diff options
Diffstat (limited to 'drivers/iommu/iommufd/pages.c')
| -rw-r--r-- | drivers/iommu/iommufd/pages.c | 1993 |
1 files changed, 1993 insertions, 0 deletions
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c new file mode 100644 index 0000000000..528f356238 --- /dev/null +++ b/drivers/iommu/iommufd/pages.c @@ -0,0 +1,1993 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES. + * + * The iopt_pages is the center of the storage and motion of PFNs. Each + * iopt_pages represents a logical linear array of full PFNs. The array is 0 + * based and has npages in it. Accessors use 'index' to refer to the entry in + * this logical array, regardless of its storage location. + * + * PFNs are stored in a tiered scheme: + * 1) iopt_pages::pinned_pfns xarray + * 2) An iommu_domain + * 3) The origin of the PFNs, i.e. the userspace pointer + * + * PFN have to be copied between all combinations of tiers, depending on the + * configuration. + * + * When a PFN is taken out of the userspace pointer it is pinned exactly once. + * The storage locations of the PFN's index are tracked in the two interval + * trees. If no interval includes the index then it is not pinned. + * + * If access_itree includes the PFN's index then an in-kernel access has + * requested the page. The PFN is stored in the xarray so other requestors can + * continue to find it. + * + * If the domains_itree includes the PFN's index then an iommu_domain is storing + * the PFN and it can be read back using iommu_iova_to_phys(). To avoid + * duplicating storage the xarray is not used if only iommu_domains are using + * the PFN's index. + * + * As a general principle this is designed so that destroy never fails. This + * means removing an iommu_domain or releasing a in-kernel access will not fail + * due to insufficient memory. In practice this means some cases have to hold + * PFNs in the xarray even though they are also being stored in an iommu_domain. + * + * While the iopt_pages can use an iommu_domain as storage, it does not have an + * IOVA itself. Instead the iopt_area represents a range of IOVA and uses the + * iopt_pages as the PFN provider. Multiple iopt_areas can share the iopt_pages + * and reference their own slice of the PFN array, with sub page granularity. + * + * In this file the term 'last' indicates an inclusive and closed interval, eg + * [0,0] refers to a single PFN. 'end' means an open range, eg [0,0) refers to + * no PFNs. + * + * Be cautious of overflow. An IOVA can go all the way up to U64_MAX, so + * last_iova + 1 can overflow. An iopt_pages index will always be much less than + * ULONG_MAX so last_index + 1 cannot overflow. + */ +#include <linux/overflow.h> +#include <linux/slab.h> +#include <linux/iommu.h> +#include <linux/sched/mm.h> +#include <linux/highmem.h> +#include <linux/kthread.h> +#include <linux/iommufd.h> + +#include "io_pagetable.h" +#include "double_span.h" + +#ifndef CONFIG_IOMMUFD_TEST +#define TEMP_MEMORY_LIMIT 65536 +#else +#define TEMP_MEMORY_LIMIT iommufd_test_memory_limit +#endif +#define BATCH_BACKUP_SIZE 32 + +/* + * More memory makes pin_user_pages() and the batching more efficient, but as + * this is only a performance optimization don't try too hard to get it. A 64k + * allocation can hold about 26M of 4k pages and 13G of 2M pages in an + * pfn_batch. Various destroy paths cannot fail and provide a small amount of + * stack memory as a backup contingency. If backup_len is given this cannot + * fail. + */ +static void *temp_kmalloc(size_t *size, void *backup, size_t backup_len) +{ + void *res; + + if (WARN_ON(*size == 0)) + return NULL; + + if (*size < backup_len) + return backup; + + if (!backup && iommufd_should_fail()) + return NULL; + + *size = min_t(size_t, *size, TEMP_MEMORY_LIMIT); + res = kmalloc(*size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY); + if (res) + return res; + *size = PAGE_SIZE; + if (backup_len) { + res = kmalloc(*size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY); + if (res) + return res; + *size = backup_len; + return backup; + } + return kmalloc(*size, GFP_KERNEL); +} + +void interval_tree_double_span_iter_update( + struct interval_tree_double_span_iter *iter) +{ + unsigned long last_hole = ULONG_MAX; + unsigned int i; + + for (i = 0; i != ARRAY_SIZE(iter->spans); i++) { + if (interval_tree_span_iter_done(&iter->spans[i])) { + iter->is_used = -1; + return; + } + + if (iter->spans[i].is_hole) { + last_hole = min(last_hole, iter->spans[i].last_hole); + continue; + } + + iter->is_used = i + 1; + iter->start_used = iter->spans[i].start_used; + iter->last_used = min(iter->spans[i].last_used, last_hole); + return; + } + + iter->is_used = 0; + iter->start_hole = iter->spans[0].start_hole; + iter->last_hole = + min(iter->spans[0].last_hole, iter->spans[1].last_hole); +} + +void interval_tree_double_span_iter_first( + struct interval_tree_double_span_iter *iter, + struct rb_root_cached *itree1, struct rb_root_cached *itree2, + unsigned long first_index, unsigned long last_index) +{ + unsigned int i; + + iter->itrees[0] = itree1; + iter->itrees[1] = itree2; + for (i = 0; i != ARRAY_SIZE(iter->spans); i++) + interval_tree_span_iter_first(&iter->spans[i], iter->itrees[i], + first_index, last_index); + interval_tree_double_span_iter_update(iter); +} + +void interval_tree_double_span_iter_next( + struct interval_tree_double_span_iter *iter) +{ + unsigned int i; + + if (iter->is_used == -1 || + iter->last_hole == iter->spans[0].last_index) { + iter->is_used = -1; + return; + } + + for (i = 0; i != ARRAY_SIZE(iter->spans); i++) + interval_tree_span_iter_advance( + &iter->spans[i], iter->itrees[i], iter->last_hole + 1); + interval_tree_double_span_iter_update(iter); +} + +static void iopt_pages_add_npinned(struct iopt_pages *pages, size_t npages) +{ + int rc; + + rc = check_add_overflow(pages->npinned, npages, &pages->npinned); + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(rc || pages->npinned > pages->npages); +} + +static void iopt_pages_sub_npinned(struct iopt_pages *pages, size_t npages) +{ + int rc; + + rc = check_sub_overflow(pages->npinned, npages, &pages->npinned); + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(rc || pages->npinned > pages->npages); +} + +static void iopt_pages_err_unpin(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, + struct page **page_list) +{ + unsigned long npages = last_index - start_index + 1; + + unpin_user_pages(page_list, npages); + iopt_pages_sub_npinned(pages, npages); +} + +/* + * index is the number of PAGE_SIZE units from the start of the area's + * iopt_pages. If the iova is sub page-size then the area has an iova that + * covers a portion of the first and last pages in the range. + */ +static unsigned long iopt_area_index_to_iova(struct iopt_area *area, + unsigned long index) +{ + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(index < iopt_area_index(area) || + index > iopt_area_last_index(area)); + index -= iopt_area_index(area); + if (index == 0) + return iopt_area_iova(area); + return iopt_area_iova(area) - area->page_offset + index * PAGE_SIZE; +} + +static unsigned long iopt_area_index_to_iova_last(struct iopt_area *area, + unsigned long index) +{ + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(index < iopt_area_index(area) || + index > iopt_area_last_index(area)); + if (index == iopt_area_last_index(area)) + return iopt_area_last_iova(area); + return iopt_area_iova(area) - area->page_offset + + (index - iopt_area_index(area) + 1) * PAGE_SIZE - 1; +} + +static void iommu_unmap_nofail(struct iommu_domain *domain, unsigned long iova, + size_t size) +{ + size_t ret; + + ret = iommu_unmap(domain, iova, size); + /* + * It is a logic error in this code or a driver bug if the IOMMU unmaps + * something other than exactly as requested. This implies that the + * iommu driver may not fail unmap for reasons beyond bad agruments. + * Particularly, the iommu driver may not do a memory allocation on the + * unmap path. + */ + WARN_ON(ret != size); +} + +static void iopt_area_unmap_domain_range(struct iopt_area *area, + struct iommu_domain *domain, + unsigned long start_index, + unsigned long last_index) +{ + unsigned long start_iova = iopt_area_index_to_iova(area, start_index); + + iommu_unmap_nofail(domain, start_iova, + iopt_area_index_to_iova_last(area, last_index) - + start_iova + 1); +} + +static struct iopt_area *iopt_pages_find_domain_area(struct iopt_pages *pages, + unsigned long index) +{ + struct interval_tree_node *node; + + node = interval_tree_iter_first(&pages->domains_itree, index, index); + if (!node) + return NULL; + return container_of(node, struct iopt_area, pages_node); +} + +/* + * A simple datastructure to hold a vector of PFNs, optimized for contiguous + * PFNs. This is used as a temporary holding memory for shuttling pfns from one + * place to another. Generally everything is made more efficient if operations + * work on the largest possible grouping of pfns. eg fewer lock/unlock cycles, + * better cache locality, etc + */ +struct pfn_batch { + unsigned long *pfns; + u32 *npfns; + unsigned int array_size; + unsigned int end; + unsigned int total_pfns; +}; + +static void batch_clear(struct pfn_batch *batch) +{ + batch->total_pfns = 0; + batch->end = 0; + batch->pfns[0] = 0; + batch->npfns[0] = 0; +} + +/* + * Carry means we carry a portion of the final hugepage over to the front of the + * batch + */ +static void batch_clear_carry(struct pfn_batch *batch, unsigned int keep_pfns) +{ + if (!keep_pfns) + return batch_clear(batch); + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(!batch->end || + batch->npfns[batch->end - 1] < keep_pfns); + + batch->total_pfns = keep_pfns; + batch->pfns[0] = batch->pfns[batch->end - 1] + + (batch->npfns[batch->end - 1] - keep_pfns); + batch->npfns[0] = keep_pfns; + batch->end = 1; +} + +static void batch_skip_carry(struct pfn_batch *batch, unsigned int skip_pfns) +{ + if (!batch->total_pfns) + return; + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(batch->total_pfns != batch->npfns[0]); + skip_pfns = min(batch->total_pfns, skip_pfns); + batch->pfns[0] += skip_pfns; + batch->npfns[0] -= skip_pfns; + batch->total_pfns -= skip_pfns; +} + +static int __batch_init(struct pfn_batch *batch, size_t max_pages, void *backup, + size_t backup_len) +{ + const size_t elmsz = sizeof(*batch->pfns) + sizeof(*batch->npfns); + size_t size = max_pages * elmsz; + + batch->pfns = temp_kmalloc(&size, backup, backup_len); + if (!batch->pfns) + return -ENOMEM; + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && WARN_ON(size < elmsz)) + return -EINVAL; + batch->array_size = size / elmsz; + batch->npfns = (u32 *)(batch->pfns + batch->array_size); + batch_clear(batch); + return 0; +} + +static int batch_init(struct pfn_batch *batch, size_t max_pages) +{ + return __batch_init(batch, max_pages, NULL, 0); +} + +static void batch_init_backup(struct pfn_batch *batch, size_t max_pages, + void *backup, size_t backup_len) +{ + __batch_init(batch, max_pages, backup, backup_len); +} + +static void batch_destroy(struct pfn_batch *batch, void *backup) +{ + if (batch->pfns != backup) + kfree(batch->pfns); +} + +/* true if the pfn was added, false otherwise */ +static bool batch_add_pfn(struct pfn_batch *batch, unsigned long pfn) +{ + const unsigned int MAX_NPFNS = type_max(typeof(*batch->npfns)); + + if (batch->end && + pfn == batch->pfns[batch->end - 1] + batch->npfns[batch->end - 1] && + batch->npfns[batch->end - 1] != MAX_NPFNS) { + batch->npfns[batch->end - 1]++; + batch->total_pfns++; + return true; + } + if (batch->end == batch->array_size) + return false; + batch->total_pfns++; + batch->pfns[batch->end] = pfn; + batch->npfns[batch->end] = 1; + batch->end++; + return true; +} + +/* + * Fill the batch with pfns from the domain. When the batch is full, or it + * reaches last_index, the function will return. The caller should use + * batch->total_pfns to determine the starting point for the next iteration. + */ +static void batch_from_domain(struct pfn_batch *batch, + struct iommu_domain *domain, + struct iopt_area *area, unsigned long start_index, + unsigned long last_index) +{ + unsigned int page_offset = 0; + unsigned long iova; + phys_addr_t phys; + + iova = iopt_area_index_to_iova(area, start_index); + if (start_index == iopt_area_index(area)) + page_offset = area->page_offset; + while (start_index <= last_index) { + /* + * This is pretty slow, it would be nice to get the page size + * back from the driver, or have the driver directly fill the + * batch. + */ + phys = iommu_iova_to_phys(domain, iova) - page_offset; + if (!batch_add_pfn(batch, PHYS_PFN(phys))) + return; + iova += PAGE_SIZE - page_offset; + page_offset = 0; + start_index++; + } +} + +static struct page **raw_pages_from_domain(struct iommu_domain *domain, + struct iopt_area *area, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + unsigned int page_offset = 0; + unsigned long iova; + phys_addr_t phys; + + iova = iopt_area_index_to_iova(area, start_index); + if (start_index == iopt_area_index(area)) + page_offset = area->page_offset; + while (start_index <= last_index) { + phys = iommu_iova_to_phys(domain, iova) - page_offset; + *(out_pages++) = pfn_to_page(PHYS_PFN(phys)); + iova += PAGE_SIZE - page_offset; + page_offset = 0; + start_index++; + } + return out_pages; +} + +/* Continues reading a domain until we reach a discontinuity in the pfns. */ +static void batch_from_domain_continue(struct pfn_batch *batch, + struct iommu_domain *domain, + struct iopt_area *area, + unsigned long start_index, + unsigned long last_index) +{ + unsigned int array_size = batch->array_size; + + batch->array_size = batch->end; + batch_from_domain(batch, domain, area, start_index, last_index); + batch->array_size = array_size; +} + +/* + * This is part of the VFIO compatibility support for VFIO_TYPE1_IOMMU. That + * mode permits splitting a mapped area up, and then one of the splits is + * unmapped. Doing this normally would cause us to violate our invariant of + * pairing map/unmap. Thus, to support old VFIO compatibility disable support + * for batching consecutive PFNs. All PFNs mapped into the iommu are