[PATCH RFC v2 07/13] iommufd: Data structure to provide IOVA to PFN mapping

Jason Gunthorpe
2022-09-02T19:59:54Z

This is the remainder of the IOAS data structure. Provide an object called
an io_pagetable that is composed of iopt_areas pointing at iopt_pages,
along with a list of iommu_domains that mirror the IOVA to PFN map.

At the top this is a simple interval tree of iopt_areas indicating the map
of IOVA to iopt_pages. An xarray keeps track of a list of domains. Based
on the attached domains there is a minimum alignment for areas (which may
be smaller than PAGE_SIZE), an interval tree of reserved IOVA that can't
be mapped and an IOVA of allowed IOVA that can always be mappable.

The concept of a 'user' refers to something like a VFIO mdev that is
accessing the IOVA and using a 'struct page *' for CPU based access.

Externally an API is provided that matches the requirements of the IOCTL
interface for map/unmap and domain attachment.

The API provides a 'copy' primitive to establish a new IOVA map in a
different IOAS from an existing mapping.

This is designed to support a pre-registration flow where userspace would
setup an dummy IOAS with no domains, map in memory and then establish a
user to pin all PFNs into the xarray.

Copy can then be used to create new IOVA mappings in a different IOAS,
with iommu_domains attached. Upon copy the PFNs will be read out of the
xarray and mapped into the iommu_domains, avoiding any pin_user_pages()
overheads.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/Makefile | 1 +
drivers/iommu/iommufd/io_pagetable.c | 981 ++++++++++++++++++++++++
drivers/iommu/iommufd/io_pagetable.h | 12 +
drivers/iommu/iommufd/iommufd_private.h | 33 +
include/linux/iommufd.h | 8 +
5 files changed, 1035 insertions(+)
create mode 100644 drivers/iommu/iommufd/io_pagetable.c

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile
index 05a0e91e30afad..b66a8c47ff55ec 100644
--- a/drivers/iommu/iommufd/Makefile
+++ b/drivers/iommu/iommufd/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
iommufd-y := \
+ io_pagetable.o \
main.o \
pages.o

