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d45d464b11
Add a HMM_FAULT_SNAPSHOT flag so that hmm_range_snapshot can be merged into the almost identical hmm_range_fault function. Link: https://lore.kernel.org/r/20190726005650.2566-5-rcampbell@nvidia.com Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
1195 lines
31 KiB
C
1195 lines
31 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright 2013 Red Hat Inc.
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*
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* Authors: Jérôme Glisse <jglisse@redhat.com>
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*/
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/*
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* Refer to include/linux/hmm.h for information about heterogeneous memory
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* management or HMM for short.
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*/
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#include <linux/mm.h>
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#include <linux/hmm.h>
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#include <linux/init.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/mmzone.h>
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#include <linux/pagemap.h>
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#include <linux/swapops.h>
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#include <linux/hugetlb.h>
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#include <linux/memremap.h>
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#include <linux/sched/mm.h>
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#include <linux/jump_label.h>
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#include <linux/dma-mapping.h>
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#include <linux/mmu_notifier.h>
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#include <linux/memory_hotplug.h>
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static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
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/**
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* hmm_get_or_create - register HMM against an mm (HMM internal)
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*
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* @mm: mm struct to attach to
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* Return: an HMM object, either by referencing the existing
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* (per-process) object, or by creating a new one.
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*
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* This is not intended to be used directly by device drivers. If mm already
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* has an HMM struct then it get a reference on it and returns it. Otherwise
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* it allocates an HMM struct, initializes it, associate it with the mm and
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* returns it.
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*/
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static struct hmm *hmm_get_or_create(struct mm_struct *mm)
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{
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struct hmm *hmm;
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lockdep_assert_held_write(&mm->mmap_sem);
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/* Abuse the page_table_lock to also protect mm->hmm. */
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spin_lock(&mm->page_table_lock);
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hmm = mm->hmm;
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if (mm->hmm && kref_get_unless_zero(&mm->hmm->kref))
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goto out_unlock;
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spin_unlock(&mm->page_table_lock);
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hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
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if (!hmm)
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return NULL;
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init_waitqueue_head(&hmm->wq);
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INIT_LIST_HEAD(&hmm->mirrors);
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init_rwsem(&hmm->mirrors_sem);
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hmm->mmu_notifier.ops = NULL;
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INIT_LIST_HEAD(&hmm->ranges);
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spin_lock_init(&hmm->ranges_lock);
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kref_init(&hmm->kref);
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hmm->notifiers = 0;
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hmm->mm = mm;
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hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
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if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
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kfree(hmm);
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return NULL;
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}
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mmgrab(hmm->mm);
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/*
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* We hold the exclusive mmap_sem here so we know that mm->hmm is
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* still NULL or 0 kref, and is safe to update.
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*/
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spin_lock(&mm->page_table_lock);
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mm->hmm = hmm;
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out_unlock:
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spin_unlock(&mm->page_table_lock);
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return hmm;
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}
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static void hmm_free_rcu(struct rcu_head *rcu)
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{
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struct hmm *hmm = container_of(rcu, struct hmm, rcu);
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mmdrop(hmm->mm);
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kfree(hmm);
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}
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static void hmm_free(struct kref *kref)
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{
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struct hmm *hmm = container_of(kref, struct hmm, kref);
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spin_lock(&hmm->mm->page_table_lock);
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if (hmm->mm->hmm == hmm)
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hmm->mm->hmm = NULL;
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spin_unlock(&hmm->mm->page_table_lock);
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mmu_notifier_unregister_no_release(&hmm->mmu_notifier, hmm->mm);
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mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu);
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}
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static inline void hmm_put(struct hmm *hmm)
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{
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kref_put(&hmm->kref, hmm_free);
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}
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static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
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{
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struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
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struct hmm_mirror *mirror;
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/* Bail out if hmm is in the process of being freed */
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if (!kref_get_unless_zero(&hmm->kref))
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return;
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/*
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* Since hmm_range_register() holds the mmget() lock hmm_release() is
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* prevented as long as a range exists.
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*/
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WARN_ON(!list_empty_careful(&hmm->ranges));
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down_read(&hmm->mirrors_sem);
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list_for_each_entry(mirror, &hmm->mirrors, list) {
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/*
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* Note: The driver is not allowed to trigger
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* hmm_mirror_unregister() from this thread.
