Re: [PATCH 4/4] target/riscv: Enable/Disable S/VS-mode Timer when STCE bit is changed

[Jim Shu <jim.shu@sifive.com>]

OK, I will fix it in the v2 patchset.


Jim Shu

On Fri, Apr 4, 2025 at 2:03 PM Alistair Francis <alistair23@gmail.com> wrote:
>
> On Thu, Mar 20, 2025 at 5:24 AM Jim Shu <jim.shu@sifive.com> wrote:
> >
> > Updating STCE will enable/disable SSTC in S-mode or/and VS-mode, so we
> > also need to update S/VS-mode Timer and S/VSTIP bits in $mip CSR.
> >
> > Signed-off-by: Jim Shu <jim.shu@sifive.com>
> > ---
> >  target/riscv/csr.c         | 44 ++++++++++++++++++++++++++++++++
> >  target/riscv/time_helper.c | 51 ++++++++++++++++++++++++++++++++++++++
> >  target/riscv/time_helper.h |  1 +
> >  3 files changed, 96 insertions(+)
> >
> > diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> > index ba026dfc8e..c954e49cae 100644
> > --- a/target/riscv/csr.c
> > +++ b/target/riscv/csr.c
> > @@ -3156,6 +3156,7 @@ static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
> >      const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
> >      uint64_t mask = MENVCFG_FIOM | MENVCFG_CBIE | MENVCFG_CBCFE |
> >                      MENVCFG_CBZE | MENVCFG_CDE;
> > +    bool stce_changed = false;
> >
> >      if (riscv_cpu_mxl(env) == MXL_RV64) {
> >          mask |= (cfg->ext_svpbmt ? MENVCFG_PBMTE : 0) |
> > @@ -3181,10 +3182,19 @@ static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
> >          if ((val & MENVCFG_DTE) == 0) {
> >              env->mstatus &= ~MSTATUS_SDT;
> >          }
> > +
> > +        if (cfg->ext_sstc &&
> > +            ((env->menvcfg & MENVCFG_STCE) != (val & MENVCFG_STCE))) {
> > +            stce_changed = true;
> > +        }
> >      }
> >      env->menvcfg = (env->menvcfg & ~mask) | (val & mask);
> >      write_henvcfg(env, CSR_HENVCFG, env->henvcfg);
> >
> > +    if (stce_changed) {
> > +        riscv_timer_stce_changed(env, true, !!(val & MENVCFG_STCE));
> > +    }
> > +
> >      return RISCV_EXCP_NONE;
> >  }
> >
> > @@ -3207,6 +3217,12 @@ static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
> >                      (cfg->ext_smcdeleg ? MENVCFG_CDE : 0) |
> >                      (cfg->ext_ssdbltrp ? MENVCFG_DTE : 0);
> >      uint64_t valh = (uint64_t)val << 32;
> > +    bool stce_changed = false;
> > +
> > +    if (cfg->ext_sstc &&
> > +        ((env->menvcfg & MENVCFG_STCE) != (valh & MENVCFG_STCE))) {
> > +        stce_changed = true;
> > +    }
> >
> >      if ((valh & MENVCFG_DTE) == 0) {
> >          env->mstatus &= ~MSTATUS_SDT;
> > @@ -3215,6 +3231,10 @@ static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
> >      env->menvcfg = (env->menvcfg & ~mask) | (valh & mask);
> >      write_henvcfgh(env, CSR_HENVCFGH, env->henvcfg >> 32);
> >
> > +    if (stce_changed) {
> > +        riscv_timer_stce_changed(env, true, !!(valh & MENVCFG_STCE));
> > +    }
> > +
> >      return RISCV_EXCP_NONE;
> >  }
> >
> > @@ -3292,8 +3312,10 @@ static RISCVException read_henvcfg(CPURISCVState *env, int csrno,
> >  static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
> >                                      target_ulong val)
> >  {
> > +    const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
> >      uint64_t mask = HENVCFG_FIOM | HENVCFG_CBIE | HENVCFG_CBCFE | HENVCFG_CBZE;
> >      RISCVException ret;
> > +    bool stce_changed = false;
> >
> >      ret = smstateen_acc_ok(env, 0, SMSTATEEN0_HSENVCFG);
> >      if (ret != RISCV_EXCP_NONE) {
> > @@ -3319,6 +3341,11 @@ static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
> >              get_field(val, HENVCFG_PMM) != PMM_FIELD_RESERVED) {
> >              mask |= HENVCFG_PMM;
> >          }
> > +
> > +        if (cfg->ext_sstc &&
> > +            ((env->henvcfg & HENVCFG_STCE) != (val & HENVCFG_STCE))) {
> > +            stce_changed = true;
> > +        }
> >      }
> >
> >      env->henvcfg = val & mask;
> > @@ -3326,6 +3353,10 @@ static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
> >          env->vsstatus &= ~MSTATUS_SDT;
> >      }
> >
> > +    if (stce_changed) {
> > +        riscv_timer_stce_changed(env, false, !!(val & HENVCFG_STCE));
> > +    }
> > +
> >      return RISCV_EXCP_NONE;
> >  }
> >
> > @@ -3347,19 +3378,32 @@ static RISCVException read_henvcfgh(CPURISCVState *env, int csrno,
> >  static RISCVException write_henvcfgh(CPURISCVState *env, int csrno,
