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![Souptick Joarder](/assets/img/avatar_default.png)
Convert to use vm_fault_t type as return type for fault handler. kbuild reported warning during testing of *mm-create-the-new-vm_fault_t-type.patch* available in below link - https://patchwork.kernel.org/patch/10752741/ kernel/memremap.c:46:34: warning: incorrect type in return expression (different base types) kernel/memremap.c:46:34: expected restricted vm_fault_t kernel/memremap.c:46:34: got int This patch has fixed the warnings and also hmm_devmem_fault() is converted to return vm_fault_t to avoid further warnings. [sfr@canb.auug.org.au: drm/nouveau/dmem: update for struct hmm_devmem_ops member change] Link: http://lkml.kernel.org/r/20190220174407.753d94e5@canb.auug.org.au Link: http://lkml.kernel.org/r/20190110145900.GA1317@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1240 lines
33 KiB
C
1240 lines
33 KiB
C
/*
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* Copyright 2013 Red Hat Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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/jump_label.h>
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#include <linux/mmu_notifier.h>
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#include <linux/memory_hotplug.h>
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#define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT)
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#if IS_ENABLED(CONFIG_HMM_MIRROR)
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static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
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/*
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* struct hmm - HMM per mm struct
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*
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* @mm: mm struct this HMM struct is bound to
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* @lock: lock protecting ranges list
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* @ranges: list of range being snapshotted
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* @mirrors: list of mirrors for this mm
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* @mmu_notifier: mmu notifier to track updates to CPU page table
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* @mirrors_sem: read/write semaphore protecting the mirrors list
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*/
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struct hmm {
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struct mm_struct *mm;
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spinlock_t lock;
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struct list_head ranges;
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struct list_head mirrors;
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struct mmu_notifier mmu_notifier;
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struct rw_semaphore mirrors_sem;
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};
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/*
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* hmm_register - 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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*
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* This is not intended to be used directly by device drivers. It allocates an
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* HMM struct if mm does not have one, and initializes it.
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*/
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static struct hmm *hmm_register(struct mm_struct *mm)
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{
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struct hmm *hmm = READ_ONCE(mm->hmm);
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bool cleanup = false;
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/*
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* The hmm struct can only be freed once the mm_struct goes away,
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* hence we should always have pre-allocated an new hmm struct
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* above.
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*/
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if (hmm)
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return hmm;
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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_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->lock);
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hmm->mm = mm;
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spin_lock(&mm->page_table_lock);
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if (!mm->hmm)
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mm->hmm = hmm;
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else
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cleanup = true;
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spin_unlock(&mm->page_table_lock);
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if (cleanup)
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goto error;
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/*
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* We should only get here if hold the mmap_sem in write mode ie on
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* registration of first mirror through hmm_mirror_register()
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*/
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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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goto error_mm;
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return mm->hmm;
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error_mm:
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spin_lock(&mm->page_table_lock);
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if (mm->hmm == hmm)
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mm->hmm = NULL;
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spin_unlock(&mm->page_table_lock);
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error:
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kfree(hmm);
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return NULL;
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}
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void hmm_mm_destroy(struct mm_struct *mm)
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{
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kfree(mm->hmm);
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}
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static int hmm_invalidate_range(struct hmm *hmm, bool device,
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const struct hmm_update *update)
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{
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struct hmm_mirror *mirror;
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struct hmm_range *range;
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spin_lock(&hmm->lock);
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list_for_each_entry(range, &hmm->ranges, list) {
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unsigned long addr, idx, npages;
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if (update->end < range->start || update->start >= range->end)
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continue;
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range->valid = false;
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addr = max(update->start, range->start);
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idx = (addr - range->start) >> PAGE_SHIFT;
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npages = (min(range->end, update->end) - addr) >> PAGE_SHIFT;
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memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages);
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}
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spin_unlock(&hmm->lock);
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if (!device)
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return 0;
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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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int ret;
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ret = mirror->ops->sync_cpu_device_pagetables(mirror, update);
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if (!update->blockable && ret == -EAGAIN) {
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up_read(&hmm->mirrors_sem);
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return -EAGAIN;
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}
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}
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up_read(&hmm->mirrors_sem);
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return 0;
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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_mirror *mirror;
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struct hmm *hmm = mm->hmm;
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down_write(&hmm->mirrors_sem);
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mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror,
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list);
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while (mirror) {
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list_del_init(&mirror->list);
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if (mirror->ops->release) {
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/*
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* Drop mirrors_sem so callback can wait on any pending
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* work that might itself trigger mmu_notifier callback
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* and thus would deadlock with us.
