Re: [PATCH] KVM: arm/arm64: Fix young bit from mmu notifier

[Marc Zyngier <maz@kernel.org>]

On 2020-01-21 05:56, Gavin Shan wrote:
> kvm_test_age_hva() is called upon mmu_notifier_test_young(), but wrong
> address range has been passed to handle_hva_to_gpa(). With the wrong
> address range, no young bits will be checked in handle_hva_to_gpa().
> It means zero is always returned from mmu_notifier_test_young().
> 
> This fixes the issue by passing correct address range to the underly
> function handle_hva_to_gpa(), so that the hardware young (access) bit
> will be visited.
> 
> Cc: stable@vger.kernel.org # v4.1+
> Fixes: 35307b9a5f7e ("arm/arm64: KVM: Implement Stage-2 page aging")
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  virt/kvm/arm/mmu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 0b32a904a1bb..a2777efb558e 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -2147,7 +2147,8 @@ 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);
> +	return handle_hva_to_gpa(kvm, hva, hva + PAGE_SIZE,
> +				 kvm_test_age_hva_handler, NULL);
>  }
> 
>  void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)

I knew this start/end thing (instead of start/size) would bite us
one of these days. Terribly embarrassing. On the other hand, who
really wants to swap things out? ;-)

Out of curiosity, how did you find this one?

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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