done in + * PAGE_SIZE units, not larger or smaller. + */ +static int batch_iommu_map_small(struct iommu_domain *domain, + unsigned long iova, phys_addr_t paddr, + size_t size, int prot) +{ + unsigned long start_iova = iova; + int rc; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(paddr % PAGE_SIZE || iova % PAGE_SIZE || + size % PAGE_SIZE); + + while (size) { + rc = iommu_map(domain, iova, paddr, PAGE_SIZE, prot, + GFP_KERNEL_ACCOUNT); + if (rc) + goto err_unmap; + iova += PAGE_SIZE; + paddr += PAGE_SIZE; + size -= PAGE_SIZE; + } + return 0; + +err_unmap: + if (start_iova != iova) + iommu_unmap_nofail(domain, start_iova, iova - start_iova); + return rc; +} + +static int batch_to_domain(struct pfn_batch *batch, struct iommu_domain *domain, + struct iopt_area *area, unsigned long start_index) +{ + bool disable_large_pages = area->iopt->disable_large_pages; + unsigned long last_iova = iopt_area_last_iova(area); + unsigned int page_offset = 0; + unsigned long start_iova; + unsigned long next_iova; + unsigned int cur = 0; + unsigned long iova; + int rc; + + /* The first index might be a partial page */ + if (start_index == iopt_area_index(area)) + page_offset = area->page_offset; + next_iova = iova = start_iova = + iopt_area_index_to_iova(area, start_index); + while (cur < batch->end) { + next_iova = min(last_iova + 1, + next_iova + batch->npfns[cur] * PAGE_SIZE - + page_offset); + if (disable_large_pages) + rc = batch_iommu_map_small( + domain, iova, + PFN_PHYS(batch->pfns[cur]) + page_offset, + next_iova - iova, area->iommu_prot); + else + rc = iommu_map(domain, iova, + PFN_PHYS(batch->pfns[cur]) + page_offset, + next_iova - iova, area->iommu_prot, + GFP_KERNEL_ACCOUNT); + if (rc) + goto err_unmap; + iova = next_iova; + page_offset = 0; + cur++; + } + return 0; +err_unmap: + if (start_iova != iova) + iommu_unmap_nofail(domain, start_iova, iova - start_iova); + return rc; +} + +static void batch_from_xarray(struct pfn_batch *batch, struct xarray *xa, + unsigned long start_index, + unsigned long last_index) +{ + XA_STATE(xas, xa, start_index); + void *entry; + + rcu_read_lock(); + while (true) { + entry = xas_next(&xas); + if (xas_retry(&xas, entry)) + continue; + WARN_ON(!xa_is_value(entry)); + if (!batch_add_pfn(batch, xa_to_value(entry)) || + start_index == last_index) + break; + start_index++; + } + rcu_read_unlock(); +} + +static void batch_from_xarray_clear(struct pfn_batch *batch, struct xarray *xa, + unsigned long start_index, + unsigned long last_index) +{ + XA_STATE(xas, xa, start_index); + void *entry; + + xas_lock(&xas); + while (true) { + entry = xas_next(&xas); + if (xas_retry(&xas, entry)) + continue; + WARN_ON(!xa_is_value(entry)); + if (!batch_add_pfn(batch, xa_to_value(entry))) + break; + xas_store(&xas, NULL); + if (start_index == last_index) + break; + start_index++; + } + xas_unlock(&xas); +} + +static void clear_xarray(struct xarray *xa, unsigned long start_index, + unsigned long last_index) +{ + XA_STATE(xas, xa, start_index); + void *entry; + + xas_lock(&xas); + xas_for_each(&xas, entry, last_index) + xas_store(&xas, NULL); + xas_unlock(&xas); +} + +static int pages_to_xarray(struct xarray *xa, unsigned long start_index, + unsigned long last_index, struct page **pages) +{ + struct page **end_pages = pages + (last_index - start_index) + 1; + struct page **half_pages = pages + (end_pages - pages) / 2; + XA_STATE(xas, xa, start_index); + + do { + void *old; + + xas_lock(&xas); + while (pages != end_pages) { + /* xarray does not participate in fault injection */ + if (pages == half_pages && iommufd_should_fail()) { + xas_set_err(&xas, -EINVAL); + xas_unlock(&xas); + /* aka xas_destroy() */ + xas_nomem(&xas, GFP_KERNEL); + goto err_clear; + } + + old = xas_store(&xas, xa_mk_value(page_to_pfn(*pages))); + if (xas_error(&xas)) + break; + WARN_ON(old); + pages++; + xas_next(&xas); + } + xas_unlock(&xas); + } while (xas_nomem(&xas, GFP_KERNEL)); + +err_clear: + if (xas_error(&xas)) { + if (xas.xa_index != start_index) + clear_xarray(xa, start_index, xas.xa_index - 1); + return xas_error(&xas); + } + return 0; +} + +static void batch_from_pages(struct pfn_batch *batch, struct page **pages, + size_t npages) +{ + struct page **end = pages + npages; + + for (; pages != end; pages++) + if (!batch_add_pfn(batch, page_to_pfn(*pages))) + break; +} + +static void batch_unpin(struct pfn_batch *batch, struct iopt_pages *pages, + unsigned int first_page_off, size_t npages) +{ + unsigned int cur = 0; + + while (first_page_off) { + if (batch->npfns[cur] > first_page_off) + break; + first_page_off -= batch->npfns[cur]; + cur++; + } + + while (npages) { + size_t to_unpin = min_t(size_t, npages, + batch->npfns[cur] - first_page_off); + + unpin_user_page_range_dirty_lock( + pfn_to_page(batch->pfns[cur] + first_page_off), + to_unpin, pages->writable); + iopt_pages_sub_npinned(pages, to_unpin); + cur++; + first_page_off = 0; + npages -= to_unpin; + } +} + +static void copy_data_page(struct page *page, void *data, unsigned long offset, + size_t length, unsigned int flags) +{ + void *mem; + + mem = kmap_local_page(page); + if (flags & IOMMUFD_ACCESS_RW_WRITE) { + memcpy(mem + offset, data, length); + set_page_dirty_lock(page); + } else { + memcpy(data, mem + offset, length); + } + kunmap_local(mem); +} + +static unsigned long batch_rw(struct pfn_batch *batch, void *data, + unsigned long offset, unsigned long length, + unsigned int flags) +{ + unsigned long copied = 0; + unsigned int npage = 0; + unsigned int cur = 0; + + while (cur < batch->end) { + unsigned long bytes = min(length, PAGE_SIZE - offset); + + copy_data_page(pfn_to_page(batch->pfns[cur] + npage), data, + offset, bytes, flags); + offset = 0; + length -= bytes; + data += bytes; + copied += bytes; + npage++; + if (npage == batch->npfns[cur]) { + npage = 0; + cur++; + } + if (!length) + break; + } + return copied; +} + +/* pfn_reader_user is just the pin_user_pages() path */ +struct pfn_reader_user { + struct page **upages; + size_t upages_len; + unsigned long upages_start; + unsigned long upages_end; + unsigned int gup_flags; + /* + * 1 means mmget() and mmap_read_lock(), 0 means only mmget(), -1 is + * neither + */ + int locked; +}; + +static void pfn_reader_user_init(struct pfn_reader_user *user, + struct iopt_pages *pages) +{ + user->upages = NULL; + user->upages_start = 0; + user->upages_end = 0; + user->locked = -1; + + user->gup_flags = FOLL_LONGTERM; + if (pages->writable) + user->gup_flags |= FOLL_WRITE; +} + +static void pfn_reader_user_destroy(struct pfn_reader_user *user, + struct iopt_pages *pages) +{ + if (user->locked != -1) { + if (user->locked) + mmap_read_unlock(pages->source_mm); + if (pages->source_mm != current->mm) + mmput(pages->source_mm); + user->locked = -1; + } + + kfree(user->upages); + user->upages = NULL; +} + +static int pfn_reader_user_pin(struct pfn_reader_user *user, + struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index) +{ + bool remote_mm = pages->source_mm != current->mm; + unsigned long npages; + uintptr_t uptr; + long rc; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + WARN_ON(last_index < start_index)) + return -EINVAL; + + if (!user->upages) { + /* All undone in pfn_reader_destroy() */ + user->upages_len = + (last_index - start_index + 1) * sizeof(*user->upages); + user->upages = temp_kmalloc(&user->upages_len, NULL, 0); + if (!user->upages) + return -ENOMEM; + } + + if (user->locked == -1) { + /* + * The majority of usages will run the map task within the mm + * providing the pages, so we can optimize into + * get_user_pages_fast() + */ + if (remote_mm) { + if (!mmget_not_zero(pages->source_mm)) + return -EFAULT; + } + user->locked = 0; + } + + npages = min_t(unsigned long, last_index - start_index + 1, + user->upages_len / sizeof(*user->upages)); + + + if (iommufd_should_fail()) + return -EFAULT; + + uptr = (uintptr_t)(pages->uptr + start_index * PAGE_SIZE); + if (!remote_mm) + rc = pin_user_pages_fast(uptr, npages, user->gup_flags, + user->upages); + else { + if (!user->locked) { + mmap_read_lock(pages->source_mm); + user->locked = 1; + } + rc = pin_user_pages_remote(pages->source_mm, uptr, npages, + user->gup_flags, user->upages, + &user->locked); + } + if (rc <= 0) { + if (WARN_ON(!rc)) + return -EFAULT; + return rc; + } + iopt_pages_add_npinned(pages, rc); + user->upages_start = start_index; + user->upages_end = start_index + rc; + return 0; +} + +/* This is the "modern" and faster accounting method used by io_uring */ +static int incr_user_locked_vm(struct iopt_pages *pages, unsigned long npages) +{ + unsigned long lock_limit; + unsigned long cur_pages; + unsigned long new_pages; + + lock_limit = task_rlimit(pages->source_task, RLIMIT_MEMLOCK) >> + PAGE_SHIFT; + do { + cur_pages = atomic_long_read(&pages->source_user->locked_vm); + new_pages = cur_pages + npages; + if (new_pages > lock_limit) + return -ENOMEM; + } while (atomic_long_cmpxchg(&pages->source_user->locked_vm, cur_pages, + new_pages) != cur_pages); + return 0; +} + +static void decr_user_locked_vm(struct iopt_pages *pages, unsigned long npages) +{ + if (WARN_ON(atomic_long_read(&pages->source_user->locked_vm) < npages)) + return; + atomic_long_sub(npages, &pages->source_user->locked_vm); +} + +/* This is the accounting method used for compatibility with VFIO */ +static int update_mm_locked_vm(struct iopt_pages *pages, unsigned long npages, + bool inc, struct pfn_reader_user *user) +{ + bool do_put = false; + int rc; + + if (user && user->locked) { + mmap_read_unlock(pages->source_mm); + user->locked = 0; + /* If we had the lock then we also have a get */ + } else if ((!user || !user->upages) && + pages->source_mm != current->mm) { + if (!mmget_not_zero(pages->source_mm)) + return -EINVAL; + do_put = true; + } + + mmap_write_lock(pages->source_mm); + rc = __account_locked_vm(pages->source_mm, npages, inc, + pages->source_task, false); + mmap_write_unlock(pages->source_mm); + + if (do_put) + mmput(pages->source_mm); + return rc; +} + +static int do_update_pinned(struct iopt_pages *pages, unsigned long npages, + bool inc, struct pfn_reader_user *user) +{ + int rc = 0; + + switch (pages->account_mode) { + case IOPT_PAGES_ACCOUNT_NONE: + break; + case IOPT_PAGES_ACCOUNT_USER: + if (inc) + rc = incr_user_locked_vm(pages, npages); + else + decr_user_locked_vm(pages, npages); + break; + case IOPT_PAGES_ACCOUNT_MM: + rc = update_mm_locked_vm(pages, npages, inc, user); + break; + } + if (rc) + return rc; + + pages->last_npinned = pages->npinned; + if (inc) + atomic64_add(npages, &pages->source_mm->pinned_vm); + else + atomic64_sub(npages, &pages->source_mm->pinned_vm); + return 0; +} + +static void update_unpinned(struct iopt_pages *pages) +{ + if (WARN_ON(pages->npinned > pages->last_npinned)) + return; + if (pages->npinned == pages->last_npinned) + return; + do_update_pinned(pages, pages->last_npinned - pages->npinned, false, + NULL); +} + +/* + * Changes in the number of pages pinned is done after the pages have been read + * and processed. If the user lacked the limit then the error unwind will unpin + * everything that was just pinned. This is because it is expensive to calculate + * how many pages we have already pinned within a range to generate an accurate + * prediction in advance of doing the work to actually pin them. + */ +static int pfn_reader_user_update_pinned(struct pfn_reader_user *user, + struct iopt_pages *pages) +{ + unsigned long npages; + bool inc; + + lockdep_assert_held(&pages->mutex); + + if (pages->npinned == pages->last_npinned) + return 0; + + if (pages->npinned < pages->last_npinned) { + npages = pages->last_npinned - pages->npinned; + inc = false; + } else { + if (iommufd_should_fail()) + return -ENOMEM; + npages = pages->npinned - pages->last_npinned; + inc = true; + } + return do_update_pinned(pages, npages, inc, user); +} + +/* + * PFNs are stored in three places, in order of preference: + * - The iopt_pages xarray. This is only populated if there is a + * iopt_pages_access + * - The iommu_domain under an area + * - The original PFN source, ie pages->source_mm + * + * This iterator reads the pfns optimizing to load according to the + * above order. + */ +struct pfn_reader { + struct iopt_pages *pages; + struct interval_tree_double_span_iter span; + struct pfn_batch batch; + unsigned long batch_start_index; + unsigned long batch_end_index; + unsigned long last_index; + + struct pfn_reader_user user; +}; + +static int pfn_reader_update_pinned(struct pfn_reader *pfns) +{ + return pfn_reader_user_update_pinned(&pfns->user, pfns->pages); +} + +/* + * The batch can contain a mixture of pages that are still in use and pages that + * need to be unpinned. Unpin only pages that are not held anywhere else. + */ +static void pfn_reader_unpin(struct pfn_reader *pfns) +{ + unsigned long last = pfns->batch_end_index - 1; + unsigned long start = pfns->batch_start_index; + struct interval_tree_double_span_iter span; + struct iopt_pages *pages = pfns->pages; + + lockdep_assert_held(&pages->mutex); + + interval_tree_for_each_double_span(&span, &pages->access_itree, + &pages->domains_itree, start, last) { + if (span.is_used) + continue; + + batch_unpin(&pfns->batch, pages, span.start_hole - start, + span.last_hole - span.start_hole + 1); + } +} + +/* Process a single span to load it from the proper storage */ +static int pfn_reader_fill_span(struct pfn_reader *pfns) +{ + struct interval_tree_double_span_iter *span = &pfns->span; + unsigned long start_index = pfns->batch_end_index; + struct iopt_area *area; + int rc; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + WARN_ON(span->last_used < start_index)) + return -EINVAL; + + if (span->is_used == 1) { + batch_from_xarray(&pfns->batch, &pfns->pages->pinned_pfns, + start_index, span->last_used); + return 0; + } + + if (span->is_used == 2) { + /* + * Pull as many pages from the first domain we find in the + * target span. If it is too small then we will be called again + * and we'll find another area. + */ + area = iopt_pages_find_domain_area(pfns->pages, start_index); + if (WARN_ON(!area)) + return -EINVAL; + + /* The storage_domain cannot change without the pages