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|
// 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,
GFP_KERNEL);
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);
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, 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);
}
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