[PATCH v8 05/81] KVM: add kvm_get_max_gfn()

["Adalbert Lazăr" <alazar@bitdefender.com>]

From: Ștefan Șicleru <ssicleru@bitdefender.com>

This function is needed for the KVMI_VM_GET_MAX_GFN command.

Signed-off-by: Ștefan Șicleru <ssicleru@bitdefender.com>
Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6890f0a85dba..6680592f2de1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -765,6 +765,7 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
 bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
 unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn);
 void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
+gfn_t kvm_get_max_gfn(struct kvm *kvm);
 
 struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
 struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4c69ce5aa79c..a6eb3f8ea62f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1175,6 +1175,29 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 	return kvm_set_memory_region(kvm, mem);
 }
 
+gfn_t kvm_get_max_gfn(struct kvm *kvm)
+{
+	struct kvm_memory_slot *memslot;
+	struct kvm_memslots *slots;
+	gfn_t max_gfn = 0;
+	int i, idx;
+
+	idx = srcu_read_lock(&kvm->srcu);
+	spin_lock(&kvm->mmu_lock);
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		slots = __kvm_memslots(kvm, i);
+		kvm_for_each_memslot(memslot, slots)
+			max_gfn = max(max_gfn, memslot->base_gfn
+						+ memslot->npages);
+	}
+
+	spin_unlock(&kvm->mmu_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	return max_gfn;
+}
+
 int kvm_get_dirty_log(struct kvm *kvm,
 			struct kvm_dirty_log *log, int *is_dirty)
 {