mutex */ + batch_from_domain( + &pfns->batch, area->storage_domain, area, start_index, + min(iopt_area_last_index(area), span->last_used)); + return 0; + } + + if (start_index >= pfns->user.upages_end) { + rc = pfn_reader_user_pin(&pfns->user, pfns->pages, start_index, + span->last_hole); + if (rc) + return rc; + } + + batch_from_pages(&pfns->batch, + pfns->user.upages + + (start_index - pfns->user.upages_start), + pfns->user.upages_end - start_index); + return 0; +} + +static bool pfn_reader_done(struct pfn_reader *pfns) +{ + return pfns->batch_start_index == pfns->last_index + 1; +} + +static int pfn_reader_next(struct pfn_reader *pfns) +{ + int rc; + + batch_clear(&pfns->batch); + pfns->batch_start_index = pfns->batch_end_index; + + while (pfns->batch_end_index != pfns->last_index + 1) { + unsigned int npfns = pfns->batch.total_pfns; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + WARN_ON(interval_tree_double_span_iter_done(&pfns->span))) + return -EINVAL; + + rc = pfn_reader_fill_span(pfns); + if (rc) + return rc; + + if (WARN_ON(!pfns->batch.total_pfns)) + return -EINVAL; + + pfns->batch_end_index = + pfns->batch_start_index + pfns->batch.total_pfns; + if (pfns->batch_end_index == pfns->span.last_used + 1) + interval_tree_double_span_iter_next(&pfns->span); + + /* Batch is full */ + if (npfns == pfns->batch.total_pfns) + return 0; + } + return 0; +} + +static int pfn_reader_init(struct pfn_reader *pfns, struct iopt_pages *pages, + unsigned long start_index, unsigned long last_index) +{ + int rc; + + lockdep_assert_held(&pages->mutex); + + pfns->pages = pages; + pfns->batch_start_index = start_index; + pfns->batch_end_index = start_index; + pfns->last_index = last_index; + pfn_reader_user_init(&pfns->user, pages); + rc = batch_init(&pfns->batch, last_index - start_index + 1); + if (rc) + return rc; + interval_tree_double_span_iter_first(&pfns->span, &pages->access_itree, + &pages->domains_itree, start_index, + last_index); + return 0; +} + +/* + * There are many assertions regarding the state of pages->npinned vs + * pages->last_pinned, for instance something like unmapping a domain must only + * decrement the npinned, and pfn_reader_destroy() must be called only after all + * the pins are updated. This is fine for success flows, but error flows + * sometimes need to release the pins held inside the pfn_reader before going on + * to complete unmapping and releasing pins held in domains. + */ +static void pfn_reader_release_pins(struct pfn_reader *pfns) +{ + struct iopt_pages *pages = pfns->pages; + + if (pfns->user.upages_end > pfns->batch_end_index) { + size_t npages = pfns->user.upages_end - pfns->batch_end_index; + + /* Any pages not transferred to the batch are just unpinned */ + unpin_user_pages(pfns->user.upages + (pfns->batch_end_index - + pfns->user.upages_start), + npages); + iopt_pages_sub_npinned(pages, npages); + pfns->user.upages_end = pfns->batch_end_index; + } + if (pfns->batch_start_index != pfns->batch_end_index) { + pfn_reader_unpin(pfns); + pfns->batch_start_index = pfns->batch_end_index; + } +} + +static void pfn_reader_destroy(struct pfn_reader *pfns) +{ + struct iopt_pages *pages = pfns->pages; + + pfn_reader_release_pins(pfns); + pfn_reader_user_destroy(&pfns->user, pfns->pages); + batch_destroy(&pfns->batch, NULL); + WARN_ON(pages->last_npinned != pages->npinned); +} + +static int pfn_reader_first(struct pfn_reader *pfns, struct iopt_pages *pages, + unsigned long start_index, unsigned long last_index) +{ + int rc; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + WARN_ON(last_index < start_index)) + return -EINVAL; + + rc = pfn_reader_init(pfns, pages, start_index, last_index); + if (rc) + return rc; + rc = pfn_reader_next(pfns); + if (rc) { + pfn_reader_destroy(pfns); + return rc; + } + return 0; +} + +struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length, + bool writable) +{ + struct iopt_pages *pages; + unsigned long end; + + /* + * The iommu API uses size_t as the length, and protect the DIV_ROUND_UP + * below from overflow + */ + if (length > SIZE_MAX - PAGE_SIZE || length == 0) + return ERR_PTR(-EINVAL); + + if (check_add_overflow((unsigned long)uptr, length, &end)) + return ERR_PTR(-EOVERFLOW); + + pages = kzalloc(sizeof(*pages), GFP_KERNEL_ACCOUNT); + if (!pages) + return ERR_PTR(-ENOMEM); + + kref_init(&pages->kref); + xa_init_flags(&pages->pinned_pfns, XA_FLAGS_ACCOUNT); + mutex_init(&pages->mutex); + pages->source_mm = current->mm; + mmgrab(pages->source_mm); + pages->uptr = (void __user *)ALIGN_DOWN((uintptr_t)uptr, PAGE_SIZE); + pages->npages = DIV_ROUND_UP(length + (uptr - pages->uptr), PAGE_SIZE); + pages->access_itree = RB_ROOT_CACHED; + pages->domains_itree = RB_ROOT_CACHED; + pages->writable = writable; + if (capable(CAP_IPC_LOCK)) + pages->account_mode = IOPT_PAGES_ACCOUNT_NONE; + else + pages->account_mode = IOPT_PAGES_ACCOUNT_USER; + pages->source_task = current->group_leader; + get_task_struct(current->group_leader); + pages->source_user = get_uid(current_user()); + return pages; +} + +void iopt_release_pages(struct kref *kref) +{ + struct iopt_pages *pages = container_of(kref, struct iopt_pages, kref); + + WARN_ON(!RB_EMPTY_ROOT(&pages->access_itree.rb_root)); + WARN_ON(!RB_EMPTY_ROOT(&pages->domains_itree.rb_root)); + WARN_ON(pages->npinned); + WARN_ON(!xa_empty(&pages->pinned_pfns)); + mmdrop(pages->source_mm); + mutex_destroy(&pages->mutex); + put_task_struct(pages->source_task); + free_uid(pages->source_user); + kfree(pages); +} + +static void +iopt_area_unpin_domain(struct pfn_batch *batch, struct iopt_area *area, + struct iopt_pages *pages, struct iommu_domain *domain, + unsigned long start_index, unsigned long last_index, + unsigned long *unmapped_end_index, + unsigned long real_last_index) +{ + while (start_index <= last_index) { + unsigned long batch_last_index; + + if (*unmapped_end_index <= last_index) { + unsigned long start = + max(start_index, *unmapped_end_index); + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + batch->total_pfns) + WARN_ON(*unmapped_end_index - + batch->total_pfns != + start_index); + batch_from_domain(batch, domain, area, start, + last_index); + batch_last_index = start_index + batch->total_pfns - 1; + } else { + batch_last_index = last_index; + } + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(batch_last_index > real_last_index); + + /* + * unmaps must always 'cut' at a place where the pfns are not + * contiguous to pair with the maps that always install + * contiguous pages. Thus, if we have to stop unpinning in the + * middle of the domains we need to keep reading pfns until we + * find a cut point to do the unmap. The pfns we read are + * carried over and either skipped or integrated into the next + * batch. + */ + if (batch_last_index == last_index && + last_index != real_last_index) + batch_from_domain_continue(batch, domain, area, + last_index + 1, + real_last_index); + + if (*unmapped_end_index <= batch_last_index) { + iopt_area_unmap_domain_range( + area, domain, *unmapped_end_index, + start_index + batch->total_pfns - 