diff options
| -rw-r--r-- | arch/riscv/include/asm/cpu_ops.h | 34 | ||||
| -rw-r--r-- | arch/riscv/kernel/Makefile | 2 | ||||
| -rw-r--r-- | arch/riscv/kernel/cpu_ops.c | 38 | ||||
| -rw-r--r-- | arch/riscv/kernel/cpu_ops_spinwait.c | 43 | ||||
| -rw-r--r-- | arch/riscv/kernel/smpboot.c | 51 |
5 files changed, 147 insertions, 21 deletions
diff --git a/arch/riscv/include/asm/cpu_ops.h b/arch/riscv/include/asm/cpu_ops.h new file mode 100644 index 000000000000..5ce81a28e1d9 --- /dev/null +++ b/arch/riscv/include/asm/cpu_ops.h @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2020 Western Digital Corporation or its affiliates. + * Based on arch/arm64/include/asm/cpu_ops.h + */ +#ifndef __ASM_CPU_OPS_H +#define __ASM_CPU_OPS_H + +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/threads.h> + +/** + * struct cpu_operations - Callback operations for hotplugging CPUs. + * + * @name: Name of the boot protocol. + * @cpu_prepare: Early one-time preparation step for a cpu. If there + * is a mechanism for doing so, tests whether it is + * possible to boot the given HART. + * @cpu_start: Boots a cpu into the kernel. + */ +struct cpu_operations { + const char *name; + int (*cpu_prepare)(unsigned int cpu); + int (*cpu_start)(unsigned int cpu, + struct task_struct *tidle); +}; + +extern const struct cpu_operations *cpu_ops[NR_CPUS]; +void __init cpu_set_ops(int cpu); +void cpu_update_secondary_bootdata(unsigned int cpuid, + struct task_struct *tidle); + +#endif /* ifndef __ASM_CPU_OPS_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index d189bd3d8501..43d49ea36a3f 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -34,6 +34,8 @@ obj-$(CONFIG_RISCV_M_MODE) += clint.o obj-$(CONFIG_FPU) += fpu.o obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o +obj-$(CONFIG_SMP) += cpu_ops.o +obj-$(CONFIG_SMP) += cpu_ops_spinwait.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o diff --git a/arch/riscv/kernel/cpu_ops.c b/arch/riscv/kernel/cpu_ops.c new file mode 100644 index 000000000000..62705908eee5 --- /dev/null +++ b/arch/riscv/kernel/cpu_ops.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2020 Western Digital Corporation or its affiliates. + */ + +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/of.h> +#include <linux/string.h> +#include <linux/sched.h> +#include <linux/sched/task_stack.h> +#include <asm/cpu_ops.h> +#include <asm/sbi.h> +#include <asm/smp.h> + +const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init; + +void *__cpu_up_stack_pointer[NR_CPUS]; +void *__cpu_up_task_pointer[NR_CPUS]; + +extern const struct cpu_operations cpu_ops_spinwait; + +void cpu_update_secondary_bootdata(unsigned int cpuid, + struct task_struct *tidle) +{ + int hartid = cpuid_to_hartid_map(cpuid); + + /* Make sure tidle is updated */ + smp_mb(); + WRITE_ONCE(__cpu_up_stack_pointer[hartid], + task_stack_page(tidle) + THREAD_SIZE); + WRITE_ONCE(__cpu_up_task_pointer[hartid], tidle); +} + +void __init cpu_set_ops(int cpuid) +{ + cpu_ops[cpuid] = &cpu_ops_spinwait; +} diff --git a/arch/riscv/kernel/cpu_ops_spinwait.c b/arch/riscv/kernel/cpu_ops_spinwait.c new file mode 100644 index 000000000000..b2c957bb68c1 --- /dev/null +++ b/arch/riscv/kernel/cpu_ops_spinwait.