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*/
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up_write(&hmm->mirrors_sem);
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mirror->ops->release(mirror);
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down_write(&hmm->mirrors_sem);
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}
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mirror = list_first_entry_or_null(&hmm->mirrors,
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struct hmm_mirror, list);
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}
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up_write(&hmm->mirrors_sem);
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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 *range)
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{
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struct hmm_update update;
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struct hmm *hmm = range->mm->hmm;
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VM_BUG_ON(!hmm);
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update.start = range->start;
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update.end = range->end;
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update.event = HMM_UPDATE_INVALIDATE;
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update.blockable = range->blockable;
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return hmm_invalidate_range(hmm, true, &update);
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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 *range)
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{
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struct hmm_update update;
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struct hmm *hmm = range->mm->hmm;
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VM_BUG_ON(!hmm);
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update.start = range->start;
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update.end = range->end;
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update.event = HMM_UPDATE_INVALIDATE;
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update.blockable = true;
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hmm_invalidate_range(hmm, false, &update);
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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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*
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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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* THE mm->mmap_sem MUST BE HELD IN WRITE MODE !
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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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/* Sanity check */
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if (!mm || !mirror || !mirror->ops)
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return -EINVAL;
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again:
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mirror->hmm = hmm_register(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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if (mirror->hmm->mm == NULL) {
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/*
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* A racing hmm_mirror_unregister() is about to destroy the hmm
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* struct. Try again to allocate a new one.
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*/
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up_write(&mirror->hmm->mirrors_sem);
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mirror->hmm = NULL;
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goto again;
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} else {
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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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}
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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: new mirror struct to register
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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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bool should_unregister = false;
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struct mm_struct *mm;
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struct hmm *hmm;
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if (mirror->hmm == NULL)
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return;
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hmm = mirror->hmm;
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down_write(&hmm->mirrors_sem);
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list_del_init(&mirror->list);
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should_unregister = list_empty(&hmm->mirrors);
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mirror->hmm = NULL;
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mm = hmm->mm;
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hmm->mm = NULL;
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up_write(&hmm->mirrors_sem);
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if (!should_unregister || mm == NULL)
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return;
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mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm);
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spin_lock(&mm->page_table_lock);
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if (mm->hmm == hmm)
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mm->hmm = NULL;
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spin_unlock(&mm->page_table_lock);
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kfree(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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unsigned long last;
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bool fault;
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bool block;
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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_ALLOW_RETRY | 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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flags |= hmm_vma_walk->block ? 0 : FAULT_FLAG_ALLOW_RETRY;
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flags |= write_fault ? FAULT_FLAG_WRITE : 0;
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ret = handle_mm_fault(vma, addr, flags);
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if (ret & VM_FAULT_RETRY)
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return -EBUSY;
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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 -EAGAIN;
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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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* @start: 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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* Returns: 0 on success, -EAGAIN 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;
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hmm_vma_walk->last = addr;
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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_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 != -EAGAIN)
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return ret;
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}
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}
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return (fault || write_fault) ? -EAGAIN : 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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*fault = *write_fault = false;
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if (!hmm_vma_walk->fault)
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return;
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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 than 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->fault) {
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*fault = *write_fault = false;
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return;
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}
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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 ((*fault) || (*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 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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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);
|
|
for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
|
|
pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags;
|
|
hmm_vma_walk->last = end;
|
|
return 0;
|
|
}
|
|
|
|
static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
|
|
{
|
|
if (pte_none(pte) || !pte_present(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;
|
|
struct vm_area_struct *vma = walk->vma;
|
|
bool fault, write_fault;
|
|
uint64_t cpu_flags;
|
|
pte_t pte = *ptep;
|
|
uint64_t orig_pfn = *pfn;
|
|
|
|
*pfn = range->values[HMM_PFN_NONE];
|
|
cpu_flags = pte_to_hmm_pfn_flags(range, pte);
|
|
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
|
|
&fault, &write_fault);
|
|
|
|
if (pte_none(pte)) {
|
|
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_pfn_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(vma->vm_mm,
|
|
pmdp, addr);
|
|
return -EAGAIN;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Report error for everything else */
|
|
*pfn = range->values[HMM_PFN_ERROR];
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (fault || write_fault)
|
|
goto fault;
|
|
|
|
*pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags;
|
|
return 0;
|
|
|
|
fault:
|
|
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;
|
|
struct vm_area_struct *vma = walk->vma;
|
|
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(vma->vm_mm, pmdp);
|
|
return -EAGAIN;
|
|
}
|
|
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 threads
|
|
* is splitting the huge pmd we will get that event through
|
|
* mmu_notifier callback.
