KVM: Introduce gfn_to_index() which returns the index for a given level

This patch cleans up the code and removes the "(void)level;" warning
suppressor.

Note that we can also use this for PT_PAGE_TABLE_LEVEL to treat every
level uniformly later.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9698080c902b..7a08496b974a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -681,6 +681,13 @@ static inline int memslot_id(struct kvm *kvm, gfn_t gfn)
         return gfn_to_memslot(kvm, gfn)->id;
 }
 
+static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
+{
+        /* KVM_HPAGE_GFN_SHIFT(PT_PAGE_TABLE_LEVEL) must be 0. */
+        return (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
+                (base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
+}
+
 static inline unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot,
                                                gfn_t gfn)
 {