KVM: s390: introduce ais mode modify function

Provide an interface for userspace to modify AIS
(adapter-interruption-suppression) mode state, and add documentation
for the interface. Allowed target modes are ALL-Interruptions mode
and SINGLE-Interruption mode.

We introduce the 'simm' and 'nimm' fields in kvm_s390_float_interrupt
to store interruption modes for each ISC. Each bit in 'simm' and
'nimm' targets to one ISC, and collaboratively indicate three modes:
ALL-Interruptions, SINGLE-Interruption and NO-Interruptions. This
interface can initiate most transitions between the states; transition
from SINGLE-Interruption to NO-Interruptions via adapter interrupt
injection will be introduced in a following patch. The meaningful
combinations are as follows:

    interruption mode | simm bit | nimm bit
    ------------------|----------|----------
             ALL      |    0     |     0
           SINGLE     |    1     |     0
             NO       |    1     |     1

Besides, add tracepoint to track AIS mode transitions.

Co-Authored-By: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Signed-off-by: Fei Li <sherrylf@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

5 files changed, 94 insertions, 0 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 499c72c2280d..552c319483c6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -521,6 +521,12 @@ struct kvm_s390_local_interrupt {
 #define FIRQ_CNTR_PFAULT   3
 #define FIRQ_MAX_COUNT     4
 
+/* mask the AIS mode for a given ISC */
+#define AIS_MODE_MASK(isc) (0x80 >> isc)
+
+#define KVM_S390_AIS_MODE_ALL    0
+#define KVM_S390_AIS_MODE_SINGLE 1
+
 struct kvm_s390_float_interrupt {
 	unsigned long pending_irqs;
 	spinlock_t lock;
@@ -530,6 +536,10 @@ struct kvm_s390_float_interrupt {
 	struct kvm_s390_ext_info srv_signal;
 	int next_rr_cpu;
 	unsigned long idle_mask[BITS_TO_LONGS(KVM_MAX_VCPUS)];
+	struct mutex ais_lock;
+	u8 simm;
+	u8 nimm;
+	int ais_enabled;
 };
 
 struct kvm_hw_wp_info_arch {
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 5fa144d1df0a..50d2a927c990 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -26,6 +26,7 @@
 #define KVM_DEV_FLIC_ADAPTER_REGISTER	6
 #define KVM_DEV_FLIC_ADAPTER_MODIFY	7
 #define KVM_DEV_FLIC_CLEAR_IO_IRQ	8
+#define KVM_DEV_FLIC_AISM		9
 /*
  * We can have up to 4*64k pending subchannels + 8 adapter interrupts,
  * as well as up  to ASYNC_PF_PER_VCPU*KVM_MAX_VCPUS pfault done interrupts.
@@ -46,6 +47,11 @@ struct kvm_s390_io_adapter {
 
 #define KVM_S390_ADAPTER_SUPPRESSIBLE 0x01
 
+struct kvm_s390_ais_req {
+	__u8 isc;
+	__u16 mode;
+};
+
 #define KVM_S390_IO_ADAPTER_MASK 1
 #define KVM_S390_IO_ADAPTER_MAP 2
 #define KVM_S390_IO_ADAPTER_UNMAP 3
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index dba51ad62570..96b689e48c08 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2152,6 +2152,45 @@ static int clear_io_irq(struct kvm *kvm, struct kvm_device_attr *attr)
 	return 0;
 }
 
