target/arm: Support PAuth extension for hvf

target/arm: Support PAuth extension for hvf

Currently we don't allow guests under hvf to use the PAuth extension,
because we didn't have any special code to handle that, and therefore
in arm_cpu_pauth_finalize() we will sanitize the ID_AA64ISAR1 value
the guest sees to clear the PAuth related fields.

Add support for this in the same way that KVM does it, by defaulting
to "PAuth enabled" if the host CPU has it and allowing the user to
disable it via '-cpu pauth=no' on the command line.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Alexander Graf <agraf@csgraf.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220204165506.2846058-7-peter.maydell@linaro.org