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