+static int modify_ais_mode(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_float_interrupt *fi = &kvm->arch.float_int;
+	struct kvm_s390_ais_req req;
+	int ret = 0;
+
+	if (!fi->ais_enabled)
+		return -ENOTSUPP;
+
+	if (copy_from_user(&req, (void __user *)attr->addr, sizeof(req)))
+		return -EFAULT;
+
+	if (req.isc > MAX_ISC)
+		return -EINVAL;
+
+	trace_kvm_s390_modify_ais_mode(req.isc,
+				       (fi->simm & AIS_MODE_MASK(req.isc)) ?
+				       (fi->nimm & AIS_MODE_MASK(req.isc)) ?
+				       2 : KVM_S390_AIS_MODE_SINGLE :
+				       KVM_S390_AIS_MODE_ALL, req.mode);
+
+	mutex_lock(&fi->ais_lock);
+	switch (req.mode) {
+	case KVM_S390_AIS_MODE_ALL:
+		fi->simm &= ~AIS_MODE_MASK(req.isc);
+		fi->nimm &= ~AIS_MODE_MASK(req.isc);
+		break;
+	case KVM_S390_AIS_MODE_SINGLE:
+		fi->simm |= AIS_MODE_MASK(req.isc);
+		fi->nimm &= ~AIS_MODE_MASK(req.isc);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&fi->ais_lock);
+
+	return ret;
+}
+
 static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 {
 	int r = 0;
@@ -2188,6 +2227,9 @@ static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 	case KVM_DEV_FLIC_CLEAR_IO_IRQ:
 		r = clear_io_irq(dev->kvm, attr);
 		break;
+	case KVM_DEV_FLIC_AISM:
+		r = modify_ais_mode(dev->kvm, attr);
+		break;
 	default:
 		r = -EINVAL;
 	}
@@ -2207,6 +2249,7 @@ static int flic_has_attr(struct kvm_device *dev,
 	case KVM_DEV_FLIC_ADAPTER_REGISTER:
 	case KVM_DEV_FLIC_ADAPTER_MODIFY:
 	case KVM_DEV_FLIC_CLEAR_IO_IRQ:
+	case KVM_DEV_FLIC_AISM:
 		return 0;
 	}
 	return -ENXIO;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f83f18b77f3d..977cc1660a83 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1515,6 +1515,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 	kvm_s390_crypto_init(kvm);
 
+	mutex_init(&kvm->arch.float_int.ais_lock);
+	kvm->arch.float_int.simm = 0;
+	kvm->arch.float_int.nimm = 0;
+	kvm->arch.float_int.ais_enabled = 0;
 	spin_lock_init(&kvm->arch.float_int.lock);
 	for (i = 0; i < FIRQ_LIST_COUNT; i++)
 		INIT_LIST_HEAD(&kvm->arch.float_int.lists[i]);
diff --git a/arch/s390/kvm/trace-s390.h b/arch/s390/kvm/trace-s390.h
index 396485bca191..b32994d1546a 100644
--- a/arch/s390/kvm/trace-s390.h
+++ b/arch/s390/kvm/trace-s390.h
@@ -280,6 +280,37 @@ TRACE_EVENT(kvm_s390_enable_disable_ibs,
 		      __entry->state ? "enabling" : "disabling", __entry->id)
 	);
 
+/*
+ * Trace point for modifying ais mode for a given isc.
+ */
+TRACE_EVENT(kvm_s390_modify_ais_mode,
+	    TP_PROTO(__u8 isc, __u16 from, __u16 to),
+	    TP_ARGS(isc, from, to),
+
+	    TP_STRUCT__entry(
+		    __field(__u8, isc)
+		    __field(__u16, from)
+		    __field(__u16, to)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->isc = isc;
+		    __entry->from = from;
+		    __entry->to = to;
+		    ),
+
+	    TP_printk("for isc %x, modifying interruption mode from %s to %s",
+		      __entry->isc,
+		      (__entry->from == KVM_S390_AIS_MODE_ALL) ?
+		      "ALL-Interruptions Mode" :
+		      (__entry->from == KVM_S390_AIS_MODE_SINGLE) ?
+		      "Single-Interruption Mode" : "No-Interruptions Mode",
+		      (__entry->to == KVM_S390_AIS_MODE_ALL) ?
+		      "ALL-Interruptions Mode" :
+		      (__entry->to == KVM_S390_AIS_MODE_SINGLE) ?
+		      "Single-Interruption Mode" : "No-Interruptions Mode")
+	);
+
 
 #endif /* _TRACE_KVMS390_H */