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
new file mode 100644
index 00000000000000..7434bc8b393bbd
--- /dev/null
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -0,0 +1,981 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES.
+ *
+ * The io_pagetable is the top of datastructure that maps IOVA's to PFNs. The
+ * PFNs can be placed into an iommu_domain, or returned to the caller as a page
+ * list for access by an in-kernel user.
+ *
+ * The datastructure uses the iopt_pages to optimize the storage of the PFNs
+ * between the domains and xarray.
+ */
+#include <linux/iommufd.h>
+#include <linux/lockdep.h>
+#include <linux/iommu.h>
+#include <linux/sched/mm.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+
+#include "io_pagetable.h"
+
+static unsigned long iopt_area_iova_to_index(struct iopt_area *area,
+ unsigned long iova)
+{
+ if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
+ WARN_ON(iova < iopt_area_iova(area) ||
+ iova > iopt_area_last_iova(area));
+ return (iova - (iopt_area_iova(area) - area->page_offset)) / PAGE_SIZE;
+}
+
+static struct iopt_area *iopt_find_exact_area(struct io_pagetable *iopt,
+ unsigned long iova,
+ unsigned long last_iova)
+{
+ struct iopt_area *area;
+
+ area = iopt_area_iter_first(iopt, iova, last_iova);
+ if (!area || !area->pages || iopt_area_iova(area) != iova ||
+ iopt_area_last_iova(area) != last_iova)
+ return NULL;
+ return area;
+}
+
+static bool __alloc_iova_check_hole(struct interval_tree_span_iter *span,
+ unsigned long length,
+ unsigned long iova_alignment,
+ unsigned long page_offset)
+{
+ if (!span->is_hole || span->last_hole - span->start_hole < length - 1)
+ return false;
+
+ span->start_hole = ALIGN(span->start_hole, iova_alignment) |
+ page_offset;
+ if (span->start_hole > span->last_hole ||
+ span->last_hole - span->start_hole < length - 1)
+ return false;
+ return true;
+}
+
+static bool __alloc_iova_check_used(struct interval_tree_span_iter *span,
+ unsigned long length,
+ unsigned long iova_alignment,
+ unsigned long page_offset)
+{
+ if (span->is_hole || span->last_used - span->start_used < length - 1)
+ return false;
+
+ span->start_used = ALIGN(span->start_used, iova_alignment) |
+ page_offset;
+ if (span->start_used > span->last_used ||
+ span->last_used - span->start_used < length - 1)
+ return false;
+ return true;
+}
+
+/*
+ * Automatically find a block of IOVA that is not being used and not reserved.
+ * Does not return a 0 IOVA even if it is valid.
+ */
+static int iopt_alloc_iova(struct io_pagetable *iopt, unsigned long *iova,
+ unsigned long uptr, unsigned long length)
+{
+ struct interval_tree_span_iter reserved_span;
+ unsigned long page_offset = uptr % PAGE_SIZE;
+ struct interval_tree_span_iter allowed_span;
+ struct interval_tree_span_iter area_span;
+ unsigned long iova_alignment;
+
+ lockdep_assert_held(&iopt->iova_rwsem);
+
+ /* Protect roundup_pow-of_two() from overflow */
+ if (length == 0 || length >= ULONG_MAX / 2)
+ return -EOVERFLOW;
+
+ /*
+ * Keep alignment present in the uptr when building the IOVA, this
+ * increases the chance we can map a THP.
+ */
+ if (!uptr)
+ iova_alignment = roundup_pow_of_two(length);
+ else
+ iova_alignment =
+ min_t(unsigned long, roundup_pow_of_two(length),
+ 1UL << __ffs64(uptr));
+
+ if (iova_alignment < iopt->iova_alignment)
+ return -EINVAL;
+
+ interval_tree_for_each_span(&allowed_span, &iopt->allowed_itree,
+ PAGE_SIZE, ULONG_MAX - PAGE_SIZE) {
+ if (RB_EMPTY_ROOT(&iopt->allowed_itree.rb_root)) {
+ allowed_span.start_used = PAGE_SIZE;
+ allowed_span.last_used = ULONG_MAX - PAGE_SIZE;
+ allowed_span.is_hole = false;
+ }
+
+ if (!__alloc_iova_check_used(&allowed_span, length,
+ iova_alignment, page_offset))
+ continue;
+
+ interval_tree_for_each_span(&area_span, &iopt->area_itree,
+ allowed_span.start_used,
+ allowed_span.last_used) {
+ if (!__alloc_iova_check_hole(&area_span, length,
+ iova_alignment,
+ page_offset))
+ continue;
+
+ interval_tree_for_each_span(&reserved_span,
+ &iopt->reserved_itree,
+ area_span.start_used,
+ area_span.last_used) {
+ if (!__alloc_iova_check_hole(
+ &reserved_span, length,
+ iova_alignment, page_offset))
+ continue;
+
+ *iova = reserved_span.start_hole;
+ return 0;
+ }
+ }
+ }
+ return -ENOSPC;
+}
+
+/*
+ * The area takes a slice of the pages from start_bytes to start_byte + length
+ */
+static struct iopt_area *
+iopt_alloc_area(struct io_pagetable *iopt, struct iopt_pages *pages,
+ unsigned long iova, unsigned long start_byte,
