Re: [PATCH 15/32] KVM: s390: pci: enable host forwarding of Adapter Event Notifications

Christian Borntraeger
2021-12-17T16:56:45Z

Am 07.12.21 um 21:57 schrieb Matthew Rosato:
> In cases where interrupts are not forwarded to the guest via firmware,
> KVM is responsible for ensuring delivery. When an interrupt presents
> with the forwarding bit, we must process the forwarding tables until
> all interrupts are delivered.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
[...]

> +static void aen_host_forward(struct zpci_aift *aift, unsigned long si)
> +{
> + struct kvm_s390_gisa_interrupt *gi;
> + struct zpci_gaite *gaite;
> + struct kvm *kvm;
> +
> + gaite = (struct zpci_gaite *)aift->gait +
> + (si * sizeof(struct zpci_gaite));
> + if (gaite->count == 0)
> + return;
> + if (gaite->aisb != 0)
> + set_bit_inv(gaite->aisbo, (unsigned long *)gaite->aisb);
> +
> + kvm = kvm_s390_pci_si_to_kvm(aift, si);
> + if (kvm == 0)
> + return;
> + gi = &kvm->arch.gisa_int;
> +
> + if (!(gi->origin->g1.simm & AIS_MODE_MASK(gaite->gisc)) ||
> + !(gi->origin->g1.nimm & AIS_MODE_MASK(gaite->gisc))) {
> + gisa_set_ipm_gisc(gi->origin, gaite->gisc);
> + if (hrtimer_active(&gi->timer))
> + hrtimer_cancel(&gi->timer);
> + hrtimer_start(&gi->timer, 0, HRTIMER_MODE_REL);
> + kvm->stat.aen_forward++;
> + }
> +}
> +
> +static void aen_process_gait(u8 isc)
> +{
> + bool found = false, first = true;
> + union zpci_sic_iib iib = {{0}};
> + unsigned long si, flags;
> + struct zpci_aift *aift;
> +
> + aift = kvm_s390_pci_get_aift();
> + spin_lock_irqsave(&aift->gait_lock, flags);
> +
> + if (!aift->gait) {
> + spin_unlock_irqrestore(&aift->gait_lock, flags);
> + return;
> + }
> +
> + for (si = 0;;) {
> + /* Scan adapter summary indicator bit vector */
> + si = airq_iv_scan(aift->sbv, si, airq_iv_end(aift->sbv));
> + if (si == -1UL) {
> + if (first || found) {
> + /* Reenable interrupts. */
> + if (zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, isc,
> + &iib))
> + break;
> + first = found = false;
> + } else {
> + /* Interrupts on and all bits processed */
> + break;
> + }
> + found = false;
> + si = 0;
> + continue;
> + }
> + found = true;
> + aen_host_forward(aift, si);
> + }
> +
> + spin_unlock_irqrestore(&aift->gait_lock, flags);
> +}
> +
> static void gib_alert_irq_handler(struct airq_struct *airq,
> struct tpi_info *tpi_info)
> {
> + struct tpi_adapter_info *info = (struct tpi_adapter_info *)tpi_info;
> +
> inc_irq_stat(IRQIO_GAL);
> - process_gib_alert_list();
> +
> + if (info->forward || info->error)
> + aen_process_gait(info->isc);
> + else
> + process_gib_alert_list();
> }

Not sure, would it make sense to actually do both after an alert interrupt or do we always get a separate interrupt for event vs. irq?
[..]