linux-kernel - [PATCH 5.18 224/231] ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory

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Date:   Tue, 19 Jul 2022 13:55:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mario Limonciello <mario.limonciello@....com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Oleksandr Natalenko <oleksandr@...alenko.name>
Subject: [PATCH 5.18 224/231] ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory

From: Mario Limonciello <mario.limonciello@....com>

commit fbd74d16890b9f5d08ea69b5282b123c894f8860 upstream.

When commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all
and when CPPC_LIB is supported") was introduced, we found collateral
damage that a number of AMD systems that supported CPPC but
didn't advertise support in _OSC stopped having a functional
amd-pstate driver. The _OSC was only enforced on Intel systems at that
time.

This was fixed for the MSR based designs by commit 8b356e536e69f
("ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported")
but some shared memory based designs also support CPPC but haven't
advertised support in the _OSC.  Add support for those designs as well by
hardcoding the list of systems.

Fixes: 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Fixes: 8b356e536e69f ("ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported")
Link: https://lore.kernel.org/all/3559249.JlDtxWtqDm@natalenko.name/
Cc: 5.18+ <stable@...r.kernel.org> # 5.18+
Reported-and-tested-by: Oleksandr Natalenko <oleksandr@...alenko.name>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/acpi/cppc.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/x86/kernel/acpi/cppc.c
+++ b/arch/x86/kernel/acpi/cppc.c
@@ -16,6 +16,12 @@ bool cpc_supported_by_cpu(void)
 	switch (boot_cpu_data.x86_vendor) {
 	case X86_VENDOR_AMD:
 	case X86_VENDOR_HYGON:
+		if (boot_cpu_data.x86 == 0x19 && ((boot_cpu_data.x86_model <= 0x0f) ||
+		    (boot_cpu_data.x86_model >= 0x20 && boot_cpu_data.x86_model <= 0x2f)))
+			return true;
+		else if (boot_cpu_data.x86 == 0x17 &&
+			 boot_cpu_data.x86_model >= 0x70 && boot_cpu_data.x86_model <= 0x7f)
+			return true;
 		return boot_cpu_has(X86_FEATURE_CPPC);
 	}
 	return false;