Re: [Qemu-ppc] [RFC PATCH 08/26] ppc/xive: add flags to the XIVE interrupt source

[Cédric Le Goater]

On 07/25/2017 07:47 AM, Benjamin Herrenschmidt wrote:
> On Tue, 2017-07-25 at 14:18 +1000, David Gibson wrote:
>>> Well, at this point I think nothing will set that flag.... It's there
>>> for workaround around HW bugs on some chips. At least in full emu it
>>> shouldn't happen unless we try to emulate those bugs. Hopefully direct
>>> MMIO will just work.
>>
>> Hm.  That doesn't seem like a good match for a per-irq state
>> structure.
> 
> The flag is returned to the guest on a per-IRQ basis, so are the LSI
> etc... flags, but at the HW level, indeed, they correspond to
> attributes of blocks of interrupts.
> 
> It might be easier in qemu to keep that in the per-source flags
> though.

Theses flags are at the source level :

  XIVE_SRC_H_INT_ESB 
  XIVE_SRC_TRIGGER    
  XIVE_SRC_STORE_EOI  


The XIVE_SRC_LSI flag is only returned in the GET_SOURCE_INFO hcall 
but, internally, we use the ICSIRQState flags XICS_FLAGS_IRQ_LSI to 
store the information per-irq.       
 
Thanks,

C.


> Especially when we start having actual HW interrupts under the
> hood with KVM. it's easier to keep the state self contained
> for each of them.
> 
> Ben.
>