Re: [Xen-devel] Question, How to share interrupt between Doms

[Julien Grall <julien.grall@xxxxxxx>]

On 02/10/2018 09:32, Peng Fan wrote:
> Hi Julien, Stefano,
Hi Peng,

> Do you have any suggestions on how to share one interrupt between Doms?
Sharing interrupts are usually a pain. You would need to forward the 
interrupts to all the domains using that interrupt and wait for them to 
EOI. This has security implications because you don't want DomA to 
prevent DomB receiving another interrupt because the previous one has 
not been EOIed correctly.
> The issue is that a gpio controller has 32 in/out port, however it only has one 
> binded interrupt. The interrupt handler needs to check the status bits to check 
> which port has interrupt coming.
> In my case, there are different devices using gpio interrupt that needs to be 
> assigned to different doms.
From what you wrote, it looks like you expect the GPIO controller to be 
shared with multiple domains.
I don't think it is safe to do that. You need one domain (or Xen) to 
fully manage the controller. All the other domain will have to access 
either a virtual GPIO controller or PV one. In the former, interrupt 
would be virtual, while the latter the interrupt would be through even 
channel.
So sharing interrupt should not be necessary. Did I miss anything?

Cheers,

--
Julien Grall

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