KVM: x86/mmu: add comment explaining arguments to kvm_zap_gfn_range

This comment makes it clear that the range of gfns that this
function receives is non inclusive.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210810205251.424103-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -5675,6 +5675,10 @@ void kvm_mmu_uninit_vm(struct kvm *kvm)
 	kvm_mmu_uninit_tdp_mmu(kvm);
 }
 
+/*
+ * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end
+ * (not including it)
+ */
 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 {
 	struct kvm_memslots *slots;