[PATCH v9 33/84] KVM: x86: page track: add track_create_slot() callback

[Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>]

From: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>

This is used to add page access notifications as soon as a slot appears.

Signed-off-by: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/kvm_page_track.h | 13 ++++++++++++-
 arch/x86/kvm/mmu/page_track.c         | 16 +++++++++++++++-
 arch/x86/kvm/x86.c                    |  7 ++++---
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index 9a261e463eb3..00a66c4d4d3c 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -36,6 +36,17 @@ struct kvm_page_track_notifier_node {
 	void (*track_write)(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva,
 			    const u8 *new, int bytes,
 			    struct kvm_page_track_notifier_node *node);
+	/*
+	 * It is called when memory slot is being created
+	 *
+	 * @kvm: the kvm where memory slot being moved or removed
+	 * @slot: the memory slot being moved or removed
+	 * @npages: the number of pages
+	 * @node: this node
+	 */
+	void (*track_create_slot)(struct kvm *kvm, struct kvm_memory_slot *slot,
+				  unsigned long npages,
+				  struct kvm_page_track_notifier_node *node);
 	/*
 	 * It is called when memory slot is being moved or removed
 	 * users can drop write-protection for the pages in that memory slot
@@ -52,7 +63,7 @@ void kvm_page_track_init(struct kvm *kvm);
 void kvm_page_track_cleanup(struct kvm *kvm);
 
 void kvm_page_track_free_memslot(struct kvm_memory_slot *slot);
-int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
+int kvm_page_track_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 				  unsigned long npages);
 
 void kvm_slot_page_track_add_page(struct kvm *kvm,
diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 9642af1b2c21..02759b81a04c 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -28,9 +28,12 @@ void kvm_page_track_free_memslot(struct kvm_memory_slot *slot)
 	}
 }
 
-int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
+int kvm_page_track_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 				  unsigned long npages)
 {
+	struct kvm_page_track_notifier_head *head;
+	struct kvm_page_track_notifier_node *n;
+	int idx;
 	int  i;
 
 	for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) {
@@ -41,6 +44,17 @@ int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
 			goto track_free;
 	}
 
+	head = &kvm->arch.track_notifier_head;
+
+	if (hlist_empty(&head->track_notifier_list))
+		return 0;
+
+	idx = srcu_read_lock(&head->track_srcu);
+	hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
+		if (n->track_create_slot)
+			n->track_create_slot(kvm, slot, npages, n);
+	srcu_read_unlock(&head->track_srcu, idx);
+
 	return 0;
 
 track_free:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a59c935f4bbe..83424339ea9d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10070,7 +10070,8 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 	kvm_page_track_free_memslot(slot);
 }
 
-static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
+static int kvm_alloc_memslot_metadata(struct kvm *kvm,
+				      struct kvm_memory_slot *slot,
 				      unsigned long npages)
 {
 	int i;
@@ -10122,7 +10123,7 @@ static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
 		}
 	}
 
-	if (kvm_page_track_create_memslot(slot, npages))
+	if (kvm_page_track_create_memslot(kvm, slot, npages))
 		goto out_free;
 
 	return 0;
@@ -10162,7 +10163,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				enum kvm_mr_change change)
 {
 	if (change == KVM_MR_CREATE || change == KVM_MR_MOVE)
-		return kvm_alloc_memslot_metadata(memslot,
+		return kvm_alloc_memslot_metadata(kvm, memslot,
 						  mem->memory_size >> PAGE_SHIFT);
 	return 0;
 }