linux-kernel - Re: [PATCH] KVM: Remove unnecessary export of kvm_{inc,dec}_notifier

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Date:   Sun, 05 Sep 2021 10:12:57 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: Remove unnecessary export of
 kvm_{inc,dec}_notifier_count()

On Thu, 2021-09-02 at 10:59 -0700, Sean Christopherson wrote:
> Don't export KVM's MMU notifier count helpers, under no circumstance
> should any downstream module, including x86's vendor code, have a
> legitimate reason to piggyback KVM's MMU notifier logic.  E.g in the x86
> case, only KVM's MMU should be elevating the notifier count, and that
> code is always built into the core kvm.ko module.
> 
> Fixes: edb298c663fc ("KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range")
> Cc: Maxim Levitsky <mlevitsk@...hat.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  virt/kvm/kvm_main.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3e67c93ca403..140c7d311021 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -638,7 +638,6 @@ void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
>  			max(kvm->mmu_notifier_range_end, end);
>  	}
>  }
> -EXPORT_SYMBOL_GPL(kvm_inc_notifier_count);
>  
>  static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
>  					const struct mmu_notifier_range *range)
> @@ -690,8 +689,6 @@ void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
>  	 */
>  	kvm->mmu_notifier_count--;
>  }
> -EXPORT_SYMBOL_GPL(kvm_dec_notifier_count);
> -
>  
>  static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
>  					const struct mmu_notifier_range *range)

Ah, I somehow thought when I wrote this that those two will be used by kvm_amd.

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky