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KVM: s390: limit floating irqs

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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>
This commit is contained in:
Jens Freimann 2014-01-30 08:40:23 +01:00 committed by Christian Borntraeger
parent c05c4186bb
commit a91b8ebe86
3 changed files with 23 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/s390/include/asm/kvm_host.h
View File

@ -214,6 +214,7 @@ struct kvm_s390_float_interrupt {
unsigned long idle_mask[(KVM_MAX_VCPUS + sizeof(long) - 1)
/ sizeof(long)];
struct kvm_s390_local_interrupt *local_int[KVM_MAX_VCPUS];
unsigned int irq_count;
};

2
arch/s390/include/uapi/asm/kvm.h
View File

@ -27,7 +27,7 @@
* sizeof(kvm_s390_irq)*(4*65536+8+64*64+1+1) = 72 * 266250 = 19170000
* Lets round up to 8192 pages.
*/
#define KVM_S390_MAX_FLOAT_IRQS 266250
#define KVM_S390_FLIC_MAX_BUFFER 0x2000000
/* for KVM_GET_REGS and KVM_SET_REGS */

26
arch/s390/kvm/interrupt.c
View File

@ -528,6 +528,7 @@ void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
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 @@ void kvm_s390_deliver_pending_machine_checks(struct kvm_vcpu *vcpu)
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 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
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 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
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 @@ static void __inject_vm(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
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 @@ int kvm_s390_inject_vm(struct kvm *kvm,
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 @@ static void clear_floating_interrupts(struct kvm *kvm)
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 @@ static int enqueue_floating_irq(struct kvm_device *dev,
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);
}