target/arm: Implement FEAT_ECV CNTPOFF_EL2 handling

When ID_AA64MMFR0_EL1.ECV is 0b0010, a new register CNTPOFF_EL2 is
implemented.  This is similar to the existing CNTVOFF_EL2, except
that it controls a hypervisor-adjustable offset made to the physical
counter and timer.

Implement the handling for this register, which includes control/trap
bits in SCR_EL3 and CNTHCTL_EL2.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240301183219.2424889-8-peter.maydell@linaro.org
4 files changed