1); + *unmapped_end_index = start_index + batch->total_pfns; + } + + /* unpin must follow unmap */ + batch_unpin(batch, pages, 0, + batch_last_index - start_index + 1); + start_index = batch_last_index + 1; + + batch_clear_carry(batch, + *unmapped_end_index - batch_last_index - 1); + } +} + +static void __iopt_area_unfill_domain(struct iopt_area *area, + struct iopt_pages *pages, + struct iommu_domain *domain, + unsigned long last_index) +{ + struct interval_tree_double_span_iter span; + unsigned long start_index = iopt_area_index(area); + unsigned long unmapped_end_index = start_index; + u64 backup[BATCH_BACKUP_SIZE]; + struct pfn_batch batch; + + lockdep_assert_held(&pages->mutex); + + /* + * For security we must not unpin something that is still DMA mapped, + * so this must unmap any IOVA before we go ahead and unpin the pages. + * This creates a complexity where we need to skip over unpinning pages + * held in the xarray, but continue to unmap from the domain. + * + * The domain unmap cannot stop in the middle of a contiguous range of + * PFNs. To solve this problem the unpinning step will read ahead to the + * end of any contiguous span, unmap that whole span, and then only + * unpin the leading part that does not have any accesses. The residual + * PFNs that were unmapped but not unpinned are called a "carry" in the + * batch as they are moved to the front of the PFN list and continue on + * to the next iteration(s). + */ + batch_init_backup(&batch, last_index + 1, backup, sizeof(backup)); + interval_tree_for_each_double_span(&span, &pages->domains_itree, + &pages->access_itree, start_index, + last_index) { + if (span.is_used) { + batch_skip_carry(&batch, + span.last_used - span.start_used + 1); + continue; + } + iopt_area_unpin_domain(&batch, area, pages, domain, + span.start_hole, span.last_hole, + &unmapped_end_index, last_index); + } + /* + * If the range ends in a access then we do the residual unmap without + * any unpins. + */ + if (unmapped_end_index != last_index + 1) + iopt_area_unmap_domain_range(area, domain, unmapped_end_index, + last_index); + WARN_ON(batch.total_pfns); + batch_destroy(&batch, backup); + update_unpinned(pages); +} + +static void iopt_area_unfill_partial_domain(struct iopt_area *area, + struct iopt_pages *pages, + struct iommu_domain *domain, + unsigned long end_index) +{ + if (end_index != iopt_area_index(area)) + __iopt_area_unfill_domain(area, pages, domain, end_index - 1); +} + +/** + * iopt_area_unmap_domain() - Unmap without unpinning PFNs in a domain + * @area: The IOVA range to unmap + * @domain: The domain to unmap + * + * The caller must know that unpinning is not required, usually because there + * are other domains in the iopt. + */ +void iopt_area_unmap_domain(struct iopt_area *area, struct iommu_domain *domain) +{ + iommu_unmap_nofail(domain, iopt_area_iova(area), + iopt_area_length(area)); +} + +/** + * iopt_area_unfill_domain() - Unmap and unpin PFNs in a domain + * @area: IOVA area to use + * @pages: page supplier for the area (area->pages is NULL) + * @domain: Domain to unmap from + * + * The domain should be removed from the domains_itree before calling. The + * domain will always be unmapped, but the PFNs may not be unpinned if there are + * still accesses. + */ +void iopt_area_unfill_domain(struct iopt_area *area, struct iopt_pages *pages, + struct iommu_domain *domain) +{ + __iopt_area_unfill_domain(area, pages, domain, + iopt_area_last_index(area)); +} + +/** + * iopt_area_fill_domain() - Map PFNs from the area into a domain + * @area: IOVA area to use + * @domain: Domain to load PFNs into + * + * Read the pfns from the area's underlying iopt_pages and map them into the + * given domain. Called when attaching a new domain to an io_pagetable. + */ +int iopt_area_fill_domain(struct iopt_area *area, struct iommu_domain *domain) +{ + unsigned long done_end_index; + struct pfn_reader pfns; + int rc; + + lockdep_assert_held(&area->pages->mutex); + + rc = pfn_reader_first(&pfns, area->pages, iopt_area_index(area), + iopt_area_last_index(area)); + if (rc) + return rc; + + while (!pfn_reader_done(&pfns)) { + done_end_index = pfns.batch_start_index; + rc = batch_to_domain(&pfns.batch, domain, area, + pfns.batch_start_index); + if (rc) + goto out_unmap; + done_end_index = pfns.batch_end_index; + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_unmap; + } + + rc = pfn_reader_update_pinned(&pfns); + if (rc) + goto out_unmap; + goto out_destroy; + +out_unmap: + pfn_reader_release_pins(&pfns); + iopt_area_unfill_partial_domain(area, area->pages, domain, + done_end_index); +out_destroy: + pfn_reader_destroy(&pfns); + return rc; +} + +/** + * iopt_area_fill_domains() - Install PFNs into the area's domains + * @area: The area to act on + * @pages: The pages associated with the area (area->pages is NULL) + * + * Called during area creation. The area is freshly created and not inserted in + * the domains_itree yet. PFNs are read and loaded into every domain held in the + * area's io_pagetable and the area is installed in the domains_itree. + * + * On failure all domains are left unchanged. + */ +int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages) +{ + unsigned long done_first_end_index; + unsigned long done_all_end_index; + struct iommu_domain *domain; + unsigned long unmap_index; + struct pfn_reader pfns; + unsigned long index; + int rc; + + lockdep_assert_held(&area->iopt->domains_rwsem); + + if (xa_empty(&area->iopt->domains)) + return 0; + + mutex_lock(&pages->mutex); + rc = pfn_reader_first(&pfns, pages, iopt_area_index(area), + iopt_area_last_index(area)); + if (rc) + goto out_unlock; + + while (!pfn_reader_done(&pfns)) { + done_first_end_index = pfns.batch_end_index; + done_all_end_index = pfns.batch_start_index; + xa_for_each(&area->iopt->domains, index, domain) { + rc = batch_to_domain(&pfns.batch, domain, area, + pfns.batch_start_index); + if (rc) + goto out_unmap; + } + done_all_end_index = done_first_end_index; + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_unmap; + } + rc = pfn_reader_update_pinned(&pfns); + if (rc) + goto out_unmap; + + area->storage_domain = xa_load(&area->iopt->domains, 0); + interval_tree_insert(&area->pages_node, &pages->domains_itree); + goto out_destroy; + +out_unmap: + pfn_reader_release_pins(&pfns); + xa_for_each(&area->iopt->domains, unmap_index, domain) { + unsigned long end_index; + + if (unmap_index < index) + end_index = done_first_end_index; + else + end_index = done_all_end_index; + + /* + * The area is not yet part of the domains_itree so we have to + * manage the unpinning specially. The last domain does the + * unpin, every other domain is just unmapped. + */ + if (unmap_index != area->iopt->next_domain_id - 1) { + if (end_index != iopt_area_index(area)) + iopt_area_unmap_domain_range( + area, domain, iopt_area_index(area), + end_index - 1); + } else { + iopt_area_unfill_partial_domain(area, pages, domain, + end_index); + } + } +out_destroy: + pfn_reader_destroy(&pfns); +out_unlock: + mutex_unlock(&pages->mutex); + return rc; +} + +/** + * iopt_area_unfill_domains() - unmap