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>

1 files changed, 13 insertions, 0 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index ded1e8e0a8..d091a7e2e8 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -2576,6 +2576,19 @@ struct ARMCPRegInfo {
      * fieldoffset is 0 then no reset will be done.
      */
     CPResetFn *resetfn;
+
+    /*
+     * "Original" writefn and readfn.
+     * For ARMv8.1-VHE register aliases, we overwrite the read/write
+     * accessor functions of various EL1/EL0 to perform the runtime
+     * check for which sysreg should actually be modified, and then
+     * forwards the operation.  Before overwriting the accessors,
+     * the original function is copied here, so that accesses that
+     * really do go to the EL1/EL0 version proceed normally.
+     * (The corresponding EL2 register is linked via opaque.)
+     */
+    CPReadFn *orig_readfn;
+    CPWriteFn *orig_writefn;
 };
 
 /* Macros which are lvalues for the field in CPUARMState for the