device) return ERR_PTR(-ENOMEM); spin_lock(&hmm_device_lock); hmm_device->minor = find_first_zero_bit(hmm_device_mask, HMM_DEVICE_MAX); if (hmm_device->minor >= HMM_DEVICE_MAX) { spin_unlock(&hmm_device_lock); kfree(hmm_device); return ERR_PTR(-EBUSY); } set_bit(hmm_device->minor, hmm_device_mask); spin_unlock(&hmm_device_lock); dev_set_name(&hmm_device->device, "hmm_device%d", hmm_device->minor); hmm_device->device.devt = MKDEV(MAJOR(hmm_device_devt), hmm_device->minor); hmm_device->device.release = hmm_device_release; dev_set_drvdata(&hmm_device->device, drvdata); hmm_device->device.class = hmm_device_class; device_initialize(&hmm_device->device); return hmm_device; } EXPORT_SYMBOL(hmm_device_new); void hmm_device_put(struct hmm_device *hmm_device) { put_device(&hmm_device->device); } EXPORT_SYMBOL(hmm_device_put); static int __init hmm_init(void) { int ret; ret = alloc_chrdev_region(&hmm_device_devt, 0, HMM_DEVICE_MAX, "hmm_device"); if (ret) return ret; hmm_device_class = class_create(THIS_MODULE, "hmm_device"); if (IS_ERR(hmm_device_class)) { unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX); return PTR_ERR(hmm_device_class); } return 0; } device_initcall(hmm_init); #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */