The TLFS structures are used for hypervisor-guest communication and must
exactly meet the specification.

Compilers can add alignment padding to structures or reorder struct members
for randomization and optimization, which would break the hypervisor ABI.

Mark the structures as packed to prevent this. 'struct hv_vp_assist_page'
and 'struct hv_enlightened_vmcs' need to be properly padded to support the
change.
Suggested-by: NNadav Amit <nadav.amit@gmail.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NNadav Amit <nadav.amit@gmail.com>
Reviewed-by: NMichael Kelley <mikelley@microsoft.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>