[PATCH v8 04/14] powerpc/vas: Alloc and setup IRQ and trigger port address

[Cédric Le Goater]

On 3/23/20 10:06 AM, Cédric Le Goater wrote:
> On 3/19/20 7:14 AM, Haren Myneni wrote:
>>
>> Alloc IRQ and get trigger port address for each VAS instance. Kernel
>> register this IRQ per VAS instance and sets this port for each send
>> window. NX interrupts the kernel when it sees page fault.
> 
> I don't understand why this is not done by the OPAL driver for each VAS 
> of the system. Is the VAS unit very different from OpenCAPI regarding
> the fault ? 

I checked the previous patchsets and I see that v3 was more like I expected
it: one interrupt for faults allocated by the skiboot driver and exposed  
in the DT.

What made you change your mind ? 

This version is hijacking the lowlevel routines of the XIVE irqchip which
is not the best approach. OCXL is doing that because it needs to allocate
interrupts for the user space processes using the AFU and we should rework 
that part. 

However, the translation fault interrupt is allocated by skiboot.

Sorry for the noise, I would like to understand more how this works. I also
have passthrough in mind.

C.