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Re: [PATCH v5 09/23] target/riscv: Implement AIA local interrupt priorit


From: Alistair Francis
Subject: Re: [PATCH v5 09/23] target/riscv: Implement AIA local interrupt priorities
Date: Fri, 17 Dec 2021 13:14:48 +1000

On Sat, Dec 11, 2021 at 2:27 PM Anup Patel <anup.patel@wdc.com> wrote:
>
> The AIA spec defines programmable 8-bit priority for each local interrupt
> at M-level, S-level and VS-level so we extend local interrupt processing
> to consider AIA interrupt priorities. The AIA CSRs which help software
> configure local interrupt priorities will be added by subsequent patches.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>

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

Alistair

> ---
>  target/riscv/cpu.c        |  19 ++++
>  target/riscv/cpu.h        |  12 ++
>  target/riscv/cpu_helper.c | 231 ++++++++++++++++++++++++++++++++++----
>  target/riscv/machine.c    |   3 +
>  4 files changed, 244 insertions(+), 21 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 827cff0d2b..916319afcd 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -348,6 +348,10 @@ void restore_state_to_opc(CPURISCVState *env, 
> TranslationBlock *tb,
>
>  static void riscv_cpu_reset(DeviceState *dev)
>  {
> +#ifndef CONFIG_USER_ONLY
> +    uint8_t iprio;
> +    int i, irq, rdzero;
> +#endif
>      CPUState *cs = CPU(dev);
>      RISCVCPU *cpu = RISCV_CPU(cs);
>      RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(cpu);
> @@ -370,6 +374,21 @@ static void riscv_cpu_reset(DeviceState *dev)
>      env->miclaim = MIP_SGEIP;
>      env->pc = env->resetvec;
>      env->two_stage_lookup = false;
> +
> +    /* Initialized default priorities of local interrupts. */
> +    for (i = 0; i < ARRAY_SIZE(env->miprio); i++) {
> +        iprio = riscv_cpu_default_priority(i);
> +        env->miprio[i] = (i == IRQ_M_EXT) ? 0 : iprio;
> +        env->siprio[i] = (i == IRQ_S_EXT) ? 0 : iprio;
> +        env->hviprio[i] = 0;
> +    }
> +    i = 0;
> +    while (!riscv_cpu_hviprio_index2irq(i, &irq, &rdzero)) {
> +        if (!rdzero) {
> +            env->hviprio[irq] = env->miprio[irq];
> +        }
> +        i++;
> +    }
>      /* mmte is supposed to have pm.current hardwired to 1 */
>      env->mmte |= (PM_EXT_INITIAL | MMTE_M_PM_CURRENT);
>  #endif
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index df1d792951..69d9c42ad3 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -180,6 +180,10 @@ struct CPURISCVState {
>      target_ulong mcause;
>      target_ulong mtval;  /* since: priv-1.10.0 */
>
> +    /* Machine and Supervisor interrupt priorities */
> +    uint8_t miprio[64];
> +    uint8_t siprio[64];
> +
>      /* Hypervisor CSRs */
>      target_ulong hstatus;
>      target_ulong hedeleg;
> @@ -192,6 +196,9 @@ struct CPURISCVState {
>      target_ulong hgeip;
>      uint64_t htimedelta;
>
> +    /* Hypervisor controlled virtual interrupt priorities */
> +    uint8_t hviprio[64];
> +
>      /* Virtual CSRs */
>      /*
>       * For RV32 this is 32-bit vsstatus and 32-bit vsstatush.
