KVM: s390: pci: enable host forwarding of Adapter Event Notifications

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.

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-14-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

3 files changed, 89 insertions, 2 deletions

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 37ff4358121a..d8e1fce78b7c 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -3313,11 +3313,87 @@ out:
 }
 EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
 
+static void aen_host_forward(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)
+		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;
+
+	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) {
+				/* Re-enable interrupts. */
+				zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, isc,
+						  &iib);
+				first = found = false;
+			} else {
+				/* Interrupts on and all bits processed */
+				break;
+			}
+			found = false;
+			si = 0;
+			/* Scan again after re-enabling interrupts */
+			continue;
+		}
+		found = true;
+		aen_host_forward(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) &&
+	    IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
+		aen_process_gait(info->isc);
+		if (info->aism != 0)
+			process_gib_alert_list();
+	} else {
+		process_gib_alert_list();
+	}
 }
 
 static struct airq_struct gib_alert_irq = {
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 251eaaff9c67..d96c9be0480b 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -64,7 +64,8 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	STATS_DESC_COUNTER(VM, inject_float_mchk),
 	STATS_DESC_COUNTER(VM, inject_pfault_done),
 	STATS_DESC_COUNTER(VM, inject_service_signal),
-	STATS_DESC_COUNTER(VM, inject_virtio)
+	STATS_DESC_COUNTER(VM, inject_virtio),
+	STATS_DESC_COUNTER(VM, aen_forward)
 };
 
 const struct kvm_stats_header kvm_vm_stats_header = {
diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
index c357d900f8b0..9f7828d97605 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -13,6 +13,7 @@
 #include <linux/kvm_host.h>
 #include <linux/pci.h>
 #include <linux/mutex.h>
+#include <linux/kvm_host.h>
 #include <asm/airq.h>
 #include <asm/cpu.h>
 
@@ -40,6 +41,15 @@ struct zpci_aift {
 
 extern struct zpci_aift *aift;
 
+static inline struct kvm *kvm_s390_pci_si_to_kvm(struct zpci_aift *aift,
+						 unsigned long si)
+{
+	if (!IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM) || aift->kzdev == 0 ||
+	    aift->kzdev[si] == 0)
+		return 0;
+	return aift->kzdev[si]->kvm;
+};
+
 int kvm_s390_pci_aen_init(u8 nisc);
 void kvm_s390_pci_aen_exit(void);