On 21.11.2017 16:08, Christian Borntraeger wrote: > Old kernels did not check for zero in the irq_state.flags field and old > QEMUs did not zero the flag field when calling KVM_S390_*_IRQ_STATE. > Let's add a comment and dummy code to prevent future usage of flags > and pad. > > Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > --- > arch/s390/kvm/kvm-s390.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 6a5e02f..1baa393 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -3834,6 +3834,16 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > r = -EINVAL; > break; > } > + if (irq_state.flags) { I don't see the need for if (do I need more coffee?). > + /* > + * This is a placeholder to make sure that nobody uses > + * flags and pad. Old kernels did not check for zero > + * and old QEMUs did not zero the flag field. > + * That means that we cannot use the flags field for > + * any possible extension. > + */ > + irq_state.flags = 0; > + } > r = kvm_s390_set_irq_state(vcpu, > (void __user *) irq_state.buf, > irq_state.len); > @@ -3849,6 +3859,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > r = -EINVAL; > break; > } > + if (irq_state.flags) { dito > + /* see above */ /* same handling as for kvm_s390_set_irq_state() */ > + irq_state.flags = 0; > + } > r = kvm_s390_get_irq_state(vcpu, > (__u8 __user *) irq_state.buf, > irq_state.len); > -- Thanks, David / dhildenb -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html