linux-kernel - Re: [PATCH v2 09/12] Retry fault before vmentry

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Message-ID: <4B0D2C90.2060200@redhat.com>
Date:	Wed, 25 Nov 2009 15:09:36 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Gleb Natapov <gleb@...hat.com>
CC:	kvm@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	a.p.zijlstra@...llo.nl, tglx@...utronix.de, hpa@...or.com,
	riel@...hat.com
Subject: Re: [PATCH v2 09/12] Retry fault before vmentry

On 11/23/2009 04:06 PM, Gleb Natapov wrote:
> When page is swapped in it is mapped into guest memory only after guest
> tries to access it again and generate another fault. To save this fault
> we can map it immediately since we know that guest is going to access
> the page.
>
>
> -static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
> +static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t cr3, gva_t gpa,
>   				u32 error_code)
>   {
>   	pfn_t pfn;
> @@ -2230,7 +2233,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
>   	mmu_seq = vcpu->kvm->mmu_notifier_seq;
>   	smp_rmb();
>
> -	if (can_do_async_pf(vcpu)) {
> +	if (cr3 == vcpu->arch.cr3&&  can_do_async_pf(vcpu)) {
>    

Why check cr3 here?

> -static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
> +static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t cr3, gva_t addr,
>   			       u32 error_code)
>    

I'd be slightly happier if we had a page_fault_other_cr3() op that 
switched cr3, called the original, then switched back (the tdp version 
need not change anything).

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

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