linux-kernel - [PATCH v5 03/18] ACPI: processor: Register deferred CPUs from acpi_processor_get

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Date: Fri, 12 Apr 2024 15:37:04 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: <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>
CC: <linuxarm@...wei.com>, <justin.he@....com>, <jianyong.wu@....com>
Subject: [PATCH v5 03/18] ACPI: processor: Register deferred CPUs from acpi_processor_get_info()

From: James Morse <james.morse@....com>

The arm64 specific arch_register_cpu() call may defer CPU registration
until the ACPI interpreter is available and the _STA method can
be evaluated.

If this occurs, then a second attempt is made in
acpi_processor_get_info(). Note that the arm64 specific call has
not yet been added so for now this will never be successfully
called.

Systems can still be booted with 'acpi=off', or not include an
ACPI description at all as in these cases arch_register_cpu()
will not have deferred registration when first called.

This moves the CPU register logic back to a subsys_initcall(),
while the memory nodes will have been registered earlier.
Note this is where the call was prior to the cleanup series so
there should be no side effects of moving it back again for this
specific case.

[PATCH 00/21] Initial cleanups for vCPU HP.
https://lore.kernel.org/all/ZVyz%2FVe5pPu8AWoA@shell.armlinux.org.uk/

e.g. 5b95f94c3b9f ("x86/topology: Switch over to GENERIC_CPU_DEVICES")

Signed-off-by: James Morse <james.morse@....com>
Reviewed-by: Gavin Shan <gshan@...hat.com>
Tested-by: Miguel Luis <miguel.luis@...cle.com>
Tested-by: Vishnu Pajjuri <vishnu@...amperecomputing.com>
Tested-by: Jianyong Wu <jianyong.wu@....com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
Co-developed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Joanthan Cameron <Jonathan.Cameron@...wei.com>
---
v5: Update commit message to make it clear this is moving the
    init back to where it was until very recently.

    No longer change the condition in the earlier registration point
    as that will be handled by the arm64 registration routine
    deferring until called again here.
---
 drivers/acpi/acpi_processor.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 93e029403d05..c78398cdd060 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -317,6 +317,18 @@ static int acpi_processor_get_info(struct acpi_device *device)
 
 	c = &per_cpu(cpu_devices, pr->id);
 	ACPI_COMPANION_SET(&c->dev, device);
+	/*
+	 * Register CPUs that are present. get_cpu_device() is used to skip
+	 * duplicate CPU descriptions from firmware.
+	 */
+	if (!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) &&
+	    !get_cpu_device(pr->id)) {
+		int ret = arch_register_cpu(pr->id);
+
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 *  Extra Processor objects may be enumerated on MP systems with
 	 *  less than the max # of CPUs. They should be ignored _iff
-- 
2.39.2