|
|
*
|
|
* So just read pmd value and check again its 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 case 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;
|
|
}
|
|
}
|
|
pte_unmap(ptep - 1);
|
|
|
|
hmm_vma_walk->last = addr;
|
|
return 0;
|
|
}
|
|
|
|
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];
|
|
}
|
|
|
|
static void hmm_pfns_special(struct hmm_range *range)
|
|
{
|
|
unsigned long addr = range->start, i = 0;
|
|
|
|
for (; addr < range->end; addr += PAGE_SIZE, i++)
|
|
range->pfns[i] = range->values[HMM_PFN_SPECIAL];
|
|
}
|
|
|
|
/*
|
|
* hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses
|
|
* @range: range being snapshotted
|
|
* Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
|
|
* vma permission, 0 success
|
|
*
|
|
* This snapshots the CPU page table for a range of virtual addresses. Snapshot
|
|
* validity is tracked by range struct. See hmm_vma_range_done() for further
|
|
* information.
|
|
*
|
|
* The range struct is initialized here. It tracks the CPU page table, but only
|
|
* if the function returns success (0), in which case the caller must then call
|
|
* hmm_vma_range_done() to stop CPU page table update tracking on this range.
|
|
*
|
|
* NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS
|
|
* MEMORY CORRUPTION ! YOU HAVE BEEN WARNED !
|
|
*/
|
|
int hmm_vma_get_pfns(struct hmm_range *range)
|
|
{
|
|
struct vm_area_struct *vma = range->vma;
|
|
struct hmm_vma_walk hmm_vma_walk;
|
|
struct mm_walk mm_walk;
|
|
struct hmm *hmm;
|
|
|
|
/* Sanity check, this really should not happen ! */
|
|
if (range->start < vma->vm_start || range->start >= vma->vm_end)
|
|
return -EINVAL;
|
|
if (range->end < vma->vm_start || range->end > vma->vm_end)
|
|
return -EINVAL;
|
|
|
|
hmm = hmm_register(vma->vm_mm);
|
|
if (!hmm)
|
|
return -ENOMEM;
|
|
/* Caller must have registered a mirror, via hmm_mirror_register() ! */
|
|
if (!hmm->mmu_notifier.ops)
|
|
return -EINVAL;
|
|
|
|
/* FIXME support hugetlb fs */
|
|
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) ||
|
|
vma_is_dax(vma)) {
|
|
hmm_pfns_special(range);
|
|
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. Architecture that allow
|
|
* write without read access are not supported by HMM, because
|
|
* operations such has atomic access would not work.
|
|
*/
|
|
hmm_pfns_clear(range, range->pfns, range->start, range->end);
|
|
return -EPERM;
|
|
}
|
|
|
|
/* Initialize range to track CPU page table update */
|
|
spin_lock(&hmm->lock);
|
|
range->valid = true;
|
|
list_add_rcu(&range->list, &hmm->ranges);
|
|
spin_unlock(&hmm->lock);
|
|
|
|
hmm_vma_walk.fault = false;
|
|
hmm_vma_walk.range = range;
|
|
mm_walk.private = &hmm_vma_walk;
|
|
|
|
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.pmd_entry = hmm_vma_walk_pmd;
|
|
mm_walk.pte_hole = hmm_vma_walk_hole;
|
|
|
|
walk_page_range(range->start, range->end, &mm_walk);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(hmm_vma_get_pfns);
|
|
|
|
/*
|
|
* hmm_vma_range_done() - stop tracking change to CPU page table over a range
|
|
* @range: range being tracked
|
|
* Returns: false if range data has been invalidated, true otherwise
|
|
*
|
|
* Range struct is used to track updates to the CPU page table after a call to
|
|
* either hmm_vma_get_pfns() or hmm_vma_fault(). Once the device driver is done
|
|
* using the data, or wants to lock updates to the data it got from those
|
|
* functions, it must call the hmm_vma_range_done() function, which will then
|
|
* stop tracking CPU page table updates.