+ unsigned long length, int iommu_prot, unsigned int flags)
+{
+ struct iopt_area *area;
+ int rc;
+
+ area = kzalloc(sizeof(*area), GFP_KERNEL_ACCOUNT);
+ if (!area)
+ return ERR_PTR(-ENOMEM);
+
+ area->iopt = iopt;
+ area->iommu_prot = iommu_prot;
+ area->page_offset = start_byte % PAGE_SIZE;
+ area->pages_node.start = start_byte / PAGE_SIZE;
+ if (check_add_overflow(start_byte, length - 1,
+ &area->pages_node.last)) {
+ rc = -EOVERFLOW;
+ goto out_free;
+ }
+ area->pages_node.last = area->pages_node.last / PAGE_SIZE;
+ if (WARN_ON(area->pages_node.last >= pages->npages)) {
+ rc = -EOVERFLOW;
+ goto out_free;
+ }
+
+ down_write(&iopt->iova_rwsem);
+ if (flags & IOPT_ALLOC_IOVA) {
+ rc = iopt_alloc_iova(iopt, &iova,
+ (uintptr_t)pages->uptr + start_byte,
+ length);
+ if (rc)
+ goto out_unlock;
+ }
+
+ if (check_add_overflow(iova, length - 1, &area->node.last)) {
+ rc = -EOVERFLOW;
+ goto out_unlock;
+ }
+
+ if (!(flags & IOPT_ALLOC_IOVA)) {
+ if ((iova & (iopt->iova_alignment - 1)) ||
+ (length & (iopt->iova_alignment - 1)) || !length) {
+ rc = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* No reserved IOVA intersects the range */
+ if (iopt_reserved_iter_first(iopt, iova, area->node.last)) {
+ rc = -ENOENT;
+ goto out_unlock;
+ }
+
+ /* Check that there is not already a mapping in the range */
+ if (iopt_area_iter_first(iopt, iova, area->node.last)) {
+ rc = -EADDRINUSE;
+ goto out_unlock;
+ }
+ }
+
+ /*
+ * The area is inserted with a NULL pages indicating it is not fully
+ * initialized yet.
+ */
+ area->node.start = iova;
+ interval_tree_insert(&area->node, &area->iopt->area_itree);
+ up_write(&iopt->iova_rwsem);
+ return area;
+
+out_unlock:
+ up_write(&iopt->iova_rwsem);
+out_free:
+ kfree(area);
+ return ERR_PTR(rc);
+}
+
+static void iopt_abort_area(struct iopt_area *area)
+{
+ down_write(&area->iopt->iova_rwsem);
+ interval_tree_remove(&area->node, &area->iopt->area_itree);
+ up_write(&area->iopt->iova_rwsem);
+ kfree(area);
+}
+
+static int iopt_finalize_area(struct iopt_area *area, struct iopt_pages *pages)
+{
+ int rc;
+
+ down_read(&area->iopt->domains_rwsem);
+ rc = iopt_area_fill_domains(area, pages);
+ if (!rc) {
+ /*
+ * area->pages must be set inside the domains_rwsem to ensure
+ * any newly added domains will get filled. Moves the reference
+ * in from the caller
+ */
+ down_write(&area->iopt->iova_rwsem);
+ area->pages = pages;
+ up_write(&area->iopt->iova_rwsem);
+ }
+ up_read(&area->iopt->domains_rwsem);
+ return rc;
+}
+
+int iopt_map_pages(struct io_pagetable *iopt, struct iopt_pages *pages,
+ unsigned long *dst_iova, unsigned long start_bytes,
+ unsigned long length, int iommu_prot, unsigned int flags)
+{
+ struct iopt_area *area;
+ int rc;
+
+ if ((iommu_prot & IOMMU_WRITE) && !pages->writable)
+ return -EPERM;
+
+ area = iopt_alloc_area(iopt, pages, *dst_iova, start_bytes, length,
+ iommu_prot, flags);
+ if (IS_ERR(area))
+ return PTR_ERR(area);
+ *dst_iova = iopt_area_iova(area);
+
+ rc = iopt_finalize_area(area, pages);
+ if (rc) {
+ iopt_abort_area(area);
+ return rc;
+ }
+ return 0;
+}
+
+/**
+ * iopt_map_user_pages() - Map a user VA to an iova in the io page table
+ * @iopt: io_pagetable to act on
+ * @iova: If IOPT_ALLOC_IOVA is set this is unused on input and contains
+ * the chosen iova on output. Otherwise is the iova to map to on input
+ * @uptr: User VA to map
+ * @length: Number of bytes to map
+ * @iommu_prot: Combination of IOMMU_READ/WRITE/etc bits for the mapping
+ * @flags: IOPT_ALLOC_IOVA or zero
+ *
+ * iova, uptr, and length must be aligned to iova_alignment. For domain backed
+ * page tables this will pin the pages and load them into the domain at iova.
+ * For non-domain page tables this will only setup a lazy reference and the
+ * caller must use iopt_access_pages() to touch them.
+ *
+ * iopt_unmap_iova() must be called to undo this before the io_pagetable can be
+ * destroyed.
+ */
+int iopt_map_user_pages(struct io_pagetable *iopt, unsigned long *iova,
+ void __user *uptr, unsigned long length, int iommu_prot,
+ unsigned int flags)
+{
+ struct iopt_pages *pages;
+ int rc;
+
+ pages = iopt_alloc_pages(uptr, length, iommu_prot & IOMMU_WRITE);
+ if (IS_ERR(pages))
+ return PTR_ERR(pages);
+
+ rc = iopt_map_pages(iopt, pages, iova, uptr - pages->uptr, length,
+ iommu_prot, flags);
+ if (rc) {
+ iopt_put_pages(pages);
+ return rc;
+ }
+ return 0;
+}
+
+struct iopt_pages *iopt_get_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long *start_byte,
+ unsigned long length)
