Re: [PATCH v10 4/5] target/riscv: smstateen check for fcsr

[weiwei]

On 2022/10/3 19:47, Mayuresh Chitale wrote:
> If smstateen is implemented and sstateen0.fcsr is clear then the floating point
> operations must return illegal instruction exception or virtual instruction
> trap, if relevant.
>
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
> ---
>   target/riscv/csr.c                        | 23 ++++++++++++
>   target/riscv/insn_trans/trans_rvf.c.inc   | 43 +++++++++++++++++++++--
>   target/riscv/insn_trans/trans_rvzfh.c.inc | 12 +++++++
>   3 files changed, 75 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 71236f2b5d..8b25f885ec 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -84,6 +84,10 @@ static RISCVException fs(CPURISCVState *env, int csrno)
>           !RISCV_CPU(env_cpu(env))->cfg.ext_zfinx) {
>           return RISCV_EXCP_ILLEGAL_INST;
>       }
> +
> +    if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
> +        return smstateen_acc_ok(env, 0, SMSTATEEN0_FCSR);
> +    }
>   #endif
>       return RISCV_EXCP_NONE;
>   }
> @@ -2023,6 +2027,9 @@ static RISCVException write_mstateen0(CPURISCVState *env, 
> int csrno,
>                                         target_ulong new_val)
>   {
>       uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
> +    if (!riscv_has_ext(env, RVF)) {
> +        wr_mask |= SMSTATEEN0_FCSR;
> +    }
>   
>       return write_mstateen(env, csrno, wr_mask, new_val);
>   }
> @@ -2059,6 +2066,10 @@ static RISCVException write_mstateen0h(CPURISCVState 
> *env, int csrno,
>   {
>       uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
>   
> +    if (!riscv_has_ext(env, RVF)) {
> +        wr_mask |= SMSTATEEN0_FCSR;
> +    }
> +
>       return write_mstateenh(env, csrno, wr_mask, new_val);
>   }
>   
> @@ -2096,6 +2107,10 @@ static RISCVException write_hstateen0(CPURISCVState *env, int csrno,
>   {
>       uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
>   
> +    if (!riscv_has_ext(env, RVF)) {
> +        wr_mask |= SMSTATEEN0_FCSR;
> +    }
> +
>       return write_hstateen(env, csrno, wr_mask, new_val);
>   }
>   
> @@ -2135,6 +2150,10 @@ static RISCVException write_hstateen0h(CPURISCVState *env, int csrno,
>   {
>       uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
>   
> +    if (!riscv_has_ext(env, RVF)) {
> +        wr_mask |= SMSTATEEN0_FCSR;
> +    }
> +
>       return write_hstateenh(env, csrno, wr_mask, new_val);
>   }
>   
> @@ -2182,6 +2201,10 @@ static RISCVException write_sstateen0(CPURISCVState *env, int csrno,
>   {
>       uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
>   
> +    if (!riscv_has_ext(env, RVF)) {
> +        wr_mask |= SMSTATEEN0_FCSR;
> +    }
> +
>       return write_sstateen(env, csrno, wr_mask, new_val);
>   }
>   
> diff --git a/target/riscv/insn_trans/trans_rvf.c.inc b/target/riscv/insn_trans/trans_rvf.c.inc
> index a1d3eb52ad..93657680c6 100644
> --- a/target/riscv/insn_trans/trans_rvf.c.inc
> +++ b/target/riscv/insn_trans/trans_rvf.c.inc
> @@ -24,9 +24,46 @@
>               return false; \
>   } while (0)
>   
> -#define REQUIRE_ZFINX_OR_F(ctx) do {\
> -    if (!ctx->cfg_ptr->ext_zfinx) { \
> -        REQUIRE_EXT(ctx, RVF); \
> +#ifndef CONFIG_USER_ONLY
> +static inline bool smstateen_fcsr_check(DisasContext *ctx, int index)
> +{
> +    CPUState *cpu = ctx->cs;
> +    CPURISCVState *env = cpu->env_ptr;
> +    uint64_t stateen = env->mstateen[index];
> +
> +    if (!ctx->cfg_ptr->ext_smstateen || env->priv == PRV_M) {
> +        return true;
> +    }
> +
> +    if (ctx->virt_enabled) {
> +        stateen &= env->hstateen[index];
> +    }
> +
> +    if (env->priv == PRV_U && has_ext(ctx, RVS)) {
> +        stateen &= env->sstateen[index];
> +    }
> +
> +    if (!(stateen & SMSTATEEN0_FCSR)) {
> +        if (ctx->virt_enabled) {
> +            ctx->virt_inst_excp = true;
> +        }

Are there any considerations for adding  virt_inst_excp instead of directly

"generate_exception(ctx, RISCV_EXCP_VIRT_INSTRUCTION_FAULT)" here?

Regards,

Weiwei Li

> +        return false;
> +    }
> +
> +    return true;
> +}
> +#else
> +#define smstateen_fcsr_check(ctx, index) (true)
> +#endif
> +
> +#define REQUIRE_ZFINX_OR_F(ctx) do { \
> +    if (!has_ext(ctx, RVF)) { \
> +        if (!ctx->cfg_ptr->ext_zfinx) { \
> +            return false; \
> +        } \
> +        if (!smstateen_fcsr_check(ctx, 0)) { \
> +            return false; \
> +        } \
>       } \
>   } while (0)
>   
> diff --git a/target/riscv/insn_trans/trans_rvzfh.c.inc b/target/riscv/insn_trans/trans_rvzfh.c.inc
> index 5d07150cd0..6c2e338c0a 100644
> --- a/target/riscv/insn_trans/trans_rvzfh.c.inc
> +++ b/target/riscv/insn_trans/trans_rvzfh.c.inc
> @@ -20,18 +20,27 @@
>       if (!ctx->cfg_ptr->ext_zfh) {      \
>           return false;         \
>       }                         \
> +    if (!smstateen_fcsr_check(ctx, 0)) { \
> +        return false; \
> +    } \
>   } while (0)
>   
>   #define REQUIRE_ZHINX_OR_ZFH(ctx) do { \
>       if (!ctx->cfg_ptr->ext_zhinx && !ctx->cfg_ptr->ext_zfh) { \
>           return false;                  \
>       }                                  \
> +    if (!smstateen_fcsr_check(ctx, 0)) { \
> +        return false; \
> +    } \
>   } while (0)
>   
>   #define REQUIRE_ZFH_OR_ZFHMIN(ctx) do {       \
>       if (!(ctx->cfg_ptr->ext_zfh || ctx->cfg_ptr->ext_zfhmin)) { \
>           return false;                         \
>       }                                         \
> +    if (!smstateen_fcsr_check(ctx, 0)) { \
> +        return false; \
> +    } \
>   } while (0)
>   
>   #define REQUIRE_ZFH_OR_ZFHMIN_OR_ZHINX_OR_ZHINXMIN(ctx) do { \
> @@ -39,6 +48,9 @@
>             ctx->cfg_ptr->ext_zhinx || ctx->cfg_ptr->ext_zhinxmin)) {     \
>           return false;                                        \
>       }                                                        \
> +    if (!smstateen_fcsr_check(ctx, 0)) { \
> +        return false; \
> +    } \
>   } while (0)
>   
>   static bool trans_flh(DisasContext *ctx, arg_flh *a)