This is a note to let you know that I've just added the patch titled
ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
acpi-cppc-don-t-require-_osc-if-x86_feature_cppc-is-.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 119915e9746c76a142be4e1c2625ee5e38f20510
Author: Mario Limonciello <mario.limonciello@xxxxxxx>
Date: Tue Jul 5 13:29:15 2022 -0500
ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported
[ Upstream commit 8b356e536e69f3a4d6778ae9f0858a1beadabb1f ]
commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
when CPPC_LIB is supported") added support for claiming to
support CPPC in _OSC on non-Intel platforms.
This unfortunately caused a regression on a vartiety of AMD
platforms in the field because a number of AMD platforms don't set
the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
As these AMD platforms already claim CPPC support via a dedicated
MSR from `X86_FEATURE_CPPC`, use this enable this feature rather
than requiring the `_OSC` on platforms with a dedicated MSR.
If there is additional breakage on the shared memory designs also
missing this _OSC, additional follow up changes may be needed.
Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Reported-by: Perry Yuan <perry.yuan@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
index df1644d9b3b6..3677df836e91 100644
--- a/arch/x86/kernel/acpi/cppc.c
+++ b/arch/x86/kernel/acpi/cppc.c
@@ -11,6 +11,16 @@
/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
+bool cpc_supported_by_cpu(void)
+{
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ case X86_VENDOR_HYGON:
+ return boot_cpu_has(X86_FEATURE_CPPC);
+ }
+ return false;
+}
+
bool cpc_ffh_supported(void)
{
return true;
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6aff8019047b..57ca7aa0e169 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -559,6 +559,19 @@ bool __weak cpc_ffh_supported(void)
return false;
}
+/**
+ * cpc_supported_by_cpu() - check if CPPC is supported by CPU
+ *
+ * Check if the architectural support for CPPC is present even
+ * if the _OSC hasn't prescribed it
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_supported_by_cpu(void)
+{
+ return false;
+}
+
/**
* pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
*
@@ -668,7 +681,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
if (!osc_sb_cppc2_support_acked) {
pr_debug("CPPC v2 _OSC not acked\n");
- return -ENODEV;
+ if (!cpc_supported_by_cpu())
+ return -ENODEV;
}
/* Parse the ACPI _CPC table for this CPU. */
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 92b7ea8d8f5e..181907349b49 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -144,6 +144,7 @@ extern bool acpi_cpc_valid(void);
extern int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data);
extern unsigned int cppc_get_transition_latency(int cpu);
extern bool cpc_ffh_supported(void);
+extern bool cpc_supported_by_cpu(void);
extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
#else /* !CONFIG_ACPI_CPPC_LIB */
