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Re: [PATCH v7 09/23] target/riscv: Implement AIA local interrupt priorit


From: Anup Patel
Subject: Re: [PATCH v7 09/23] target/riscv: Implement AIA local interrupt priorities
Date: Tue, 18 Jan 2022 09:11:08 +0530

On Tue, Jan 18, 2022 at 9:04 AM Frank Chang <frank.chang@sifive.com> wrote:
>
> Anup Patel <anup@brainfault.org> 於 2022年1月17日 週一 下午10:28寫道:
>>
>> From: Anup Patel <anup.patel@wdc.com>
>>
>> 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>
>> Signed-off-by: Anup Patel <anup@brainfault.org>
>> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
>> ---
>>  target/riscv/cpu.c        |  19 +++
>>  target/riscv/cpu.h        |  12 ++
>>  target/riscv/cpu_helper.c | 242 ++++++++++++++++++++++++++++++++++----
>>  target/riscv/machine.c    |   3 +
>>  4 files changed, 255 insertions(+), 21 deletions(-)
>>
>> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
>> index 76f9786836..167d86eef7 100644
>> --- a/target/riscv/cpu.c
>> +++ b/target/riscv/cpu.c
>> @@ -370,6 +370,10 @@ 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);
>> @@ -392,6 +396,21 @@ 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 cee70f8608..65d2b606fc 100644
>> --- a/target/riscv/cpu.h
>> +++ b/target/riscv/cpu.h
>> @@ -190,6 +190,10 @@ 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;
>> @@ -202,6 +206,9 @@ struct CPURISCVState {
>>      target_ulong hgeip;
>>      uint64_t htimedelta;
>>
>> +    /* Hypervisor controlled virtual interrupt priorities */
>> +    uint8_t hviprio[64];
>> +
>>      /* Upper 64-bits of 128-bit CSRs */
>>      uint64_t mscratchh;
>>      uint64_t sscratchh;
>> @@ -392,6 +399,11 @@ 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 59c8f900df..3a36200780 100644
>> --- a/target/riscv/cpu_helper.c
>> +++ b/target/riscv/cpu_helper.c
>> @@ -151,36 +151,236 @@ 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,
>> +                                    int extirq, unsigned int 
>> extirq_def_prio,
>> +                                    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) {
>> +            if (irq == extirq) {
>> +                prio = extirq_def_prio;
>> +            } else {
>> +                prio = (riscv_cpu_default_priority(irq) < extirq_def_prio) ?
>> +                       1 : IPRIO_MMAXIPRIO;
>> +            }
>> +        }
>> +        if ((pending & 0x1) && (prio <= best_prio)) {
>> +            best_irq = irq;
>> +            best_prio = prio;
>> +        }
>> +        irq++;
>> +        pending = pending >> 1;
>> +    }
>> +
>> +    return best_irq;
>> +}
>
>
> Hi Anup,
>
> RISC-V Priv spec defines the priority order:
>   Multiple simultaneous interrupts destined for the same privilege mode
>   are handled in the following decreasing priority order: MEI, MSI, MTI, SEI, 
> SSI, STI, UEI,
>   USI, UTI.
>
> So the priority order should be: MEI (11) > MSI (3) > MTI (7).
>
> But if MSI and MTI are pending-and-enabled,
> with all of their iprio assigned to their default priority orders 
> (IPRIO_DEFAULT_M)
> (or iprio assigned to zero, which the default priority orders are applied as 
> well).
> riscv_cpu_pending_to_irq() would incorrectly pick MTI (7), instead of MSI (3),
> because they all have the same default priority order: IPRIO_DEFAULT_M.

Ahh yes, I missed addressing this one.

If you can review other patches as well then I can send v8 this week itself.

Thanks,
Anup

>
> Regards,
> Frank Chang
>
>>
>> +
>> +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, IRQ_M_EXT, IPRIO_DEFAULT_M,
>> +                                    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, IRQ_S_EXT, IPRIO_DEFAULT_S,
>> +                                    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, IRQ_S_EXT, IPRIO_DEFAULT_S,
>> +                                    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, IRQ_M_EXT, IPRIO_DEFAULT_M,
>> +                                        irqs, env->miprio);
>> +    }
>> +
>> +    /* Check HS-mode interrupts */
>> +    irqs = pending & env->mideleg & ~env->hideleg & -hsie;
>> +    if (irqs) {
>> +        return riscv_cpu_pending_to_irq(env, IRQ_S_EXT, IPRIO_DEFAULT_S,
>> +                                        irqs, env->siprio);
>> +    }
>> +
>> +    /* Check VS-mode interrupts */
>> +    irqs = pending & env->mideleg & env->hideleg & -vsie;
>> +    if (irqs) {
>> +        virq = riscv_cpu_pending_to_irq(env, IRQ_S_EXT, IPRIO_DEFAULT_S,
>> +                                        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 c11eb4639c..bae4f69725 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),
>> @@ -194,6 +195,8 @@ 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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