On Wed, Jul 03, 2019 at 07:22:20PM +0200, Greg Kurz wrote: > The ics_set_kvm_state_one() function is called either to restore the > state of an interrupt source during migration or to set the interrupt > source to a default state during reset. > > Since always, ie. 2013, the code only sets the MASKED bit if the 'current > priority' and the 'saved priority' are different. This is likely true > when restoring an interrupt that had been previously masked with the > ibm,int-off RTAS call. However this is always false in the case of > reset since both 'current priority' and 'saved priority' are equal to > 0xff, and the MASKED bit is never set. > > The legacy KVM XICS device gets away with that because it ends updating > its internal structure the same way, whether the MASKED bit is set or > the priority is 0xff. > > The XICS-on-XIVE device for POWER9 is different. It sticks to the KVM > documentation [1] and _really_ relies on the MASKED bit to correctly > set. If not, it will configure the interrupt source in the XIVE HW, even > though the guest hasn't configured the interrupt yet. This disturbs the > complex logic implemented in XICS-on-XIVE and may result in the loss of > subsequent queued events. > > Always set the MASKED bit if interrupt is masked as expected by the KVM > XICS-on-XIVE device. This has no impact on the legacy KVM XICS. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/virtual/kvm/devices/xics.txt > > Signed-off-by: Greg Kurz <gr...@kaod.org>
Applied to ppc-for-4.1, thanks.
> ---
> hw/intc/xics_kvm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index 51433b19b076..2df1f3e92c7e 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -257,6 +257,9 @@ int ics_set_kvm_state_one(ICSState *ics, int srcno, Error
> **errp)
> << KVM_XICS_PRIORITY_SHIFT;
> if (irq->priority != irq->saved_priority) {
> assert(irq->priority == 0xff);
> + }
> +
> + if (irq->priority == 0xff) {
> state |= KVM_XICS_MASKED;
> }
>
>
--
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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