// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2013 Red Hat Inc.
*
* Authors: Jérôme Glisse <jglisse@redhat.com>
*/
/*
* Refer to include/linux/hmm.h for information about heterogeneous memory
* management or HMM for short.
*/
#include <linux/mm.h>
#include <linux/hmm.h>
#include <linux/init.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memremap.h>
#include <linux/sched/mm.h>
#include <linux/jump_label.h>
#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
#include <linux/memory_hotplug.h>
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
/**
* hmm_get_or_create - register HMM against an mm (HMM internal)
*
* @mm: mm struct to attach to
* Returns: returns an HMM object, either by referencing the existing
* (per-process) object, or by creating a new one.
*
* This is not intended to be used directly by device drivers. If mm already
* has an HMM struct then it get a reference on it and returns it. Otherwise
* it allocates an HMM struct, initializes it, associate it with the mm and
* returns it.
*/
static struct hmm *hmm_get_or_create(struct mm_struct *mm)
{
struct hmm *hmm;
lockdep_assert_held_write(&mm->mmap_sem);
/* Abuse the page_table_lock to also protect mm->hmm. */
spin_lock(&mm->page_table_lock);
hmm = mm->hmm;
if (mm->hmm && kref_get_unless_zero(&mm->hmm->kref))
goto out_unlock;
spin_unlock(&mm->page_table_lock);
hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
if (!hmm)
return NULL;
init_waitqueue_head(&hmm->wq);
INIT_LIST_HEAD(&hmm->mirrors);
init_rwsem(&hmm->mirrors_sem);
hmm->mmu_notifier.ops = NULL;
INIT_LIST_HEAD(&hmm->ranges);
spin_lock_init(&hmm->ranges_lock);
kref_init(&hmm->kref);
hmm->notifiers = 0;
hmm->mm = mm;
hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
kfree(hmm);
return NULL;
}
mmgrab(hmm->mm);
/*
* We hold the exclusive mmap_sem here so we know that mm->hmm is
* still NULL or 0 kref, and is safe to update.
*/
spin_lock(&mm->page_table_lock);
mm->hmm = hmm;
out_unlock:
spin_unlock(&mm->page_table_lock);
return hmm;
}
static void hmm_free_rcu(struct rcu_head *rcu)
{
struct hmm *hmm = container_of(rcu, struct hmm, rcu);
mmdrop(hmm->mm);
kfree(hmm);
}
static void hmm_free(struct kref *kref)
{
struct