268 lines
6.7 KiB
C
268 lines
6.7 KiB
C
/*
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* Support KVM gust page tracking
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*
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* This feature allows us to track page access in guest. Currently, only
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* write access is tracked.
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*
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* Copyright(C) 2015 Intel Corporation.
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*
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* Author:
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* Xiao Guangrong <guangrong.xiao@linux.intel.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/kvm_host.h>
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#include <linux/rculist.h>
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#include <asm/kvm_host.h>
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#include <asm/kvm_page_track.h>
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#include "mmu.h"
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void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
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struct kvm_memory_slot *dont)
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{
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int i;
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for (i = 0; i < KVM_PAGE_TRACK_MAX; i++)
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if (!dont || free->arch.gfn_track[i] !=
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dont->arch.gfn_track[i]) {
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kvfree(free->arch.gfn_track[i]);
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free->arch.gfn_track[i] = NULL;
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}
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}
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int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
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unsigned long npages)
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{
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int i;
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for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) {
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slot->arch.gfn_track[i] =
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kvcalloc(npages, sizeof(*slot->arch.gfn_track[i]),
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GFP_KERNEL_ACCOUNT);
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if (!slot->arch.gfn_track[i])
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goto track_free;
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}
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return 0;
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track_free:
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kvm_page_track_free_memslot(slot, NULL);
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return -ENOMEM;
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}
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static inline bool page_track_mode_is_valid(enum kvm_page_track_mode mode)
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{
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if (mode < 0 || mode >= KVM_PAGE_TRACK_MAX)
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return false;
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return true;
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}
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static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn,
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enum kvm_page_track_mode mode, short count)
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{
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int index, val;
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index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
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val = slot->arch.gfn_track[mode][index];
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if (WARN_ON(val + count < 0 || val + count > USHRT_MAX))
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return;
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slot->arch.gfn_track[mode][index] += count;
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}
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/*
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* add guest page to the tracking pool so that corresponding access on that
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* page will be intercepted.
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*
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* It should be called under the protection both of mmu-lock and kvm->srcu
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* or kvm->slots_lock.
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*
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* @kvm: the guest instance we are interested in.
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* @slot: the @gfn belongs to.
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* @gfn: the guest page.
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* @mode: tracking mode, currently only write track is supported.
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*/
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void kvm_slot_page_track_add_page(struct kvm *kvm,
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struct kvm_memory_slot *slot, gfn_t gfn,
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enum kvm_page_track_mode mode)
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{
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if (WARN_ON(!page_track_mode_is_valid(mode)))
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return;
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update_gfn_track(slot, gfn, mode, 1);
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/*
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* new track stops large page mapping for the
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* tracked page.
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*/
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kvm_mmu_gfn_disallow_lpage(slot, gfn);
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if (mode == KVM_PAGE_TRACK_WRITE)
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if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn))
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kvm_flush_remote_tlbs(kvm);
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}
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EXPORT_SYMBOL_GPL(kvm_slot_page_track_add_page);
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/*
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* remove the guest page from the tracking pool which stops the interception
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* of corresponding access on that page. It is the opposed operation of
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* kvm_slot_page_track_add_page().
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*
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* It should be called under the protection both of mmu-lock and kvm->srcu
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* or kvm->slots_lock.
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*
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* @kvm: the guest instance we are interested in.
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* @slot: the @gfn belongs to.
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* @gfn: the guest page.
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* @mode: tracking mode, currently only write track is supported.
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*/
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void kvm_slot_page_track_remove_page(struct kvm *kvm,
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struct kvm_memory_slot *slot, gfn_t gfn,
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enum kvm_page_track_mode mode)
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{
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if (WARN_ON(!page_track_mode_is_valid(mode)))
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return;
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update_gfn_track(slot, gfn, mode, -1);
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/*
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* allow large page mapping for the tracked page
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* after the tracker is gone.
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*/
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kvm_mmu_gfn_allow_lpage(slot, gfn);
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}
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EXPORT_SYMBOL_GPL(kvm_slot_page_track_remove_page);
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/*
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* check if the corresponding access on the specified guest page is tracked.
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*/
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bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
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enum kvm_page_track_mode mode)
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{
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struct kvm_memory_slot *slot;
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int index;
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if (WARN_ON(!page_track_mode_is_valid(mode)))
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return false;
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slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
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if (!slot)
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return false;
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index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
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return !!READ_ONCE(slot->arch.gfn_track[mode][index]);
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}
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void kvm_page_track_cleanup(struct kvm *kvm)
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{
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struct kvm_page_track_notifier_head *head;
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head = &kvm->arch.track_notifier_head;
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cleanup_srcu_struct(&head->track_srcu);
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}
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void kvm_page_track_init(struct kvm *kvm)
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{
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struct kvm_page_track_notifier_head *head;
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head = &kvm->arch.track_notifier_head;
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init_srcu_struct(&head->track_srcu);
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INIT_HLIST_HEAD(&head->track_notifier_list);
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}
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/*
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* register the notifier so that event interception for the tracked guest
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* pages can be received.
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*/
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void
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kvm_page_track_register_notifier(struct kvm *kvm,
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struct kvm_page_track_notifier_node *n)
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{
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struct kvm_page_track_notifier_head *head;
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head = &kvm->arch.track_notifier_head;
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spin_lock(&kvm->mmu_lock);
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hlist_add_head_rcu(&n->node, &head->track_notifier_list);
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spin_unlock(&kvm->mmu_lock);
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}
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EXPORT_SYMBOL_GPL(kvm_page_track_register_notifier);
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/*
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* stop receiving the event interception. It is the opposed operation of
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* kvm_page_track_register_notifier().
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*/
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void
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kvm_page_track_unregister_notifier(struct kvm *kvm,
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struct kvm_page_track_notifier_node *n)
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{
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struct kvm_page_track_notifier_head *head;
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head = &kvm->arch.track_notifier_head;
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spin_lock(&kvm->mmu_lock);
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hlist_del_rcu(&n->node);
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spin_unlock(&kvm->mmu_lock);
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synchronize_srcu(&head->track_srcu);
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}
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EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier);
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/*
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* Notify the node that write access is intercepted and write emulation is
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* finished at this time.
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*
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* The node should figure out if the written page is the one that node is
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* interested in by itself.
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*/
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void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
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int bytes)
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{
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struct kvm_page_track_notifier_head *head;
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struct kvm_page_track_notifier_node *n;
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int idx;
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head = &vcpu->kvm->arch.track_notifier_head;
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if (hlist_empty(&head->track_notifier_list))
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return;
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idx = srcu_read_lock(&head->track_srcu);
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hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
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if (n->track_write)
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n->track_write(vcpu, gpa, new, bytes, n);
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srcu_read_unlock(&head->track_srcu, idx);
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}
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/*
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* Notify the node that memory slot is being removed or moved so that it can
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* drop write-protection for the pages in the memory slot.
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*
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* The node should figure out it has any write-protected pages in this slot
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* by itself.
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*/
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void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot)
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{
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struct kvm_page_track_notifier_head *head;
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struct kvm_page_track_notifier_node *n;
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int idx;
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head = &kvm->arch.track_notifier_head;
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if (hlist_empty(&head->track_notifier_list))
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return;
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idx = srcu_read_lock(&head->track_srcu);
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hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
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if (n->track_flush_slot)
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n->track_flush_slot(kvm, slot, n);
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srcu_read_unlock(&head->track_srcu, idx);
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}
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