Whether SMCCC calls use HVC or SMC generally depends on the exception
level that the firmware executes at, but also on whether or not EL2 is
implemented.
This is almost always known at build time, which is why the default
ArmMonitorLib used to model this as a feature PCD. However, on QEMU,
things are not that simple.
However, SMCCC specifies that the conduit is the same as the one used
for PSCI calls (which has been retrofitted into SMCCC when it was
defined). Given that QEMU provides this information via the device tree,
let's use it to select the conduit, using a special ArmMonitorLib
implementation.
This also removes the need to set the associated PCD at runtime, given
that its updated value will no longer be used.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Ard Biesheuvel