KVM: Disable large pages on misaligned memory slots

[safe/jmp/linux-2.6] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5fed9bf..5f865ed 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1086,7 +1086,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 {
        int r;
        gfn_t base_gfn;
-       unsigned long npages;
+       unsigned long npages, ugfn;
        int largepages;
        unsigned long i;
        struct kvm_memory_slot *memslot;
@@ -1177,6 +1177,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
                        new.lpage_info[0].write_count = 1;
                if ((base_gfn+npages) % KVM_PAGES_PER_HPAGE)
                        new.lpage_info[largepages-1].write_count = 1;
+               ugfn = new.userspace_addr >> PAGE_SHIFT;
+               /*
+                * If the gfn and userspace address are not aligned wrt each
+                * other, disable large page support for this slot
+                */
+               if ((base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE - 1))
+                       for (i = 0; i < largepages; ++i)
+                               new.lpage_info[i].write_count = 1;
        }
 
        /* Allocate page dirty bitmap if needed */