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-rw-r--r--virt/kvm/kvm_main.c24
1 files changed, 2 insertions, 22 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d2836788561e..0fc25aed79a8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -102,28 +102,8 @@ static bool largepages_enabled = true;
102 102
103bool kvm_is_mmio_pfn(pfn_t pfn) 103bool kvm_is_mmio_pfn(pfn_t pfn)
104{ 104{
105 if (pfn_valid(pfn)) { 105 if (pfn_valid(pfn))
106 int reserved; 106 return PageReserved(pfn_to_page(pfn));
107 struct page *tail = pfn_to_page(pfn);
108 struct page *head = compound_trans_head(tail);
109 reserved = PageReserved(head);
110 if (head != tail) {
111 /*
112 * "head" is not a dangling pointer
113 * (compound_trans_head takes care of that)
114 * but the hugepage may have been splitted
115 * from under us (and we may not hold a
116 * reference count on the head page so it can
117 * be reused before we run PageReferenced), so
118 * we've to check PageTail before returning
119 * what we just read.
120 */
121 smp_rmb();
122 if (PageTail(tail))
123 return reserved;
124 }
125 return PageReserved(tail);
126 }
127 107
128 return true; 108 return true;
129} 109}