Re: [PATCH RFC v3 16/21] arm64: psci: Ignore DENIED CPUs

Jonathan Cameron <[email protected]> Fri, 15 Dec 2023 16:40:27 +0000
Newsgroups org.kernel.vger.linux-ia64,dev.linux.lists.acpica-devel,dev.linux.lists.kvmarm,dev.linux.lists.loongarch,org.infradead.lists.linux-arm-kernel,org.infradead.lists.linux-riscv,org.kernel.vger.linux-acpi,org.kernel.vger.linux-arch,org.kernel.vger.linux-csky,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel,org.kernel.vger.linux-parisc,org.kernel.vger.linux-pm
Organization Huawei Technologies Research and Development (UK) Ltd.
Message-ID <[email protected]>
On Wed, 13 Dec 2023 12:50:33 +0000
Russell King (Oracle) <[email protected]> wrote:

> From: Jean-Philippe Brucker <[email protected]>
> 
> 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 <[email protected]>
> [ morse: Rewrote commit message ]
> Signed-off-by: James Morse <[email protected]>
> Tested-by: Miguel Luis <[email protected]>
> Tested-by: Vishnu Pajjuri <[email protected]>
> Tested-by: Jianyong Wu <[email protected]>
> Signed-off-by: Russell King (Oracle) <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>