From: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/include/asm/kvm_host.h | 1 +
arch/s390/include/uapi/asm/kvm.h | 2 +-
arch/s390/kvm/interrupt.c | 26 +++++++++++++++++++++-----
3 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 59635b5..c3c5e10 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -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;
};
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 38d5f98..058b178 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -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 */
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 @@ 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);
}
--
1.8.4.2
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