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*/
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if (mirror->ops->release)
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mirror->ops->release(mirror);
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}
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up_read(&hmm->mirrors_sem);
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hmm_put(hmm);
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}
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static void notifiers_decrement(struct hmm *hmm)
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{
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unsigned long flags;
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spin_lock_irqsave(&hmm->ranges_lock, flags);
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hmm->notifiers--;
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if (!hmm->notifiers) {
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struct hmm_range *range;
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list_for_each_entry(range, &hmm->ranges, list) {
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if (range->valid)
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continue;
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range->valid = true;
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}
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wake_up_all(&hmm->wq);
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}
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spin_unlock_irqrestore(&hmm->ranges_lock, flags);
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}
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static int hmm_invalidate_range_start(struct mmu_notifier *mn,
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const struct mmu_notifier_range *nrange)
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{
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struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
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struct hmm_mirror *mirror;
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struct hmm_range *range;
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unsigned long flags;
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int ret = 0;
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if (!kref_get_unless_zero(&hmm->kref))
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return 0;
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spin_lock_irqsave(&hmm->ranges_lock, flags);
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hmm->notifiers++;
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list_for_each_entry(range, &hmm->ranges, list) {
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if (nrange->end < range->start || nrange->start >= range->end)
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continue;
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range->valid = false;
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}
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spin_unlock_irqrestore(&hmm->ranges_lock, flags);
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if (mmu_notifier_range_blockable(nrange))
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down_read(&hmm->mirrors_sem);
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else if (!down_read_trylock(&hmm->mirrors_sem)) {
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ret = -EAGAIN;
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goto out;
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}
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list_for_each_entry(mirror, &hmm->mirrors, list) {
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int rc;
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rc = mirror->ops->sync_cpu_device_pagetables(mirror, nrange);
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if (rc) {
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if (WARN_ON(mmu_notifier_range_blockable(nrange) ||
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rc != -EAGAIN))
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continue;
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ret = -EAGAIN;
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break;
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}
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}
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up_read(&hmm->mirrors_sem);
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out:
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if (ret)
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notifiers_decrement(hmm);
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hmm_put(hmm);
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return ret;
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}
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static void hmm_invalidate_range_end(struct mmu_notifier *mn,
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const struct mmu_notifier_range *nrange)
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{
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struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
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if (!kref_get_unless_zero(&hmm->kref))
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return;
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notifiers_decrement(hmm);
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hmm_put(hmm);
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}
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static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
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.release = hmm_release,
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.invalidate_range_start = hmm_invalidate_range_start,
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.invalidate_range_end = hmm_invalidate_range_end,
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};
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/*
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* hmm_mirror_register() - register a mirror against an mm
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*
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* @mirror: new mirror struct to register
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* @mm: mm to register against
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* Return: 0 on success, -ENOMEM if no memory, -EINVAL if invalid arguments
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*
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* To start mirroring a process address space, the device driver must register
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* an HMM mirror struct.
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*/
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int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
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{
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lockdep_assert_held_write(&mm->mmap_sem);
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/* Sanity check */
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if (!mm || !mirror || !mirror->ops)
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return -EINVAL;
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mirror->hmm = hmm_get_or_create(mm);
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if (!mirror->hmm)
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return -ENOMEM;
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down_write(&mirror->hmm->mirrors_sem);
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list_add(&mirror->list, &mirror->hmm->mirrors);
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up_write(&mirror->hmm->mirrors_sem);
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return 0;
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}
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EXPORT_SYMBOL(hmm_mirror_register);
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/*
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* hmm_mirror_unregister() - unregister a mirror
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*
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* @mirror: mirror struct to unregister
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*
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* Stop mirroring a process address space, and cleanup.
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*/
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void hmm_mirror_unregister(struct hmm_mirror *mirror)
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{
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struct hmm *hmm = mirror->hmm;
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down_write(&hmm->mirrors_sem);
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list_del(&mirror->list);
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up_write(&hmm->mirrors_sem);
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hmm_put(hmm);
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}
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EXPORT_SYMBOL(hmm_mirror_unregister);
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struct hmm_vma_walk {
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struct hmm_range *range;
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struct dev_pagemap *pgmap;
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unsigned long last;
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unsigned int flags;
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};
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static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
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bool write_fault, uint64_t *pfn)
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{
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unsigned int flags = FAULT_FLAG_REMOTE;
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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struct vm_area_struct *vma = walk->vma;
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vm_fault_t ret;
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if (hmm_vma_walk->flags & HMM_FAULT_ALLOW_RETRY)
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flags |= FAULT_FLAG_ALLOW_RETRY;
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if (write_fault)
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flags |= FAULT_FLAG_WRITE;
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ret = handle_mm_fault(vma, addr, flags);
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if (ret & VM_FAULT_RETRY) {
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/* Note, handle_mm_fault did up_read(&mm->mmap_sem)) */
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return -EAGAIN;
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}
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if (ret & VM_FAULT_ERROR) {
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*pfn = range->values[HMM_PFN_ERROR];
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return -EFAULT;
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}
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return -EBUSY;
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}
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static int hmm_pfns_bad(unsigned long addr,
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unsigned long end,
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struct mm_walk *walk)
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{
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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uint64_t *pfns = range->pfns;
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unsigned long i;
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i = (addr - range->start) >> PAGE_SHIFT;
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for (; addr < end; addr += PAGE_SIZE, i++)
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pfns[i] = range->values[HMM_PFN_ERROR];
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return 0;
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}
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/*
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* hmm_vma_walk_hole_() - handle a range lacking valid pmd or pte(s)
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* @addr: range virtual start address (inclusive)
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* @end: range virtual end address (exclusive)
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* @fault: should we fault or not ?
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* @write_fault: write fault ?
