[PATCH v3 17/30] KVM: s390: pci: enable host forwarding of Adapter Event Notifications

[Matthew Rosato <mjrosato@linux.ibm.com>]

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>
---
 arch/s390/include/asm/kvm_host.h |  1 +
 arch/s390/include/asm/tpi.h      | 13 ++++++
 arch/s390/kvm/interrupt.c        | 77 +++++++++++++++++++++++++++++++-
 arch/s390/kvm/kvm-s390.c         |  3 +-
 arch/s390/kvm/pci.h              | 10 +++++
 5 files changed, 102 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a22c9266ea05..b468d3a2215e 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -757,6 +757,7 @@ struct kvm_vm_stat {
 	u64 inject_pfault_done;
 	u64 inject_service_signal;
 	u64 inject_virtio;
+	u64 aen_forward;
 };
 
 struct kvm_arch_memory_slot {
diff --git a/arch/s390/include/asm/tpi.h b/arch/s390/include/asm/tpi.h
index 1ac538b8cbf5..f76e5fdff23a 100644
--- a/arch/s390/include/asm/tpi.h
+++ b/arch/s390/include/asm/tpi.h
@@ -19,6 +19,19 @@ struct tpi_info {
 	u32 :12;
 } __packed __aligned(4);
 
+/* I/O-Interruption Code as stored by TPI for an Adapter I/O */
+struct tpi_adapter_info {
+	u32 aism:8;
+	u32 :22;
+	u32 error:1;
+	u32 forward:1;
+	u32 reserved;
+	u32 adapter_IO:1;
+	u32 directed_irq:1;
+	u32 isc:3;
+	u32 :27;
+} __packed __aligned(4);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_S390_TPI_H */
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 5e638f7c86f8..74a549d3d1e4 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -3271,11 +3271,86 @@ int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
 }
 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 == 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;
+
+	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(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 (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV) &&
+	    (info->forward || info->error)) {
+		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 dd4f4bfb326b..24837d6050dc 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -65,7 +65,8 @@ 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 53e9968707c8..4d3db58beb74 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -12,6 +12,7 @@
 
 #include <linux/pci.h>
 #include <linux/mutex.h>
+#include <linux/kvm_host.h>
 #include <asm/airq.h>
 #include <asm/kvm_pci.h>
 
@@ -34,6 +35,15 @@ 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) || 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);
 
-- 
2.27.0