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Message-ID: <4F6AE403.8070500@cn.fujitsu.com>
Date: Thu, 22 Mar 2012 16:34:11 +0800
From: Wen Congyang <wency@...fujitsu.com>
To: Anthony Liguori <anthony@...emonkey.ws>
CC: Avi Kivity <avi@...hat.com>, Jan Kiszka <jan.kiszka@...mens.com>,
Gleb Natapov <gleb@...hat.com>,
qemu-devel <qemu-devel@...gnu.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Eric Northup <digitaleric@...gle.com>,
kvm list <kvm@...r.kernel.org>,
Amit Shah <amit.shah@...hat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked
At 03/22/2012 03:12 AM, Anthony Liguori Wrote:
> On 03/15/2012 06:46 AM, Avi Kivity wrote:
>> On 03/15/2012 01:25 PM, Jan Kiszka wrote:
>>>>>
>>>> There was such vm exit (KVM_EXIT_HYPERCALL), but it was deemed to be a
>>>> bad idea.
>>>
>>> BTW, this would help a lot in emulating hypercalls of other hypervisors
>>> (or of KVM's VAPIC in the absence of in-kernel irqchip - I had to jump
>>> through hoops therefore) in user space. Not all those hypercall handlers
>>> actually have to reside in the KVM module.
>>>
>>
>> That is true. On the other hand the hypercall ABI might go to pieces if
>> there was no central implementation.
>
> Just declare that outl 0x505 is a megaultracall and s/vmcall/outb/g and
> call it a day.
Why use 0x505? Is it a reserved port, and it will not be used by any device?
How can I get all reserved port?
Thanks
Wen Congyang
>
> The performance difference between vmcall and outl is so tiny compared
> to the cost of dropping to userspace that it really doesn't matter which
> instruction is used.
>
> Regards,
>
> Anthony Liguori
>
>>
>
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