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authorAvi Kivity <avi@redhat.com>2009-03-29 09:31:25 -0400
committerAvi Kivity <avi@redhat.com>2009-04-22 06:52:09 -0400
commit99894a799f09cf9e28296bb16e75bd5830fd2c4e (patch)
tree33fa687fa78b3c8b89d032ca11b89443296449a2
parent091069740304c979f957ceacec39c461d0192158 (diff)
KVM: MMU: Fix off-by-one calculating large page count
The large page initialization code concludes there are two large pages spanned by a slot covering 1 (small) page starting at gfn 1. This is incorrect, and also results in incorrect write_count initialization in some cases (base = 1, npages = 513 for example). Cc: stable@kernel.org Signed-off-by: Avi Kivity <avi@redhat.com>
-rw-r--r--virt/kvm/kvm_main.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 605697e9c4dd..28d693a1ee8f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -920,6 +920,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
920 int r; 920 int r;
921 gfn_t base_gfn; 921 gfn_t base_gfn;
922 unsigned long npages; 922 unsigned long npages;
923 int largepages;
923 unsigned long i; 924 unsigned long i;
924 struct kvm_memory_slot *memslot; 925 struct kvm_memory_slot *memslot;
925 struct kvm_memory_slot old, new; 926 struct kvm_memory_slot old, new;
@@ -995,11 +996,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
995 new.userspace_addr = 0; 996 new.userspace_addr = 0;
996 } 997 }
997 if (npages && !new.lpage_info) { 998 if (npages && !new.lpage_info) {
998 int largepages = npages / KVM_PAGES_PER_HPAGE; 999 largepages = 1 + (base_gfn + npages - 1) / KVM_PAGES_PER_HPAGE;
999 if (npages % KVM_PAGES_PER_HPAGE) 1000 largepages -= base_gfn / KVM_PAGES_PER_HPAGE;
1000 largepages++;
1001 if (base_gfn % KVM_PAGES_PER_HPAGE)
1002 largepages++;
1003 1001
1004 new.lpage_info = vmalloc(largepages * sizeof(*new.lpage_info)); 1002 new.lpage_info = vmalloc(largepages * sizeof(*new.lpage_info));
1005 1003