+{
+ unsigned long iova_end;
+ struct iopt_pages *pages;
+ struct iopt_area *area;
+
+ if (check_add_overflow(iova, length - 1, &iova_end))
+ return ERR_PTR(-EOVERFLOW);
+
+ down_read(&iopt->iova_rwsem);
+ area = iopt_find_exact_area(iopt, iova, iova_end);
+ if (!area) {
+ up_read(&iopt->iova_rwsem);
+ return ERR_PTR(-ENOENT);
+ }
+ pages = area->pages;
+ *start_byte = area->page_offset + iopt_area_index(area) * PAGE_SIZE;
+ kref_get(&pages->kref);
+ up_read(&iopt->iova_rwsem);
+
+ return pages;
+}
+
+static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
+ unsigned long end, unsigned long *unmapped)
+{
+ struct iopt_area *area;
+ unsigned long unmapped_bytes = 0;
+ int rc = -ENOENT;
+
+ /*
+ * The domains_rwsem must be held in read mode any time any area->pages
+ * is NULL. This prevents domain attach/detatch from running
+ * concurrently with cleaning up the area.
+ */
+ down_read(&iopt->domains_rwsem);
+ down_write(&iopt->iova_rwsem);
+ while ((area = iopt_area_iter_first(iopt, start, end))) {
+ unsigned long area_last = iopt_area_last_iova(area);
+ unsigned long area_first = iopt_area_iova(area);
+ struct iopt_pages *pages;
+
+ /* Userspace should not race map/unmap's of the same area */
+ if (!area->pages) {
+ rc = -EBUSY;
+ goto out_unlock_iova;
+ }
+
+ if (area_first < start || area_last > end) {
+ rc = -ENOENT;
+ goto out_unlock_iova;
+ }
+
+ /*
+ * num_users writers must hold the iova_rwsem too, so we can
+ * safely read it under the write side of the iovam_rwsem
+ * without the pages->mutex.
+ */
+ if (area->num_users) {
+ start = area_first;
+ area->prevent_users = true;
+ up_write(&iopt->iova_rwsem);
+ up_read(&iopt->domains_rwsem);
+ /* Later patch calls back to drivers to unmap */
+ return -EBUSY;
+ }
+
+ pages = area->pages;
+ area->pages = NULL;
+ up_write(&iopt->iova_rwsem);
+
+ iopt_area_unfill_domains(area, pages);
+ iopt_abort_area(area);
+ iopt_put_pages(pages);
+
+ unmapped_bytes += area_last - area_first + 1;
+
+ down_write(&iopt->iova_rwsem);
+ }
+ if (unmapped_bytes)
+ rc = 0;
+
+out_unlock_iova:
+ up_write(&iopt->iova_rwsem);
+ up_read(&iopt->domains_rwsem);
+ if (unmapped)
+ *unmapped = unmapped_bytes;
+ return rc;
+}
+
+/**
+ * iopt_unmap_iova() - Remove a range of iova
+ * @iopt: io_pagetable to act on
+ * @iova: Starting iova to unmap
+ * @length: Number of bytes to unmap
+ * @unmapped: Return number of bytes unmapped
+ *
+ * The requested range must be a superset of existing ranges.
+ * Splitting/truncating IOVA mappings is not allowed.
+ */
+int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length, unsigned long *unmapped)
+{
+ unsigned long iova_end;
+
+ if (!length)
+ return -EINVAL;
+
+ if (check_add_overflow(iova, length - 1, &iova_end))
+ return -EOVERFLOW;
+
+ return iopt_unmap_iova_range(iopt, iova, iova_end, unmapped);
+}
+
+int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped)
+{
+ return iopt_unmap_iova_range(iopt, 0, ULONG_MAX, unmapped);
+}
+
+/**
+ * iopt_access_pages() - Return a list of pages under the iova
+ * @iopt: io_pagetable to act on
+ * @iova: Starting IOVA
+ * @length: Number of bytes to access
+ * @out_pages: Output page list
+ * @write: True if access is for writing
+ *
+ * Reads @length bytes starting at iova and returns the struct page * pointers.
+ * These can be kmap'd by the caller for CPU access.
+ *
+ * The caller must perform iopt_unaccess_pages() when done to balance this.
+ *
+ * iova can be unaligned from PAGE_SIZE. The first returned byte starts at
+ * page_to_phys(out_pages[0]) + (iova % PAGE_SIZE). The caller promises not to
+ * touch memory outside the requested iova slice.
+ */
+int iopt_access_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length, struct page **out_pages, bool write)
+{
+ unsigned long cur_iova = iova;
+ unsigned long last_iova;
+ struct iopt_area *area;
+ int rc;
+
+ if (!length)
+ return -EINVAL;
+ if (check_add_overflow(iova, length - 1, &last_iova))
+ return -EOVERFLOW;
+
+ down_read(&iopt->iova_rwsem);
+ for (area = iopt_area_iter_first(iopt, iova, last_iova); area;
+ area = iopt_area_iter_next(area, iova, last_iova)) {
+ unsigned long last = min(last_iova, iopt_area_last_iova(area));
+ unsigned long last_index;
+ unsigned long index;
+
+ /* Need contiguous areas in the access */
+ if (iopt_area_iova(area) > cur_iova || !area->pages ||
+ area->prevent_users) {
+ rc = -EINVAL;
+ goto out_remove;
+ }
+
+ index = iopt_area_iova_to_index(area, cur_iova);
+ last_index = iopt_area_iova_to_index(area, last);
