[PATCH v7 12/16] arm64: psci: Ignore DENIED CPUs

[Jonathan Cameron]

On Thu, 18 Apr 2024 14:54:08 +0100
Jonathan Cameron <Jonathan.Cameron at huawei.com> wrote:

> From: Jean-Philippe Brucker <jean-philippe at linaro.org>
> 
> When a CPU is marked as disabled, but online capable in the MADT, PSCI
> applies some firmware policy to control when it can be brought online.
> PSCI returns DENIED to a CPU_ON request if this is not currently
> permitted. The OS can learn the current policy from the _STA enabled bit.
> 
> Handle the PSCI DENIED return code gracefully instead of printing an
> error.
> 
> See https://developer.arm.com/documentation/den0022/f/?lang=en page 58.
> 
> Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
> [ morse: Rewrote commit message ]
> Signed-off-by: James Morse <james.morse at arm.com>
> Tested-by: Miguel Luis <miguel.luis at oracle.com>
> Tested-by: Vishnu Pajjuri <vishnu at os.amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu at arm.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>

Focus until now as ACPI side of things (hopefully we are now close on that)
but upshot is we failed to +CC some other relevant maintainers.

+CC Mark and Lorenzo - Not 100% sure who is right person for this, but
PSCI in general seems to be your problem.


> ---
> v7: No change
> ---
>  arch/arm64/kernel/psci.c | 2 +-
>  arch/arm64/kernel/smp.c  | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
> index 29a8e444db83..fabd732d0a2d 100644
> --- a/arch/arm64/kernel/psci.c
> +++ b/arch/arm64/kernel/psci.c
> @@ -40,7 +40,7 @@ static int cpu_psci_cpu_boot(unsigned int cpu)
>  {
>  	phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
>  	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);
> -	if (err)
> +	if (err && err != -EPERM)
>  		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
>  
>  	return err;
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 4ced34f62dab..dc0e0b3ec2d4 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -132,7 +132,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
>  	/* Now bring the CPU into our world */
>  	ret = boot_secondary(cpu, idle);
>  	if (ret) {
> -		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
> +		if (ret != -EPERM)
> +			pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
>  		return ret;
>  	}
>