[07/11] KVM: page track: add notifier support
diff mbox

Message ID 1448907973-36066-8-git-send-email-guangrong.xiao@linux.intel.com
State New
Headers show

Commit Message

Xiao Guangrong Nov. 30, 2015, 6:26 p.m. UTC
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>
---
 arch/x86/include/asm/kvm_host.h       |  1 +
 arch/x86/include/asm/kvm_page_track.h | 39 ++++++++++++++++++++
 arch/x86/kvm/page_track.c             | 67 +++++++++++++++++++++++++++++++++++
 arch/x86/kvm/x86.c                    |  4 +++
 4 files changed, 111 insertions(+)

Comments

Jike Song Dec. 16, 2015, 5:53 a.m. UTC | #1
On 12/01/2015 02:26 AM, Xiao Guangrong wrote:
> 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>
> ---
>   arch/x86/include/asm/kvm_host.h       |  1 +
>   arch/x86/include/asm/kvm_page_track.h | 39 ++++++++++++++++++++
>   arch/x86/kvm/page_track.c             | 67 +++++++++++++++++++++++++++++++++++
>   arch/x86/kvm/x86.c                    |  4 +++
>   4 files changed, 111 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index afff1f1..0f7b940 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -658,6 +658,7 @@ 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;
> diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
> index f223201..6744234 100644
> --- a/arch/x86/include/asm/kvm_page_track.h
> +++ b/arch/x86/include/asm/kvm_page_track.h
> @@ -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);

Sir, is it possible to make this non-void? as you described below, the
callback may find this gpa isn't the page being tracked, so it probably
want to return something to indicate: not my business, continue :)

> +};
> +
> +void kvm_page_track_init(struct kvm *kvm);
> +
>   int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
>   				  unsigned long npages);
>   void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
> @@ -17,4 +47,13 @@ void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
>   				enum kvm_page_track_mode mode);
>   bool kvm_page_track_check_mode(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
> diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
> index dc2da12..84420df 100644
> --- a/arch/x86/kvm/page_track.c
> +++ b/arch/x86/kvm/page_track.c
> @@ -165,3 +165,70 @@ bool kvm_page_track_check_mode(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;
> +
> +	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);
> +}
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ad4888a..64dbc69 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4328,6 +4328,7 @@ 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;
>   }
>
> @@ -4586,6 +4587,7 @@ 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;
>
> @@ -7691,6 +7693,8 @@ 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;
>   }
>
>
--
Thanks,
Jike
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Xiao Guangrong Dec. 16, 2015, 6:26 a.m. UTC | #2
On 12/16/2015 01:53 PM, Jike Song wrote:
> On 12/01/2015 02:26 AM, Xiao Guangrong wrote:
>> 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>
>> ---
>>   arch/x86/include/asm/kvm_host.h       |  1 +
>>   arch/x86/include/asm/kvm_page_track.h | 39 ++++++++++++++++++++
>>   arch/x86/kvm/page_track.c             | 67 +++++++++++++++++++++++++++++++++++
>>   arch/x86/kvm/x86.c                    |  4 +++
>>   4 files changed, 111 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index afff1f1..0f7b940 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -658,6 +658,7 @@ 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;
>> diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
>> index f223201..6744234 100644
>> --- a/arch/x86/include/asm/kvm_page_track.h
>> +++ b/arch/x86/include/asm/kvm_page_track.h
>> @@ -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);
>
> Sir, is it possible to make this non-void? as you described below, the
> callback may find this gpa isn't the page being tracked, so it probably
> want to return something to indicate: not my business, continue :)

Currently the return value is useless and it is not ABI so we can extend
it if it is needed in the future.

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Patch
diff mbox

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index afff1f1..0f7b940 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -658,6 +658,7 @@  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;
diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index f223201..6744234 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -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);
+
 int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
 				  unsigned long npages);
 void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
@@ -17,4 +47,13 @@  void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
 				enum kvm_page_track_mode mode);
 bool kvm_page_track_check_mode(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
diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index dc2da12..84420df 100644
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -165,3 +165,70 @@  bool kvm_page_track_check_mode(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;
+
+	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);
+}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ad4888a..64dbc69 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4328,6 +4328,7 @@  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;
 }
 
@@ -4586,6 +4587,7 @@  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;
 
@@ -7691,6 +7693,8 @@  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;
 }