+
+ /*
+ * The API can only return aligned pages, so the starting point
+ * must be at a page boundary.
+ */
+ if ((cur_iova - (iopt_area_iova(area) - area->page_offset)) %
+ PAGE_SIZE) {
+ rc = -EINVAL;
+ goto out_remove;
+ }
+
+ /*
+ * and an interior ending point must be at a page boundary
+ */
+ if (last != last_iova &&
+ (iopt_area_last_iova(area) - cur_iova + 1) % PAGE_SIZE) {
+ rc = -EINVAL;
+ goto out_remove;
+ }
+
+ mutex_lock(&area->pages->mutex);
+ rc = iopt_pages_add_user(area->pages, index, last_index,
+ out_pages, write);
+ if (rc) {
+ mutex_unlock(&area->pages->mutex);
+ goto out_remove;
+ }
+ area->num_users++;
+ mutex_unlock(&area->pages->mutex);
+ if (last == last_iova)
+ break;
+ cur_iova = last + 1;
+ out_pages += last_index - index;
+ }
+ if (cur_iova != last_iova)
+ goto out_remove;
+
+ up_read(&iopt->iova_rwsem);
+ return 0;
+
+out_remove:
+ if (cur_iova != iova)
+ iopt_unaccess_pages(iopt, iova, cur_iova - iova);
+ up_read(&iopt->iova_rwsem);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(iopt_access_pages);
+
+/**
+ * iopt_unaccess_pages() - Undo iopt_access_pages
+ * @iopt: io_pagetable to act on
+ * @iova: Starting IOVA
+ * @length:- Number of bytes to access
+ *
+ * Return the struct page's. The caller must stop accessing them before calling
+ * this. The iova/length must exactly match the one provided to access_pages.
+ */
+void iopt_unaccess_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length)
+{
+ unsigned long cur_iova = iova;
+ unsigned long last_iova;
+ struct iopt_area *area;
+
+ if (WARN_ON(!length) ||
+ WARN_ON(check_add_overflow(iova, length - 1, &last_iova)))
+ return;
+
+ down_read(&iopt->iova_rwsem);
+ for (area = iopt_area_iter_first(iopt, iova, last_iova); area;
+ area = iopt_area_iter_next(area, iova, last_iova)) {
+ unsigned long last = min(last_iova, iopt_area_last_iova(area));
+
+ iopt_pages_remove_user(area,
+ iopt_area_iova_to_index(area, cur_iova),
+ iopt_area_iova_to_index(area, last));
+ if (last == last_iova)
+ break;
+ cur_iova = last + 1;
+ }
+ up_read(&iopt->iova_rwsem);
+}
+EXPORT_SYMBOL_GPL(iopt_unaccess_pages);
+
+/* The caller must always free all the nodes in the allowed_iova rb_root. */
+int iopt_set_allow_iova(struct io_pagetable *iopt,
+ struct rb_root_cached *allowed_iova)
+{
+ struct iopt_allowed *allowed;
+
+ down_write(&iopt->iova_rwsem);
+ swap(*allowed_iova, iopt->allowed_itree);
+
+ for (allowed = iopt_allowed_iter_first(iopt, 0, ULONG_MAX); allowed;
+ allowed = iopt_allowed_iter_next(allowed, 0, ULONG_MAX)) {
+ if (iopt_reserved_iter_first(iopt, allowed->node.start,
+ allowed->node.last)) {
+ swap(*allowed_iova, iopt->allowed_itree);
+ up_write(&iopt->iova_rwsem);
+ return -EADDRINUSE;
+ }
+ }
+ up_write(&iopt->iova_rwsem);
+ return 0;
+}
+
+int iopt_reserve_iova(struct io_pagetable *iopt, unsigned long start,
+ unsigned long last, void *owner)
+{
+ struct iopt_reserved *reserved;
+
+ lockdep_assert_held_write(&iopt->iova_rwsem);
+
+ if (iopt_area_iter_first(iopt, start, last) ||
+ iopt_allowed_iter_first(iopt, start, last))
+ return -EADDRINUSE;
+
+ reserved = kzalloc(sizeof(*reserved), GFP_KERNEL_ACCOUNT);
+ if (!reserved)
+ return -ENOMEM;
+ reserved->node.start = start;
+ reserved->node.last = last;
+ reserved->owner = owner;
+ interval_tree_insert(&reserved->node, &iopt->reserved_itree);
+ return 0;
+}
+
+static void __iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner)
+{
+ struct iopt_reserved *reserved, *next;
+
+ lockdep_assert_held_write(&iopt->iova_rwsem);
+
+ for (reserved = iopt_reserved_iter_first(iopt, 0, ULONG_MAX);
+ reserved; reserved = next) {
+ next = iopt_reserved_iter_next(reserved, 0, ULONG_MAX);
+
+ if (reserved->owner == owner) {
+ interval_tree_remove(&reserved->node,
+ &iopt->reserved_itree);
+ kfree(reserved);
+ }
+ }
+}
+
+void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner)
+{
+ down_write(&iopt->iova_rwsem);
+ __iopt_remove_reserved_iova(iopt, owner);
+ up_write(&iopt->iova_rwsem);
+}
+
+int iopt_init_table(struct io_pagetable *iopt)
+{
+ init_rwsem(&iopt->iova_rwsem);
+ init_rwsem(&iopt->domains_rwsem);
+ iopt->area_itree = RB_ROOT_CACHED;
+ iopt->allowed_itree = RB_ROOT_CACHED;
+ iopt->reserved_itree = RB_ROOT_CACHED;
+ xa_init_flags(&iopt->domains, XA_FLAGS_ACCOUNT);
+
+ /*
+ * iopt's start as SW tables that can use the entire size_t IOVA space
+ * due to the use of size_t in the APIs. They have no alignment
+ * restriction.
+ */
+ iopt->iova_alignment = 1;
+
