Re: [PATCH v9 15/20] target/riscv/cpu.c: introduce cpu_cfg_ext_auto_update()

[Andrew Jones]

On Fri, Sep 01, 2023 at 04:46:21PM -0300, Daniel Henrique Barboza wrote:
> During realize() time we're activating a lot of extensions based on some
> criteria, e.g.:
> 
>     if (cpu->cfg.ext_zk) {
>         cpu->cfg.ext_zkn = true;
>         cpu->cfg.ext_zkr = true;
>         cpu->cfg.ext_zkt = true;
>     }
> 
> This practice resulted in at least one case where we ended up enabling
> something we shouldn't: RVC enabling zca/zcd/zcf when using a CPU that
> has priv_spec older than 1.12.0.
> 
> We're also not considering user choice. There's no way of doing it now
> but this is about to change in the next few patches.
> 
> cpu_cfg_ext_auto_update() will check for priv version mismatches before
> enabling extensions. If we have a mismatch between the current priv
> version and the extension we want to enable, do not enable it. In the
> near future, this same function will also consider user choice when
> deciding if we're going to enable/disable an extension or not.
> 
> For now let's use it to handle zca/zcd/zcf enablement if RVC is enabled.
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c | 43 ++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 40 insertions(+), 3 deletions(-)
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>