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>
82 lines
1.7 KiB
C
82 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* HSM extension and cpu_ops implementation.
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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/init.h>
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#include <linux/mm.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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extern char secondary_start_sbi[];
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const struct cpu_operations cpu_ops_sbi;
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static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
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unsigned long priv)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
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hartid, saddr, priv, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return 0;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static int sbi_hsm_hart_stop(void)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return 0;
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}
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static int sbi_hsm_hart_get_status(unsigned long hartid)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
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hartid, 0, 0, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return ret.value;
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}
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#endif
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static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
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{
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int rc;
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unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
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int hartid = cpuid_to_hartid_map(cpuid);
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cpu_update_secondary_bootdata(cpuid, tidle);
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rc = sbi_hsm_hart_start(hartid, boot_addr, 0);
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return rc;
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}
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static int sbi_cpu_prepare(unsigned int cpuid)
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{
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if (!cpu_ops_sbi.cpu_start) {
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pr_err("cpu start method not defined for CPU [%d]\n", cpuid);
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return -ENODEV;
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}
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return 0;
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}
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const struct cpu_operations cpu_ops_sbi = {
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.name = "sbi",
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.cpu_prepare = sbi_cpu_prepare,
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.cpu_start = sbi_cpu_start,
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};
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