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Commit 0eb05bf2 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Paolo Bonzini
Browse files

KVM: page track: add notifier support 



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: default avatarXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e5691a81

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -704,6 +704,7 @@ struct kvm_arch { 
	 */

	struct list_head active_mmu_pages;

	struct list_head zapped_obsolete_pages;

	struct kvm_page_track_notifier_head track_notifier_head;



	struct list_head assigned_dev_head;

	struct iommu_domain *iommu_domain;

arch/x86/include/asm/kvm_page_track.h

+39 −0
Original line number Diff line number Diff line
@@ -6,6 +6,36 @@ enum kvm_page_track_mode { 
	KVM_PAGE_TRACK_MAX,

};



/*

 * The notifier represented by @kvm_page_track_notifier_node is linked into

 * the head which will be notified when guest is triggering the track event.

 *

 * Write access on the head is protected by kvm->mmu_lock, read access

 * is protected by track_srcu.

 */

struct kvm_page_track_notifier_head {

	struct srcu_struct track_srcu;

	struct hlist_head track_notifier_list;

};



struct kvm_page_track_notifier_node {

	struct hlist_node node;



	/*

	 * It is called when guest is writing the write-tracked page

	 * and write emulation is finished at that time.

	 *

	 * @vcpu: the vcpu where the write access happened.

	 * @gpa: the physical address written by guest.

	 * @new: the data was written to the address.

	 * @bytes: the written length.

	 */

	void (*track_write)(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,

			    int bytes);

};



void kvm_page_track_init(struct kvm *kvm);



void kvm_page_track_free_memslot(struct kvm_memory_slot *free,

				 struct kvm_memory_slot *dont);

int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
@@ -19,4 +49,13 @@ void kvm_slot_page_track_remove_page(struct kvm *kvm, 
				     enum kvm_page_track_mode mode);

bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,

			      enum kvm_page_track_mode mode);



void

kvm_page_track_register_notifier(struct kvm *kvm,

				 struct kvm_page_track_notifier_node *n);

void

kvm_page_track_unregister_notifier(struct kvm *kvm,

				   struct kvm_page_track_notifier_node *n);

void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,

			  int bytes);

#endif

arch/x86/kvm/page_track.c

+70 −0
Original line number Diff line number Diff line
@@ -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);

}

arch/x86/kvm/x86.c

+4 −0
Original line number Diff line number Diff line
@@ -4346,6 +4346,7 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, 
	if (ret < 0)

		return 0;

	kvm_mmu_pte_write(vcpu, gpa, val, bytes);

	kvm_page_track_write(vcpu, gpa, val, bytes);

	return 1;

}
@@ -4604,6 +4605,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, 


	kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT);

	kvm_mmu_pte_write(vcpu, gpa, new, bytes);

	kvm_page_track_write(vcpu, gpa, new, bytes);



	return X86EMUL_CONTINUE;
@@ -7724,6 +7726,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 
	INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);

	INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);



	kvm_page_track_init(kvm);



	return 0;

}