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* @walk: mm_walk structure
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* Return: 0 on success, -EBUSY after page fault, or page fault error
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*
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* This function will be called whenever pmd_none() or pte_none() returns true,
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* or whenever there is no page directory covering the virtual address range.
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*/
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static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
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bool fault, bool write_fault,
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struct mm_walk *walk)
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{
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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uint64_t *pfns = range->pfns;
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unsigned long i, page_size;
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hmm_vma_walk->last = addr;
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page_size = hmm_range_page_size(range);
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i = (addr - range->start) >> range->page_shift;
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for (; addr < end; addr += page_size, i++) {
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pfns[i] = range->values[HMM_PFN_NONE];
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if (fault || write_fault) {
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int ret;
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ret = hmm_vma_do_fault(walk, addr, write_fault,
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&pfns[i]);
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if (ret != -EBUSY)
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return ret;
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}
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}
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return (fault || write_fault) ? -EBUSY : 0;
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}
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static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
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uint64_t pfns, uint64_t cpu_flags,
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bool *fault, bool *write_fault)
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{
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struct hmm_range *range = hmm_vma_walk->range;
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if (hmm_vma_walk->flags & HMM_FAULT_SNAPSHOT)
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return;
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/*
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* So we not only consider the individual per page request we also
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* consider the default flags requested for the range. The API can
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* be used 2 ways. The first one where the HMM user coalesces
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* multiple page faults into one request and sets flags per pfn for
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* those faults. The second one where the HMM user wants to pre-
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* fault a range with specific flags. For the latter one it is a
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* waste to have the user pre-fill the pfn arrays with a default
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* flags value.
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*/
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pfns = (pfns & range->pfn_flags_mask) | range->default_flags;
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/* We aren't ask to do anything ... */
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if (!(pfns & range->flags[HMM_PFN_VALID]))
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return;
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/* If this is device memory then only fault if explicitly requested */
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if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
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/* Do we fault on device memory ? */
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if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {
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*write_fault = pfns & range->flags[HMM_PFN_WRITE];
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*fault = true;
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}
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return;
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}
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/* If CPU page table is not valid then we need to fault */
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*fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
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/* Need to write fault ? */
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if ((pfns & range->flags[HMM_PFN_WRITE]) &&
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!(cpu_flags & range->flags[HMM_PFN_WRITE])) {
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*write_fault = true;
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*fault = true;
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}
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}
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static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
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const uint64_t *pfns, unsigned long npages,
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uint64_t cpu_flags, bool *fault,
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bool *write_fault)
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{
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unsigned long i;
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if (hmm_vma_walk->flags & HMM_FAULT_SNAPSHOT) {
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*fault = *write_fault = false;
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return;
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}
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*fault = *write_fault = false;
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for (i = 0; i < npages; ++i) {
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hmm_pte_need_fault(hmm_vma_walk, pfns[i], cpu_flags,
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fault, write_fault);
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if ((*write_fault))
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return;
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}
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}
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static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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bool fault, write_fault;
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unsigned long i, npages;
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uint64_t *pfns;
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i = (addr - range->start) >> PAGE_SHIFT;
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npages = (end - addr) >> PAGE_SHIFT;
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pfns = &range->pfns[i];
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hmm_range_need_fault(hmm_vma_walk, pfns, npages,
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0, &fault, &write_fault);
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return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
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}
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static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd)
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{
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if (pmd_protnone(pmd))
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return 0;
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return pmd_write(pmd) ? range->flags[HMM_PFN_VALID] |
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range->flags[HMM_PFN_WRITE] :
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range->flags[HMM_PFN_VALID];
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}
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static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud)
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{
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if (!pud_present(pud))
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return 0;
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return pud_write(pud) ? range->flags[HMM_PFN_VALID] |
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range->flags[HMM_PFN_WRITE] :
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range->flags[HMM_PFN_VALID];
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}
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static int hmm_vma_handle_pmd(struct mm_walk *walk,
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unsigned long addr,
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unsigned long end,
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uint64_t *pfns,
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pmd_t pmd)
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{
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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unsigned long pfn, npages, i;
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bool fault, write_fault;
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uint64_t cpu_flags;
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npages = (end - addr) >> PAGE_SHIFT;
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cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
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hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags,
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&fault, &write_fault);
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if (pmd_protnone(pmd) || fault || write_fault)
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return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
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pfn = pmd_pfn(pmd) + pte_index(addr);
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for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
|
|
if (pmd_devmap(pmd)) {
|
|
hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
|
|
hmm_vma_walk->pgmap);
|
|
if (unlikely(!hmm_vma_walk->pgmap))
|
|
return -EBUSY;
|
|
}
|
|
pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags;
|
|
}
|
|
if (hmm_vma_walk->pgmap) {
|
|
put_dev_pagemap(hmm_vma_walk->pgmap);
|
|
hmm_vma_walk->pgmap = NULL;
|
|
}
|
|
hmm_vma_walk->last = end;
|
|
return 0;
|
|
#else
|
|
/* If THP is not enabled then we should never reach this code ! */
|
|
return -EINVAL;
|
|
#endif
|
|
}
|
|
|
|
static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
|
|
{
|
|
if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
|
|
return 0;
|
|
return pte_write(pte) ? range->flags[HMM_PFN_VALID] |
|
|
range->flags[HMM_PFN_WRITE] :
|
|
range->flags[HMM_PFN_VALID];
|
|
}
|
|
|
|
static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
|
|
unsigned long end, pmd_t *pmdp, pte_t *ptep,
|
|
uint64_t *pfn)
|
|
{
|
|
struct hmm_vma_walk *hmm_vma_walk = walk->private;
|
|
struct hmm_range *range = hmm_vma_walk->range;
|
|
bool fault, write_fault;
|
|
uint64_t cpu_flags;
|
|
pte_t pte = *ptep;
|
|
uint64_t orig_pfn = *pfn;
|
|
|
|
*pfn = range->values[HMM_PFN_NONE];
|
|
fault = write_fault = false;
|
|
|
|
if (pte_none(pte)) {
|
|
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0,
|
|
&fault, &write_fault);
|
|
if (fault || write_fault)
|
|
goto fault;
|
|
return 0;
|
|
}
|
|
|
|
if (!pte_present(pte)) {
|
|
swp_entry_t entry = pte_to_swp_entry(pte);
|
|
|
|
if (!non_swap_entry(entry)) {
|
|
if (fault || write_fault)
|
|
goto fault;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This is a special swap entry, ignore migration, use
|
|
* device and report anything else as error.
