On Fri, 30 Nov 2018, Roman Kagan wrote:
> On Fri, Nov 30, 2018 at 01:15:11PM +0100, Vitaly Kuznetsov wrote:
> > Without 'packed' compiler is free to add optimization paddings and re-order
> > structure fields for randomization/optimization. And structures from
> > hyperv-tlfs.h are used for hypervisor-guest communication, we need to
> > ultimately forbid such practices.
>
> Note that __packed also reduces the structure alignment to 1, which is
> not necessarily what you want.
>
> E.g. some of these structures are passed by pointer to the hypercall,
> which requires its arguments to be 8byte-aligned. I'm also not sure
> that passing unaligned argument to [rw]msr is ok, need to double-check.
If you have alignment requirements then you need to express them too.
Thanks,
tglx
