KVM: Introduce kvm_arch_memslots_updated()

This is called right after the memslots is updated, i.e. when the result
of update_memslots() gets installed in install_new_memslots().  Since
the memslots needs to be updated twice when we delete or move a memslot,
kvm_arch_commit_memory_region() does not correspond to this exactly.

In the following patch, x86 will use this new API to check if the mmio
generation has reached its maximum value, in which case mmio sptes need
to be flushed out.
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Acked-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/arm/kvm/arm.c

@@ -219,6 +219,10 @@ long kvm_arch_dev_ioctl(struct file *filp,
 	return -EINVAL;
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
 				   struct kvm_userspace_memory_region *mem,

arch/ia64/kvm/kvm-ia64.c

@@ -1560,6 +1560,10 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return 0;
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 		struct kvm_memory_slot *memslot,
 		struct kvm_userspace_memory_region *mem,

arch/mips/kvm/kvm_mips.c

@@ -208,6 +208,10 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return 0;
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
                                 struct kvm_memory_slot *memslot,
                                 struct kvm_userspace_memory_region *mem,

arch/powerpc/kvm/powerpc.c

@@ -420,6 +420,10 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return kvmppc_core_create_memslot(slot, npages);
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
 				   struct kvm_userspace_memory_region *mem,

arch/s390/kvm/kvm-s390.c

@@ -1056,6 +1056,10 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return 0;
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 /* Section: memory related */
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,

arch/x86/kvm/x86.c

@@ -7019,6 +7019,10 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 	return -ENOMEM;
 }
 
+void kvm_arch_memslots_updated(struct kvm *kvm)
+{
+}
+
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
 				struct kvm_userspace_memory_region *mem,

include/linux/kvm_host.h

@@ -503,6 +503,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 void kvm_arch_free_memslot(struct kvm_memory_slot *free,
 			   struct kvm_memory_slot *dont);
 int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages);
+void kvm_arch_memslots_updated(struct kvm *kvm);
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
 				struct kvm_userspace_memory_region *mem,

virt/kvm/kvm_main.c

@@ -731,7 +731,10 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 	update_memslots(slots, new, kvm->memslots->generation);
 	rcu_assign_pointer(kvm->memslots, slots);
 	synchronize_srcu_expedited(&kvm->srcu);
-	return old_memslots; 
+
+	kvm_arch_memslots_updated(kvm);
+
+	return old_memslots;
 }
 
 /*