kvm: optimize away THP checks in kvm_is_mmio_pfn()

[karo-tx-linux.git] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d2836788561e1f42437f71ec0bbe08c637384668..0fc25aed79a8d84222c124f52bd3d131d5403070 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -102,28 +102,8 @@ static bool largepages_enabled = true;
 
 bool kvm_is_mmio_pfn(pfn_t pfn)
 {
-       if (pfn_valid(pfn)) {
-               int reserved;
-               struct page *tail = pfn_to_page(pfn);
-               struct page *head = compound_trans_head(tail);
-               reserved = PageReserved(head);
-               if (head != tail) {
-                       /*
-                        * "head" is not a dangling pointer
-                        * (compound_trans_head takes care of that)
-                        * but the hugepage may have been splitted
-                        * from under us (and we may not hold a
-                        * reference count on the head page so it can
-                        * be reused before we run PageReferenced), so
-                        * we've to check PageTail before returning
-                        * what we just read.
-                        */
-                       smp_rmb();
-                       if (PageTail(tail))
-                               return reserved;
-               }
-               return PageReserved(tail);
-       }
+       if (pfn_valid(pfn))
+               return PageReserved(pfn_to_page(pfn));
 
        return true;
 }