PFNs from the area's domains + * @area: The area to act on + * @pages: The pages associated with the area (area->pages is NULL) + * + * Called during area destruction. This unmaps the iova's covered by all the + * area's domains and releases the PFNs. + */ +void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages) +{ + struct io_pagetable *iopt = area->iopt; + struct iommu_domain *domain; + unsigned long index; + + lockdep_assert_held(&iopt->domains_rwsem); + + mutex_lock(&pages->mutex); + if (!area->storage_domain) + goto out_unlock; + + xa_for_each(&iopt->domains, index, domain) + if (domain != area->storage_domain) + iopt_area_unmap_domain_range( + area, domain, iopt_area_index(area), + iopt_area_last_index(area)); + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) + WARN_ON(RB_EMPTY_NODE(&area->pages_node.rb)); + interval_tree_remove(&area->pages_node, &pages->domains_itree); + iopt_area_unfill_domain(area, pages, area->storage_domain); + area->storage_domain = NULL; +out_unlock: + mutex_unlock(&pages->mutex); +} + +static void iopt_pages_unpin_xarray(struct pfn_batch *batch, + struct iopt_pages *pages, + unsigned long start_index, + unsigned long end_index) +{ + while (start_index <= end_index) { + batch_from_xarray_clear(batch, &pages->pinned_pfns, start_index, + end_index); + batch_unpin(batch, pages, 0, batch->total_pfns); + start_index += batch->total_pfns; + batch_clear(batch); + } +} + +/** + * iopt_pages_unfill_xarray() - Update the xarry after removing an access + * @pages: The pages to act on + * @start_index: Starting PFN index + * @last_index: Last PFN index + * + * Called when an iopt_pages_access is removed, removes pages from the itree. + * The access should already be removed from the access_itree. + */ +void iopt_pages_unfill_xarray(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index) +{ + struct interval_tree_double_span_iter span; + u64 backup[BATCH_BACKUP_SIZE]; + struct pfn_batch batch; + bool batch_inited = false; + + lockdep_assert_held(&pages->mutex); + + interval_tree_for_each_double_span(&span, &pages->access_itree, + &pages->domains_itree, start_index, + last_index) { + if (!span.is_used) { + if (!batch_inited) { + batch_init_backup(&batch, + last_index - start_index + 1, + backup, sizeof(backup)); + batch_inited = true; + } + iopt_pages_unpin_xarray(&batch, pages, span.start_hole, + span.last_hole); + } else if (span.is_used == 2) { + /* Covered by a domain */ + clear_xarray(&pages->pinned_pfns, span.start_used, + span.last_used); + } + /* Otherwise covered by an existing access */ + } + if (batch_inited) + batch_destroy(&batch, backup); + update_unpinned(pages); +} + +/** + * iopt_pages_fill_from_xarray() - Fast path for reading PFNs + * @pages: The pages to act on + * @start_index: The first page index in the range + * @last_index: The last page index in the range + * @out_pages: The output array to return the pages + * + * This can be called if the caller is holding a refcount on an + * iopt_pages_access that is known to have already been filled. It quickly reads + * the pages directly from the xarray. + * + * This is part of the SW iommu interface to read pages for in-kernel use. + */ +void iopt_pages_fill_from_xarray(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + XA_STATE(xas, &pages->pinned_pfns, start_index); + void *entry; + + rcu_read_lock(); + while (start_index <= last_index) { + entry = xas_next(&xas); + if (xas_retry(&xas, entry)) + continue; + WARN_ON(!xa_is_value(entry)); + *(out_pages++) = pfn_to_page(xa_to_value(entry)); + start_index++; + } + rcu_read_unlock(); +} + +static int iopt_pages_fill_from_domain(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + while (start_index != last_index + 1) { + unsigned long domain_last; + struct iopt_area *area; + + area = iopt_pages_find_domain_area(pages, start_index); + if (WARN_ON(!area)) + return -EINVAL; + + domain_last = min(iopt_area_last_index(area), last_index); + out_pages = raw_pages_from_domain(area->storage_domain, area, + start_index, domain_last, + out_pages); + start_index = domain_last + 1; + } + return 0; +} + +static int iopt_pages_fill_from_mm(struct iopt_pages *pages, + struct pfn_reader_user *user, + unsigned long start_index, + unsigned long last_index, + struct page **out_pages) +{ + unsigned long cur_index = start_index; + int rc; + + while (cur_index != last_index + 1) { + user->upages = out_pages + (cur_index - start_index); + rc = pfn_reader_user_pin(user, pages, cur_index, last_index); + if (rc) + goto out_unpin; + cur_index = user->upages_end; + } + return 0; + +out_unpin: + if (start_index != cur_index) + iopt_pages_err_unpin(pages, start_index, cur_index - 1, + out_pages); + return rc; +} + +/** + * iopt_pages_fill_xarray() - Read PFNs + * @pages: The pages to act on + * @start_index: The first page index in the range + * @last_index: The last page index in the range + * @out_pages: The output array to return the pages, may be NULL + * + * This populates the xarray and returns the pages in out_pages. As the slow + * path this is able to copy pages from other storage tiers into the xarray. + * + * On failure the xarray is left unchanged. + * + * This is part of the SW iommu interface to read pages for in-kernel use. + */ +int iopt_pages_fill_xarray(struct iopt_pages *pages, unsigned long start_index, + unsigned long last_index, struct page **out_pages) +{ + struct interval_tree_double_span_iter span; + unsigned long xa_end = start_index; + struct pfn_reader_user user; + int rc; + + lockdep_assert_held(&pages->mutex); + + pfn_reader_user_init(&user, pages); + user.upages_len = (last_index - start_index + 1) * sizeof(*out_pages); + interval_tree_for_each_double_span(&span, &pages->access_itree, + &pages->domains_itree, start_index, + last_index) { + struct page **cur_pages; + + if (span.is_used == 1) { + cur_pages = out_pages + (span.start_used - start_index); + iopt_pages_fill_from_xarray(pages, span.start_used, + span.last_used, cur_pages); + continue; + } + + if (span.is_used == 2) { + cur_pages = out_pages + (span.start_used - start_index); + iopt_pages_fill_from_domain(pages, span.start_used, + span.last_used, cur_pages); + rc = pages_to_xarray(&pages->pinned_pfns, + span.start_used, span.last_used, + cur_pages); + if (rc) + goto out_clean_xa; + xa_end = span.last_used + 1; + continue; + } + + /* hole */ + cur_pages = out_pages + (span.start_hole - start_index); + rc = iopt_pages_fill_from_mm(pages, &user, span.start_hole, + span.last_hole, cur_pages); + if (rc) + goto out_clean_xa; + rc = pages_to_xarray(&pages->pinned_pfns, span.start_hole, + span.last_hole, cur_pages); + if (rc) { + iopt_pages_err_unpin(pages, span.start_hole, + span.last_hole, cur_pages); + goto out_clean_xa; + } + xa_end = span.last_hole + 1; + } + rc = pfn_reader_user_update_pinned(&user, pages); + if (rc) + goto out_clean_xa; + user.upages = NULL; + pfn_reader_user_destroy(&user, pages); + return 0; + +out_clean_xa: + if (start_index != xa_end) + iopt_pages_unfill_xarray(pages, start_index, xa_end - 