From: Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [PATCH] kvm: notify host when guest panicked
Date: Tue, 12 Jun 2012 09:49:28 +0200
Message-ID: <4FD6F488.7090303@de.ibm.com>
References: <4FB9E4CE.8060709@cn.fujitsu.com> <4FD6E5EC.3090802@cn.fujitsu.com>
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Cc: kvm list <kvm@vger.kernel.org>, Avi Kivity <avi@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Daniel P. Berrange" <berrange@redhat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Gleb Natapov <gleb@redhat.com>
To: Wen Congyang <wency@cn.fujitsu.com>
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>> We have three solutions to implement this feature:
>> 1. use vmcall
>> 2. use I/O port
>> 3. use virtio-serial.
> 
>> We have decided to avoid touching hypervisor. The reason why I choose
>> choose the I/O port is:
>> 1. it is easier to implememt
>> 2. it does not depend any virtual device
>> 3. it can work when startint the kernel

Havent looked deeply into that, butz wouldnt kvm_hypercall0 also fulfill all of these
points? You just have to define the number for each architecture and then it should be 
possible to write a simple panic driver that works on all architectures.

>> --- a/include/linux/kvm_para.h
>> +++ b/include/linux/kvm_para.h
>> @@ -20,6 +20,14 @@
>>  #define KVM_HC_FEATURES			3
>>  #define KVM_HC_PPC_MAP_MAGIC_PAGE	4
>>  
>> +#define KVM_PV_PORT	(0x505UL)
>> +

ignoring the above, shouldnt a port number go into an architecture specific file?


Christian