From: Len Brown <len.brown@intel.com>
Date: Fri, 19 Sep 2025 18:07:02 +0000 (-0400)
Subject: tools/power x86_energy_perf_policy: Enhance HWP enable
X-Git-Tag: v5.4.302~140
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3c37caffe38194283c44e60925e82e2b350f8007;p=thirdparty%2Fkernel%2Fstable.git

tools/power x86_energy_perf_policy: Enhance HWP enable

[ Upstream commit c97c057d357c4b39b153e9e430bbf8976e05bd4e ]

On enabling HWP, preserve the reserved bits in MSR_PM_ENABLE.

Also, skip writing the MSR_PM_ENABLE if HWP is already enabled.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
index 165eb4da8a644..0cb17e13c002b 100644
--- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
+++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
@@ -1024,13 +1024,18 @@ int update_hwp_request_pkg(int pkg)
 
 int enable_hwp_on_cpu(int cpu)
 {
-	unsigned long long msr;
+	unsigned long long old_msr, new_msr;
+
+	get_msr(cpu, MSR_PM_ENABLE, &old_msr);
+
+	if (old_msr & 1)
+		return 0;	/* already enabled */
 
-	get_msr(cpu, MSR_PM_ENABLE, &msr);
-	put_msr(cpu, MSR_PM_ENABLE, 1);
+	new_msr = old_msr | 1;
+	put_msr(cpu, MSR_PM_ENABLE, new_msr);
 
 	if (verbose)
-		printf("cpu%d: MSR_PM_ENABLE old: %d new: %d\n", cpu, (unsigned int) msr, 1);
+		printf("cpu%d: MSR_PM_ENABLE old: %llX new: %llX\n", cpu, old_msr, new_msr);
 
 	return 0;
 }