KVM: s390: mark irq_state.flags as non-usable

Old kernels did not check for zero in the irq_state.flags field and old
QEMUs did not zero the flag/reserved fields when calling
KVM_S390_*_IRQ_STATE.  Let's add comments to prevent future uses of
these fields.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 282d7613fce8..496e59a2738b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -630,9 +630,9 @@ struct kvm_s390_irq {
 
 struct kvm_s390_irq_state {
         __u64 buf;
-        __u32 flags;
+        __u32 flags;        /* will stay unused for compatibility reasons */
         __u32 len;
-        __u32 reserved[4];
+        __u32 reserved[4];  /* will stay unused for compatibility reasons */
 };
 
 /* for KVM_SET_GUEST_DEBUG */