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2020 Western Digital Corporation or its affiliates. + */ + +#include <linux/errno.h> +#include <linux/of.h> +#include <linux/string.h> +#include <asm/cpu_ops.h> +#include <asm/sbi.h> +#include <asm/smp.h> + +const struct cpu_operations cpu_ops_spinwait; + +static int spinwait_cpu_prepare(unsigned int cpuid) +{ + if (!cpu_ops_spinwait.cpu_start) { + pr_err("cpu start method not defined for CPU [%d]\n", cpuid); + return -ENODEV; + } + return 0; +} + +static int spinwait_cpu_start(unsigned int cpuid, struct task_struct *tidle) +{ + /* + * In this protocol, all cpus boot on their own accord. _start + * selects the first cpu to boot the kernel and causes the remainder + * of the cpus to spin in a loop waiting for their stack pointer to be + * setup by that main cpu. Writing to bootdata + * (i.e __cpu_up_stack_pointer) signals to the spinning cpus that they + * can continue the boot process. + */ + cpu_update_secondary_bootdata(cpuid, tidle); + + return 0; +} + +const struct cpu_operations cpu_ops_spinwait = { + .name = "spinwait", + .cpu_prepare = spinwait_cpu_prepare, + .cpu_start = spinwait_cpu_start, +}; diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index 8bc01f0ca73b..e89396a2a1af 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -25,6 +25,7 @@ #include <linux/sched/task_stack.h> #include <linux/sched/mm.h> #include <asm/clint.h> +#include <asm/cpu_ops.h> #include <asm/irq.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> @@ -34,8 +35,6 @@ #include "head.h" -void *__cpu_up_stack_pointer[NR_CPUS]; -void *__cpu_up_task_pointer[NR_CPUS]; static DECLARE_COMPLETION(cpu_running); void __init smp_prepare_boot_cpu(void) @@ -46,6 +45,7 @@ void __init smp_prepare_boot_cpu(void) void __init smp_prepare_cpus(unsigned int max_cpus) { int cpuid; + int ret; /* This covers non-smp usecase mandated by "nosmp" option */ if (max_cpus == 0) @@ -54,6 +54,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus) for_each_possible_cpu(cpuid) { if (cpuid == smp_processor_id()) continue; + if (cpu_ops[cpuid]->cpu_prepare) { + ret = cpu_ops[cpuid]->cpu_prepare(cpuid); + if (ret) + continue; + } set_cpu_present(cpuid, true); } } @@ -65,6 +70,8 @@ void __init setup_smp(void) bool found_boot_cpu = false; int cpuid = 1; + cpu_set_ops(0); + for_each_of_cpu_node(dn) { hart = riscv_of_processor_hartid(dn); if (hart < 0) @@ -92,36 +99,38 @@ void __init setup_smp(void) cpuid, nr_cpu_ids); for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) { - if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) + if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) { + cpu_set_ops(cpuid); set_cpu_possible(cpuid, true); + } } } +int start_secondary_cpu(int cpu, struct task_struct *tidle) +{ + if (cpu_ops[cpu]->cpu_start) + return cpu_ops[cpu]->cpu_start(cpu, tidle); + + return -EOPNOTSUPP; +} + int __cpu_up(unsigned int cpu, struct task_struct *tidle) { int ret = 0; - int hartid = cpuid_to_hartid_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 - * of the harts to spin in a loop waiting for their stack pointer to be - * setup by that main hart. Writing __cpu_up_stack_pointer signals to - * the spinning harts that they can continue the boot process. - */ - smp_mb(); - WRITE_ONCE(__cpu_up_stack_pointer[hartid], - task_stack_page(tidle) + THREAD_SIZE); - WRITE_ONCE(__cpu_up_task_pointer[hartid], tidle); - - lockdep_assert_held(&cpu_running); - wait_for_completion_timeout(&cpu_running, + ret = start_secondary_cpu(cpu, tidle); + if (!ret) { + lockdep_assert_held(&cpu_running); + wait_for_completion_timeout(&cpu_running, msecs_to_jiffies(1000)); - if (!cpu_online(cpu)) { - pr_crit("CPU%u: failed to come online\n", cpu); - ret = -EIO; + if (!cpu_online(cpu)) { + pr_crit("CPU%u: failed to come online\n", cpu); + ret = -EIO; + } + } else { + pr_crit("CPU%u: failed to start\n", cpu); } return ret; |