linux-kernel - Re: [PATCH v3 02/11] KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}

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Message-ID: <56C6F7D3.3000205@redhat.com>
Date:	Fri, 19 Feb 2016 12:09:07 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Xiao Guangrong <guangrong.xiao@...ux.intel.com>
Cc:	gleb@...nel.org, mtosatti@...hat.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, kai.huang@...ux.intel.com,
	jike.song@...el.com
Subject: Re: [PATCH v3 02/11] KVM: MMU: introduce
 kvm_mmu_gfn_{allow,disallow}_lpage



On 14/02/2016 12:31, Xiao Guangrong wrote:
> Abstract the common operations from account_shadowed() and
> unaccount_shadowed(), then introduce kvm_mmu_gfn_disallow_lpage()
> and kvm_mmu_gfn_allow_lpage()
> 
> These two functions will be used by page tracking in the later patch
> 
> Signed-off-by: Xiao Guangrong <guangrong.xiao@...ux.intel.com>
> ---
>  arch/x86/kvm/mmu.c | 38 +++++++++++++++++++++++++-------------
>  arch/x86/kvm/mmu.h |  3 +++
>  2 files changed, 28 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index de9e992..e1bb66c 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -776,21 +776,39 @@ static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn,
>  	return &slot->arch.lpage_info[level - 2][idx];
>  }
>  
> +static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot,
> +					    gfn_t gfn, int count)
> +{
> +	struct kvm_lpage_info *linfo;
> +	int i;
> +
> +	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
> +		linfo = lpage_info_slot(gfn, slot, i);
> +		linfo->disallow_lpage += count;
> +		WARN_ON(linfo->disallow_lpage < 0);
> +	}
> +}
> +
> +void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
> +{
> +	update_gfn_disallow_lpage_count(slot, gfn, 1);
> +}
> +
> +void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
> +{
> +	update_gfn_disallow_lpage_count(slot, gfn, -1);
> +}
> +
>  static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
>  {
>  	struct kvm_memslots *slots;
>  	struct kvm_memory_slot *slot;
> -	struct kvm_lpage_info *linfo;
>  	gfn_t gfn;
> -	int i;
>  
>  	gfn = sp->gfn;
>  	slots = kvm_memslots_for_spte_role(kvm, sp->role);
>  	slot = __gfn_to_memslot(slots, gfn);
> -	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
> -		linfo = lpage_info_slot(gfn, slot, i);
> -		linfo->disallow_lpage += 1;
> -	}
> +	kvm_mmu_gfn_disallow_lpage(slot, gfn);
>  	kvm->arch.indirect_shadow_pages++;
>  }
>  
> @@ -798,18 +816,12 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
>  {
>  	struct kvm_memslots *slots;
>  	struct kvm_memory_slot *slot;
> -	struct kvm_lpage_info *linfo;
>  	gfn_t gfn;
> -	int i;
>  
>  	gfn = sp->gfn;
>  	slots = kvm_memslots_for_spte_role(kvm, sp->role);
>  	slot = __gfn_to_memslot(slots, gfn);
> -	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
> -		linfo = lpage_info_slot(gfn, slot, i);
> -		linfo->disallow_lpage -= 1;
> -		WARN_ON(linfo->disallow_lpage < 0);
> -	}
> +	kvm_mmu_gfn_allow_lpage(slot, gfn);
>  	kvm->arch.indirect_shadow_pages--;
>  }
>  
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 55ffb7b..de92bed 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -174,4 +174,7 @@ static inline bool permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
>  
>  void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
>  void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
> +
> +void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
> +void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
>  #endif
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>