KVM: MMU: fix mmu notifier invalidate handler for huge spte

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@redhat.com>
Reviewed-by: Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 36c62f33513f..812770cddc8d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -850,8 +850,12 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
                         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 sh;
+
+                                sh = KVM_HPAGE_GFN_SHIFT(PT_DIRECTORY_LEVEL+j);
+                                idx = ((memslot->base_gfn+gfn_offset) >> sh) -
+                                        (memslot->base_gfn >> sh);
                                 ret |= handler(kvm,
                                         &memslot->lpage_info[j][idx].rmap_pde,
                                         data);