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From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
To: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>, Catalin
 Marinas <catalin.marinas@arm.com>, <linux-acpi@vger.kernel.org>,
	<linux-arch@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <linux-pm@vger.kernel.org>
CC: Mark Rutland <mark.rutland@arm.com>, Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>, <loongarch@lists.linux.dev>,
	<x86@kernel.org>, Russell King <linux@armlinux.org.uk>, "Rafael J . Wysocki"
	<rafael@kernel.org>, Miguel Luis <miguel.luis@oracle.com>, James Morse
	<james.morse@arm.com>, Salil Mehta <salil.mehta@huawei.com>, Jean-Philippe
 Brucker <jean-philippe@linaro.org>, Hanjun Guo <guohanjun@huawei.com>, Gavin
 Shan <gshan@redhat.com>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov
	<bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>,
	<linuxarm@huawei.com>, <justin.he@arm.com>, <jianyong.wu@arm.com>
Subject: [PATCH v10 17/19] arm64: Kconfig: Enable hotplug CPU on arm64 if ACPI_PROCESSOR is enabled.
Date: Wed, 29 May 2024 14:34:44 +0100
Message-ID: <20240529133446.28446-18-Jonathan.Cameron@huawei.com>
In-Reply-To: <20240529133446.28446-1-Jonathan.Cameron@huawei.com>
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In order to move arch_register_cpu() to be called via the same path
for initially present CPUs described by ACPI and hotplugged CPUs
ACPI_HOTPLUG_CPU needs to be enabled.

The protection against invalid IDs in acpi_map_cpu() is needed as
at least one production BIOS is in the wild which reports entries
in DSDT (with no _STA method, so assumed enabled and present)
that don't match MADT.

Tested-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 arch/arm64/Kconfig       |  1 +
 arch/arm64/kernel/acpi.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5d91259ee7b5..e8f2ef2312db 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -5,6 +5,7 @@ config ARM64
 	select ACPI_CCA_REQUIRED if ACPI
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_GTDT if ACPI
+	select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR
 	select ACPI_IORT if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
 	select ACPI_MCFG if (ACPI && PCI)
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index e0e7b93c16cc..9360ba86678b 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -30,6 +30,7 @@
 #include <linux/pgtable.h>
 
 #include <acpi/ghes.h>
+#include <acpi/processor.h>
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
 #include <asm/daifflags.h>
@@ -423,6 +424,27 @@ void arch_reserve_mem_area(acpi_physical_address addr, size_t size)
 	memblock_mark_nomap(addr, size);
 }
 
+#ifdef CONFIG_ACPI_HOTPLUG_CPU
+int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 apci_id,
+		 int *pcpu)
+{
+	/* If an error code is passed in this stub can't fix it */
+	if (*pcpu < 0) {
+		pr_warn_once("Unable to map CPU to valid ID\n");
+		return *pcpu;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(acpi_map_cpu);
+
+int acpi_unmap_cpu(int cpu)
+{
+	return 0;
+}
+EXPORT_SYMBOL(acpi_unmap_cpu);
+#endif /* CONFIG_ACPI_HOTPLUG_CPU */
+
 #ifdef CONFIG_ACPI_FFH
 /*
  * Implements ARM64 specific callbacks to support ACPI FFH Operation Region as
-- 
2.39.2