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From: Avi Kivity <avi@redhat.com>
To: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Gleb Natapov <gleb@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 1/7] KVM: MMU: fix release noslot pfn
Date: Thu, 27 Sep 2012 18:25:47 +0200	[thread overview]
Message-ID: <50647E0B.6080303@redhat.com> (raw)
In-Reply-To: <506052D1.5000006@linux.vnet.ibm.com>

On 09/24/2012 02:32 PM, Xiao Guangrong wrote:

> 3 places after the whole patchset (There are some cleanups after this patch).
> 
>> and one by even stronger is_error_pfn(). 
> 
> This one is:
> 
> |	if (!is_error_pfn(pfn)) {
> |                kvm_release_pfn_clean(pfn);
> |                return true;
> |	}
> |
> |	return false;
> 
> We can change it to:
> 
> | if (is_error_pfn(pfn))
> |	return false;
> |
> | kvm_release_pfn_clean(pfn);
> | return true;
> 
>> I guess when/if other architectures will add MMIO MMU
>> caching they will need to guard kvm_release_pfn_clean() by is_noslot_pfn()
>> too in most cases. I am not insisting, but as this patch shows it is
>> easy to miss the check before calling the function.
> 
> Sounds reasonable. I will consider it if Avi/Marcelo have no object on
> it.

I think it's a good idea.

Looks like we traded the unscalable error pages for these branches, I
think it's a reasonable tradeoff.

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

  reply	other threads:[~2012-09-27 16:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-21  6:56 [PATCH v3 0/7] KVM: MMU: fix release pfn in mmu code Xiao Guangrong
2012-09-21  6:57 ` [PATCH v3 1/7] KVM: MMU: fix release noslot pfn Xiao Guangrong
2012-09-23  9:13   ` Gleb Natapov
2012-09-24  4:59     ` Xiao Guangrong
2012-09-24 11:24       ` Gleb Natapov
2012-09-24 11:49         ` Xiao Guangrong
2012-09-24 12:04           ` Gleb Natapov
2012-09-24 12:32             ` Xiao Guangrong
2012-09-27 16:25               ` Avi Kivity [this message]
2012-09-21  6:57 ` [PATCH v3 2/7] KVM: MMU: remove mmu_is_invalid Xiao Guangrong
2012-09-21  6:58 ` [PATCH v3 3/7] KVM: MMU: do not release pfn in mmu_set_spte Xiao Guangrong
2012-09-21  6:58 ` [PATCH v3 4/7] KVM: MMU: cleanup FNAME(page_fault) Xiao Guangrong
2012-09-21  6:59 ` [PATCH v3 5/7] KVM: MMU: introduce FNAME(prefetch_gpte) Xiao Guangrong
2012-09-21  6:59 ` [PATCH v3 6/7] KVM: MMU: move prefetch_invalid_gpte out of pagaing_tmp.h Xiao Guangrong
2012-09-21  7:00 ` [PATCH v3 7/7] KVM: MMU: introduce page_fault_start/page_fault_end Xiao Guangrong

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