ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory

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@vger.kernel.org> # 5.18+
Reported-and-tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
index 734b964..8d8752b 100644 (file)
--- 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;