|
|
*/
|
|
if (is_device_private_entry(entry)) {
|
|
cpu_flags = range->flags[HMM_PFN_VALID] |
|
|
range->flags[HMM_PFN_DEVICE_PRIVATE];
|
|
cpu_flags |= is_write_device_private_entry(entry) ?
|
|
range->flags[HMM_PFN_WRITE] : 0;
|
|
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
|
|
&fault, &write_fault);
|
|
if (fault || write_fault)
|
|
goto fault;
|
|
*pfn = hmm_device_entry_from_pfn(range,
|
|
swp_offset(entry));
|
|
*pfn |= cpu_flags;
|
|
return 0;
|
|
}
|
|
|
|
if (is_migration_entry(entry)) {
|
|
if (fault || write_fault) {
|
|
pte_unmap(ptep);
|
|
hmm_vma_walk->last = addr;
|
|
migration_entry_wait(walk->mm, pmdp, addr);
|
|
return -EBUSY;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Report error for everything else */
|
|
*pfn = range->values[HMM_PFN_ERROR];
|
|
return -EFAULT;
|
|
} else {
|
|
cpu_flags = pte_to_hmm_pfn_flags(range, pte);
|
|
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
|
|
&fault, &write_fault);
|
|
}
|
|
|
|
if (fault || write_fault)
|
|
goto fault;
|
|
|
|
if (pte_devmap(pte)) {
|
|
hmm_vma_walk->pgmap = get_dev_pagemap(pte_pfn(pte),
|
|
hmm_vma_walk->pgmap);
|
|
if (unlikely(!hmm_vma_walk->pgmap))
|
|
return -EBUSY;
|
|
} else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) {
|
|
*pfn = range->values[HMM_PFN_SPECIAL];
|
|
return -EFAULT;
|
|
}
|
|
|
|
*pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags;
|
|
return 0;
|
|
|
|
fault:
|
|
if (hmm_vma_walk->pgmap) {
|
|
put_dev_pagemap(hmm_vma_walk->pgmap);
|
|
hmm_vma_walk->pgmap = NULL;
|
|
}
|
|
pte_unmap(ptep);
|
|
/* Fault any virtual address we were asked to fault */
|
|
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
|
|
}
|
|
|
|
static int hmm_vma_walk_pmd(pmd_t *pmdp,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct hmm_vma_walk *hmm_vma_walk = walk->private;
|
|
struct hmm_range *range = hmm_vma_walk->range;
|
|
uint64_t *pfns = range->pfns;
|
|
unsigned long addr = start, i;
|
|
pte_t *ptep;
|
|
pmd_t pmd;
|
|
|
|
again:
|
|
pmd = READ_ONCE(*pmdp);
|
|
if (pmd_none(pmd))
|
|
return hmm_vma_walk_hole(start, end, walk);
|
|
|
|
if (pmd_huge(pmd) && (range->vma->vm_flags & VM_HUGETLB))
|
|
return hmm_pfns_bad(start, end, walk);
|
|
|
|
if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
|
|
bool fault, write_fault;
|
|
unsigned long npages;
|
|
uint64_t *pfns;
|
|
|
|
i = (addr - range->start) >> PAGE_SHIFT;
|
|
npages = (end - addr) >> PAGE_SHIFT;
|
|
pfns = &range->pfns[i];
|
|
|
|
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
|
|
0, &fault, &write_fault);
|
|
if (fault || write_fault) {
|
|
hmm_vma_walk->last = addr;
|
|
pmd_migration_entry_wait(walk->mm, pmdp);
|
|
return -EBUSY;
|
|
}
|
|
return 0;
|
|
} else if (!pmd_present(pmd))
|
|
return hmm_pfns_bad(start, end, walk);
|
|
|
|
if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
|
|
/*
|
|
* No need to take pmd_lock here, even if some other thread
|
|
* is splitting the huge pmd we will get that event through
|
|
* mmu_notifier callback.
|
|
*
|
|
* So just read pmd value and check again it's a transparent
|
|
* huge or device mapping one and compute corresponding pfn
|
|
* values.
|
|
*/
|
|
pmd = pmd_read_atomic(pmdp);
|
|
barrier();
|
|
if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
|
|
goto again;
|
|
|
|
i = (addr - range->start) >> PAGE_SHIFT;
|
|
return hmm_vma_handle_pmd(walk, addr, end, &pfns[i], pmd);
|
|
}
|
|
|
|
/*
|
|
* We have handled all the valid cases above ie either none, migration,
|
|
* huge or transparent huge. At this point either it is a valid pmd
|
|
* entry pointing to pte directory or it is a bad pmd that will not
|
|
* recover.
|
|
*/
|
|
if (pmd_bad(pmd))
|
|
return hmm_pfns_bad(start, end, walk);
|
|
|
|
ptep = pte_offset_map(pmdp, addr);
|
|
i = (addr - range->start) >> PAGE_SHIFT;
|
|
for (; addr < end; addr += PAGE_SIZE, ptep++, i++) {
|
|
int r;
|
|
|
|
r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, &pfns[i]);
|
|
if (r) {
|
|
/* hmm_vma_handle_pte() did unmap pte directory */
|
|
hmm_vma_walk->last = addr;
|
|
return r;
|
|
}
|
|
}
|
|
if (hmm_vma_walk->pgmap) {
|
|
/*
|
|
* We do put_dev_pagemap() here and not in hmm_vma_handle_pte()
|
|
* so that we can leverage get_dev_pagemap() optimization which
|
|
* will not re-take a reference on a pgmap if we already have
|
|
* one.
|
|
*/
|
|
put_dev_pagemap(hmm_vma_walk->pgmap);
|
|
hmm_vma_walk->pgmap = NULL;
|
|
}
|
|
pte_unmap(ptep - 1);
|
|
|
|
hmm_vma_walk->last = addr;
|
|
return 0;
|
|
}
|
|
|
|
static int hmm_vma_walk_pud(pud_t *pudp,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct hmm_vma_walk *hmm_vma_walk = walk->private;
|
|
struct hmm_range *range = hmm_vma_walk->range;
|
|
unsigned long addr = start, next;
|
|
pmd_t *pmdp;
|
|
pud_t pud;
|
|
int ret;
|
|
|
|
again:
|
|
pud = READ_ONCE(*pudp);
|
|
if (pud_none(pud))
|
|
return hmm_vma_walk_hole(start, end, walk);
|
|
|
|
if (pud_huge(pud) && pud_devmap(pud)) {
|
|
unsigned long i, npages, pfn;
|
|
uint64_t *pfns, cpu_flags;
|
|
bool fault, write_fault;
|
|
|
|
if (!pud_present(pud))
|
|
return hmm_vma_walk_hole(start, end, walk);
|
|
|
|
i = (addr - range->start) >> PAGE_SHIFT;
|
|
npages = (end - addr) >> PAGE_SHIFT;
|
|
pfns = &range->pfns[i];
|
|
|
|
cpu_flags = pud_to_hmm_pfn_flags(range, pud);
|
|
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
|
|
cpu_flags, &fault, &write_fault);
|
|
if (fault || write_fault)
|
|
return hmm_vma_walk_hole_(addr, end, fault,
|
|
write_fault, walk);
|
|
|
|
pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
|
|
for (i = 0; i < npages; ++i, ++pfn) {
|
|
hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
|
|
hmm_vma_walk->pgmap);
|
|
if (unlikely(!hmm_vma_walk->pgmap))
|
|
return -EBUSY;
|
|
pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
|
|
cpu_flags;
|
|
}
|
|
if (hmm_vma_walk->pgmap) {
|
|
put_dev_pagemap(hmm_vma_walk->pgmap);
|
|
hmm_vma_walk->pgmap = NULL;
|
|
}
|
|
hmm_vma_walk->last = end;
|
|
return 0;
|
|
}
|
|
|
|
split_huge_pud(walk->vma, pudp, addr);
|
|
if (pud_none(*pudp))
|
|
goto again;
|
|
|
|
pmdp = pmd_offset(pudp, addr);
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
ret = hmm_vma_walk_pmd(pmdp, addr, next, walk);
|
|
if (ret)
|
|
return ret;
|
|
} while (pmdp++, addr = next, addr != end);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
|
|
unsigned long start, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
unsigned long addr = start, i, pfn, mask, size, pfn_inc;
|
|
struct hmm_vma_walk *hmm_vma_walk = walk->private;
|
|
struct hmm_range *range = hmm_vma_walk->range;
|
|
struct vm_area_struct *vma = walk->vma;
|
|
struct hstate *h = hstate_vma(vma);
|
|
uint64_t orig_pfn, cpu_flags;
|
|
bool fault, write_fault;
|
|
spinlock_t *ptl;
|
|
pte_t entry;
|
|
int ret = 0;
|
|
|
|
size = huge_page_size(h);
|
|
mask = size - 1;
|
|
