Re: [PATCH v4 05/10] hyper-v: use fast hypercall for HVCALL_SIGNAL_EVENT

[Andy Shevchenko]

On Wed, May 24, 2017 at 3:04 PM, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
> We need to pass only 8 bytes of input for HvSignalEvent which makes it a
> perfect fit for fast hypercall. hv_input_signal_event_buffer is not needed
> any more and hv_input_signal_event is converted to union for convenience.

> +union hv_input_signal_event {

Union aliasing is UB. Avoid it for good.

> +       u64 as_uint64;
> +       struct {
> +               union hv_connection_id connectionid;
> +               u16 flag_number;
> +               u16 rsvdz;
> +       };
>  };

-- 
With Best Regards,
Andy Shevchenko