Jon Doron <arilou@xxxxxxxxx> writes: > Signed-off-by: Jon Doron <arilou@xxxxxxxxx> > --- > include/uapi/linux/kvm.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 4b95f9a31a2f..24b7c48ccc6f 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -197,6 +197,7 @@ struct kvm_hyperv_exit { > __u64 msg_page; > } synic; > struct { > + __u32 pad; > __u64 input; > __u64 result; > __u64 params[2]; This doesn't seem to be correct, __u64 get aligned at 8 byte boundary so implicitly you now (pre-patch) have the following: struct kvm_hyperv_exit { __u32 type; __u32 pad1; union { struct { __u32 msr; __u32 pad2; __u64 control; __u64 evt_page; __u64 msg_page; } synic; struct { __u64 input; __u64 result; __u64 params[2]; } hcall; } u; }; and the suggestion is only to make it explicit. Adding something before 'input' will actually break ABI. -- Vitaly