Re: [PATCH] Fixes: f32fb32820b1 ("KVM: x86: Add hook for determining max NPT mapping level")

[Paolo Bonzini <pbonzini@redhat.com>]

On Thu, Aug 1, 2024 at 7:40 PM Ackerley Tng <ackerleytng@google.com> wrote:
>
> The `if (req_max_level)` test was meant ignore req_max_level if
> PG_LEVEL_NONE was returned. Hence, this function should return
> max_level instead of the ignored req_max_level.
>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Change-Id: I403898aacc379ed98ba5caa41c9f1c52f277adc2

It's worth pointing out that this is only a latent issue for now,
since guest_memfd does not support large pages ( __kvm_gmem_get_pfn
always returns 0).

Queued with a small note in the commit message and fixed subject.

Thanks,

Paolo


> ---
>  arch/x86/kvm/mmu/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 901be9e420a4..e6b73774645d 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4335,7 +4335,7 @@ static u8 kvm_max_private_mapping_level(struct kvm *kvm, kvm_pfn_t pfn,
>         if (req_max_level)
>                 max_level = min(max_level, req_max_level);
>
> -       return req_max_level;
> +       return max_level;
>  }
>
>  static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu,
> --
> 2.46.0.rc2.264.g509ed76dc8-goog
>