Re: KVM handling external interrupts

[Jan Kiszka <jan.kiszka@web.de>]

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On 2012-06-07 12:47, Abel Gordon wrote:
> 
> 
> Jan Kiszka <jan.kiszka@web.de> wrote on 07/06/2012 12:02:31:
> 
>>>> Yes, that's exactly something we already did in a research project.
>>>> You can read our paper published in ASPLOS 2012: ELI: Bare-metal
>>>> performance for I/O virtualization
>>>> (
>>>> http://dl.acm.org/citation.cfm?
>> id=2151020&dl=ACM&coll=DL&CFID=86701665&CFTOKEN=26302003
>>>
>>> Interesting. Can you provide it publicly (or send a version privately)?
>>
>> Sorry, should have googled first:
>>
>> http://www.mulix.org/pubs/eli/eli.pdf :)
> np ;)
> 
>>>> Note this is not so simple, there are many other issues you should
>>>> consider.
>>>
>>> Is it just complicated, not upstreamable, or are the unsolved issues
>>> like security holes or the need to paravirtualize the guest?
>>
>> My first feeling is that it's not easily upstreamable due to the need to
>> fiddle with the host's IDT, specifically on VCPU task migration. But I
>> need to read the requirements of this more carefully. Still interesting
>> work!
> 
> You don't need to fiddle with the host's IDT, you need to fiddle with
> the shadow IDT and interrupt vector mapping/remapping.

Yes, but you need to sync the host IDT into the shadow table. This may
require some hooks in generic code to avoid scanning the host table on
each guest entry.

BTW, the shadow IDT has to be put in the guest address space, right? So
we need to make it read-only for the guest?

Jan


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