blob: 7fcfba162e0d3400f62a190648522b21a09d3ece [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IOMMU helpers in MMU context.
*
* Copyright (C) 2015 IBM Corp. <aik@ozlabs.ru>
*/
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/vmalloc.h>
#include <linux/mutex.h>
#include <linux/migrate.h>
#include <linux/hugetlb.h>
#include <linux/swap.h>
#include <linux/sizes.h>
#include <linux/mm.h>
#include <asm/mmu_context.h>
#include <asm/pte-walk.h>
#include <linux/mm_inline.h>
static DEFINE_MUTEX(mem_list_mutex);
#define MM_IOMMU_TABLE_GROUP_PAGE_DIRTY 0x1
#define MM_IOMMU_TABLE_GROUP_PAGE_MASK ~(SZ_4K - 1)
struct mm_iommu_table_group_mem_t {
struct list_head next;
struct rcu_head rcu;
unsigned long used;
atomic64_t mapped;
unsigned int pageshift;
u64 ua; /* userspace address */
u64 entries; /* number of entries in hpas/hpages[] */
/*
* in mm_iommu_get we temporarily use this to store
* struct page address.
*
* We need to convert ua to hpa in real mode. Make it
* simpler by storing physical address.
*/
union {
struct page **hpages; /* vmalloc'ed */
phys_addr_t *hpas;
};
#define MM_IOMMU_TABLE_INVALID_HPA ((uint64_t)-1)
u64 dev_hpa; /* Device memory base address */
};
bool mm_iommu_preregistered(struct mm_struct *mm)
{
return !list_empty(&mm->context.iommu_group_mem_list);
}
EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
unsigned long entries, unsigned long dev_hpa,
struct mm_iommu_table_group_mem_t **pmem)
{
struct mm_iommu_table_group_mem_t *mem, *mem2;
long i, ret, locked_entries = 0, pinned = 0;
unsigned int pageshift;
unsigned long entry, chunk;
if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
ret = account_locked_vm(mm, entries, true);
if (ret)
return ret;
locked_entries = entries;
}
mem = kzalloc(sizeof(*mem), GFP_KERNEL);
if (!mem) {
ret = -ENOMEM;
goto unlock_exit;
}
if (dev_hpa != MM_IOMMU_TABLE_INVALID_HPA) {
mem->pageshift = __ffs(dev_hpa | (entries << PAGE_SHIFT));
mem->dev_hpa = dev_hpa;
goto good_exit;
}
mem->dev_hpa = MM_IOMMU_TABLE_INVALID_HPA;
/*
* For a starting point for a maximum page size calculation
* we use @ua and @entries natural alignment to allow IOMMU pages
* smaller than huge pages but still bigger than PAGE_SIZE.
*/
mem->pageshift = __ffs(ua | (entries << PAGE_SHIFT));
mem->hpas = vzalloc(array_size(entries, sizeof(mem->hpas[0])));
if (!mem->hpas) {
kfree(mem);
ret = -ENOMEM;
goto unlock_exit;
}
mmap_read_lock(mm);
chunk = (1UL << (PAGE_SHIFT + MAX_ORDER - 1)) /
sizeof(struct vm_area_struct *);
chunk = min(chunk, entries);
for (entry = 0; entry < entries; entry += chunk) {
unsigned long n = min(entries - entry, chunk);
ret = pin_user_pages(ua + (entry << PAGE_SHIFT), n,
FOLL_WRITE | FOLL_LONGTERM,
mem->hpages + entry, NULL);
if (ret == n) {
pinned += n;
continue;
}
if (ret > 0)
pinned += ret;
break;
}
mmap_read_unlock(mm);
if (pinned != entries) {
if (!ret)
ret = -EFAULT;
goto free_exit;
}
good_exit:
atomic64_set(&mem->mapped, 1);
mem->used = 1;
mem->ua = ua;
mem->entries = entries;
mutex_lock(&mem_list_mutex);
list_for_each_entry_rcu(mem2, &mm->context.iommu_group_mem_list, next,
lockdep_is_held(&mem_list_mutex)) {
/* Overlap? */
if ((mem2->ua < (ua + (entries << PAGE_SHIFT))) &&
(ua < (mem2->ua +
(mem2->entries << PAGE_SHIFT)))) {
ret = -EINVAL;
mutex_unlock(&mem_list_mutex);
goto free_exit;
}
}
if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
/*
* Allow to use larger than 64k IOMMU pages. Only do that
* if we are backed by hugetlb. Skip device memory as it is not
* backed with page structs.
*/
pageshift = PAGE_SHIFT;
for (i = 0; i < entries; ++i) {
struct page *page = mem->hpages[i];
if ((mem->pageshift > PAGE_SHIFT) && PageHuge(page))
pageshift = page_shift(compound_head(page));
mem->pageshift = min(mem->pageshift, pageshift);
/*
* We don't need struct page reference any more, switch
* to physical address.