> >                                       target_ulong val)
> >  {
> > +    const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
> >      uint64_t mask = env->menvcfg & (HENVCFG_PBMTE | HENVCFG_STCE |
> >                                      HENVCFG_ADUE | HENVCFG_DTE);
> >      uint64_t valh = (uint64_t)val << 32;
> >      RISCVException ret;
> > +    bool stce_changed = false;
> >
> >      ret = smstateen_acc_ok(env, 0, SMSTATEEN0_HSENVCFG);
> >      if (ret != RISCV_EXCP_NONE) {
> >          return ret;
> >      }
> > +
> > +    if (cfg->ext_sstc &&
> > +        ((env->henvcfg & HENVCFG_STCE) != (valh & HENVCFG_STCE))) {
> > +        stce_changed = true;
> > +    }
> > +
> >      env->henvcfg = (env->henvcfg & 0xFFFFFFFF) | (valh & mask);
> >      if ((env->henvcfg & HENVCFG_DTE) == 0) {
> >          env->vsstatus &= ~MSTATUS_SDT;
> >      }
> > +
> > +    if (stce_changed) {
> > +        riscv_timer_stce_changed(env, false, !!(val & HENVCFG_STCE));
> > +    }
> > +
> >      return RISCV_EXCP_NONE;
> >  }
> >
> > diff --git a/target/riscv/time_helper.c b/target/riscv/time_helper.c
> > index aebf0798d0..c648c9fac7 100644
> > --- a/target/riscv/time_helper.c
> > +++ b/target/riscv/time_helper.c
> > @@ -140,6 +140,57 @@ void riscv_timer_write_timecmp(CPURISCVState *env, QEMUTimer *timer,
> >      timer_mod(timer, next);
> >  }
> >
> > +/*
> > + * When disabling xenvcfg.STCE, the S/VS Timer may be disabled at the same time.
> > + * It is safe to call this function regardless of whether the timer has been
> > + * deleted or not. timer_del() will do nothing if the timer has already
> > + * been deleted.
> > + */
> > +static void riscv_timer_disable_timecmp(CPURISCVState *env, QEMUTimer *timer,
> > +                                 uint32_t timer_irq)
> > +{
> > +    /* Disable S-mode Timer IRQ and HW-based STIP */
> > +    if ((timer_irq == MIP_STIP) && !get_field(env->menvcfg, MENVCFG_STCE)) {
> > +        riscv_cpu_update_mip(env, timer_irq, BOOL_TO_MASK(0));
> > +        timer_del(timer);
> > +        return;
> > +    }
> > +
> > +    /* Disable VS-mode Timer IRQ and HW-based VSTIP */
> > +    if ((timer_irq == MIP_VSTIP) &&
> > +        (!get_field(env->menvcfg, MENVCFG_STCE) ||
> > +         !get_field(env->henvcfg, HENVCFG_STCE))) {
> > +        env->vstime_irq = 0;
> > +        riscv_cpu_update_mip(env, 0, BOOL_TO_MASK(0));
> > +        timer_del(timer);
> > +        return;
> > +    }
> > +}
> > +
> > +/* Enable or disable S/VS-mode Timer when xenvcfg.STCE is changed */
> > +void riscv_timer_stce_changed(CPURISCVState *env, bool is_m_mode, bool enable)
> > +{
> > +    if (is_m_mode) {
> > +        /* menvcfg.STCE changes */
> > +        if (enable) {
> > +            riscv_timer_write_timecmp(env, env->stimer, env->stimecmp, 0, MIP_STIP);
> > +            riscv_timer_write_timecmp(env, env->vstimer, env->vstimecmp,
> > +                                      env->htimedelta, MIP_VSTIP);
>
> This line and ...
>
> > +        } else {
> > +            riscv_timer_disable_timecmp(env, env->stimer, MIP_STIP);
> > +            riscv_timer_disable_timecmp(env, env->vstimer, MIP_VSTIP);
>
> This line are duplicated below.
>
> > +        }
> > +    } else {
>
> We can remove the else
>
> > +        /* henvcfg.STCE changes */
> > +        if (enable) {
> > +            riscv_timer_write_timecmp(env, env->vstimer, env->vstimecmp,
> > +                                      env->htimedelta, MIP_VSTIP);
> > +        } else {
> > +            riscv_timer_disable_timecmp(env, env->vstimer, MIP_VSTIP);
> > +        }
>
> and always run this branch to remove the duplicated code above
>
> Alistair
>
> > +    }
> > +}
> > +
> >  void riscv_timer_init(RISCVCPU *cpu)
> >  {
> >      CPURISCVState *env;
> > diff --git a/target/riscv/time_helper.h b/target/riscv/time_helper.h
> > index cacd79b80c..af1f634f89 100644
> > --- a/target/riscv/time_helper.h
> > +++ b/target/riscv/time_helper.h
> > @@ -25,6 +25,7 @@
> >  void riscv_timer_write_timecmp(CPURISCVState *env, QEMUTimer *timer,
> >                                 uint64_t timecmp, uint64_t delta,
> >                                 uint32_t timer_irq);
> > +void riscv_timer_stce_changed(CPURISCVState *env, bool is_m_mode, bool enable);
> >  void riscv_timer_init(RISCVCPU *cpu);
> >
> >  #endif
> > --
> > 2.17.1
> >
> >