Re: [PATCH 17/19] arm64: smp: Pass secondary CPU boot parameters via firmware if possible

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/9/8 0:40, Will Deacon 写道:
> In preparation for parallel bringup of secondary CPUs, the global
> 'secondary_data' structure used for initial paramater passing must be
> localised.
> 
> Pass the idle 'task_struct' pointer for secondary CPUs directly to
> ->cpu_boot() if the backend supports it.
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>

> 
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/include/asm/smp.h |  1 +
>  arch/arm64/kernel/head.S     | 12 +++++++++++-
>  arch/arm64/kernel/psci.c     |  4 ++--
>  arch/arm64/kernel/smp.c      | 25 +++++++++++--------------
>  4 files changed, 25 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
> index 7b986a6a765b..7f2cd84b7785 100644
> --- a/arch/arm64/include/asm/smp.h
> +++ b/arch/arm64/include/asm/smp.h
> @@ -95,6 +95,7 @@ struct secondary_data {
>  extern struct secondary_data secondary_data;
>  extern long __early_cpu_boot_status;
>  extern void secondary_entry(void);
> +extern void secondary_entry_with_arg(void);
>  
>  extern void arch_send_call_function_single_ipi(int cpu);
>  extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 87a822e5c4ca..17868b497d7c 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -335,6 +335,7 @@ SYM_FUNC_END(init_kernel_el)
>  	 * cores are held until we're ready for them to initialise.
>  	 */
>  SYM_FUNC_START(secondary_holding_pen)
> +	mov	x19, xzr
>  	mov	x0, xzr
>  	bl	init_kernel_el			// w0=cpu_boot_mode
>  	mrs	x2, mpidr_el1
> @@ -353,10 +354,16 @@ SYM_FUNC_END(secondary_holding_pen)
>  	 * be used where CPUs are brought online dynamically by the kernel.
>  	 */
>  SYM_FUNC_START(secondary_entry)
> +	mov	x0, xzr
> +	b	secondary_entry_with_arg
> +SYM_FUNC_END(secondary_entry)
> +
> +SYM_FUNC_START(secondary_entry_with_arg)
> +	mov	x19, x0
>  	mov	x0, xzr
>  	bl	init_kernel_el			// w0=cpu_boot_mode
>  	b	secondary_startup
> -SYM_FUNC_END(secondary_entry)
> +SYM_FUNC_END(secondary_entry_with_arg)
>  
>  SYM_FUNC_START_LOCAL(secondary_startup)
>  	/*
> @@ -391,10 +398,13 @@ SYM_FUNC_START_LOCAL(__secondary_switched)
>  	msr	vbar_el1, x5
>  	isb
>  
> +	mov	x2, x19
> +	cbnz	x2, 1f
>  	adr_l	x0, secondary_data
>  	ldr	x2, [x0, #CPU_BOOT_TASK]
>  	cbz	x2, __secondary_too_slow
>  
> +1:
>  	init_cpu_task x2, x1, x3
>  
>  #ifdef CONFIG_ARM64_PTR_AUTH
> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
> index 3ba4fa14b9e3..c13e635e8a11 100644
> --- a/arch/arm64/kernel/psci.c
> +++ b/arch/arm64/kernel/psci.c
> @@ -38,8 +38,8 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu)
>  
>  static int cpu_psci_cpu_boot(unsigned int cpu, unsigned long context)
>  {
> -	phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
> -	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry,
> +	void *entry_va = context ? secondary_entry_with_arg : secondary_entry;
> +	int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(entry_va),
>  				  context);
>  	if (err && err != -EPERM)
>  		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index b57f8f752f78..95d5328c3f5a 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -93,34 +93,31 @@ static inline int op_cpu_kill(unsigned int cpu)
>  }
>  #endif
>  
> -
>  /*
>   * Boot a secondary CPU, and assign it the specified idle task.
>   * This also gives us the initial stack to use for this CPU.
>   */
> -static int boot_secondary(unsigned int cpu, struct task_struct *idle)
> -{
> -	const struct cpu_operations *ops = get_secondary_cpu_ops();
> -
> -	if (ops->cpu_boot)
> -		return ops->cpu_boot(cpu, 0);
> -
> -	return -EOPNOTSUPP;
> -}
> -
>  int arch_cpuhp_kick_ap_alive(unsigned int cpu, struct task_struct *idle)
>  {
> -	int ret;
> +	const struct cpu_operations *ops = get_secondary_cpu_ops();
> +	int ret = -EOPNOTSUPP;
> +	void *arg = NULL;
>  
>  	/*
>  	 * We need to tell the secondary core where to find its stack and the
>  	 * page tables.
>  	 */
> -	secondary_data.task = idle;
> +	if (ops->cpu_boot_has_arg && ops->cpu_boot_has_arg())
> +		arg = idle;
> +	else
> +		secondary_data.task = idle;
> +
>  	update_cpu_boot_status(CPU_MMU_OFF);
>  
>  	/* Now bring the CPU into our world */
> -	ret = boot_secondary(cpu, idle);
> +	if (ops->cpu_boot)
> +		ret = ops->cpu_boot(cpu, (unsigned long)arg);
> +
>  	if (ret && ret != -EPERM)
>  		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
>  	return ret;