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cpufreq: amd-pstate: cpufreq: amd-pstate: reset MSR_AMD_PERF_CTL register at init

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MSR_AMD_PERF_CTL is guaranteed to be 0 on a cold boot. However, on a
kexec boot, for instance, it may have a non-zero value (if the cpu was
in a non-P0 Pstate).  In such cases, the cores with non-P0 Pstates at
boot will never be pushed to P0, let alone boost frequencies.

Kexec is a common workflow for reboot on Linux and this creates a
regression in performance. Fix it by explicitly setting the
MSR_AMD_PERF_CTL to 0 during amd_pstate driver init.

Cc: All applicable <stable@vger.kernel.org>
Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Wyes Karny 2022-11-17 15:35:37 +08:00 committed by Rafael J. Wysocki
parent cdcc5ef26b
commit 919f455769
1 changed files with 10 additions and 0 deletions
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10
drivers/cpufreq/amd-pstate.c
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@ -424,12 +424,22 @@ static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
amd_pstate_driver.boost_enabled = true; amd_pstate_driver.boost_enabled = true;
} }
static void amd_perf_ctl_reset(unsigned int cpu)
{
wrmsrl_on_cpu(cpu, MSR_AMD_PERF_CTL, 0);
}
static int amd_pstate_cpu_init(struct cpufreq_policy *policy) static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
{ {
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret; int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
struct device *dev; struct device *dev;
struct amd_cpudata *cpudata; struct amd_cpudata *cpudata;
/*
* Resetting PERF_CTL_MSR will put the CPU in P0 frequency,
* which is ideal for initialization process.
*/
amd_perf_ctl_reset(policy->cpu);
dev = get_cpu_device(policy->cpu); dev = get_cpu_device(policy->cpu);
if (!dev) if (!dev)
return -ENODEV; return -ENODEV;