BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 Add support to the #VC exception handler to handle string IO. This requires expanding the IO instruction parsing to recognize string based IO instructions as well as preparing an un-encrypted buffer to be used to transfer (either to or from the guest) the string contents for the IO operation. The SW_EXITINFO2 and SW_SCRATCH fields of the GHCB are set appropriately for the operation. Multiple VMGEXIT invocations may be needed to complete the string IO operation. Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com> Acked-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Regression-tested-by: Laszlo Ersek <lersek@redhat.com>