From: Len Brown <lenb@kernel.org>
To: linux-pm@vger.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@intel.com>,
Len Brown <len.brown@intel.com>
Subject: [PATCH 02/18] x86_energy_perf_policy: Enhance MSR probe
Date: Mon, 19 Oct 2026 12:43:23 -0400 [thread overview]
Message-ID: <8a047427531a00a7ceeaa389657c2d7bd1e2dbf4.1792428130.git.len.brown@intel.com> (raw)
In-Reply-To: <e160a0ae497702e1c32ab163faa63c0043ea9298.1792428130.git.len.brown@intel.com>
From: Len Brown <len.brown@intel.com>
If Linux MSR driver isn't running,
modprobe and try the Linux path again.
If still no joy, try Android path.
Signed-off-by: Len Brown <len.brown@intel.com>
---
.../x86_energy_perf_policy.c | 40 ++++++++++++-------
1 file changed, 26 insertions(+), 14 deletions(-)
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 a963c0430794..abd3cf2fdd39 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
@@ -15,6 +15,7 @@
#include <sys/types.h>
#include <sched.h>
#include <sys/stat.h>
+#include <sys/wait.h>
#include <sys/resource.h>
#include <getopt.h>
#include <err.h>
@@ -1611,30 +1612,41 @@ void set_base_cpu(void)
err(-ENODEV, "No valid cpus found");
}
-static void probe_android_msr_path(void)
+/* return 0 if path exists */
+static int check_msr_path(void)
{
struct stat sb;
- set_msr_path(base_cpu); /* called with use_android_path = 0, to probe Linux path */
- if (stat(msr_path, &sb))
- use_android_msr_path = 1;
+ return stat(msr_path, &sb);
}
+/*
+ * Check Linux MSR path
+ * If it fails, try modprobe and check it again
+ * If still no joy, enable Android path and try again
+ */
void probe_dev_msr(void)
{
- struct stat sb;
+ int retval;
+
+ use_android_msr_path = 0;
+ set_msr_path(base_cpu);
+ if (check_msr_path() == 0)
+ return;
- probe_android_msr_path();
+ retval = system("/sbin/modprobe msr > /dev/null 2>&1");
+ if (check_msr_path() == 0)
+ return;
+
+ use_android_msr_path = 1;
set_msr_path(base_cpu);
- if (stat(msr_path, &sb)) {
- if (system("/sbin/modprobe msr > /dev/null 2>&1")) {
- if (use_android_msr_path)
- err(-5, "no /dev/msr0, Try \"# modprobe msr\" ");
- else
- err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
- }
- }
+ if (check_msr_path() == 0)
+ return;
+
+ if (WIFEXITED(retval))
+ retval = WEXITSTATUS(retval);
+ err(-1, "\"msr\" driver support required, modprobe msr returned %d", retval);
}
static void get_cpuid_or_exit(unsigned int leaf, unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx)
--
2.45.2
next prev parent reply other threads:[~2026-10-19 16:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-19 16:43 [PATCH 0/18] x86_energy_perf_policy cleanups Len Brown
2026-10-19 16:43 ` [PATCH 01/18] x86_energy_perf_policy: Create msr_path helper Len Brown
2026-10-19 16:43 ` Len Brown [this message]
2026-10-19 16:43 ` [PATCH 03/18] x86_energy_perf_policy: Prevent unlikely buffer overflow Len Brown
2026-10-19 16:43 ` [PATCH 04/18] x86_energy_perf_policy: Cleanup: Harden with strtol() Len Brown
2026-10-19 16:43 ` [PATCH 05/18] x86_energy_perf_policy: Cleanup: Use snprintf() for platform-profile Len Brown
2026-10-19 16:43 ` [PATCH 06/18] x86_energy_perf_policy: Fix optarg keyword matching Len Brown
2026-10-19 16:43 ` [PATCH 07/18] x86_energy_perf_policy: Cleanup: Fix potential ratio overflow Len Brown
2026-10-19 16:43 ` [PATCH 08/18] x86_energy_perf_policy: Bound package iteration Len Brown
2026-10-19 16:43 ` [PATCH 09/18] x86_energy_perf_policy: Cleanup: Define HWP window max Len Brown
2026-10-19 16:43 ` [PATCH 10/18] x86_energy_perf_policy: Cleanup: Define BCLK_MHZ Len Brown
2026-10-19 16:43 ` [PATCH 11/18] x86_energy_perf_policy: Cleanup: Check fseek() in VM path Len Brown
2026-10-19 16:43 ` [PATCH 12/18] x86_energy_perf_policy: Document MSRHEADER Len Brown
2026-10-19 16:43 ` [PATCH 13/18] x86_energy_perf_policy: Cleanup: Drop unused signal.h Len Brown
2026-10-19 16:43 ` [PATCH 14/18] x86_energy_perf_policy: Cleanup: Constify profile name arg Len Brown
2026-10-19 16:43 ` [PATCH 15/18] x86_energy_perf_policy: Cleanup: Constify HWP strings Len Brown
2026-10-19 16:43 ` [PATCH 16/18] x86_energy_perf_policy: Fix use-after-free in err_on_hypervisor() Len Brown
2026-10-19 16:43 ` [PATCH 17/18] x86_energy_perf_policy: Fix write_sysfs() return type Len Brown
2026-10-19 16:43 ` [PATCH 18/18] MAINTAINERS: Add x86_energy_perf_policy Len Brown
2026-10-19 18:33 ` [PATCH 01/18] x86_energy_perf_policy: Create msr_path helper Andy Shevchenko
2026-10-20 9:35 ` Andy Shevchenko
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