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From:   Anup Patel <anup@brainfault.org>
Date:   Thu, 27 Dec 2018 09:28:03 +0530
Message-ID: <CAAhSdy20-r5e1EQ7yTawbxXs0NgFkfg8L8VLRUFLL=NcXfCD2w@mail.gmail.com>
Subject: Re: [PATCH 3/3] RISC-V: Fix non-smp kernel boot on SMP systems
To:     Atish Patra <atish.patra@wdc.com>
Cc:     linux-riscv@lists.infradead.org, Albert Ou <aou@eecs.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Dmitriy Cherkasov <dmitriy@oss-tech.org>,
        Jason Cooper <jason@lakedaemon.net>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Michael Clark <michaeljclark@mac.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        =?UTF-8?Q?Patrick_St=C3=A4hlin?= <me@packi.ch>,
        Rob Herring <robh@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Damien Le Moal <Damien.LeMoal@wdc.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Thu, Dec 27, 2018 at 4:39 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> In non-smp configuration, hartid can be higher that NR_CPUS.
> riscv_of_processor_hartid should not be compared to hartid to
> NR_CPUS in that case. Moreover, this function checks all the
> DT properties of a hart node. NR_CPUS comparison seems out of
> place.

This only explains change in arch/riscv/kernel/cpu.c

Create separate patch for it.

>
> Do cpuid comparison with NR_CPUs in smp setup code. Update the

Create separate patch for change in arch/riscv/kernel/smp.c

> drivers to handle appropriate code as well.

Create separate patches for riscv_timer and irq-sifive-plic.c
because they will probably go via different gitrepos.

>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  arch/riscv/kernel/cpu.c           |  4 ----
>  arch/riscv/kernel/smp.c           |  1 -
>  arch/riscv/kernel/smpboot.c       |  5 +++++
>  drivers/clocksource/riscv_timer.c | 21 ++++++++++++++++++---
>  drivers/irqchip/irq-sifive-plic.c |  5 +++++
>  5 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index b4a7d442..251ffab6 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -34,10 +34,6 @@ int riscv_of_processor_hartid(struct device_node *node)
>                 pr_warn("Found CPU without hart ID\n");
>                 return -(ENODEV);
>         }
> -       if (hart >= NR_CPUS) {
> -               pr_info("Found hart ID %d, which is above NR_CPUs.  Disabling this hart\n", hart);
> -               return -(ENODEV);
> -       }
>
>         if (of_property_read_string(node, "status", &status)) {
>                 pr_warn("CPU with hartid=%d has no \"status\" property\n", hart);
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index 57b1383e..9ea7ac7d 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -49,7 +49,6 @@ int riscv_hartid_to_cpuid(int hartid)
>                         return i;
>
>         pr_err("Couldn't find cpu id for hartid [%d]\n", hartid);
> -       BUG();

Have a separate patch with explanation about why
we don't need BUG() here.

>         return i;
>  }
>
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index bb8cd242..05291840 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -66,6 +66,11 @@ void __init setup_smp(void)
>                         found_boot_cpu = 1;
>                         continue;
>                 }
> +               if (cpuid >= NR_CPUS) {
> +                       pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
> +                               cpuid, hart);
> +                       break;
> +               }
>
>                 cpuid_to_hartid_map(cpuid) = hart;
>                 set_cpu_possible(cpuid, true);
> diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
> index 084e97dc..acf2af10 100644
> --- a/drivers/clocksource/riscv_timer.c
> +++ b/drivers/clocksource/riscv_timer.c
> @@ -89,20 +89,35 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>         struct clocksource *cs;
>
>         hartid = riscv_of_processor_hartid(n);
> +       if (hartid < 0) {
> +               pr_warn("Not valid hartid for node [%pOF] error = [%d]\n",
> +                       n, hartid);
> +               return hartid;
> +       }
>         cpuid = riscv_hartid_to_cpuid(hartid);
>
> +       if (cpuid < 0)
> +               pr_warn("Invalid cpuid for hartid [%d]\n", hartid);
> +
>         if (cpuid != smp_processor_id())
>                 return 0;
>
> +       pr_err("%s: Registering clocksource cpuid [%d] hartid [%d]\n",
> +              __func__, cpuid, hartid);
>         cs = per_cpu_ptr(&riscv_clocksource, cpuid);
> -       clocksource_register_hz(cs, riscv_timebase);
> +       error = clocksource_register_hz(cs, riscv_timebase);
>
> +       if (error) {
> +               pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
> +                      error, cpuid);
> +               return error;
> +       }
>         error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
>                          "clockevents/riscv/timer:starting",
>                          riscv_timer_starting_cpu, riscv_timer_dying_cpu);
>         if (error)
> -               pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
> -                      error, cpuid);
> +               pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
> +                      error);
>         return error;
>  }
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 357e9daf..254ecd76 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -237,6 +237,11 @@ static int __init plic_init(struct device_node *node,
>                 }
>
>                 cpu = riscv_hartid_to_cpuid(hartid);
> +               if (cpu < 0) {
> +                       pr_warn("Invalid cpuid for context %d\n", i);
> +                       continue;
> +               }
> +
>                 handler = per_cpu_ptr(&plic_handlers, cpu);
>                 handler->present = true;
>                 handler->ctxid = i;
> --
> 2.7.4
>

Regards,
Anup