--- /dev/null
- if (pages->writable) {
- user->gup_flags = FOLL_LONGTERM | FOLL_WRITE;
- } else {
- /* Still need to break COWs on read */
- user->gup_flags = FOLL_LONGTERM | FOLL_FORCE | FOLL_WRITE;
- }
+ // 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->npfns[0] = keep_pfns;
+ batch->pfns[0] = batch->pfns[batch->end - 1] +
+ (batch->npfns[batch->end - 1] - keep_pfns);
+ batch->end = 0;
+ }
+
+ 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);
+ 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);
+ 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;
+
- /*
- * FIXME: last NULL can be &pfns->locked once the GUP patch
- * is merged.
- */
++ 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;
+ }
- NULL);
+ rc = pin_user_pages_remote(pages->source_mm, uptr, npages,
+ user->gup_flags, user->upages, NULL,
++ &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;
+
+ /*
+ * 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);
+
+ 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);
+
+ batch_from_domain(batch, domain, area, start,
+ last_index);
+ batch_last_index = start + batch->total_pfns - 1;
+ } else {
+ batch_last_index = 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));
+
+ 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, 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);
+ }
git.samba.org / sfrench / cifs-2.6.git / commitdiff