Re: [PATCH v8 03/19] target/riscv/cpu.c: set satp_max_supported in cpu_riscv_set_satp()

[Andrew Jones]

On Wed, Nov 01, 2023 at 05:41:48PM -0300, Daniel Henrique Barboza wrote:
> The setter() for the boolean attributes that set satp_mode (sv32, sv39,
> sv48, sv57, sv64) considers that the CPU will always do a
> set_satp_mode_max_supported() during cpu_init().
> 
> This is not the case for the KVM 'host' CPU, and we'll add another CPU
> that won't set satp_mode_max() during cpu_init(). Users should be able
> to set a max_support in these circunstances.
> 
> Allow cpu_riscv_set_satp() to set satp_mode_max_supported if the CPU
> didn't set one prior.
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 822970345c..9f6837ecb7 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -1100,6 +1100,7 @@ static void cpu_riscv_get_satp(Object *obj, Visitor *v, 
> const char *name,
>  static void cpu_riscv_set_satp(Object *obj, Visitor *v, const char *name,
>                                 void *opaque, Error **errp)
>  {
> +    RISCVCPU *cpu = RISCV_CPU(obj);
>      RISCVSATPMap *satp_map = opaque;
>      uint8_t satp = satp_mode_from_str(name);
>      bool value;
> @@ -1108,6 +1109,16 @@ static void cpu_riscv_set_satp(Object *obj, Visitor 
> *v, const char *name,
>          return;
>      }
>  
> +    /*
> +     * Allow users to set satp max supported if the CPU didn't
> +     * set any during cpu_init(). First value set to 'true'
> +     * in this case is assumed to be the max supported for
> +     * the CPU.

Hmm, doesn't that mean if a user does

 -cpu rv64,sv39=true,sv48=true

then the max is set to sv39 instead of sv48?

I made a mistake in my last review by stating we shouldn't set the max
supported satp for rv64i to the maximum satp that TCG supports. I forgot
how all of it worked. Setting the _supported_ modes to the maximum that
TCG supports makes sense as long as we don't default to any of them for
rv64i. So, I think we should return the set_satp_mode_max_supported() to
rv64i's definition (passing VM_1_10_SV57 or maybe even VM_1_10_SV64) and
then change set_satp_mode_default_map() to error out for rv64i (or maybe
for all "bare" type cpus).

> +     */
> +    if (value && cpu->cfg.satp_mode.supported == 0) {
> +        set_satp_mode_max_supported(cpu, satp);
> +    }
> +
>      satp_map->map = deposit32(satp_map->map, satp, 1, value);
>      satp_map->init |= 1 << satp;
>  }
> -- 
> 2.41.0
>

Thanks,
drew