Re: [PATCH v4 1/2] target/riscv: use misa_mxl_max to populate isa string rather than TARGET_LONG_BITS

[Andrew Jones]

On Wed, Jan 24, 2024 at 12:55:49PM +0000, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley@microchip.com>
> 
> A cpu may not have the same xlen as the compile time target, and
> misa_mxl_max is the source of truth for what the hart supports.
> 
> The conversion from misa_mxl_max to xlen already has one user, so
> introduce a helper and use that to populate the isa string.
> 
> Link: 
> https://lore.kernel.org/qemu-riscv/20240108-efa3f83dcd3997dc0af458d7@orel/
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
> I dropped the tags since I added the helper
> ---
>  target/riscv/cpu.c     | 9 ++++++++-
>  target/riscv/cpu.h     | 1 +
>  target/riscv/gdbstub.c | 2 +-
>  3 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index ad1df2318b..4aa4b2e988 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -307,6 +307,11 @@ void riscv_cpu_set_misa(CPURISCVState *env, RISCVMXL 
> mxl, uint32_t ext)
>      env->misa_ext_mask = env->misa_ext = ext;
>  }
>  
> +int riscv_cpu_max_xlen(CPURISCVState env)
> +{
> +    return 16 << env.misa_mxl_max;
> +}

Something like this could probably be a static inline in the header.

> +
>  #ifndef CONFIG_USER_ONLY
>  static uint8_t satp_mode_from_str(const char *satp_mode_str)
>  {
> @@ -2332,7 +2337,9 @@ char *riscv_isa_string(RISCVCPU *cpu)
>      int i;
>      const size_t maxlen = sizeof("rv128") + sizeof(riscv_single_letter_exts);
>      char *isa_str = g_new(char, maxlen);
> -    char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", TARGET_LONG_BITS);
> +    int xlen = riscv_cpu_max_xlen(cpu->env);
> +    char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", xlen);
> +
>      for (i = 0; i < sizeof(riscv_single_letter_exts) - 1; i++) {
>          if (cpu->env.misa_ext & RV(riscv_single_letter_exts[i])) {
>              *p++ = qemu_tolower(riscv_single_letter_exts[i]);
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 05e83c4ac9..aacc031397 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -511,6 +511,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int 
> size,
>                          MMUAccessType access_type, int mmu_idx,
>                          bool probe, uintptr_t retaddr);
>  char *riscv_isa_string(RISCVCPU *cpu);
> +int riscv_cpu_max_xlen(CPURISCVState env);
>  bool riscv_cpu_option_set(const char *optname);
>  
>  #define cpu_mmu_index riscv_cpu_mmu_index
> diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
> index 58b3ace0fe..f15980fdcf 100644
> --- a/target/riscv/gdbstub.c
> +++ b/target/riscv/gdbstub.c
> @@ -218,7 +218,7 @@ static int riscv_gen_dynamic_csr_xml(CPUState *cs, int 
> base_reg)
>      CPURISCVState *env = &cpu->env;
>      GString *s = g_string_new(NULL);
>      riscv_csr_predicate_fn predicate;
> -    int bitsize = 16 << env->misa_mxl_max;
> +    int bitsize = riscv_cpu_max_xlen(*env);
>      int i;
>  
>  #if !defined(CONFIG_USER_ONLY)
> -- 
> 2.43.0
> 

Otherwise,

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