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authorWyes Karny <wyes.karny@amd.com>2022-11-17 15:35:37 +0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2022-11-22 19:57:14 +0100
commit919f4557696939625085435ebde09a539de2349c (patch)
tree02bf191d46ee888ab41ffa7ed2b33c35090f2cae
parentcdcc5ef26b39c3d02d4e69c0352b007ebe438a22 (diff)
downloadlinux-919f4557696939625085435ebde09a539de2349c.tar.bz2
cpufreq: amd-pstate: cpufreq: amd-pstate: reset MSR_AMD_PERF_CTL register at init
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>
-rw-r--r--drivers/cpufreq/amd-pstate.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index ace7d50cf2ac..d844c6f97caf 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -424,12 +424,22 @@ static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
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)
{
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
struct device *dev;
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);
if (!dev)
return -ENODEV;