Re: [PATCH v5 12/15] KVM: s390: do not restore IAM immediately before SIE entry

[Michael Mueller]

On 03.01.19 16:00, Pierre Morel wrote:
> On 19/12/2018 20:17, Michael Mueller wrote:
> > The IAM shall no be restored when deliverable interruptions are
> > delivered to vcpus by means of the PSW swap mechanism. That would
> > trigger the GIB alert millicode although we know that SIE will be
> > able to handle the pending interruption on entry.
> >
> > Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
> > ---
> > Â arch/s390/kvm/interrupt.c | 8 ++++----
> > Â 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> > index 8307717e3caf..48a93f5e5333 100644
> > --- a/arch/s390/kvm/interrupt.c
> > +++ b/arch/s390/kvm/interrupt.c
> > @@ -328,11 +328,11 @@ static unsigned long disable_iscs(struct 
> > kvm_vcpu *vcpu,
> > ÂÂÂÂÂ return active_mask;
> > Â }
> > -static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)
> > +static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu, u16 
> > irq_flags)
> > Â {
> > ÂÂÂÂÂ unsigned long active_mask;
> > -ÂÂÂ active_mask = pending_irqs(vcpu, IRQ_MASK_ALL);
> > +ÂÂÂ active_mask = pending_irqs(vcpu, irq_flags);
> > ÂÂÂÂÂ if (!active_mask)
> > ÂÂÂÂÂÂÂÂÂ return 0;
> > @@ -1090,7 +1090,7 @@ int kvm_s390_ext_call_pending(struct kvm_vcpu 
> > *vcpu)
> > Â int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop)
> > Â {
> > -ÂÂÂ if (deliverable_irqs(vcpu))
> > +ÂÂÂ if (deliverable_irqs(vcpu, IRQ_MASK_ALL | IRQ_FLAG_IAM))
>
> Why do we need to restore IAM here?


please see kvm_s390_handle_wait()

It calls kvm_arch_vcpu_runnable() / kvm_s390_vcpu_has_irq()

That's the place where we want the IAM to be restored when
no ISC is pending in the IPM anymore.

>