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Date: Mon, 13 Apr 2009 12:49:28 +0300
From: Avi Kivity <avi@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH] kvm: Fix overlapping check for memory slots
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To: Jan Kiszka <jan.kiszka@web.de>
Cc: Glauber Costa <glommer@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, kvm-devel <kvm@vger.kernel.org>

Jan Kiszka wrote:
> Avi Kivity wrote:
>   
>> Jan Kiszka wrote:
>>     
>>> This nice little buglet complicates a smarter slot management in qemu
>>> user space just "slightly". Sigh...
>>>
>>> -------->
>>>
>>> When checking for overlapping slots on registration of a new one, kvm
>>> currently also considers zero-length (ie. deleted) slots and rejects
>>> requests incorrectly. This finally denies user space from joining slots.
>>> Fix the check by skipping deleted slots.
>>>   
>>>       
>> Can userspace fail gracefully when the bug is present?  If not, the you
>> should add a KVM_CAP_ to advertise the fix; without the capability don't
>> attempt the smarter slot management.
>>     
>
> I already thought about adding some
> KVM_CAP_DESTROY_MEMORY_REGION_NOW_REALLY_WORKS and skip the workaround
> in [1]. Maybe a good idea, comments welcome.
>
>   

It's a good idea regardless of how qemu handles it.  There can be other 
users.

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