|
|
*
|
|
* Note that device driver must still implement general CPU page table update
|
|
* tracking either by using hmm_mirror (see hmm_mirror_register()) or by using
|
|
* the mmu_notifier API directly.
|
|
*
|
|
* CPU page table update tracking done through hmm_range is only temporary and
|
|
* to be used while trying to duplicate CPU page table contents for a range of
|
|
* virtual addresses.
|
|
*
|
|
* There are two ways to use this :
|
|
* again:
|
|
* hmm_vma_get_pfns(range); or hmm_vma_fault(...);
|
|
* trans = device_build_page_table_update_transaction(pfns);
|
|
* device_page_table_lock();
|
|
* if (!hmm_vma_range_done(range)) {
|
|
* device_page_table_unlock();
|
|
* goto again;
|
|
* }
|
|
* device_commit_transaction(trans);
|
|
* device_page_table_unlock();
|
|
*
|
|
* Or:
|
|
* hmm_vma_get_pfns(range); or hmm_vma_fault(...);
|
|
* device_page_table_lock();
|
|
* hmm_vma_range_done(range);
|
|
* device_update_page_table(range->pfns);
|
|
* device_page_table_unlock();
|
|
*/
|
|
bool hmm_vma_range_done(struct hmm_range *range)
|
|
{
|
|
unsigned long npages = (range->end - range->start) >> PAGE_SHIFT;
|
|
struct hmm *hmm;
|
|
|
|
if (range->end <= range->start) {
|
|
BUG();
|
|
return false;
|
|
}
|
|
|
|
hmm = hmm_register(range->vma->vm_mm);
|
|
if (!hmm) {
|
|
memset(range->pfns, 0, sizeof(*range->pfns) * npages);
|
|
return false;
|
|
}
|
|
|
|
spin_lock(&hmm->lock);
|
|
list_del_rcu(&range->list);
|
|
spin_unlock(&hmm->lock);
|
|
|
|
return range->valid;
|
|
}
|
|
EXPORT_SYMBOL(hmm_vma_range_done);
|
|
|
|
/*
|
|
* hmm_vma_fault() - try to fault some address in a virtual address range
|
|
* @range: range being faulted
|
|
* @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
|
|
* Returns: 0 success, error otherwise (-EAGAIN means mmap_sem have been drop)
|
|
*
|
|
* 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.
|
|
*
|
|
* On error, for one virtual address in the range, the function will mark the
|
|
* corresponding HMM pfn entry with an error flag.
|
|
*
|
|
* Expected use pattern:
|
|
* retry:
|
|
* down_read(&mm->mmap_sem);
|
|
* // Find vma and address device wants to fault, initialize hmm_pfn_t
|
|
* // array accordingly
|
|
* ret = hmm_vma_fault(range, write, block);
|
|
* switch (ret) {
|
|
* case -EAGAIN:
|
|
* hmm_vma_range_done(range);
|
|
* // You might want to rate limit or yield to play nicely, you may
|
|
* // also commit any valid pfn in the array assuming that you are
|
|
* // getting true from hmm_vma_range_monitor_end()
|
|
* goto retry;
|
|
* case 0:
|
|
* break;
|
|
* case -ENOMEM:
|
|
* case -EINVAL:
|
|
* case -EPERM:
|
|
* default:
|
|
* // Handle error !
|
|
* up_read(&mm->mmap_sem)
|
|
* return;
|
|
* }
|
|
* // Take device driver lock that serialize device page table update
|
|
* driver_lock_device_page_table_update();
|
|
* hmm_vma_range_done(range);
|
|
* // Commit pfns we got from hmm_vma_fault()
|
|
* driver_unlock_device_page_table_update();
|
|
* up_read(&mm->mmap_sem)
|
|
*
|
|
* YOU MUST CALL hmm_vma_range_done() AFTER THIS FUNCTION RETURN SUCCESS (0)
|
|
* BEFORE FREEING THE range struct OR YOU WILL HAVE SERIOUS MEMORY CORRUPTION !