if (range->page_shift != PAGE_SHIFT) {
|
|
/* Make sure we are looking at a full page. */
|
|
if (start & mask)
|
|
return -EINVAL;
|
|
if (end < (start + size))
|
|
return -EINVAL;
|
|
pfn_inc = size >> PAGE_SHIFT;
|
|
} else {
|
|
pfn_inc = 1;
|
|
size = PAGE_SIZE;
|
|
}
|
|
|
|
ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
|
|
entry = huge_ptep_get(pte);
|
|
|
|
i = (start - range->start) >> range->page_shift;
|
|
orig_pfn = range->pfns[i];
|
|
range->pfns[i] = range->values[HMM_PFN_NONE];
|
|
cpu_flags = pte_to_hmm_pfn_flags(range, entry);
|
|
fault = write_fault = false;
|
|
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
|
|
&fault, &write_fault);
|
|
if (fault || write_fault) {
|
|
ret = -ENOENT;
|
|
goto unlock;
|
|
}
|
|
|
|
pfn = pte_pfn(entry) + ((start & mask) >> range->page_shift);
|
|
for (; addr < end; addr += size, i++, pfn += pfn_inc)
|
|
range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
|
|
cpu_flags;
|
|
hmm_vma_walk->last = end;
|
|
|
|
unlock:
|
|
spin_unlock(ptl);
|
|
|
|
if (ret == -ENOENT)
|
|
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
|
|
|
|
return ret;
|
|
#else /* CONFIG_HUGETLB_PAGE */
|
|
return -EINVAL;
|
|
#endif
|
|
}
|
|
|
|
static void hmm_pfns_clear(struct hmm_range *range,
|
|
uint64_t *pfns,
|
|
unsigned long addr,
|
|
unsigned long end)
|
|
{
|
|
for (; addr < end; addr += PAGE_SIZE, pfns++)
|
|
*pfns = range->values[HMM_PFN_NONE];
|
|
}
|
|
|
|
/*
|
|
* hmm_range_register() - start tracking change to CPU page table over a range
|
|
* @range: range
|
|
* @mm: the mm struct for the range of virtual address
|
|
* @start: start virtual address (inclusive)
|
|
* @end: end virtual address (exclusive)
|
|
* @page_shift: expect page shift for the range
|
|
* Return: 0 on success, -EFAULT if the address space is no longer valid
|
|
*
|
|
* Track updates to the CPU page table see include/linux/hmm.h
|
|
*/
|
|
int hmm_range_register(struct hmm_range *range,
|
|
struct hmm_mirror *mirror,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
unsigned page_shift)
|
|
{
|
|
unsigned long mask = ((1UL << page_shift) - 1UL);
|
|
struct hmm *hmm = mirror->hmm;
|
|
unsigned long flags;
|
|
|
|
range->valid = false;
|
|
range->hmm = NULL;
|
|
|
|
if ((start & mask) || (end & mask))
|
|
return -EINVAL;
|
|
if (start >= end)
|
|
return -EINVAL;
|
|
|
|
range->page_shift = page_shift;
|
|
range->start = start;
|
|
range->end = end;
|
|
|
|
/* Prevent hmm_release() from running while the range is valid */
|
|
if (!mmget_not_zero(hmm->mm))
|
|
return -EFAULT;
|
|
|
|
/* Initialize range to track CPU page table updates. */
|
|
spin_lock_irqsave(&hmm->ranges_lock, flags);
|
|
|
|
range->hmm = hmm;
|
|
kref_get(&hmm->kref);
|
|
list_add(&range->list, &hmm->ranges);
|
|
|
|
/*
|
|
* If there are any concurrent notifiers we have to wait for them for
|
|
* the range to be valid (see hmm_range_wait_until_valid()).
|
|
*/
|
|
if (!hmm->notifiers)
|
|
range->valid = true;
|
|
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(hmm_range_register);
|
|
|
|
/*
|
|
* hmm_range_unregister() - stop tracking change to CPU page table over a range
|
|
* @range: range
|
|
*
|
|
* Range struct is used to track updates to the CPU page table after a call to
|
|
* hmm_range_register(). See include/linux/hmm.h for how to use it.
|
|
*/
|
|
void hmm_range_unregister(struct hmm_range *range)
|
|
{
|
|
struct hmm *hmm = range->hmm;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&hmm->ranges_lock, flags);
|
|
list_del_init(&range->list);
|
|
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
|
|
|
|
/* Drop reference taken by hmm_range_register() */
|
|
mmput(hmm->mm);
|
|
hmm_put(hmm);
|
|
|
|
/*
|
|
* The range is now invalid and the ref on the hmm is dropped, so
|
|
* poison the pointer. Leave other fields in place, for the caller's
|
|
* use.
