On Thu, Apr 26, 2018 at 11:48:06AM +0200, Cédric Le Goater wrote: > On 04/26/2018 09:25 AM, David Gibson wrote: > > On Thu, Apr 19, 2018 at 02:43:03PM +0200, Cédric Le Goater wrote: > >> The Event Queue Descriptor (EQD) table is an internal table of the > >> XIVE routing sub-engine. It specifies on which Event Queue the event > >> data should be posted when an exception occurs (later on pulled by the > >> OS) and which Virtual Processor to notify. > > > > Uhhh.. I thought the IVT said which queue and vp to notify, and the > > EQD gave metadata for event queues. > > yes. the above poorly written. The Event Queue Descriptor contains the > guest address of the event queue in which the data is written. I will > rephrase. > > The IVT contains IVEs which indeed define for an IRQ which EQ to notify > and what data to push on the queue. > > >> The Event Queue is a much > >> more complex structure but we start with a simple model for the sPAPR > >> machine. > >> > >> There is one XiveEQ per priority and these are stored under the XIVE > >> virtualization presenter (sPAPRXiveNVT). EQs are simply indexed with : > >> > >> (server << 3) | (priority & 0x7) > >> > >> This is not in the XIVE architecture but as the EQ index is never > >> exposed to the guest, in the hcalls nor in the device tree, we are > >> free to use what fits best the current model. > > This EQ indexing is important to notice because it will also show up > in KVM to build the IVE from the KVM irq state.
Ok, are you saying that while this combined EQ index will never appear
in guest <-> host interfaces, it might show up in qemu <-> KVM
interfaces?
> >> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> >
> > Is the EQD actually modifiable by a guest? Or are the settings of the
> > EQs fixed by PAPR?
>
> The guest uses the H_INT_SET_QUEUE_CONFIG hcall to define the address
> of the event queue for a couple prio/server.
Ok, so the EQD can be modified by the guest. In which case we need to
work out what object owns it, since it'll need to migrate it.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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