+ return 0;
+}
+
+void iopt_destroy_table(struct io_pagetable *iopt)
+{
+ struct interval_tree_node *node;
+
+ if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
+ iopt_remove_reserved_iova(iopt, NULL);
+
+ while ((node = interval_tree_iter_first(&iopt->allowed_itree, 0,
+ ULONG_MAX))) {
+ interval_tree_remove(node, &iopt->allowed_itree);
+ kfree(container_of(node, struct iopt_allowed, node));
+ }
+
+ WARN_ON(!RB_EMPTY_ROOT(&iopt->reserved_itree.rb_root));
+ WARN_ON(!xa_empty(&iopt->domains));
+ WARN_ON(!RB_EMPTY_ROOT(&iopt->area_itree.rb_root));
+}
+
+/**
+ * iopt_unfill_domain() - Unfill a domain with PFNs
+ * @iopt: io_pagetable to act on
+ * @domain: domain to unfill
+ *
+ * This is used when removing a domain from the iopt. Every area in the iopt
+ * will be unmapped from the domain. The domain must already be removed from the
+ * domains xarray.
+ */
+static void iopt_unfill_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain)
+{
+ struct iopt_area *area;
+
+ lockdep_assert_held(&iopt->iova_rwsem);
+ lockdep_assert_held_write(&iopt->domains_rwsem);
+
+ /*
+ * Some other domain is holding all the pfns still, rapidly unmap this
+ * domain.
+ */
+ if (iopt->next_domain_id != 0) {
+ /* Pick an arbitrary remaining domain to act as storage */
+ struct iommu_domain *storage_domain =
+ xa_load(&iopt->domains, 0);
+
+ for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+ struct iopt_pages *pages = area->pages;
+
+ if (!pages)
+ continue;
+
+ mutex_lock(&pages->mutex);
+ if (area->storage_domain != domain) {
+ mutex_unlock(&pages->mutex);
+ continue;
+ }
+ area->storage_domain = storage_domain;
+ mutex_unlock(&pages->mutex);
+ }
+
+
+ iopt_unmap_domain(iopt, domain);
+ return;
+ }
+
+ for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+ struct iopt_pages *pages = area->pages;
+
+ if (!pages)
+ continue;
+
+ mutex_lock(&pages->mutex);
+ interval_tree_remove(&area->pages_node,
+ &pages->domains_itree);
+ WARN_ON(area->storage_domain != domain);
+ area->storage_domain = NULL;
+ iopt_area_unfill_domain(area, pages, domain);
+ mutex_unlock(&pages->mutex);
+ }
+}
+
+/**
+ * iopt_fill_domain() - Fill a domain with PFNs
+ * @iopt: io_pagetable to act on
+ * @domain: domain to fill
+ *
+ * Fill the domain with PFNs from every area in the iopt. On failure the domain
+ * is left unchanged.
+ */
+static int iopt_fill_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain)
+{
+ struct iopt_area *end_area;
+ struct iopt_area *area;
+ int rc;
+
+ lockdep_assert_held(&iopt->iova_rwsem);
+ lockdep_assert_held_write(&iopt->domains_rwsem);
+
+ for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+ struct iopt_pages *pages = area->pages;
+
+ if (!pages)
+ continue;
+
+ mutex_lock(&pages->mutex);
+ rc = iopt_area_fill_domain(area, domain);
+ if (rc) {
+ mutex_unlock(&pages->mutex);
+ goto out_unfill;
+ }
+ if (!area->storage_domain) {
+ WARN_ON(iopt->next_domain_id != 0);
+ area->storage_domain = domain;
+ interval_tree_insert(&area->pages_node,
+ &pages->domains_itree);
+ }
+ mutex_unlock(&pages->mutex);
+ }
+ return 0;
+
+out_unfill:
+ end_area = area;
+ for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+ struct iopt_pages *pages = area->pages;
+
+ if (area == end_area)
+ break;
+ if (!pages)
+ continue;
+ mutex_lock(&pages->mutex);
+ if (iopt->next_domain_id == 0) {
+ interval_tree_remove(&area->pages_node,
+ &pages->domains_itree);
+ area->storage_domain = NULL;
+ }
+ iopt_area_unfill_domain(area, pages, domain);
+ mutex_unlock(&pages->mutex);
+ }
+ return rc;
+}
+
+/* All existing area's conform to an increased page size */
+static int iopt_check_iova_alignment(struct io_pagetable *iopt,
+ unsigned long new_iova_alignment)
+{
+ struct iopt_area *area;
+
+ lockdep_assert_held(&iopt->iova_rwsem);
+
+ for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX))
+ if ((iopt_area_iova(area) % new_iova_alignment) ||
+ (iopt_area_length(area) % new_iova_alignment))
+ return -EADDRINUSE;
+ return 0;
+}
+
+int iopt_table_add_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain)
+{
+ const struct iommu_domain_geometry *geometry = &domain->geometry;
+ struct iommu_domain *iter_domain;
+ unsigned int new_iova_alignment;
+ unsigned long index;
+ int rc;
+
+ down_write(&iopt->domains_rwsem);
+ down_write(&iopt->iova_rwsem);
+
+ xa_for_each (&iopt->domains, index, iter_domain) {
+ if (WARN_ON(iter_domain == domain)) {
+ rc = -EEXIST;
+ goto out_unlock;
+ }
+ }
+
+ /*
+ * The io page size drives the iova_alignment. Internally the iopt_pages
