Re: [PATCH v6 16/25] target/riscv: Set MMU_2STAGE_BIT in riscv_cpu_mmu_index

[Alistair Francis <alistair23@gmail.com>]

On Sat, Mar 25, 2023 at 9:58 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Incorporate the virt_enabled and MPV checks into the cpu_mmu_index
> function, so we don't have to keep doing it within tlb_fill and
> subroutines.  This also elides a flush on changes to MPV.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu_helper.c | 50 +++++++++++++--------------------------
>  target/riscv/csr.c        |  6 +----
>  2 files changed, 18 insertions(+), 38 deletions(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 0adfd4a12b..6c42f9c6fd 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -37,19 +37,21 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
>  #ifdef CONFIG_USER_ONLY
>      return 0;
>  #else
> -    if (ifetch) {
> -        return env->priv;
> -    }
> +    bool virt = riscv_cpu_virt_enabled(env);
> +    int mode = env->priv;
>
>      /* All priv -> mmu_idx mapping are here */
> -    int mode = env->priv;
> -    if (mode == PRV_M && get_field(env->mstatus, MSTATUS_MPRV)) {
> -        mode = get_field(env->mstatus, MSTATUS_MPP);
> +    if (!ifetch) {
> +        if (mode == PRV_M && get_field(env->mstatus, MSTATUS_MPRV)) {
> +            mode = get_field(env->mstatus, MSTATUS_MPP);
> +            virt = get_field(env->mstatus, MSTATUS_MPV);
> +        }
> +        if (mode == PRV_S && get_field(env->mstatus, MSTATUS_SUM)) {
> +            mode = MMUIdx_S_SUM;
> +        }
>      }
> -    if (mode == PRV_S && get_field(env->mstatus, MSTATUS_SUM)) {
> -        return MMUIdx_S_SUM;
> -    }
> -    return mode;
> +
> +    return mode | (virt ? MMU_2STAGE_BIT : 0);
>  #endif
>  }
>
> @@ -1165,8 +1167,7 @@ void riscv_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
>      }
>
>      env->badaddr = addr;
> -    env->two_stage_lookup = riscv_cpu_virt_enabled(env) ||
> -                            mmuidx_2stage(mmu_idx);
> +    env->two_stage_lookup = mmuidx_2stage(mmu_idx);
>      env->two_stage_indirect_lookup = false;
>      cpu_loop_exit_restore(cs, retaddr);
>  }
> @@ -1191,8 +1192,7 @@ void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
>          g_assert_not_reached();
>      }
>      env->badaddr = addr;
> -    env->two_stage_lookup = riscv_cpu_virt_enabled(env) ||
> -                            mmuidx_2stage(mmu_idx);
> +    env->two_stage_lookup = mmuidx_2stage(mmu_idx);
>      env->two_stage_indirect_lookup = false;
>      cpu_loop_exit_restore(cs, retaddr);
>  }
> @@ -1230,7 +1230,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>      int prot, prot2, prot_pmp;
>      bool pmp_violation = false;
>      bool first_stage_error = true;
> -    bool two_stage_lookup = false;
> +    bool two_stage_lookup = mmuidx_2stage(mmu_idx);
>      bool two_stage_indirect_error = false;
>      int ret = TRANSLATE_FAIL;
>      int mode = mmu_idx;
> @@ -1242,22 +1242,8 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>      qemu_log_mask(CPU_LOG_MMU, "%s ad %" VADDR_PRIx " rw %d mmu_idx %d\n",
>                    __func__, address, access_type, mmu_idx);
>
> -    /* MPRV does not affect the virtual-machine load/store
> -       instructions, HLV, HLVX, and HSV. */
> -    if (mmuidx_2stage(mmu_idx)) {
> -        ;
> -    } else if (mode == PRV_M && access_type != MMU_INST_FETCH &&
> -               get_field(env->mstatus, MSTATUS_MPRV)) {
> -        mode = get_field(env->mstatus, MSTATUS_MPP);
> -        if (riscv_has_ext(env, RVH) && get_field(env->mstatus, MSTATUS_MPV)) {
> -            two_stage_lookup = true;
> -        }
> -    }
> -
>      pmu_tlb_fill_incr_ctr(cpu, access_type);
> -    if (riscv_cpu_virt_enabled(env) ||
> -        ((mmuidx_2stage(mmu_idx) || two_stage_lookup) &&
> -         access_type != MMU_INST_FETCH)) {
> +    if (two_stage_lookup) {
>          /* Two stage lookup */
>          ret = get_physical_address(env, &pa, &prot, address,
>                                     &env->guest_phys_fault_addr, access_type,
> @@ -1352,9 +1338,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>          return false;
>      } else {
>          raise_mmu_exception(env, address, access_type, pmp_violation,
> -                            first_stage_error,
> -                            riscv_cpu_virt_enabled(env) ||
> -                                mmuidx_2stage(mmu_idx),
> +                            first_stage_error, two_stage_lookup,
>                              two_stage_indirect_error);
>          cpu_loop_exit_restore(cs, retaddr);
>      }
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index b79758a606..1b635373c6 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -1246,7 +1246,7 @@ static RISCVException write_mstatus(CPURISCVState *env, int csrno,
>      RISCVMXL xl = riscv_cpu_mxl(env);
>
>      /* flush tlb on mstatus fields that affect VM */
> -    if ((val ^ mstatus) & (MSTATUS_MXR | MSTATUS_MPV)) {
> +    if ((val ^ mstatus) & MSTATUS_MXR) {
>          tlb_flush(env_cpu(env));
>      }
>      mask = MSTATUS_SIE | MSTATUS_SPIE | MSTATUS_MIE | MSTATUS_MPIE |
> @@ -1294,10 +1294,6 @@ static RISCVException write_mstatush(CPURISCVState *env, int csrno,
>      uint64_t valh = (uint64_t)val << 32;
>      uint64_t mask = MSTATUS_MPV | MSTATUS_GVA;
>
> -    if ((valh ^ env->mstatus) & (MSTATUS_MPV)) {
> -        tlb_flush(env_cpu(env));
> -    }
> -
>      env->mstatus = (env->mstatus & ~mask) | (valh & mask);
>
>      return RISCV_EXCP_NONE;
> --
> 2.34.1
>
>