1); + user.upages = NULL; + pfn_reader_user_destroy(&user, pages); + return rc; +} + +/* + * This uses the pfn_reader instead of taking a shortcut by using the mm. It can + * do every scenario and is fully consistent with what an iommu_domain would + * see. + */ +static int iopt_pages_rw_slow(struct iopt_pages *pages, + unsigned long start_index, + unsigned long last_index, unsigned long offset, + void *data, unsigned long length, + unsigned int flags) +{ + struct pfn_reader pfns; + int rc; + + mutex_lock(&pages->mutex); + + rc = pfn_reader_first(&pfns, pages, start_index, last_index); + if (rc) + goto out_unlock; + + while (!pfn_reader_done(&pfns)) { + unsigned long done; + + done = batch_rw(&pfns.batch, data, offset, length, flags); + data += done; + length -= done; + offset = 0; + pfn_reader_unpin(&pfns); + + rc = pfn_reader_next(&pfns); + if (rc) + goto out_destroy; + } + if (WARN_ON(length != 0)) + rc = -EINVAL; +out_destroy: + pfn_reader_destroy(&pfns); +out_unlock: + mutex_unlock(&pages->mutex); + return rc; +} + +/* + * A medium speed path that still allows DMA inconsistencies, but doesn't do any + * memory allocations or interval tree searches. + */ +static int iopt_pages_rw_page(struct iopt_pages *pages, unsigned long index, + unsigned long offset, void *data, + unsigned long length, unsigned int flags) +{ + struct page *page = NULL; + int rc; + + if (!mmget_not_zero(pages->source_mm)) + return iopt_pages_rw_slow(pages, index, index, offset, data, + length, flags); + + if (iommufd_should_fail()) { + rc = -EINVAL; + goto out_mmput; + } + + mmap_read_lock(pages->source_mm); + rc = pin_user_pages_remote( + pages->source_mm, (uintptr_t)(pages->uptr + index * PAGE_SIZE), + 1, (flags & IOMMUFD_ACCESS_RW_WRITE) ? FOLL_WRITE : 0, &page, + NULL); + mmap_read_unlock(pages->source_mm); + if (rc != 1) { + if (WARN_ON(rc >= 0)) + rc = -EINVAL; + goto out_mmput; + } + copy_data_page(page, data, offset, length, flags); + unpin_user_page(page); + rc = 0; + +out_mmput: + mmput(pages->source_mm); + return rc; +} + +/** + * iopt_pages_rw_access - Copy to/from a linear slice of the pages + * @pages: pages to act on + * @start_byte: First byte of pages to copy to/from + * @data: Kernel buffer to get/put the data + * @length: Number of bytes to copy + * @flags: IOMMUFD_ACCESS_RW_* flags + * + * This will find each page in the range, kmap it and then memcpy to/from + * the given kernel buffer. + */ +int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte, + void *data, unsigned long length, unsigned int flags) +{ + unsigned long start_index = start_byte / PAGE_SIZE; + unsigned long last_index = (start_byte + length - 1) / PAGE_SIZE; + bool change_mm = current->mm != pages->source_mm; + int rc = 0; + + if (IS_ENABLED(CONFIG_IOMMUFD_TEST) && + (flags & __IOMMUFD_ACCESS_RW_SLOW_PATH)) + change_mm = true; + + if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) + return -EPERM; + + if (!(flags & IOMMUFD_ACCESS_RW_KTHREAD) && change_mm) { + if (start_index == last_index) + return iopt_pages_rw_page(pages, start_index, + start_byte % PAGE_SIZE, data, + length, flags); + return iopt_pages_rw_slow(pages, start_index, last_index, + start_byte % PAGE_SIZE, data, length, + flags); + } + + /* + * Try to copy using copy_to_user(). We do this as a fast path and + * ignore any pinning inconsistencies, unlike a real DMA path. + */ + if (change_mm) { + if (!mmget_not_zero(pages->source_mm)) + return iopt_pages_rw_slow(pages, start_index, + last_index, + start_byte % PAGE_SIZE, data, + length, flags); + kthread_use_mm(pages->source_mm); + } + + if (flags & IOMMUFD_ACCESS_RW_WRITE) { + if (copy_to_user(pages->uptr + start_byte, data, length)) + rc = -EFAULT; + } else { + if (copy_from_user(data, pages->uptr + start_byte, length)) + rc = -EFAULT; + } + + if (change_mm) { + kthread_unuse_mm(pages->source_mm); + mmput(pages->source_mm); + } + + return rc; +} + +static struct iopt_pages_access * +iopt_pages_get_exact_access(struct iopt_pages *pages, unsigned long index, + unsigned long last) +{ + struct interval_tree_node *node; + + lockdep_assert_held(&pages->mutex); + + /* There can be overlapping ranges in this interval tree */ + for (node = interval_tree_iter_first(&pages->access_itree, index, last); + node; node = interval_tree_iter_next(node, index, last)) + if (node->start == index && node->last == last) + return container_of(node, struct iopt_pages_access, + node); + return NULL; +} + +/** + * iopt_area_add_access() - Record an in-knerel access for PFNs + * @area: The source of PFNs + * @start_index: First page index + * @last_index: Inclusive last page index + * @out_pages: Output list of struct page's representing the PFNs + * @flags: IOMMUFD_ACCESS_RW_* flags + * + * Record that an in-kernel access will be accessing the pages, ensure they are + * pinned, and return the PFNs as a simple list of 'struct page *'. + * + * This should be undone through a matching call to iopt_area_remove_access() + */ +int iopt_area_add_access(struct iopt_area *area, unsigned long start_index, + unsigned long last_index, struct page **out_pages, + unsigned int flags) +{ + struct iopt_pages *pages = area->pages; + struct iopt_pages_access *access; + int rc; + + if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) + return -EPERM; + + mutex_lock(&pages->mutex); + access = iopt_pages_get_exact_access(pages, start_index, last_index); + if (access) { + area->num_accesses++; + access->users++; + iopt_pages_fill_from_xarray(pages, start_index, last_index, + out_pages); + mutex_unlock(&pages->mutex); + return 0; + } + + access = kzalloc(sizeof(*access), GFP_KERNEL_ACCOUNT); + if (!access) { + rc = -ENOMEM; + goto err_unlock; + } + + rc = iopt_pages_fill_xarray(pages, start_index, last_index, out_pages); + if (rc) + goto err_free; + + access->node.start = start_index; + access->node.last = last_index; + access->users = 1; + area->num_accesses++; + interval_tree_insert(&access->node, &pages->access_itree); + mutex_unlock(&pages->mutex); + return 0; + +err_free: + kfree(access); +err_unlock: + mutex_unlock(&pages->mutex); + return rc; +} + +/** + * iopt_area_remove_access() - Release an in-kernel access for PFNs + * @area: The source of PFNs + * @start_index: First page index + * @last_index: Inclusive last page index + * + * Undo iopt_area_add_access() and unpin the pages if necessary. The caller + * must stop using the PFNs before calling this. + */ +void iopt_area_remove_access(struct iopt_area *area, unsigned long start_index, + unsigned long last_index) +{ + struct iopt_pages *pages = area->pages; + struct iopt_pages_access *access; + + mutex_lock(&pages->mutex); + access = iopt_pages_get_exact_access(pages, start_index, last_index); + if (WARN_ON(!access)) + goto out_unlock; + + WARN_ON(area->num_accesses == 0 || access->users == 0); + area->num_accesses--; + access->users--; + if (access->users) + goto out_unlock; + + interval_tree_remove(&access->node, &pages->access_itree); + iopt_pages_unfill_xarray(pages, start_index, last_index); + kfree(access); +out_unlock: + mutex_unlock(&pages->mutex); +} |