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[209.132.180.67]) by mx.google.com with ESMTP id k184-v6si24546855pge.209.2018.08.16.01.26.09; Thu, 16 Aug 2018 01:26:24 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@brainfault-org.20150623.gappssmtp.com header.s=20150623 header.b=eBrLOZXH; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387933AbeHPH6O (ORCPT + 99 others); Thu, 16 Aug 2018 03:58:14 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:37393 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731216AbeHPH6N (ORCPT ); Thu, 16 Aug 2018 03:58:13 -0400 Received: by mail-wr1-f67.google.com with SMTP id u12-v6so2922517wrr.4 for ; Wed, 15 Aug 2018 22:02:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brainfault-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=EGPf1UZ2hZrT4KQU5HKlLuDiPxjBLB7HBsyG0z8KKTE=; b=eBrLOZXHBpQQ00Qwm30ZwOUTG672GWAABTMGAx6FmH/ZKSLlcxgmnUfXRtGtNmsgQG CnO7VfKAdB77g8OsFE/pVfLgvVuaC0k7NmHht0adodwzTWBrkNf/0tue03zq347NSmnH O+JMLTP1BLSRF7itaiXuJdbi1nFXurX09+27I70VoG3ykNYKA718qoDm0Uc6PCKAyEND 9eyWGKWML8aa8YjifyE5BraGNbtIqGPXgUsbQiHeGr81qGoCuIcwPKu3Frvm5ZXZ0x+f TOG/JbW/Xda7Y5/kj8ceeubbUjQad7RpjdBz1LrtB6+Eb/8eS9KPMpmm+w8/JU0vu5Ek Td0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=EGPf1UZ2hZrT4KQU5HKlLuDiPxjBLB7HBsyG0z8KKTE=; b=HReGyJY7GFvzAPk+uU1mksndIMJNJQS6o1rEgHANCHKviVy3XUvMt++9BNNUQSvBKK 6RgTCAzmcNwfnat1RuZQhJjPgZwEFNQ3iZ54TNf+L9OiXf67BOl7UzXLtOLXp65TCE54 gBxQFvnbp4735r7c7gXvfZGzkbFPVpxETFX2gApq7jFLHW/7cZKuaLSRRLmkBpAH1fGP kzKQAzdzchA7yHzhTlYCeXHAK1Mcl7xyOqkOAcgCiWj63zXPFa8uQB/7qZ7QOq4aD/m/ +FZqlRiu2z4ltlsawRYZaL2VHNKtGIczWtouaieNhel5bp9Q0bvBWsElyyNdhe5rDKYO EQbg== X-Gm-Message-State: AOUpUlFj5YcyhjSOwbGE0KBsPc5/BiJQnVv1OWq/5WH0S76OYSZx2/QC 9pzVrnahod+PorsibH5q/Uoxu3ouDNgVxtKbYOkASA== X-Received: by 2002:adf:f585:: with SMTP id f5-v6mr17610773wro.59.1534395749278; Wed, 15 Aug 2018 22:02:29 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:adf:9dd2:0:0:0:0:0 with HTTP; Wed, 15 Aug 2018 22:02:28 -0700 (PDT) In-Reply-To: <1534377377-70108-4-git-send-email-atish.patra@wdc.com> References: <1534377377-70108-1-git-send-email-atish.patra@wdc.com> <1534377377-70108-4-git-send-email-atish.patra@wdc.com> From: Anup Patel Date: Thu, 16 Aug 2018 10:32:28 +0530 Message-ID: Subject: Re: [RFC PATCH 3/5] RISC-V: Add cpu_operatios structure To: Atish Patra Cc: palmer@sifive.com, linux-riscv@lists.infradead.org, Mark Rutland , Christoph Hellwig , Thomas Gleixner , "linux-kernel@vger.kernel.org List" , Damien Le Moal Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 16, 2018 at 5:26 AM, Atish Patra wrote: > Defining cpu_operations now helps adding cpu hotplug > support in proper manner. Moreover, it provides flexibility > in supporting other cpu enable/boot methods can be > supported in future. This patch has been largely inspired from > ARM64. However, a default boot method is defined for RISC-V unlike > ARM64. > > Signed-off-by: Atish Patra > --- > arch/riscv/include/asm/smp.h | 10 ++++++++++ > arch/riscv/kernel/smp.c | 8 ++++++++ > arch/riscv/kernel/smpboot.c | 34 ++++++++++++++++++++++++++++------ > 3 files changed, 46 insertions(+), 6 deletions(-) > > diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h > index 0763337b..2bb6e6c2 100644 > --- a/arch/riscv/include/asm/smp.h > +++ b/arch/riscv/include/asm/smp.h > @@ -28,6 +28,15 @@ > extern u64 __cpu_logical_map[NR_CPUS]; > #define cpu_logical_map(cpu) __cpu_logical_map[cpu] > > +struct cpu_operations { > + const char *name; > + int (*cpu_init)(unsigned int); > + int (*cpu_prepare)(unsigned int); > + int (*cpu_boot)(unsigned int, struct task_struct *); > +}; > +extern struct cpu_operations