hyperv provides ghcb hvcall to handle VMBus
HVCALL_SIGNAL_EVENT and HVCALL_POST_MESSAGE
msg in SNP Isolation VM. Add such support.
Reviewed-by: NMichael Kelley <mikelley@microsoft.com>
Signed-off-by: NTianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20211025122116.264793-8-ltykernel@gmail.comSigned-off-by: NWei Liu <wei.liu@kernel.org>