[PATCH v5 14/15] KVM: s390: add and wire function gib_alert_irq_handler()

Michael Mueller
2018-12-19T19:17:55Z

The patch implements a handler for GIB alert interruptions
on the host. Its task is to alert guests that interrupts are
pending for them.

A GIB alert interrupt statistic counter is added as well:

$ cat /proc/interrupts
CPU0 CPU1
...
GAL: 23 37 [I/O] GIB Alert
...

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
---
arch/s390/include/asm/irq.h | 1 +
arch/s390/include/asm/isc.h | 1 +
arch/s390/kernel/irq.c | 1 +
arch/s390/kvm/interrupt.c | 36 ++++++++++++++++++++++++++++++++++--
4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/irq.h b/arch/s390/include/asm/irq.h
index 2f7f27e5493f..afaf5e3c57fd 100644
--- a/arch/s390/include/asm/irq.h
+++ b/arch/s390/include/asm/irq.h
@@ -62,6 +62,7 @@ enum interruption_class {
IRQIO_MSI,
IRQIO_VIR,
IRQIO_VAI,
+ IRQIO_GAL,
NMI_NMI,
CPU_RST,
NR_ARCH_IRQS
diff --git a/arch/s390/include/asm/isc.h b/arch/s390/include/asm/isc.h
index 6cb9e2ed05b6..b2cc1ec78d06 100644
--- a/arch/s390/include/asm/isc.h
+++ b/arch/s390/include/asm/isc.h
@@ -21,6 +21,7 @@
/* Adapter interrupts. */
#define QDIO_AIRQ_ISC IO_SCH_ISC /* I/O subchannel in qdio mode */
#define PCI_ISC 2 /* PCI I/O subchannels */
+#define GAL_ISC 5 /* GIB alert */
#define AP_ISC 6 /* adjunct processor (crypto) devices */

/* Functions for registration of I/O interruption subclasses */
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 0e8d68bac82c..0cd5a5f96729 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -88,6 +88,7 @@ static const struct irq_class irqclass_sub_desc[] = {
{.irq = IRQIO_MSI, .name = "MSI", .desc = "[I/O] MSI Interrupt" },
{.irq = IRQIO_VIR, .name = "VIR", .desc = "[I/O] Virtual I/O Devices"},
{.irq = IRQIO_VAI, .name = "VAI", .desc = "[I/O] Virtual I/O Devices AI"},
+ {.irq = IRQIO_GAL, .name = "GAL", .desc = "[I/O] GIB Alert"},
{.irq = NMI_NMI, .name = "NMI", .desc = "[NMI] Machine Check"},
{.irq = CPU_RST, .name = "RST", .desc = "[CPU] CPU Restart"},
};
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 03e7ba4f215a..79b9c262479b 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -26,6 +26,7 @@
#include <asm/gmap.h>
#include <asm/switch_to.h>
#include <asm/nmi.h>
+#include <asm/airq.h>
#include "kvm-s390.h"
#include "gaccess.h"
#include "trace-s390.h"
@@ -3043,7 +3044,7 @@ static void __floating_airqs_kick(struct kvm *kvm)
#define NONE_GISA_ADDR 0x00000001UL
#define GISA_ADDR_MASK 0xfffff000UL

-static void __maybe_unused process_gib_alert_list(void)
+static void process_gib_alert_list(void)
{
u32 final, next_alert, origin = 0UL;
struct kvm_s390_gisa *gisa;
@@ -3091,7 +3092,10 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
{
if (!kvm->arch.gisa)
return;
+ if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
+ process_gib_alert_list();
nullify_gisa(kvm->arch.gisa);
+ set_iam(kvm->arch.gisa, kvm->arch.iam);
VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
}

@@ -3111,6 +3115,8 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
{
if (!kvm->arch.gisa)
return;
+ if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
+ process_gib_alert_list();
kvm->arch.gisa = NULL;
}

@@ -3159,11 +3165,23 @@ int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
}
EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);

+static void gib_alert_irq_handler(struct airq_struct *airq)
+{
+ inc_irq_stat(IRQIO_GAL);
+ process_gib_alert_list();
+}
+
+static struct airq_struct gib_alert_irq = {
+ .handler = gib_alert_irq_handler,
+ .lsi_ptr = &gib_alert_irq.lsi_mask,
+};
+
void kvm_s390_gib_destroy(void)
{
if (!gib)
return;
chsc_sgib(0);
+ unregister_adapter_interrupt(&gib_alert_irq);
free_page((unsigned long)gib);
gib = NULL;
}
@@ -3183,16 +3201,30 @@ int kvm_s390_gib_init(u8 nisc)
goto out;
}

+ gib_alert_irq.isc = nisc;
+ if (register_adapter_interrupt(&gib_alert_irq)) {
+ pr_err("Registering the GIB alert interruption handler failed\n");
+ rc = -EIO;
+ goto out_free;
+ }
+
gib->nisc = nisc;
if (chsc_sgib((u32)(u64)gib)) {
pr_err("Associating the GIB with the AIV facility failed\n");
free_page((unsigned long)gib);
gib = NULL;
rc = -EIO;
- goto out;
+ goto out_unreg;
}

KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
+ goto out;
+
+out_unreg:
+ unregister_adapter_interrupt(&gib_alert_irq);
+out_free:
+ free_page((unsigned long)gib);
+ gib = NULL;
out:
return rc;
}
--
2.13.4