cpu_ops; > +void smp_set_cpu_ops(const struct cpu_operations *cpu_ops); > + > #ifdef CONFIG_SMP > > /* SMP initialization hook for setup_arch */ > @@ -57,5 +66,6 @@ static inline void cpuid_to_hartid_mask(const struct cpumask *in, > cpumask_set_cpu(cpu_logical_map(0), out); > } > > + > #endif /* CONFIG_SMP */ > #endif /* _ASM_RISCV_SMP_H */ > diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c > index 4ab70480..5de58ced 100644 > --- a/arch/riscv/kernel/smp.c > +++ b/arch/riscv/kernel/smp.c > @@ -58,6 +58,14 @@ void cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out) > for_each_cpu(cpu, in) > cpumask_set_cpu(cpu_logical_map(cpu), out); > } > +struct cpu_operations cpu_ops __ro_after_init; > + > +void smp_set_cpu_ops(const struct cpu_operations *ops) > +{ > + if (ops) > + cpu_ops = *ops; > +} > + Move both cpu_ops and smp_set_cpu_ops() to smpboot.c. This way you will not require to make cpu_ops as global. Further, I think cpu_ops should be a pointer and initial value should be &default_ops. Something like this: struct cpu_operations *cpu_ops __ro_after_init = &default_ops; > /* Unsupported */ > int setup_profiling_timer(unsigned int multiplier) > { > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c > index 6ab2bb1b..045a1a45 100644 > --- a/arch/riscv/kernel/smpboot.c > +++ b/arch/riscv/kernel/smpboot.c > @@ -30,6 +30,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -38,6 +39,7 @@ > > void *__cpu_up_stack_pointer[NR_CPUS]; > void *__cpu_up_task_pointer[NR_CPUS]; > +struct cpu_operations default_ops; > > void __init smp_prepare_boot_cpu(void) > { > @@ -53,6 +55,7 @@ void __init setup_smp(void) > int hart, found_boot_cpu = 0; > int cpuid = 1; > > + smp_set_cpu_ops(&default_ops); > while ((dn = of_find_node_by_type(dn, "cpu"))) { > hart = riscv_of_processor_hart(dn); > > @@ -73,10 +76,8 @@ void __init setup_smp(void) > BUG_ON(!found_boot_cpu); > } > > -int __cpu_up(unsigned int cpu, struct task_struct *tidle) > +int default_cpu_boot(unsigned int hartid, struct task_struct *tidle) > { > - int hartid = cpu_logical_map(cpu); > - tidle->thread_info.cpu = cpu; > /* > * On RISC-V systems, all harts boot on their own accord. Our _start > * selects the first hart to boot the kernel and causes the remainder > @@ -84,13 +85,28 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) > * setup by that main hart. Writing __cpu_up_stack_pointer signals to > * the spinning harts that they can continue the boot process. > */ > - smp_mb(); > + > __cpu_up_stack_pointer[hartid] = task_stack_page(tidle) + THREAD_SIZE; > __cpu_up_task_pointer[hartid] = tidle; > + return 0; > +} > + > +int __cpu_up(unsigned int cpu, struct task_struct *tidle) > +{ > + int err = -1; > + int hartid = cpu_logical_map(cpu); > > - while (!cpu_online(cpu)) > - cpu_relax(); > + tidle->thread_info.cpu = cpu; > + smp_mb(); > > + if (cpu_ops.cpu_boot) > + err = cpu_ops.cpu_boot(hartid, tidle); > + if (!err) { > + while (!cpu_online(cpu)) > + cpu_relax(); > + } else { > + pr_err("CPU %d [hartid %d]failed to boot\n", cpu, hartid); > + } > return 0; > } > > @@ -117,3 +133,9 @@ asmlinkage void __init smp_callin(void) > preempt_disable(); > cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); > } > + > + > +struct cpu_operations default_ops = { > + .name = "default", > + .cpu_boot = default_cpu_boot, > +}; I think having dedicated source file for default_ops makes more sense so that we have a clear/simple reference implementation of cpu_operations. Eventually, we might have one source file for each type of SMP enable method. Try to keep smpboot.c generic and independent of any cpu_operations. What say? Regards, Anup