+ * works in PAGE_SIZE units and we adjust when mapping sub-PAGE_SIZE
+ * objects into the iommu_domain.
+ *
+ * A iommu_domain must always be able to accept PAGE_SIZE to be
+ * compatible as we can't guarantee higher contiguity.
+ */
+ new_iova_alignment =
+ max_t(unsigned long, 1UL << __ffs(domain->pgsize_bitmap),
+ iopt->iova_alignment);
+ if (new_iova_alignment > PAGE_SIZE) {
+ rc = -EINVAL;
+ goto out_unlock;
+ }
+ if (new_iova_alignment != iopt->iova_alignment) {
+ rc = iopt_check_iova_alignment(iopt, new_iova_alignment);
+ if (rc)
+ goto out_unlock;
+ }
+
+ /* No area exists that is outside the allowed domain aperture */
+ if (geometry->aperture_start != 0) {
+ rc = iopt_reserve_iova(iopt, 0, geometry->aperture_start - 1,
+ domain);
+ if (rc)
+ goto out_reserved;
+ }
+ if (geometry->aperture_end != ULONG_MAX) {
+ rc = iopt_reserve_iova(iopt, geometry->aperture_end + 1,
+ ULONG_MAX, domain);
+ if (rc)
+ goto out_reserved;
+ }
+
+ rc = xa_reserve(&iopt->domains, iopt->next_domain_id, GFP_KERNEL);
+ if (rc)
+ goto out_reserved;
+
+ rc = iopt_fill_domain(iopt, domain);
+ if (rc)
+ goto out_release;
+
+ iopt->iova_alignment = new_iova_alignment;
+ xa_store(&iopt->domains, iopt->next_domain_id, domain, GFP_KERNEL);
+ iopt->next_domain_id++;
+ up_write(&iopt->iova_rwsem);
+ up_write(&iopt->domains_rwsem);
+ return 0;
+out_release:
+ xa_release(&iopt->domains, iopt->next_domain_id);
+out_reserved:
+ __iopt_remove_reserved_iova(iopt, domain);
+out_unlock:
+ up_write(&iopt->iova_rwsem);
+ up_write(&iopt->domains_rwsem);
+ return rc;
+}
+
+void iopt_table_remove_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain)
+{
+ struct iommu_domain *iter_domain = NULL;
+ unsigned long new_iova_alignment;
+ unsigned long index;
+
+ down_write(&iopt->domains_rwsem);
+ down_write(&iopt->iova_rwsem);
+
+ xa_for_each (&iopt->domains, index, iter_domain)
+ if (iter_domain == domain)
+ break;
+ if (WARN_ON(iter_domain != domain) || index >= iopt->next_domain_id)
+ goto out_unlock;
+
+ /*
+ * Compress the xarray to keep it linear by swapping the entry to erase
+ * with the tail entry and shrinking the tail.
+ */
+ iopt->next_domain_id--;
+ iter_domain = xa_erase(&iopt->domains, iopt->next_domain_id);
+ if (index != iopt->next_domain_id)
+ xa_store(&iopt->domains, index, iter_domain, GFP_KERNEL);
+
+ iopt_unfill_domain(iopt, domain);
+ __iopt_remove_reserved_iova(iopt, domain);
+
+ /* Recalculate the iova alignment without the domain */
+ new_iova_alignment = 1;
+ xa_for_each (&iopt->domains, index, iter_domain)
+ new_iova_alignment = max_t(unsigned long,
+ 1UL << __ffs(domain->pgsize_bitmap),
+ new_iova_alignment);
+ if (!WARN_ON(new_iova_alignment > iopt->iova_alignment))
+ iopt->iova_alignment = new_iova_alignment;
+
+out_unlock:
+ up_write(&iopt->iova_rwsem);
+ up_write(&iopt->domains_rwsem);
+}
+
+/* Narrow the valid_iova_itree to include reserved ranges from a group. */
+int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
+ struct iommu_group *group,
+ phys_addr_t *sw_msi_start)
+{
+ struct iommu_resv_region *resv;
+ struct iommu_resv_region *tmp;
+ LIST_HEAD(group_resv_regions);
+ int rc;
+
+ down_write(&iopt->iova_rwsem);
+ rc = iommu_get_group_resv_regions(group, &group_resv_regions);
+ if (rc)
+ goto out_unlock;
+
+ list_for_each_entry (resv, &group_resv_regions, list) {
+ if (resv->type == IOMMU_RESV_DIRECT_RELAXABLE)
+ continue;
+
+ /*
+ * The presence of any 'real' MSI regions should take precedence
+ * over the software-managed one if the IOMMU driver happens to
+ * advertise both types.
+ */
+ if (sw_msi_start && resv->type == IOMMU_RESV_MSI) {
+ *sw_msi_start = 0;
+ sw_msi_start = NULL;
+ }
+ if (sw_msi_start && resv->type == IOMMU_RESV_SW_MSI)
+ *sw_msi_start = resv->start;
+
+ rc = iopt_reserve_iova(iopt, resv->start,
+ resv->length - 1 + resv->start, group);
+ if (rc)
+ goto out_reserved;
+ }
+ rc = 0;
+ goto out_free_resv;
+
+out_reserved:
+ __iopt_remove_reserved_iova(iopt, group);
+out_free_resv:
+ list_for_each_entry_safe (resv, tmp, &group_resv_regions, list)
+ kfree(resv);
+out_unlock:
+ up_write(&iopt->iova_rwsem);
+ return rc;
+}
diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h
index fe3be8dd38240e..7fe5a700239012 100644
--- a/drivers/iommu/iommufd/io_pagetable.h
+++ b/drivers/iommu/iommufd/io_pagetable.h
@@ -46,9 +46,19 @@ struct iopt_area {
unsigned int page_offset;
/* IOMMU_READ, IOMMU_WRITE, etc */
int iommu_prot;
+ bool prevent_users : 1;
unsigned int num_users;
};