|
|
*
|
|
* YOU HAVE BEEN WARNED !
|
|
*/
|
|
int hmm_vma_fault(struct hmm_range *range, bool block)
|
|
{
|
|
struct vm_area_struct *vma = range->vma;
|
|
unsigned long start = range->start;
|
|
struct hmm_vma_walk hmm_vma_walk;
|
|
struct mm_walk mm_walk;
|
|
struct hmm *hmm;
|
|
int ret;
|
|
|
|
/* Sanity check, this really should not happen ! */
|
|
if (range->start < vma->vm_start || range->start >= vma->vm_end)
|
|
return -EINVAL;
|
|
if (range->end < vma->vm_start || range->end > vma->vm_end)
|
|
return -EINVAL;
|
|
|
|
hmm = hmm_register(vma->vm_mm);
|
|
if (!hmm) {
|
|
hmm_pfns_clear(range, range->pfns, range->start, range->end);
|
|
return -ENOMEM;
|
|
}
|
|
/* Caller must have registered a mirror using hmm_mirror_register() */
|
|
if (!hmm->mmu_notifier.ops)
|
|
return -EINVAL;
|
|
|
|
/* FIXME support hugetlb fs */
|
|
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) ||
|
|
vma_is_dax(vma)) {
|
|
hmm_pfns_special(range);
|
|
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. Architecture that allow
|
|
* write without read access are not supported by HMM, because
|
|
* operations such has atomic access would not work.
|
|
*/
|
|
hmm_pfns_clear(range, range->pfns, range->start, range->end);
|
|
return -EPERM;
|
|
}
|
|
|
|
/* Initialize range to track CPU page table update */
|
|
spin_lock(&hmm->lock);
|
|
range->valid = true;
|
|
list_add_rcu(&range->list, &hmm->ranges);
|
|
spin_unlock(&hmm->lock);
|
|
|
|
hmm_vma_walk.fault = true;
|
|
hmm_vma_walk.block = block;
|
|
hmm_vma_walk.range = range;
|
|
mm_walk.private = &hmm_vma_walk;
|
|
hmm_vma_walk.last = range->start;
|
|
|
|
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.pmd_entry = hmm_vma_walk_pmd;
|
|
mm_walk.pte_hole = hmm_vma_walk_hole;
|
|
|
|
do {
|
|
ret = walk_page_range(start, range->end, &mm_walk);
|
|
start = hmm_vma_walk.last;
|
|
} while (ret == -EAGAIN);
|
|
|
|
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);
|
|
hmm_vma_range_done(range);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(hmm_vma_fault);
|
|
#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
|
|
|
|
|
|
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
|
|
struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma,
|
|
unsigned long addr)
|
|
{
|
|
struct page *page;
|
|
|
|
page = alloc_page_vma(GFP_HIGHUSER, vma, addr);
|
|
if (!page)
|
|
return NULL;
|
|
lock_page(page);
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(hmm_vma_alloc_locked_page);
|
|
|
|
|
|
static void hmm_devmem_ref_release(struct percpu_ref *ref)
|
|
{
|
|
struct hmm_devmem *devmem;
|
|
|
|
devmem = container_of(ref, struct hmm_devmem, ref);
|
|
complete(&devmem->completion);
|
|
}
|
|
|
|
static void hmm_devmem_ref_exit(void *data)
|
|
{
|
|
struct percpu_ref *ref = data;
|
|
struct hmm_devmem *devmem;
|
|
|
|
devmem = container_of(ref, struct hmm_devmem, ref);
|
|
wait_for_completion(&devmem->completion);
|
|
percpu_ref_exit(ref);
|
|
}
|
|
|
|
static void hmm_devmem_ref_kill(struct percpu_ref *ref)
|
|
{
|
|
percpu_ref_kill(ref);
|
|
}
|
|
|
|
static vm_fault_t hmm_devmem_fault(struct vm_area_struct *vma,
|
|
unsigned long addr,
|
|
const struct page *page,
|
|
unsigned int flags,
|
|
pmd_t *pmdp)
|
|
{
|
|
struct hmm_devmem *devmem = page->pgmap->data;
|
|
|
|
return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp);
|
|
}
|
|
|
|
static void hmm_devmem_free(struct page *page, void *data)
|
|
{
|
|
struct hmm_devmem *devmem = data;
|
|
|
|
page->mapping = NULL;
|
|
|
|
devmem->ops->free(devmem, page);
|
|
}
|
|
|
|
/*
|
|
* hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory
|
|
*
|
|
* @ops: memory event device driver callback (see struct hmm_devmem_ops)
|
|
* @device: device struct to bind the resource too
|
|
* @size: size in bytes of the device memory to add
|
|
* Returns: pointer to new hmm_devmem struct ERR_PTR otherwise
|
|
*
|
|
* This function first finds an empty range of physical address big enough to
|
|
* contain the new resource, and then hotplugs it as ZONE_DEVICE memory, which
|
|
* in turn allocates struct pages. It does not do anything beyond that; all
|
|
* events affecting the memory will go through the various callbacks provided
|
|
* by hmm_devmem_ops struct.
