[PATCH v2 06/16] KVM: PPC: Book3S HV: XIVE: add controls for the EQ configuration

David Gibson david at gibson.dropbear.id.au
Wed Mar 13 15:03:27 AEDT 2019

On Tue, Mar 12, 2019 at 06:00:38PM +0100, Cédric Le Goater wrote:
> On 2/25/19 3:39 AM, David Gibson wrote:
> > On Fri, Feb 22, 2019 at 12:28:30PM +0100, Cédric Le Goater wrote:
> >> These controls will be used by the H_INT_SET_QUEUE_CONFIG and
> >> H_INT_GET_QUEUE_CONFIG hcalls from QEMU. They will also be used to
> >> restore the configuration of the XIVE EQs in the KVM device and to
> >> capture the internal runtime state of the EQs. Both 'get' and 'set'
> >> rely on an OPAL call to access from the XIVE interrupt controller the
> >> EQ toggle bit and EQ index which are updated by the HW when event
> >> notifications are enqueued in the EQ.
> >>
> >> The value of the guest physical address of the event queue is saved in
> >> the XIVE internal xive_q structure for later use. That is when
> >> migration needs to mark the EQ pages dirty to capture a consistent
> >> memory state of the VM.
> >>
> >> To be noted that H_INT_SET_QUEUE_CONFIG does not require the extra
> >> OPAL call setting the EQ toggle bit and EQ index to configure the EQ,
> >> but restoring the EQ state will.
> I think we need to add some kind of flags to differentiate the hcall
> H_INT_SET_QUEUE_CONFIG from the restore of the EQ. The hcall does
> not need OPAL support call and this could help in the code
> transition.

Hrm.  What's the actual difference in the semantics between the two
cases.  The guest shouldn't have awareness of whether or not OPAL is

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_!
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