> @@ -374,6 +381,11 @@ int riscv_cpu_write_elf32_note(WriteCoreDumpFunction f, 
> CPUState *cs,
>                                 int cpuid, void *opaque);
>  int riscv_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
>  int riscv_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
> +int riscv_cpu_hviprio_index2irq(int index, int *out_irq, int *out_rdzero);
> +uint8_t riscv_cpu_default_priority(int irq);
> +int riscv_cpu_mirq_pending(CPURISCVState *env);
> +int riscv_cpu_sirq_pending(CPURISCVState *env);
> +int riscv_cpu_vsirq_pending(CPURISCVState *env);
>  bool riscv_cpu_fp_enabled(CPURISCVState *env);
>  target_ulong riscv_cpu_get_geilen(CPURISCVState *env);
>  void riscv_cpu_set_geilen(CPURISCVState *env, target_ulong geilen);
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 57c07ba1a4..033feb3463 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -133,36 +133,225 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, 
> target_ulong *pc,
>  }
>
>  #ifndef CONFIG_USER_ONLY
> -static int riscv_cpu_local_irq_pending(CPURISCVState *env)
> +
> +/*
> + * The HS-mode is allowed to configure priority only for the
> + * following VS-mode local interrupts:
> + *
> + * 0  (Reserved interrupt, reads as zero)
> + * 1  Supervisor software interrupt
> + * 4  (Reserved interrupt, reads as zero)
> + * 5  Supervisor timer interrupt
> + * 8  (Reserved interrupt, reads as zero)
> + * 13 (Reserved interrupt)
> + * 14 "
> + * 15 "
> + * 16 "
> + * 18 Debug/trace interrupt
> + * 20 (Reserved interrupt)
> + * 22 "
> + * 24 "
> + * 26 "
> + * 28 "
> + * 30 (Reserved for standard reporting of bus or system errors)
> + */
> +
> +static int hviprio_index2irq[] =
> +    { 0, 1, 4, 5, 8, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 30 };
> +static int hviprio_index2rdzero[] =
> +    { 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
> +
> +int riscv_cpu_hviprio_index2irq(int index, int *out_irq, int *out_rdzero)
>  {
> -    target_ulong virt_enabled = riscv_cpu_virt_enabled(env);
> +    if (index < 0 || ARRAY_SIZE(hviprio_index2irq) <= index) {
> +        return -EINVAL;
> +    }
> +
> +    if (out_irq) {
> +        *out_irq = hviprio_index2irq[index];
> +    }
>
> -    target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
> -    target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
> +    if (out_rdzero) {
> +        *out_rdzero = hviprio_index2rdzero[index];
> +    }
>
> -    target_ulong vsgemask =
> -                (target_ulong)1 << get_field(env->hstatus, HSTATUS_VGEIN);
> -    target_ulong vsgein = (env->hgeip & vsgemask) ? MIP_VSEIP : 0;
> +    return 0;
> +}
>
> -    target_ulong pending = (env->mip | vsgein) & env->mie;
> +uint8_t riscv_cpu_default_priority(int irq)
> +{
> +    int u, l;
> +    uint8_t iprio = IPRIO_MMAXIPRIO;
>
> -    target_ulong mie    = env->priv < PRV_M ||
> -                          (env->priv == PRV_M && mstatus_mie);
> -    target_ulong sie    = env->priv < PRV_S ||
> -                          (env->priv == PRV_S && mstatus_sie);
> -    target_ulong hsie   = virt_enabled || sie;
> -    target_ulong vsie   = virt_enabled && sie;
> +    if (irq < 0 || irq > 63) {
> +        return iprio;
> +    }
>
> -    target_ulong irqs =
> -            (pending & ~env->mideleg & -mie) |
> -            (pending &  env->mideleg & ~env->hideleg & -hsie) |
> -            (pending &  env->mideleg &  env->hideleg & -vsie);
> +    /*
> +     * Default priorities of local interrupts are defined in the
> +     * RISC-V Advanced Interrupt Architecture specification.
