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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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cfafe26013
Currently, all harts have to jump Linux in RISC-V. This complicates the multi-stage boot process as every transient stage also has to ensure all harts enter to that stage and jump to Linux afterwards. It also obstructs a clean Kexec implementation. SBI HSM extension provides alternate solutions where only a single hart need to boot and enter Linux. The booting hart can bring up secondary harts one by one afterwards. Add SBI HSM based cpu_ops that implements an ordered booting method in RISC-V. This change is also backward compatible with older firmware not implementing HSM extension. If a latest kernel is used with older firmware, it will continue to use the default spinning booting method. Signed-off-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
47 lines
1.1 KiB
C
47 lines
1.1 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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*/
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/of.h>
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#include <linux/string.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <asm/cpu_ops.h>
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#include <asm/sbi.h>
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#include <asm/smp.h>
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const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
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void *__cpu_up_stack_pointer[NR_CPUS];
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void *__cpu_up_task_pointer[NR_CPUS];
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extern const struct cpu_operations cpu_ops_sbi;
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extern const struct cpu_operations cpu_ops_spinwait;
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void cpu_update_secondary_bootdata(unsigned int cpuid,
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struct task_struct *tidle)
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{
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int hartid = cpuid_to_hartid_map(cpuid);
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/* Make sure tidle is updated */
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smp_mb();
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WRITE_ONCE(__cpu_up_stack_pointer[hartid],
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task_stack_page(tidle) + THREAD_SIZE);
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WRITE_ONCE(__cpu_up_task_pointer[hartid], tidle);
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}
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void __init cpu_set_ops(int cpuid)
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{
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#if IS_ENABLED(CONFIG_RISCV_SBI)
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if (sbi_probe_extension(SBI_EXT_HSM) > 0) {
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if (!cpuid)
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pr_info("SBI v0.2 HSM extension detected\n");
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cpu_ops[cpuid] = &cpu_ops_sbi;
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} else
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#endif
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cpu_ops[cpuid] = &cpu_ops_spinwait;
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}
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