linux-kernel - Re: [PATCH] kvm: don't treat NULL parent_pte as multimapped in mmu_parent

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Date:	Thu, 07 Jan 2010 18:05:56 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Roel Kluin <roel.kluin@...il.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: don't treat NULL parent_pte as multimapped in mmu_parent_walk()

On 01/07/2010 05:56 PM, Roel Kluin wrote:
> If a kvm_mmu_page is not multimapped but parent_pte is NULL
> don't treat it as multimapped and dereference it.
>
> Signed-off-by: Roel Kluin<roel.kluin@...il.com>
> ---
> This wasn't tested and maybe I misunderstood so please review.
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 4c3e5b2..eb17287 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -1031,10 +1031,12 @@ static void mmu_parent_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
>   	struct kvm_mmu_page *parent_sp;
>   	int i;
>
> -	if (!sp->multimapped&&  sp->parent_pte) {
> -		parent_sp = page_header(__pa(sp->parent_pte));
> -		fn(vcpu, parent_sp);
> -		mmu_parent_walk(vcpu, parent_sp, fn);
> +	if (!sp->multimapped) {
> +		if (sp->parent_pte) {
> +			parent_sp = page_header(__pa(sp->parent_pte));
> +			fn(vcpu, parent_sp);
> +			mmu_parent_walk(vcpu, parent_sp, fn);
> +		}
>   		return;
>   	}
>   	hlist_for_each_entry(pte_chain, node,&sp->parent_ptes, link)
>
>    

If sp->parent_pte is NULL then the list walk terminates immediately.

-- 
error compiling committee.c: too many arguments to function

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