|
|
*
|
|
* Device driver should call this function during device initialization and
|
|
* is then responsible of memory management. HMM only provides helpers.
|
|
*/
|
|
struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
|
|
struct device *device,
|
|
unsigned long size)
|
|
{
|
|
struct hmm_devmem *devmem;
|
|
resource_size_t addr;
|
|
void *result;
|
|
int ret;
|
|
|
|
dev_pagemap_get_ops();
|
|
|
|
devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL);
|
|
if (!devmem)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
init_completion(&devmem->completion);
|
|
devmem->pfn_first = -1UL;
|
|
devmem->pfn_last = -1UL;
|
|
devmem->resource = NULL;
|
|
devmem->device = device;
|
|
devmem->ops = ops;
|
|
|
|
ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
|
|
0, GFP_KERNEL);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
size = ALIGN(size, PA_SECTION_SIZE);
|
|
addr = min((unsigned long)iomem_resource.end,
|
|
(1UL << MAX_PHYSMEM_BITS) - 1);
|
|
addr = addr - size + 1UL;
|
|
|
|
/*
|
|
* FIXME add a new helper to quickly walk resource tree and find free
|
|
* range
|
|
*
|
|
* FIXME what about ioport_resource resource ?
|
|
*/
|
|
for (; addr > size && addr >= iomem_resource.start; addr -= size) {
|
|
ret = region_intersects(addr, size, 0, IORES_DESC_NONE);
|
|
if (ret != REGION_DISJOINT)
|
|
continue;
|
|
|
|
devmem->resource = devm_request_mem_region(device, addr, size,
|
|
dev_name(device));
|
|
if (!devmem->resource)
|
|
return ERR_PTR(-ENOMEM);
|
|
break;
|
|
}
|
|
if (!devmem->resource)
|
|
return ERR_PTR(-ERANGE);
|
|
|
|
devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
|
|
devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
|
|
devmem->pfn_last = devmem->pfn_first +
|
|
(resource_size(devmem->resource) >> PAGE_SHIFT);
|
|
devmem->page_fault = hmm_devmem_fault;
|
|
|
|
devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
|
|
devmem->pagemap.res = *devmem->resource;
|
|
devmem->pagemap.page_free = hmm_devmem_free;
|
|
devmem->pagemap.altmap_valid = false;
|
|
devmem->pagemap.ref = &devmem->ref;
|
|
devmem->pagemap.data = devmem;
|
|
devmem->pagemap.kill = hmm_devmem_ref_kill;
|
|
|
|
result = devm_memremap_pages(devmem->device, &devmem->pagemap);
|
|
if (IS_ERR(result))
|
|
return result;
|
|
return devmem;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hmm_devmem_add);
|
|
|
|
struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
|
|
struct device *device,
|
|
struct resource *res)
|
|
{
|
|
struct hmm_devmem *devmem;
|
|
void *result;
|
|
int ret;
|
|
|
|
if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
dev_pagemap_get_ops();
|
|
|
|
devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL);
|
|
if (!devmem)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
init_completion(&devmem->completion);
|
|
devmem->pfn_first = -1UL;
|
|
devmem->pfn_last = -1UL;
|
|
devmem->resource = res;
|
|
devmem->device = device;
|
|
devmem->ops = ops;
|
|
|
|
ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
|
|
0, GFP_KERNEL);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit,
|
|
&devmem->ref);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