+struct iopt_allowed {
+ struct interval_tree_node node;
+};
+
+struct iopt_reserved {
+ struct interval_tree_node node;
+ void *owner;
+};
+
int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages);
void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages);

@@ -109,6 +119,8 @@ static inline size_t iopt_area_length(struct iopt_area *area)
}

__make_iopt_iter(area)
+__make_iopt_iter(allowed)
+__make_iopt_iter(reserved)

/*
* This holds a pinned page list for multiple areas of IO address space. The
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 47a824897bc222..560ab06fbc3366 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -9,6 +9,9 @@
#include <linux/refcount.h>
#include <linux/uaccess.h>

+struct iommu_domain;
+struct iommu_group;
+
/*
* The IOVA to PFN map. The mapper automatically copies the PFNs into multiple
* domains and permits sharing of PFNs between io_pagetable instances. This
@@ -30,8 +33,38 @@ struct io_pagetable {
struct rb_root_cached allowed_itree;
/* IOVA that cannot be allocated, struct iopt_reserved */
struct rb_root_cached reserved_itree;
+ unsigned long iova_alignment;
};

+int iopt_init_table(struct io_pagetable *iopt);
+void iopt_destroy_table(struct io_pagetable *iopt);
+struct iopt_pages *iopt_get_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long *start_byte,
+ unsigned long length);
+enum { IOPT_ALLOC_IOVA = 1 << 0 };
+int iopt_map_user_pages(struct io_pagetable *iopt, unsigned long *iova,
+ void __user *uptr, unsigned long length, int iommu_prot,
+ unsigned int flags);
+int iopt_map_pages(struct io_pagetable *iopt, struct iopt_pages *pages,
+ unsigned long *dst_iova, unsigned long start_byte,
+ unsigned long length, int iommu_prot, unsigned int flags);
+int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length, unsigned long *unmapped);
+int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped);
+
+int iopt_table_add_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain);
+void iopt_table_remove_domain(struct io_pagetable *iopt,
+ struct iommu_domain *domain);
+int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
+ struct iommu_group *group,
+ phys_addr_t *sw_msi_start);
+int iopt_set_allow_iova(struct io_pagetable *iopt,
+ struct rb_root_cached *allowed_iova);
+int iopt_reserve_iova(struct io_pagetable *iopt, unsigned long start,
+ unsigned long last, void *owner);
+void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner);
+
struct iommufd_ctx {
struct file *file;
struct xarray objects;
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index c8bbed542e923c..9c6ec4d66b4a92 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -10,9 +10,17 @@
#include <linux/errno.h>
#include <linux/err.h>

+struct page;
struct iommufd_ctx;
+struct io_pagetable;
struct file;

+int iopt_access_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length, struct page **out_pages,
+ bool write);
+void iopt_unaccess_pages(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length);
+
void iommufd_ctx_get(struct iommufd_ctx *ictx);

#if IS_ENABLED(CONFIG_IOMMUFD)
--
2.37.3