|
|
*/
|
|
range->valid = false;
|
|
memset(&range->hmm, POISON_INUSE, sizeof(range->hmm));
|
|
}
|
|
EXPORT_SYMBOL(hmm_range_unregister);
|
|
|
|
/**
|
|
* hmm_range_fault - try to fault some address in a virtual address range
|
|
* @range: range being faulted
|
|
* @flags: HMM_FAULT_* flags
|
|
*
|
|
* Return: the number of valid pages in range->pfns[] (from range start
|
|
* address), which may be zero. On error one of the following status codes
|
|
* can be returned:
|
|
*
|
|
* -EINVAL: Invalid arguments or mm or virtual address is in an invalid vma
|
|
* (e.g., device file vma).
|
|
* -ENOMEM: Out of memory.
|
|
* -EPERM: Invalid permission (e.g., asking for write and range is read
|
|
* only).
|
|
* -EAGAIN: A page fault needs to be retried and mmap_sem was dropped.
|
|
* -EBUSY: The range has been invalidated and the caller needs to wait for
|
|
* the invalidation to finish.
|
|
* -EFAULT: Invalid (i.e., either no valid vma or it is illegal to access
|
|
* that range) number of valid pages in range->pfns[] (from
|
|
* range start address).
|
|
*
|
|
* This is similar to a regular CPU page fault except that it will not trigger
|
|
* any memory migration if the memory being faulted is not accessible by CPUs
|
|
* and caller does not ask for migration.
|
|
*
|
|
* On error, for one virtual address in the range, the function will mark the
|
|
* corresponding HMM pfn entry with an error flag.
|
|
*/
|
|
long hmm_range_fault(struct hmm_range *range, unsigned int flags)
|
|
{
|
|
const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
|
|
unsigned long start = range->start, end;
|
|
struct hmm_vma_walk hmm_vma_walk;
|
|
struct hmm *hmm = range->hmm;
|
|
struct vm_area_struct *vma;
|
|
struct mm_walk mm_walk;
|
|
int ret;
|
|
|
|
lockdep_assert_held(&hmm->mm->mmap_sem);
|
|
|
|
do {
|
|
/* If range is no longer valid force retry. */
|
|
if (!range->valid)
|
|
return -EBUSY;
|
|
|
|
vma = find_vma(hmm->mm, start);
|
|
if (vma == NULL || (vma->vm_flags & device_vma))
|
|
return -EFAULT;
|
|
|
|
if (is_vm_hugetlb_page(vma)) {
|
|
if (huge_page_shift(hstate_vma(vma)) !=
|
|
range->page_shift &&
|
|
range->page_shift != PAGE_SHIFT)
|
|
return -EINVAL;
|
|
} else {
|
|
if (range->page_shift != PAGE_SHIFT)
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!(vma->vm_flags & VM_READ)) {
|
|
/*
|
|
* If vma do not allow read access, then assume that it
|
|
* does not allow write access, either. HMM does not
|
|
* support architecture that allow write without read.
|
|
*/
|
|
hmm_pfns_clear(range, range->pfns,
|
|
range->start, range->end);
|
|
return -EPERM;
|
|
}
|
|
|
|
range->vma = vma;
|
|
hmm_vma_walk.pgmap = NULL;
|
|
hmm_vma_walk.last = start;
|
|
hmm_vma_walk.flags = flags;
|
|
hmm_vma_walk.range = range;
|
|
mm_walk.private = &hmm_vma_walk;
|
|
end = min(range->end, vma->vm_end);
|
|
|
|
mm_walk.vma = vma;
|
|
mm_walk.mm = vma->vm_mm;
|
|
mm_walk.pte_entry = NULL;
|
|
mm_walk.test_walk = NULL;
|
|
mm_walk.hugetlb_entry = NULL;
|
|
mm_walk.pud_entry = hmm_vma_walk_pud;
|
|
mm_walk.pmd_entry = hmm_vma_walk_pmd;
|
|
mm_walk.pte_hole = hmm_vma_walk_hole;
|
|
mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry;
|
|
|
|
do {
|
|
ret = walk_page_range(start, end, &mm_walk);
|
|
start = hmm_vma_walk.last;
|
|
|
|
/* Keep trying while the range is valid. */
|
|
} while (ret == -EBUSY && range->valid);
|
|
|
|
if (ret) {
|
|
unsigned long i;
|
|
|
|
i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
|
|
hmm_pfns_clear(range, &range->pfns[i],
|
|
hmm_vma_walk.last, range->end);
|
|
return ret;
|
|
}
|
|
start = end;
|
|
|
|
} while (start < range->end);
|
|
|
|
return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
|
|
}
|
|
EXPORT_SYMBOL(hmm_range_fault);
|
|
|
|
/**
|
|
* hmm_range_dma_map - hmm_range_fault() and dma map page all in one.
|
|
* @range: range being faulted
|
|
* @device: device to map page to
|
|
* @daddrs: array of dma addresses for the mapped pages
|
|
* @flags: HMM_FAULT_*
|
|
*
|
|
* Return: the number of pages mapped on success (including zero), or any
|
|
* status return from hmm_range_fault() otherwise.
