linux-kernel - Re: [PATCH v2 1/10] KVM MMU: fix for calculating gpa in invlpg code

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Date:	Sun, 25 Apr 2010 12:46:21 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	KVM list <kvm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/10] KVM MMU: fix for calculating gpa in invlpg code

On 04/25/2010 10:00 AM, Xiao Guangrong wrote:
> If the guest is 32-bit, we should use 'quadrant' to adjust gpa
> offset
>
> Changlog v2:
> - when level is PT_DIRECTORY_LEVEL, the 'offset' should be
>    'role.quadrant<<  8', thanks Avi for point it out
>
> Signed-off-by: Xiao Guangrong<xiaoguangrong@...fujitsu.com>
> ---
>   arch/x86/kvm/paging_tmpl.h |   13 +++++++++++--
>   1 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index d0cc07e..83cc72f 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -478,9 +478,18 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
>   		    ((level == PT_DIRECTORY_LEVEL&&  is_large_pte(*sptep))) ||
>   		    ((level == PT_PDPE_LEVEL&&  is_large_pte(*sptep)))) {
>   			struct kvm_mmu_page *sp = page_header(__pa(sptep));
> -
> +			int offset = 0;
> +
> +			if (PTTYPE == 32) {
> +				if (level == PT_DIRECTORY_LEVEL)
> +					offset = PAGE_SHIFT - 4;
> +				else
> +					offset = PT64_LEVEL_BITS;
> +				offset = sp->role.quadrant<<  offset;
> +			}
>    

The calculation is really

   shift = (PT32_LEVEL_BITS - PT64_LEVEL_BITS) * level;

(and please don't use a variable called offset to hold a shift count)


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

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