> +     *
> +     * ----------------------------------------------------------------
> +     *  Default  |
> +     *  Priority | Major Interrupt Numbers
> +     * ----------------------------------------------------------------
> +     *  Highest  | 63 (3f), 62 (3e), 31 (1f), 30 (1e), 61 (3d), 60 (3c),
> +     *           | 59 (3b), 58 (3a), 29 (1d), 28 (1c), 57 (39), 56 (38),
> +     *           | 55 (37), 54 (36), 27 (1b), 26 (1a), 53 (35), 52 (34),
> +     *           | 51 (33), 50 (32), 25 (19), 24 (18), 49 (31), 48 (30)
> +     *           |
> +     *           | 11 (0b),  3 (03),  7 (07)
> +     *           |  9 (09),  1 (01),  5 (05)
> +     *           | 12 (0c)
> +     *           | 10 (0a),  2 (02),  6 (06)
> +     *           |
> +     *           | 47 (2f), 46 (2e), 23 (17), 22 (16), 45 (2d), 44 (2c),
> +     *           | 43 (2b), 42 (2a), 21 (15), 20 (14), 41 (29), 40 (28),
> +     *           | 39 (27), 38 (26), 19 (13), 18 (12), 37 (25), 36 (24),
> +     *  Lowest   | 35 (23), 34 (22), 17 (11), 16 (10), 33 (21), 32 (20)
> +     * ----------------------------------------------------------------
> +     */
>
> -    if (irqs) {
> -        return ctz64(irqs); /* since non-zero */
> +    u = IPRIO_DEFAULT_U(irq);
> +    l = IPRIO_DEFAULT_L(irq);
> +    if (u == 0) {
> +        if (irq == IRQ_VS_EXT || irq == IRQ_VS_TIMER ||
> +            irq == IRQ_VS_SOFT) {
> +            iprio = IPRIO_DEFAULT_VS;
> +        } else if (irq == IRQ_S_GEXT) {
> +            iprio = IPRIO_DEFAULT_SGEXT;
> +        } else if (irq == IRQ_S_EXT || irq == IRQ_S_TIMER ||
> +                   irq == IRQ_S_SOFT) {
> +            iprio = IPRIO_DEFAULT_S;
> +        } else if (irq == IRQ_M_EXT || irq == IRQ_M_TIMER ||
> +                   irq == IRQ_M_SOFT) {
> +            iprio = IPRIO_DEFAULT_M;
> +        } else {
> +            iprio = IPRIO_DEFAULT_VS;
> +        }
> +    } else if (u == 1) {
> +        if (l < 8) {
> +            iprio = IPRIO_DEFAULT_16_23(irq);
> +        } else {
> +            iprio = IPRIO_DEFAULT_24_31(irq);
> +        }
> +    } else if (u == 2) {
> +        iprio = IPRIO_DEFAULT_32_47(irq);
> +    } else if (u == 3) {
> +        iprio = IPRIO_DEFAULT_48_63(irq);
> +    }
> +
> +    return iprio;
> +}
> +
> +static int riscv_cpu_pending_to_irq(CPURISCVState *env,
> +                                    uint64_t pending, uint8_t *iprio)
> +{
> +    int irq, best_irq = RISCV_EXCP_NONE;
> +    unsigned int prio, best_prio = UINT_MAX;
> +
> +    if (!pending) {
> +        return RISCV_EXCP_NONE;
> +    }
> +
> +    irq = ctz64(pending);
> +    if (!riscv_feature(env, RISCV_FEATURE_AIA)) {
> +        return irq;
> +    }
> +
> +    pending = pending >> irq;
> +    while (pending) {
> +        prio = iprio[irq];
> +        if (!prio) {
> +            prio = (riscv_cpu_default_priority(irq) < IPRIO_DEFAULT_M) ?