|
|
*/
|
|
long hmm_range_dma_map(struct hmm_range *range, struct device *device,
|
|
dma_addr_t *daddrs, unsigned int flags)
|
|
{
|
|
unsigned long i, npages, mapped;
|
|
long ret;
|
|
|
|
ret = hmm_range_fault(range, flags);
|
|
if (ret <= 0)
|
|
return ret ? ret : -EBUSY;
|
|
|
|
npages = (range->end - range->start) >> PAGE_SHIFT;
|
|
for (i = 0, mapped = 0; i < npages; ++i) {
|
|
enum dma_data_direction dir = DMA_TO_DEVICE;
|
|
struct page *page;
|
|
|
|
/*
|
|
* FIXME need to update DMA API to provide invalid DMA address
|
|
* value instead of a function to test dma address value. This
|
|
* would remove lot of dumb code duplicated accross many arch.
|
|
*
|
|
* For now setting it to 0 here is good enough as the pfns[]
|
|
* value is what is use to check what is valid and what isn't.
|
|
*/
|
|
daddrs[i] = 0;
|
|
|
|
page = hmm_device_entry_to_page(range, range->pfns[i]);
|
|
if (page == NULL)
|
|
continue;
|
|
|
|
/* Check if range is being invalidated */
|
|
if (!range->valid) {
|
|
ret = -EBUSY;
|
|
goto unmap;
|
|
}
|
|
|
|
/* If it is read and write than map bi-directional. */
|
|
if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
|
|
dir = DMA_BIDIRECTIONAL;
|
|
|
|
daddrs[i] = dma_map_page(device, page, 0, PAGE_SIZE, dir);
|
|
if (dma_mapping_error(device, daddrs[i])) {
|
|
ret = -EFAULT;
|
|
goto unmap;
|
|
}
|
|
|
|
mapped++;
|
|
}
|
|
|
|
return mapped;
|
|
|
|
unmap:
|
|
for (npages = i, i = 0; (i < npages) && mapped; ++i) {
|
|
enum dma_data_direction dir = DMA_TO_DEVICE;
|
|
struct page *page;
|
|
|
|
page = hmm_device_entry_to_page(range, range->pfns[i]);
|
|
if (page == NULL)
|
|
continue;
|
|
|
|
if (dma_mapping_error(device, daddrs[i]))
|
|
continue;
|
|
|
|
/* If it is read and write than map bi-directional. */
|
|
if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
|
|
dir = DMA_BIDIRECTIONAL;
|
|
|
|
dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
|
|
mapped--;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(hmm_range_dma_map);
|
|
|
|
/**
|
|
* hmm_range_dma_unmap() - unmap range of that was map with hmm_range_dma_map()
|
|
* @range: range being unmapped
|
|
* @vma: the vma against which the range (optional)
|
|
* @device: device against which dma map was done
|
|
* @daddrs: dma address of mapped pages
|
|
* @dirty: dirty page if it had the write flag set
|
|
* Return: number of page unmapped on success, -EINVAL otherwise
|
|
*
|
|
* Note that caller MUST abide by mmu notifier or use HMM mirror and abide
|
|
* to the sync_cpu_device_pagetables() callback so that it is safe here to
|
|
* call set_page_dirty(). Caller must also take appropriate locks to avoid
|
|
* concurrent mmu notifier or sync_cpu_device_pagetables() to make progress.
|
|
*/
|
|
long hmm_range_dma_unmap(struct hmm_range *range,
|
|
struct vm_area_struct *vma,
|
|
struct device *device,
|
|
dma_addr_t *daddrs,
|
|
bool dirty)
|
|
{
|
|
unsigned long i, npages;
|
|
long cpages = 0;
|
|
|
|
/* Sanity check. */
|
|
if (range->end <= range->start)
|
|
return -EINVAL;
|
|
if (!daddrs)
|
|
return -EINVAL;
|
|
if (!range->pfns)
|
|
return -EINVAL;
|
|
|
|
npages = (range->end - range->start) >> PAGE_SHIFT;
|
|
for (i = 0; i < npages; ++i) {
|
|
enum dma_data_direction dir = DMA_TO_DEVICE;
|
|
struct page *page;
|
|
|
|
page = hmm_device_entry_to_page(range, range->pfns[i]);
|
|
if (page == NULL)
|
|
continue;
|
|
|
|
/* If it is read and write than map bi-directional. */
|
|
if (range->pfns[i] & range->flags[HMM_PFN_WRITE]) {
|
|
dir = DMA_BIDIRECTIONAL;
|
|
|
|
/*
|
|
* See comments in function description on why it is
|
|
* safe here to call set_page_dirty()
|
|
*/
|
|
if (dirty)
|
|
set_page_dirty(page);
|
|
}
|
|
|
|
/* Unmap and clear pfns/dma address */
|
|
dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
|
|
range->pfns[i] = range->values[HMM_PFN_NONE];
|
|
/* FIXME see comments in hmm_vma_dma_map() */
|
|
daddrs[i] = 0;
|
|
cpages++;
|
|
}
|
|
|
|
return cpages;
|
|
}
|
|
EXPORT_SYMBOL(hmm_range_dma_unmap);
|