linux/arch/x86/kernel/acpi/cppc.c
Mario Limonciello fbd74d1689 ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory
When commit 72f2ecb7ec ("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 8b356e536e
("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: 72f2ecb7ec ("ACPI: bus: Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Fixes: 8b356e536e ("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>
2022-07-13 21:13:14 +02:00

119 lines
2.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* cppc.c: CPPC Interface for x86
* Copyright (c) 2016, Intel Corporation.
*/
#include <acpi/cppc_acpi.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/topology.h>
/* 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:
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;
}
bool cpc_ffh_supported(void)
{
return true;
}
int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
{
int err;
err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
if (!err) {
u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
reg->bit_offset);
*val &= mask;
*val >>= reg->bit_offset;
}
return err;
}
int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
{
u64 rd_val;
int err;
err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
if (!err) {
u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
reg->bit_offset);
val <<= reg->bit_offset;
val &= mask;
rd_val &= ~mask;
rd_val |= val;
err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
}
return err;
}
static void amd_set_max_freq_ratio(void)
{
struct cppc_perf_caps perf_caps;
u64 highest_perf, nominal_perf;
u64 perf_ratio;
int rc;
rc = cppc_get_perf_caps(0, &perf_caps);
if (rc) {
pr_debug("Could not retrieve perf counters (%d)\n", rc);
return;
}
highest_perf = amd_get_highest_perf();
nominal_perf = perf_caps.nominal_perf;
if (!highest_perf || !nominal_perf) {
pr_debug("Could not retrieve highest or nominal performance\n");
return;
}
perf_ratio = div_u64(highest_perf * SCHED_CAPACITY_SCALE, nominal_perf);
/* midpoint between max_boost and max_P */
perf_ratio = (perf_ratio + SCHED_CAPACITY_SCALE) >> 1;
if (!perf_ratio) {
pr_debug("Non-zero highest/nominal perf values led to a 0 ratio\n");
return;
}
freq_invariance_set_perf_ratio(perf_ratio, false);
}
static DEFINE_MUTEX(freq_invariance_lock);
void init_freq_invariance_cppc(void)
{
static bool init_done;
if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
return;
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
return;
mutex_lock(&freq_invariance_lock);
if (!init_done)
amd_set_max_freq_ratio();
init_done = true;
mutex_unlock(&freq_invariance_lock);
}