target/riscv/cpu.c: introduce RISCVCPUMultiExtConfig

target/riscv/cpu.c: introduce RISCVCPUMultiExtConfig

If we want to make better decisions when auto-enabling extensions during
realize() we need a way to tell if an user set an extension manually.
The RISC-V KVM driver has its own solution via a KVMCPUConfig struct
that has an 'user_set' flag that is set during the Property set()
callback. The set() callback also does init() time validations based on
the current KVM driver capabilities.

For TCG we would want a 'user_set' mechanic too, but we would look
ad-hoc via cpu_cfg_ext_auto_update() if a certain extension was user set
or not. If we copy what was made in the KVM side we would look for
'user_set' for one into 60+ extension structs spreaded in 3 arrays
(riscv_cpu_extensions, riscv_cpu_experimental_exts,
riscv_cpu_vendor_exts).

We'll still need an extension struct but we won't be using the
'user_set' flag:

- 'RISCVCPUMultiExtConfig' will be our specialized structure, similar to what
we're already doing with the MISA extensions in 'RISCVCPUMisaExtConfig'.
DEFINE_PROP_BOOL() for all 3 extensions arrays were replaced by
MULTI_EXT_CFG_BOOL(), a macro that will init our specialized struct;

- the 'multi_ext_user_opts' hash will be used to store the offset of each
extension that the user set via the set() callback, cpu_set_multi_ext_cfg().
For now we're just initializing and populating it - next patch will use
it to determine if a certain extension was user set;

- cpu_add_multi_ext_prop() is a new helper that will replace the
qdev_property_add_static() calls that our macros are doing to populate
user properties. The macro was renamed to ADD_CPU_MULTIEXT_PROPS_ARRAY()
for clarity. Note that the non-extension properties in
riscv_cpu_options[] still need to be declared via qdev().

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20230912132423.268494-18-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>