linux-kernel - Re: [PATCH 3/4] PF: Provide additional direct page notification

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Message-Id: <A58A4C11-C6B3-4B1A-B71D-3911B9A7AAF6@suse.de>
Date:	Wed, 10 Jul 2013 12:51:18 +0200
From:	Alexander Graf <agraf@...e.de>
To:	Christian Borntraeger <borntraeger@...ibm.com>
Cc:	Dominik Dingel <dingel@...ux.vnet.ibm.com>,
	Gleb Natapov <gleb@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	Xiantao Zhang <xiantao.zhang@...el.com>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Ralf Baechle <ralf@...ux-mips.org>, kvm@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] PF: Provide additional direct page notification


On 10.07.2013, at 12:49, Christian Borntraeger wrote:

> On 10/07/13 12:39, Alexander Graf wrote:
>> 
>> On 09.07.2013, at 18:01, Christian Borntraeger wrote:
>> 
>>> On 09/07/13 15:56, Dominik Dingel wrote:
>>>> By setting a Kconfig option, the architecture can control when
>>>> guest notifications will be presented by the apf backend.
>>>> So there is the default batch mechanism, working as before, where the vcpu thread
>>>> should pull in this information. On the other hand there is now the direct
>>>> mechanism, this will directly push the information to the guest.
>>>> 
>>>> Still the vcpu thread should call check_completion to cleanup leftovers,
>>>> that leaves most of the common code untouched.
>>>> 
>>>> Signed-off-by: Dominik Dingel <dingel@...ux.vnet.ibm.com>
>>> 
>>> Acked-by: Christian Borntraeger <borntraeger@...ibm.com> 
>>> for the "why". We want to use the existing architectured interface.
>> 
>> Shouldn't this be a runtime option?
> 
> This is an a) or b) depending on the architecture. So making this a kconfig
> option is the most sane approach no?

I guess I'm just missing the patch that actually selects it. Last thing I remember you can have a kernel configured for s390x that runs on any 64bit capable system out there. What would you select? If that kernel runs on newer hardware, it would be able to do async pf, no?

There's a good chance I simply miss a critical component here :).


Alex

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