Vendor CPU overrides of non-extension properties

[Rob Bradford <rbradford@rivosinc.com>]

Hi Daniel,

Thanks for your work on improving the extension handling for vendor
CPUs. I have a query regarding the correct way to override properties
that are included in the "cpu_options" list as part of the vendor CPU
initialisation function.

i.e. these properties:

Property riscv_cpu_options[] = {
    DEFINE_PROP_UINT32("pmu-mask", RISCVCPU, cfg.pmu_mask,
MAKE_64BIT_MASK(3, 16)),
    {.name = "pmu-num", .info = &prop_pmu_num}, /* Deprecated */

    DEFINE_PROP_BOOL("mmu", RISCVCPU, cfg.mmu, true),
    DEFINE_PROP_BOOL("pmp", RISCVCPU, cfg.pmp, true),

    DEFINE_PROP_STRING("priv_spec", RISCVCPU, cfg.priv_spec),
    DEFINE_PROP_STRING("vext_spec", RISCVCPU, cfg.vext_spec),

    DEFINE_PROP_UINT16("vlen", RISCVCPU, cfg.vlen, 128),
    DEFINE_PROP_UINT16("elen", RISCVCPU, cfg.elen, 64),

    DEFINE_PROP_UINT16("cbom_blocksize", RISCVCPU, cfg.cbom_blocksize,
64),
    DEFINE_PROP_UINT16("cboz_blocksize", RISCVCPU, cfg.cboz_blocksize,
64),

    DEFINE_PROP_END_OF_LIST(),
};

I think that these values should be specifiable as part of the vendor
CPU initialisation method however unfortunately they are overwritten
with the default values from the properties as
riscv_cpu_add_user_properties which adds the properties is called from
the type post_init method which is called after the vendor CPU init
function - so any changes to e.g. cfg.vlen are lost.

I would appreciate hearing your thoughts on how these configuration
values can be set for vendor CPUs.

Cheers,

Rob