Re: [PATCH 0/6] Add rudimentary Hyper-V guest support

From: Avi Kivity <avi@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: KVM list <kvm@vger.kernel.org>, Joerg Roedel <joerg.roedel@amd.com>
Subject: Re: [PATCH 0/6] Add rudimentary Hyper-V guest support
Date: Mon, 18 May 2009 18:20:07 +0300	[thread overview]
Message-ID: <4A117CA7.5010503@redhat.com> (raw)
In-Reply-To: <059C7BD2-8EA4-4A56-AD63-D84DCF700000@suse.de>

Alexander Graf wrote:
>
> On 18.05.2009, at 15:29, Avi Kivity wrote:
>
>> Alexander Graf wrote:
>>>>
>>>> There's only a limited potential here (a factor of three, reducing 
>>>> 6 exits to 2, less the emulation overhead).  There's a lot more to 
>>>> be gained from nested npt, since you'll avoid most of the original 
>>>> exits in the first place.
>>>
>>> I think the reversed is the case. Look at those numbers (w2k8 bootup):
>>>
>>> http://pastebin.ca/1423596
>>>
>>> The only thing nested NPT would achieve is a reduction of #NPF 
>>> exits. But they are absolutely in the minority today already. Normal 
>>> #PF's do get directly passed to the guest already.
>>
>> #NPF exits are caused when guest/host mappings change, which they 
>> don't, or by mmio (which happens both for guest and nguest).
>>
>> I don't understand how you can pass #PFs directly to the guest.  
>> Surely the guest has enabled pagefault interception, and you need to 
>> set up its vmcb?
>
> I guess you're right: http://pastebin.ca/1426458

Any idea where the ioio exits come from?  If it's IDE, we can eliminate 
them by using virtio.

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