Re: [PATCH 16/19] arm64: cpu_ops: Expose optional argument to target cpu in ->cpu_boot()

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/9/8 0:40, Will Deacon 写道:
> Some backend implementations of 'struct cpu_ops', notably PSCI v0.2+,
> allow an optional argument to be passed in register X0 to the target
> CPU during boot.
> 
> Expose this functionality by extending the ->cpu_boot() CPU operation
> to take an additional argument which is ignored unless the new optional
> ->cpu_boot_has_arg() callback is present and returns 'true'. For now,
> we continue to pass zero.
> 
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/include/asm/cpu_ops.h          |  6 +++++-
>  arch/arm64/kernel/acpi_parking_protocol.c |  3 ++-
>  arch/arm64/kernel/psci.c                  | 11 +++++++++--
>  arch/arm64/kernel/smp.c                   |  2 +-
>  arch/arm64/kernel/smp_spin_table.c        |  2 +-
>  5 files changed, 18 insertions(+), 6 deletions(-)

Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>

> 
> diff --git a/arch/arm64/include/asm/cpu_ops.h b/arch/arm64/include/asm/cpu_ops.h
> index cd298a8710d8..e7662a1879d9 100644
> --- a/arch/arm64/include/asm/cpu_ops.h
> +++ b/arch/arm64/include/asm/cpu_ops.h
> @@ -21,6 +21,9 @@
>   *		mechanism for doing so, tests whether it is possible to boot
>   *		the given CPU.
>   * @cpu_boot:	Boots a cpu into the kernel.
> + * @cpu_boot_has_arg: Optionally determines whether @cpu_boot passes its
> + *		      (non-zero) second argument to the booting CPU in
> + *		      register x0.
>   * @cpu_postboot: Optionally, perform any post-boot cleanup or necessary
>   *		synchronisation. Called from the cpu being booted.
>   * @cpu_can_disable: Determines whether a CPU can be disabled based on
> @@ -36,7 +39,8 @@ struct cpu_operations {
>  	const char	*name;
>  	int		(*cpu_init)(unsigned int);
>  	int		(*cpu_prepare)(unsigned int);
> -	int		(*cpu_boot)(unsigned int);
> +	int		(*cpu_boot)(unsigned int, unsigned long);
> +	bool		(*cpu_boot_has_arg)(void);
>  	void		(*cpu_postboot)(void);
>  #ifdef CONFIG_HOTPLUG_CPU
>  	bool		(*cpu_can_disable)(unsigned int cpu);
> diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c
> index e1be29e608b7..24ebde1241bf 100644
> --- a/arch/arm64/kernel/acpi_parking_protocol.c
> +++ b/arch/arm64/kernel/acpi_parking_protocol.c
> @@ -56,7 +56,8 @@ static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
>  	return 0;
>  }
>  
> -static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
> +static int acpi_parking_protocol_cpu_boot(unsigned int cpu,
> +					  unsigned long ignored)
>  {
>  	struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
>  	struct parking_protocol_mailbox __iomem *mailbox;
> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
> index 6b25a12ed143..3ba4fa14b9e3 100644
> --- a/arch/arm64/kernel/psci.c
> +++ b/arch/arm64/kernel/psci.c
> @@ -36,16 +36,22 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu)
>  	return 0;
>  }
>  
> -static int cpu_psci_cpu_boot(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, 0);
> +	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry,
> +				  context);
>  	if (err && err != -EPERM)
>  		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
>  
>  	return err;
>  }
>  
> +static bool cpu_psci_cpu_boot_has_context(void)
> +{
> +	return psci_ops.get_version() >= PSCI_VERSION(0, 2);
> +}
> +
>  #ifdef CONFIG_HOTPLUG_CPU
>  static bool cpu_psci_cpu_can_disable(unsigned int cpu)
>  {
> @@ -114,6 +120,7 @@ const struct cpu_operations cpu_psci_ops = {
>  	.cpu_init	= cpu_psci_cpu_init,
>  	.cpu_prepare	= cpu_psci_cpu_prepare,
>  	.cpu_boot	= cpu_psci_cpu_boot,
> +	.cpu_boot_has_arg = cpu_psci_cpu_boot_has_context,
>  #ifdef CONFIG_HOTPLUG_CPU
>  	.cpu_can_disable = cpu_psci_cpu_can_disable,
>  	.cpu_disable	= cpu_psci_cpu_disable,
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 2e98a92eb764..b57f8f752f78 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -103,7 +103,7 @@ 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);
> +		return ops->cpu_boot(cpu, 0);
>  
>  	return -EOPNOTSUPP;
>  }
> diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
> index 49029eace3ad..a5e6f444c25f 100644
> --- a/arch/arm64/kernel/smp_spin_table.c
> +++ b/arch/arm64/kernel/smp_spin_table.c
> @@ -104,7 +104,7 @@ static int smp_spin_table_cpu_prepare(unsigned int cpu)
>  	return 0;
>  }
>  
> -static int smp_spin_table_cpu_boot(unsigned int cpu)
> +static int smp_spin_table_cpu_boot(unsigned int cpu, unsigned long ignored)
>  {
>  	/*
>  	 * Update the pen release flag.