target/arm: Add VHE system register redirection and aliasing

target/arm: Add VHE system register redirection and aliasing

Several of the EL1/0 registers are redirected to the EL2 version when in
EL2 and HCR_EL2.E2H is set.  Many of these registers have side effects.
Link together the two ARMCPRegInfo structures after they have been
properly instantiated.  Install common dispatch routines to all of the
relevant registers.

The same set of registers that are redirected also have additional
EL12/EL02 aliases created to access the original register that was
redirected.

Omit the generic timer registers from redirection here, because we'll
need multiple kinds of redirection from both EL0 and EL2.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-29-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>