linux-kernel - Re: [PATCH v7 12/16] arm64: psci: Ignore DENIED CPUs

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Message-ID: <20240422114445.00003047@Huawei.com>
Date: Mon, 22 Apr 2024 11:44:45 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra
	<peterz@...radead.org>, <linux-pm@...r.kernel.org>,
	<loongarch@...ts.linux.dev>, <linux-acpi@...r.kernel.org>,
	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
	<x86@...nel.org>, Russell King <linux@...linux.org.uk>, "Rafael J . Wysocki"
	<rafael@...nel.org>, Miguel Luis <miguel.luis@...cle.com>, "James Morse"
	<james.morse@....com>, Salil Mehta <salil.mehta@...wei.com>, Jean-Philippe
 Brucker <jean-philippe@...aro.org>, Catalin Marinas
	<catalin.marinas@....com>, Will Deacon <will@...nel.org>, Mark Rutland
	<mark.rutland@....com>, Lorenzo Pieralisi <lpieralisi@...nel.org>,
	<linuxarm@...wei.com>
CC: Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "Dave
 Hansen" <dave.hansen@...ux.intel.com>, <justin.he@....com>,
	<jianyong.wu@....com>
Subject: Re: [PATCH v7 12/16] arm64: psci: Ignore DENIED CPUs

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

> From: Jean-Philippe Brucker <jean-philippe@...aro.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@...aro.org>
> [ morse: Rewrote commit message ]
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Miguel Luis <miguel.luis@...cle.com>
> Tested-by: Vishnu Pajjuri <vishnu@...amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.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;
>  	}
>