> +                   1 : IPRIO_MMAXIPRIO;
> +        }
> +        if ((pending & 0x1) && (prio < best_prio)) {
> +            best_irq = irq;
> +            best_prio = prio;
> +        }
> +        irq++;
> +        pending = pending >> 1;
> +    }
> +
> +    return best_irq;
> +}
> +
> +static uint64_t riscv_cpu_all_pending(CPURISCVState *env)
> +{
> +    uint32_t gein = get_field(env->hstatus, HSTATUS_VGEIN);
> +    uint64_t vsgein = (env->hgeip & (1ULL << gein)) ? MIP_VSEIP : 0;
> +
> +    return (env->mip | vsgein) & env->mie;
> +}
> +
> +int riscv_cpu_mirq_pending(CPURISCVState *env)
> +{
> +    uint64_t irqs = riscv_cpu_all_pending(env) & ~env->mideleg &
> +                    ~(MIP_SGEIP | MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
> +
> +    return riscv_cpu_pending_to_irq(env, irqs, env->miprio);
> +}
> +
> +int riscv_cpu_sirq_pending(CPURISCVState *env)
> +{
> +    uint64_t irqs = riscv_cpu_all_pending(env) & env->mideleg &
> +                    ~(MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
> +
> +    return riscv_cpu_pending_to_irq(env, irqs, env->siprio);
> +}
> +
> +int riscv_cpu_vsirq_pending(CPURISCVState *env)
> +{
> +    uint64_t irqs = riscv_cpu_all_pending(env) & env->mideleg &
> +                    (MIP_VSSIP | MIP_VSTIP | MIP_VSEIP);
> +
> +    return riscv_cpu_pending_to_irq(env, irqs >> 1, env->hviprio);
> +}
> +
> +static int riscv_cpu_local_irq_pending(CPURISCVState *env)
> +{
> +    int virq;
> +    uint64_t irqs, pending, mie, hsie, vsie;
> +
> +    /* Determine interrupt enable state of all privilege modes */
> +    if (riscv_cpu_virt_enabled(env)) {
> +        mie = 1;
> +        hsie = 1;
> +        vsie = (env->priv < PRV_S) ||
> +               (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_SIE));
>      } else {
> -        return RISCV_EXCP_NONE; /* indicates no pending interrupt */
> +        mie = (env->priv < PRV_M) ||
> +              (env->priv == PRV_M && get_field(env->mstatus, MSTATUS_MIE));
> +        hsie = (env->priv < PRV_S) ||
> +               (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_SIE));
> +        vsie = 0;
>      }
> +
> +    /* Determine all pending interrupts */
> +    pending = riscv_cpu_all_pending(env);
> +
> +    /* Check M-mode interrupts */
> +    irqs = pending & ~env->mideleg & -mie;
> +    if (irqs) {
> +        return riscv_cpu_pending_to_irq(env, irqs, env->miprio);
> +    }
> +
> +    /* Check HS-mode interrupts */
> +    irqs = pending & env->mideleg & ~env->hideleg & -hsie;
> +    if (irqs) {
> +        return riscv_cpu_pending_to_irq(env, irqs, env->siprio);
> +    }
> +
> +    /* Check VS-mode interrupts */
> +    irqs = pending & env->mideleg & env->hideleg & -vsie;
> +    if (irqs) {
> +        virq = riscv_cpu_pending_to_irq(env, irqs >> 1, env->hviprio);
> +        return (virq <= 0) ? virq : virq + 1;
> +    }
> +
> +    /* Indicate no pending interrupt */
> +    return RISCV_EXCP_NONE;
>  }
>
>  bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
> diff --git a/target/riscv/machine.c b/target/riscv/machine.c
> index 76dd0d415c..cffc444969 100644
> --- a/target/riscv/machine.c
> +++ b/target/riscv/machine.c
> @@ -92,6 +92,7 @@ static const VMStateDescription vmstate_hyper = {
>          VMSTATE_UINTTL(env.hgeie, RISCVCPU),
>          VMSTATE_UINTTL(env.hgeip, RISCVCPU),
>          VMSTATE_UINT64(env.htimedelta, RISCVCPU),
> +        VMSTATE_UINT8_ARRAY(env.hviprio, RISCVCPU, 64),
>
>          VMSTATE_UINT64(env.vsstatus, RISCVCPU),
>          VMSTATE_UINTTL(env.vstvec, RISCVCPU),
> @@ -173,6 +174,8 @@ const VMStateDescription vmstate_riscv_cpu = {
>      .fields = (VMStateField[]) {
>          VMSTATE_UINTTL_ARRAY(env.gpr, RISCVCPU, 32),
>          VMSTATE_UINT64_ARRAY(env.fpr, RISCVCPU, 32),
> +        VMSTATE_UINT8_ARRAY(env.miprio, RISCVCPU, 64),
> +        VMSTATE_UINT8_ARRAY(env.siprio, RISCVCPU, 64),
>          VMSTATE_UINTTL(env.pc, RISCVCPU),
>          VMSTATE_UINTTL(env.load_res, RISCVCPU),
>          VMSTATE_UINTTL(env.load_val, RISCVCPU),
> --
> 2.25.1
>
>



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