commit 7e5a672289c9754d07e1c3b33649786d3d70f5e4 upstream. The mmu_notifier_release() callback of KVM triggers cleaning up the stage2 page table on kvm-arm. However there could be other notifier callbacks in parallel with the mmu_notifier_release(), which could cause the call backs ending up in an empty stage2 page table. Make sure we check it for all the notifier callbacks. Fixes: commit 293f29363 ("kvm-arm: Unmap shadow pagetables properly") Cc: stable@xxxxxxxxxxxxxxx # v4.9- Reported-by: Alex Graf <agraf@xxxxxxx> Reviewed-by: Christoffer Dall <cdall@xxxxxxxxxx> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> --- This is a back port of the patch for stable tree for version v4.9 and earlier. --- arch/arm/kvm/mmu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 332ce3b..710511c 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1664,12 +1664,16 @@ static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end) { + if (!kvm->arch.pgd) + return 0; trace_kvm_age_hva(start, end); return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL); } int kvm_test_age_hva(struct kvm *kvm, unsigned long hva) { + if (!kvm->arch.pgd) + return 0; trace_kvm_test_age_hva(hva); return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL); } -- 2.7.5