linux-kernel - Re: [PATCH 4/5] KVM: x86: MMU: Remove mapping_level_dirty

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Date:	Thu, 15 Oct 2015 17:35:27 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Takuya Yoshikawa <yoshikawa_takuya_b1@....ntt.co.jp>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] KVM: x86: MMU: Remove mapping_level_dirty_bitmap()



On 15/10/2015 12:43, Takuya Yoshikawa wrote:
> +static inline bool memslot_invalid(struct kvm_memory_slot *slot)

Can you make this function memslot_valid_for_gpte(struct kvm_memory_slot
*slot, bool no_dirty_log), and have it return

	slot && !(slot->flags & KVM_MEMSLOT_INVALID) &&
	      (!no_dirty_log || !slot->dirty_bitmap)

?  If gfn_to_memslot_dirty_bitmap and mapping_level call the same
function, it helps highlighting the similarity between them.  Your
optimization loses that similarity in the name, but I think we can bring
it back somehow.

Otherwise, the patches are great.  Thanks!

Paolo


> +{
> +	if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
> +		return true;
> +
> +	return false;
> +}
> +
>  static struct kvm_memory_slot *
>  gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
>  			    bool no_dirty_log)
> @@ -858,25 +866,22 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
>  	struct kvm_memory_slot *slot;
>  
>  	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
> -	if (!slot || slot->flags & KVM_MEMSLOT_INVALID ||
> -	      (no_dirty_log && slot->dirty_bitmap))
> +	if (memslot_invalid(slot) || (no_dirty_log && slot->dirty_bitmap))
>  		slot = NULL;
>  
>  	return slot;
>  }
>  
> -static bool mapping_level_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t large_gfn)
> -{
> -	return !gfn_to_memslot_dirty_bitmap(vcpu, large_gfn, true);
> -}
> -
>  static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
>  			 bool *force_pt_level)
>  {
>  	int host_level, level, max_level;
> +	struct kvm_memory_slot *slot;
> +
> +	slot = kvm_vcpu_gfn_to_memslot(vcpu, large_gfn);
>  
>  	if (likely(!*force_pt_level))
> -		*force_pt_level = mapping_level_dirty_bitmap(vcpu, large_gfn);
> +		*force_pt_level = memslot_invalid(slot) || slot->dirty_bitmap;
--
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