Re: KVM handling external interrupts

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

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On 2012-06-07 09:51, Abel Gordon wrote:
>> 3> if we configure not exit on external interrupt by setting some
>> field in VMCS, what will happen during the physical interrupts? will
>> the CPU use the guest IDT for response interrupt? If so, can KVM
>> redirect the CPU to use another IDT for guest (assuming modifying the
>> IDTR)?
> 
> 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)?

> )
> 
> 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?

I'm still hoping that Intel/AMD will finally enable this in hardware, at
least for MSIs. Providing direct injection for legacy line-base
interrupts is likely not worth the silicon and bits (would require some
hw-assisted IOAPIC instead of just a bit more APIC virtualization).

Jan


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