*/
mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
}
}
list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
mutex_unlock(&mem_list_mutex);
*pmem = mem;
return 0;
free_exit:
/* free the references taken */
unpin_user_pages(mem->hpages, pinned);
vfree(mem->hpas);
kfree(mem);
unlock_exit:
account_locked_vm(mm, locked_entries, false);
return ret;
}
long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
struct mm_iommu_table_group_mem_t **pmem)
{
return mm_iommu_do_alloc(mm, ua, entries, MM_IOMMU_TABLE_INVALID_HPA,
pmem);
}
EXPORT_SYMBOL_GPL(mm_iommu_new);
long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
unsigned long entries, unsigned long dev_hpa,
struct mm_iommu_table_group_mem_t **pmem)
{
return mm_iommu_do_alloc(mm, ua, entries, dev_hpa, pmem);
}
EXPORT_SYMBOL_GPL(mm_iommu_newdev);
static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
{
long i;
struct page *page = NULL;
if (!mem->hpas)
return;
for (i = 0; i < mem->entries; ++i) {
if (!mem->hpas[i])
continue;
page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
if (!page)
continue;
if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
SetPageDirty(page);
unpin_user_page(page);
mem->hpas[i] = 0;
}
}
static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
{
mm_iommu_unpin(mem);
vfree(mem->hpas);
kfree(mem);
}
static void mm_iommu_free(struct rcu_head *head)
{
struct mm_iommu_table_group_mem_t *mem = container_of(head,
struct mm_iommu_table_group_mem_t, rcu);
mm_iommu_do_free(mem);
}
static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
{
list_del_rcu(&mem->next);
call_rcu(&mem->rcu, mm_iommu_free);
}
long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
{
long ret = 0;
unsigned long unlock_entries = 0;
mutex_lock(&mem_list_mutex);
if (mem->used == 0) {
ret = -ENOENT;
goto unlock_exit;
}
--mem->used;
/* There are still users, exit */
if (mem->used)
goto unlock_exit;
/* Are there still mappings? */
if (atomic64_cmpxchg(&mem->mapped, 1, 0) != 1) {
++mem->used;
ret = -EBUSY;
goto unlock_exit;
}
if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
unlock_entries = mem->entries;
/* @mapped became 0 so now mappings are disabled, release the region */
mm_iommu_release(mem);
unlock_exit:
mutex_unlock(&mem_list_mutex);
account_locked_vm(mm, unlock_entries, false);
return ret;
}
EXPORT_SYMBOL_GPL(mm_iommu_put);
struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
unsigned long ua, unsigned long size)
{
struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
rcu_read_lock();
list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
if ((mem->ua <= ua) &&
(ua + size <= mem->ua +
(mem->entries << PAGE_SHIFT))) {
ret = mem;
break;
}
}
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(mm_iommu_lookup);
struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
unsigned long ua, unsigned long entries)
{
struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
mutex_lock(&mem_list_mutex);
list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next,
lockdep_is_held(&mem_list_mutex)) {
if ((mem->ua == ua) && (mem->entries == entries)) {
ret = mem;
++mem->used;
break;
}
}
mutex_unlock(&mem_list_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(mm_iommu_get);
long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
unsigned long ua, unsigned int pageshift, unsigned long *hpa)
{
const long entry = (ua - mem->ua) >> PAGE_SHIFT;
u64 *va;
if (entry >= mem->entries)
return -EFAULT;
if (pageshift > mem->pageshift)
return -EFAULT;
if (!mem->hpas) {
*hpa = mem->dev_hpa + (ua - mem->ua);
return 0;
}
va = &mem->hpas[entry];
*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
return 0;
}
EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
unsigned int pageshift, unsigned long *size)
{
struct mm_iommu_table_group_mem_t *mem;
unsigned long end;
rcu_read_lock();
list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
continue;
end = mem->dev_hpa + (mem->entries << PAGE_SHIFT);
if ((mem->dev_hpa <= hpa) && (hpa < end)) {
/*
* Since the IOMMU page size might be bigger than
* PAGE_SIZE, the amount of preregistered memory
* starting from @hpa might be smaller than 1<<pageshift
* and the caller needs to distinguish this situation.
*/
*size = min(1UL << pageshift, end - hpa);
return true;
}
}
rcu_read_unlock();
return false;
}
EXPORT_SYMBOL_GPL(mm_iommu_is_devmem);
long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
{
if (atomic64_inc_not_zero(&mem->mapped))
return 0;
/* Last mm_iommu_put() has been called, no more mappings allowed() */
return -ENXIO;
}
EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
{
atomic64_add_unless(&mem->mapped, -1, 1);
}
EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
void mm_iommu_init(struct mm_struct *mm)
{
INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
}