KVM: s390: limit floating irqs
Userspace can flood the kernel with interrupts as of now, so let's
limit the number of pending floating interrupts injected via either
the floating interrupt controller or the KVM_S390_INTERRUPT ioctl.
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.
There are also sclp and machine checks. This gives us
(4*65536+8+64*64+1+1) = 266250 interrupts.
Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index a5f18ba..9c9192b 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -528,6 +528,7 @@
list_for_each_entry_safe(inti, n, &fi->list, list) {
if (__interrupt_is_deliverable(vcpu, inti)) {
list_del(&inti->list);
+ fi->irq_count--;
deliver = 1;
break;
}
@@ -583,6 +584,7 @@
if ((inti->type == KVM_S390_MCHK) &&
__interrupt_is_deliverable(vcpu, inti)) {
list_del(&inti->list);
+ fi->irq_count--;
deliver = 1;
break;
}
@@ -650,8 +652,10 @@
inti = iter;
break;
}
- if (inti)
+ if (inti) {
list_del_init(&inti->list);
+ fi->irq_count--;
+ }
if (list_empty(&fi->list))
atomic_set(&fi->active, 0);
spin_unlock(&fi->lock);
@@ -659,16 +663,22 @@
return inti;
}
-static void __inject_vm(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
+static int __inject_vm(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
{
struct kvm_s390_local_interrupt *li;
struct kvm_s390_float_interrupt *fi;
struct kvm_s390_interrupt_info *iter;
int sigcpu;
+ int rc = 0;
mutex_lock(&kvm->lock);
fi = &kvm->arch.float_int;
spin_lock(&fi->lock);
+ if (fi->irq_count >= KVM_S390_MAX_FLOAT_IRQS) {
+ rc = -EINVAL;
+ goto unlock_fi;
+ }
+ fi->irq_count++;
if (!is_ioint(inti->type)) {
list_add_tail(&inti->list, &fi->list);
} else {
@@ -700,8 +710,10 @@
if (waitqueue_active(li->wq))
wake_up_interruptible(li->wq);
spin_unlock_bh(&li->lock);
+unlock_fi:
spin_unlock(&fi->lock);
mutex_unlock(&kvm->lock);
+ return rc;
}
int kvm_s390_inject_vm(struct kvm *kvm,
@@ -751,8 +763,7 @@
trace_kvm_s390_inject_vm(s390int->type, s390int->parm, s390int->parm64,
2);
- __inject_vm(kvm, inti);
- return 0;
+ return __inject_vm(kvm, inti);
}
int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
@@ -852,6 +863,7 @@
list_del(&inti->list);
kfree(inti);
}
+ fi->irq_count = 0;
atomic_set(&fi->active, 0);
spin_unlock(&fi->lock);
mutex_unlock(&kvm->lock);
@@ -992,7 +1004,11 @@
kfree(inti);
return r;
}
- __inject_vm(dev->kvm, inti);
+ r = __inject_vm(dev->kvm, inti);
+ if (r) {
+ kfree(inti);
+ return r;
+ }
len -= sizeof(struct kvm_s390_irq);
attr->addr += sizeof(struct kvm_s390_irq);
}