[58/80] KVM: MMU: fix mmu notifier invalidate handler for huge spte

[Greg KH]

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Andrea Arcangeli <aarcange@xxxxxxxxxx>

commit 6e3e243c3b6e0bbd18c6ce0fbc12bc3fe2d77b34 upstream.

The index wasn't calculated correctly (off by one) for huge spte so KVM guest
was unstable with transparent hugepages.

Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Reviewed-by: Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 arch/x86/kvm/mmu.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -799,8 +799,12 @@ static int kvm_handle_hva(struct kvm *kv
 			ret = handler(kvm, &memslot->rmap[gfn_offset], data);
 
 			for (j = 0; j < KVM_NR_PAGE_SIZES - 1; ++j) {
-				int idx = gfn_offset;
-				idx /= KVM_PAGES_PER_HPAGE(PT_DIRECTORY_LEVEL + j);
+				unsigned long idx;
+				int nr;
+
+				nr = KVM_PAGES_PER_HPAGE(PT_DIRECTORY_LEVEL+j);
+				idx = (memslot->base_gfn+gfn_offset) / nr -
+					memslot->base_gfn / nr;
 				ret |= handler(kvm,
 					&memslot->lpage_info[j][idx].rmap_pde,
 					data);


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