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>

1 files changed, 43 insertions, 0 deletions

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;