linux-kernel - Re: [PATCH 3/3] KVM: MMU: mark page dirty only when page is really written

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Message-ID: <4C56790D.60504@cn.fujitsu.com>
Date:	Mon, 02 Aug 2010 15:51:41 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: [PATCH 3/3] KVM: MMU: mark page dirty only when page is really
 written



Avi Kivity wrote:
>  On 07/27/2010 06:35 AM, Xiao Guangrong wrote:
>> Mark page dirty only when this page is really written, it's more exacter,
>> and also can fix dirty page marking in speculation path
>>
>> Signed-off-by: Xiao Guangrong<xiaoguangrong@...fujitsu.com>
>> ---
>>   arch/x86/kvm/mmu.c |   47
>> ++++++++++++++++++++++++++++-------------------
>>   1 files changed, 28 insertions(+), 19 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index dd6c192..bcc2173 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -311,24 +311,42 @@ static bool spte_bits_lost(u64 spte)
>>       if (!is_shadow_present_pte(spte))
>>           return false;
>>
>> -    if (spte&  shadow_accessed_mask)
>> +    if (spte&  shadow_accessed_mask&&
>> +          (!is_writable_pte(spte) || spte&  shadow_dirty_mask))
>>           return false;
>>
> 
> Please add parentheses around bitwise operators to reduce confusion. 
> The rest looks good.
> 

OK, will do it in the new version, thanks.
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