Messages in this thread Patch in this message | | | Date | Wed, 06 May 2009 14:45:36 -0700 | From | Greg KH <> | Subject | [patch 08/58] KVM: MMU: Fix off-by-one calculating large page count |
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2.6.29-stable review patch. If anyone has any objections, please let us know.
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From: Avi Kivity <avi@redhat.com>
upstream commit: 99894a799f09cf9e28296bb16e75bd5830fd2c4e
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> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- virt/kvm/kvm_main.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
--- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -964,6 +964,7 @@ int __kvm_set_memory_region(struct kvm * int r; gfn_t base_gfn; unsigned long npages; + int largepages; unsigned long i; struct kvm_memory_slot *memslot; struct kvm_memory_slot old, new; @@ -1039,11 +1040,8 @@ int __kvm_set_memory_region(struct kvm * new.userspace_addr = 0; } if (npages && !new.lpage_info) { - int largepages = npages / KVM_PAGES_PER_HPAGE; - if (npages % KVM_PAGES_PER_HPAGE) - largepages++; - if (base_gfn % KVM_PAGES_PER_HPAGE) - largepages++; + largepages = 1 + (base_gfn + npages - 1) / KVM_PAGES_PER_HPAGE; + largepages -= base_gfn / KVM_PAGES_PER_HPAGE; new.lpage_info = vmalloc(largepages * sizeof(*new.lpage_info));
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