Enabling HvCallSetVpRegisters and HvCallGetVpRegisters for hypercalls to
read and write to specific MSRs. This is required for implementing wrmsr
and rdmsr, which is required for Hyper-V vmbus driver for ARM64.
Also we need to use arm smccc hvc 1.2 version as we need to access
registers beyond X0-X3 for HvCallGetVpRegisters. Currently scoping
it only for Hyper-V.
Reviewed by: lwhsu, andrew, whu
Tested by: Souradeep Chakrabarti <schakrabarti@microsoft.com>
Signed-off-by: Souradeep Chakrabarti <schakrabarti@microsoft.com>
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D36256
7a58bf0443