linux-kernel - Re: [PATCH 6/8] KVM: simply wakup async pf

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Message-ID: <4CC92D6B.5090701@cn.fujitsu.com>
Date:	Thu, 28 Oct 2010 15:59:39 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Gleb Natapov <gleb@...hat.com>
CC:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH 6/8] KVM: simply wakup async pf

On 10/27/2010 06:50 PM, Gleb Natapov wrote:
> On Wed, Oct 27, 2010 at 05:07:32PM +0800, Xiao Guangrong wrote:
>> The current way is queued a complete async pf with:
>> 	asyc_pf.page = bad_page
>> 	async_pf.arch.gfn = 0
>>
>> It has two problems while kvm_check_async_pf_completion handle this
>> async_pf:
>> - since !async_pf.page, it can retry a pseudo #PF
> kvm_arch_async_page_ready checks for is_error_page()
> 
>> - it can delete gfn 0 from vcpu->arch.apf.gfns[]
> kvm_arch_async_page_present() checks for is_error_page() too and,
> in case of PV guest, injects special token if it is true. 
> 

Ah, sorry for my stupid questions.

> After your patch special token will not be injected and migration will
> not work.
> 
>> Actually, we can simply record this wakeup request and let
>> kvm_check_async_pf_completion simply break the wait
>>
> May be wakeup_all function naming is misleading. It means wake up all PV
> guest processes by sending broadcast async pf notification. It is not
> about waking host vcpu thread.
> 

I'm not good at the KVM PV way, i'll dig into it, please ignore this patch,
thanks.
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