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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f1e58583b9
This patch enable support for cpu hotplug in RISC-V. It uses SBI HSM extension to online/offline any hart. As a result, the harts are returned to firmware once they are offline. If the harts are brought online afterwards, they re-enter Linux kernel as if a secondary hart booted for the first time. All booting requirements are honored during this process. Tested both on QEMU and HighFive Unleashed board with. Test result follows. --------------------------------------------------- Offline cpu 2 --------------------------------------------------- $ echo 0 > /sys/devices/system/cpu/cpu2/online [ 32.828684] CPU2: off $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 --------------------------------------------------- online cpu 2 --------------------------------------------------- $ echo 1 > /sys/devices/system/cpu/cpu2/online $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 2 hart : 2 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 Signed-off-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Anup Patel <anup@brainfault.org>
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2020 Western Digital Corporation or its affiliates.
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* Based on arch/arm64/include/asm/cpu_ops.h
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*/
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#ifndef __ASM_CPU_OPS_H
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#define __ASM_CPU_OPS_H
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/threads.h>
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/**
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* struct cpu_operations - Callback operations for hotplugging CPUs.
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*
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* @name: Name of the boot protocol.
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* @cpu_prepare: Early one-time preparation step for a cpu. If there
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* is a mechanism for doing so, tests whether it is
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* possible to boot the given HART.
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* @cpu_start: Boots a cpu into the kernel.
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* @cpu_disable: Prepares a cpu to die. May fail for some
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* mechanism-specific reason, which will cause the hot
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* unplug to be aborted. Called from the cpu to be killed.
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* @cpu_stop: Makes a cpu leave the kernel. Must not fail. Called from
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* the cpu being stopped.
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* @cpu_is_stopped: Ensures a cpu has left the kernel. Called from another
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* cpu.
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*/
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struct cpu_operations {
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const char *name;
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int (*cpu_prepare)(unsigned int cpu);
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int (*cpu_start)(unsigned int cpu,
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struct task_struct *tidle);
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#ifdef CONFIG_HOTPLUG_CPU
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int (*cpu_disable)(unsigned int cpu);
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void (*cpu_stop)(void);
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int (*cpu_is_stopped)(unsigned int cpu);
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#endif
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};
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extern const struct cpu_operations *cpu_ops[NR_CPUS];
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void __init cpu_set_ops(int cpu);
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void cpu_update_secondary_bootdata(unsigned int cpuid,
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struct task_struct *tidle);
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#endif /* ifndef __ASM_CPU_OPS_H */
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