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Date: Fri, 15 Dec 2023 16:18:03 +0000
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
CC: <linux-pm@vger.kernel.org>, <loongarch@lists.linux.dev>,
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	<salil.mehta@huawei.com>, Jean-Philippe Brucker <jean-philippe@linaro.org>,
	<jianyong.wu@arm.com>, <justin.he@arm.com>, James Morse <james.morse@arm.com>
Subject: Re: [PATCH RFC v3 10/21] ACPI: Check _STA present bit before making
 CPUs not present
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On Wed, 13 Dec 2023 12:50:02 +0000
Russell King (Oracle) <rmk+kernel@armlinux.org.uk> wrote:

> From: James Morse <james.morse@arm.com>
> 
> When called acpi_processor_post_eject() unconditionally make a CPU
> not-present and unregisters it.
> 
> To add support for AML events where the CPU has become disabled, but
> remains present, the _STA method should be checked before calling
> acpi_processor_remove().
> 
> Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and
> check the _STA before calling.
> 
> Adding the function prototype for arch_unregister_cpu() allows the
> preprocessor guards to be removed.
> 
> After this change CPUs will remain registered and visible to
> user-space as offline if buggy firmware triggers an eject-request,
> but doesn't clear the corresponding _STA bits after _EJ0 has been
> called.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: Miguel Luis <miguel.luis@oracle.com>
> Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu@arm.com>
LGTM
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>