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KVM: page track: add notifier support

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Notifier list is introduced so that any node wants to receive the track
event can register to the list

Two APIs are introduced here:
- kvm_page_track_register_notifier(): register the notifier to receive
  track event

- kvm_page_track_unregister_notifier(): stop receiving track event by
  unregister the notifier

The callback, node->track_write() is called when a write access on the
write tracked page happens

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiao Guangrong
2016-02-24 17:51:13 +08:00
committed by Paolo Bonzini
parent e5691a81e8
commit 0eb05bf290
4 changed files with 114 additions and 0 deletions
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70
arch/x86/kvm/page_track.c
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@@ -150,3 +150,73 @@ bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
return !!ACCESS_ONCE(slot->arch.gfn_track[mode][index]);
}
void kvm_page_track_init(struct kvm *kvm)
{
struct kvm_page_track_notifier_head *head;
head = &kvm->arch.track_notifier_head;
init_srcu_struct(&head->track_srcu);
INIT_HLIST_HEAD(&head->track_notifier_list);
}
/*
* register the notifier so that event interception for the tracked guest
* pages can be received.
*/
void
kvm_page_track_register_notifier(struct kvm *kvm,
struct kvm_page_track_notifier_node *n)
{
struct kvm_page_track_notifier_head *head;
head = &kvm->arch.track_notifier_head;
spin_lock(&kvm->mmu_lock);
hlist_add_head_rcu(&n->node, &head->track_notifier_list);
spin_unlock(&kvm->mmu_lock);
}
/*
* stop receiving the event interception. It is the opposed operation of
* kvm_page_track_register_notifier().
*/
void
kvm_page_track_unregister_notifier(struct kvm *kvm,
struct kvm_page_track_notifier_node *n)
{
struct kvm_page_track_notifier_head *head;
head = &kvm->arch.track_notifier_head;
spin_lock(&kvm->mmu_lock);
hlist_del_rcu(&n->node);
spin_unlock(&kvm->mmu_lock);
synchronize_srcu(&head->track_srcu);
}
/*
* Notify the node that write access is intercepted and write emulation is
* finished at this time.
*
* The node should figure out if the written page is the one that node is
* interested in by itself.
*/
void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
int bytes)
{
struct kvm_page_track_notifier_head *head;
struct kvm_page_track_notifier_node *n;
int idx;
head = &vcpu->kvm->arch.track_notifier_head;
if (hlist_empty(&head->track_notifier_list))
return;
idx = srcu_read_lock(&head->track_srcu);
hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
if (n->track_write)
n->track_write(vcpu, gpa, new, bytes);
srcu_read_unlock(&head->track_srcu, idx);
}