|
|
devmem->pfn_last = devmem->pfn_first +
|
|
(resource_size(devmem->resource) >> PAGE_SHIFT);
|
|
devmem->page_fault = hmm_devmem_fault;
|
|
|
|
devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;
|
|
devmem->pagemap.res = *devmem->resource;
|
|
devmem->pagemap.page_free = hmm_devmem_free;
|
|
devmem->pagemap.altmap_valid = false;
|
|
devmem->pagemap.ref = &devmem->ref;
|
|
devmem->pagemap.data = devmem;
|
|
devmem->pagemap.kill = hmm_devmem_ref_kill;
|
|
|
|
result = devm_memremap_pages(devmem->device, &devmem->pagemap);
|
|
if (IS_ERR(result))
|
|
return result;
|
|
return devmem;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hmm_devmem_add_resource);
|
|
|
|
/*
|
|
* A device driver that wants to handle multiple devices memory through a
|
|
* single fake device can use hmm_device to do so. This is purely a helper
|
|
* and it is not needed to make use of any HMM functionality.
|
|
*/
|
|
#define HMM_DEVICE_MAX 256
|
|
|
|
static DECLARE_BITMAP(hmm_device_mask, HMM_DEVICE_MAX);
|
|
static DEFINE_SPINLOCK(hmm_device_lock);
|
|
static struct class *hmm_device_class;
|
|
static dev_t hmm_device_devt;
|
|
|
|
static void hmm_device_release(struct device *device)
|
|
{
|
|
struct hmm_device *hmm_device;
|
|
|
|
hmm_device = container_of(device, struct hmm_device, device);
|
|
spin_lock(&hmm_device_lock);
|
|
clear_bit(hmm_device->minor, hmm_device_mask);
|
|
spin_unlock(&hmm_device_lock);
|
|
|
|
kfree(hmm_device);
|
|
}
|
|
|
|
struct hmm_device *hmm_device_new(void *drvdata)
|
|
{
|
|
struct hmm_device *hmm_device;
|
|
|
|
hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL);
|
|
if (!hmm_device)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
spin_lock(&hmm_device_lock);
|
|
hmm_device->minor = find_first_zero_bit(hmm_device_mask, HMM_DEVICE_MAX);
|
|
if (hmm_device->minor >= HMM_DEVICE_MAX) {
|
|
spin_unlock(&hmm_device_lock);
|
|
kfree(hmm_device);
|
|
return ERR_PTR(-EBUSY);
|
|
}
|
|
set_bit(hmm_device->minor, hmm_device_mask);
|
|
spin_unlock(&hmm_device_lock);
|
|
|
|
dev_set_name(&hmm_device->device, "hmm_device%d", hmm_device->minor);
|
|
hmm_device->device.devt = MKDEV(MAJOR(hmm_device_devt),
|
|
hmm_device->minor);
|
|
hmm_device->device.release = hmm_device_release;
|
|
dev_set_drvdata(&hmm_device->device, drvdata);
|
|
hmm_device->device.class = hmm_device_class;
|
|
device_initialize(&hmm_device->device);
|
|
|
|
return hmm_device;
|
|
}
|
|
EXPORT_SYMBOL(hmm_device_new);
|
|
|
|
void hmm_device_put(struct hmm_device *hmm_device)
|
|
{
|
|
put_device(&hmm_device->device);
|
|
}
|
|
EXPORT_SYMBOL(hmm_device_put);
|
|
|
|
static int __init hmm_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = alloc_chrdev_region(&hmm_device_devt, 0,
|
|
HMM_DEVICE_MAX,
|
|
"hmm_device");
|
|
if (ret)
|
|
return ret;
|
|
|
|
hmm_device_class = class_create(THIS_MODULE, "hmm_device");
|
|
if (IS_ERR(hmm_device_class)) {
|
|
unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX);
|
|
return PTR_ERR(hmm_device_class);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
device_initcall(hmm_init);
|
|
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
|