* [PATCH] ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory
@ 2022-07-13 17:53 Mario Limonciello
2022-07-13 19:15 ` Rafael J. Wysocki
0 siblings, 1 reply; 2+ messages in thread
From: Mario Limonciello @ 2022-07-13 17:53 UTC (permalink / raw
To: mario.limonciello, Rafael J. Wysocki, Len Brown, Pavel Machek,
Sudeep Holla, Pierre Gondois
Cc: perry.yuan, ray.huang, stable, Oleksandr Natalenko,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
H. Peter Anvin, linux-pm, linux-kernel
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: stable@vger.kernel.org # 5.18
Reported-and-tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
arch/x86/kernel/acpi/cppc.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
index 734b96454896..8d8752b44f11 100644
--- 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;
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory
2022-07-13 17:53 [PATCH] ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory Mario Limonciello
@ 2022-07-13 19:15 ` Rafael J. Wysocki
0 siblings, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2022-07-13 19:15 UTC (permalink / raw
To: Mario Limonciello
Cc: Rafael J. Wysocki, Len Brown, Pavel Machek, Sudeep Holla,
Pierre Gondois, Yuan, Perry, Huang Rui, Stable,
Oleksandr Natalenko, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, the arch/x86 maintainers,
H. Peter Anvin, Linux PM, Linux Kernel Mailing List
On Wed, Jul 13, 2022 at 7:54 PM Mario Limonciello
<mario.limonciello@amd.com> wrote:
>
> 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: stable@vger.kernel.org # 5.18
> Reported-and-tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> arch/x86/kernel/acpi/cppc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
> index 734b96454896..8d8752b44f11 100644
> --- 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;
> --
Applied as 5.19-rc material, thanks!
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2022-07-13 19:15 ` Rafael J. Wysocki
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