The ARMv8.3-CCIDX extension makes the CCSIDR_EL1 system ID registers
have a format that uses the full 64 bit width of the register, and
adds a new CCSIDR2 register so AArch32 can get at the high 32 bits.
QEMU doesn't implement caches, so we just treat these ID registers as
opaque values that are set to the correct constant values for each
CPU. The only thing we need to do is allow 64-bit values in our
cssidr[] array and provide the CCSIDR2 accessors.
We don't set the CCIDX field in our 'max' CPU because the CCSIDR
constant values we use are the same as the ones used by the
Cortex-A57 and they are in the old 32-bit format. This means
that the extra regdef added here is unused currently, but it
means that whenever in the future we add a CPU that does need
the new 64-bit format it will just work when we set the cssidr
values and the ID registers for it.
Backports commit 957e615503bd0de22393fd8dbcb22a5064fd2b5c from qemu
7271ebf96d