5 files changed, 66 insertions, 4 deletions

diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
index 592ee362b877..7a83022733b2 100644
--- a/tools/power/cpupower/utils/helpers/helpers.h
+++ b/tools/power/cpupower/utils/helpers/helpers.h
@@ -96,6 +96,9 @@ struct cpupower_topology {
                 int pkg;
                 int core;
                 int cpu;
+
+                /* flags */
+                unsigned int is_online:1;
         } *core_info;
 };
 
diff --git a/tools/power/cpupower/utils/helpers/sysfs.c b/tools/power/cpupower/utils/helpers/sysfs.c
index 55e2466674c6..c6343024a611 100644
--- a/tools/power/cpupower/utils/helpers/sysfs.c
+++ b/tools/power/cpupower/utils/helpers/sysfs.c
@@ -56,6 +56,56 @@ static unsigned int sysfs_write_file(const char *path,
         return (unsigned int) numwrite;
 }
 
+/*
+ * Detect whether a CPU is online
+ *
+ * Returns:
+ *     1 -> if CPU is online
+ *     0 -> if CPU is offline
+ *     negative errno values in error case
+ */
+int sysfs_is_cpu_online(unsigned int cpu)
+{
+        char path[SYSFS_PATH_MAX];
+        int fd;
+        ssize_t numread;
+        unsigned long long value;
+        char linebuf[MAX_LINE_LEN];
+        char *endp;
+        struct stat statbuf;
+
+        snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
+
+        if (stat(path, &statbuf) != 0)
+                return 0;
+
+        /*
+         * kernel without CONFIG_HOTPLUG_CPU
+         * -> cpuX directory exists, but not cpuX/online file
+         */
+        snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
+        if (stat(path, &statbuf) != 0)
+                return 1;
+
+        fd = open(path, O_RDONLY);
+        if (fd == -1)
+                return -errno;
+
+        numread = read(fd, linebuf, MAX_LINE_LEN - 1);
+        if (numread < 1) {
+                close(fd);
+                return -EIO;
+        }
+        linebuf[numread] = '\0';
+        close(fd);
+
+        value = strtoull(linebuf, &endp, 0);
+        if (value > 1 || value < 0)
+                return -EINVAL;
+
+        return value;
+}
+
 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
 
 /*
diff --git a/tools/power/cpupower/utils/helpers/sysfs.h b/tools/power/cpupower/utils/helpers/sysfs.h
index f9373e090637..8cb797bbceb0 100644
--- a/tools/power/cpupower/utils/helpers/sysfs.h
+++ b/tools/power/cpupower/utils/helpers/sysfs.h
@@ -7,6 +7,8 @@
 
 extern unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen);
 
+extern int sysfs_is_cpu_online(unsigned int cpu);
+
 extern unsigned long sysfs_get_idlestate_latency(unsigned int cpu,
                                                 unsigned int idlestate);
 extern unsigned long sysfs_get_idlestate_usage(unsigned int cpu,
diff --git a/tools/power/cpupower/utils/helpers/topology.c b/tools/power/cpupower/utils/helpers/topology.c
index 385ee5c7570c..4eae2c47ba48 100644
--- a/tools/power/cpupower/utils/helpers/topology.c
+++ b/tools/power/cpupower/utils/helpers/topology.c
@@ -41,6 +41,8 @@ struct cpuid_core_info {
         unsigned int pkg;
         unsigned int thread;
         unsigned int cpu;
+        /* flags */
+        unsigned int is_online:1;
 };
 
 static int __compare(const void *t1, const void *t2)
@@ -78,6 +80,8 @@ int get_cpu_topology(struct cpupower_topology *cpu_top)
                 return -ENOMEM;
         cpu_top->pkgs = cpu_top->cores = 0;
         for (cpu = 0; cpu < cpus; cpu++) {
+                cpu_top->core_info[cpu].cpu = cpu;
+                cpu_top->core_info[cpu].is_online = sysfs_is_cpu_online(cpu);
                 cpu_top->core_info[cpu].pkg =
                         sysfs_topology_read_file(cpu, "physical_package_id");
                 if ((int)cpu_top->core_info[cpu].pkg != -1 &&
@@ -85,7 +89,6 @@ int get_cpu_topology(struct cpupower_topology *cpu_top)
                         cpu_top->pkgs = cpu_top->core_info[cpu].pkg;
                 cpu_top->core_info[cpu].core =
                         sysfs_topology_read_file(cpu, "core_id");
-                cpu_top->core_info[cpu].cpu = cpu;
         }
         cpu_top->pkgs++;
 
diff --git a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
index ba4bf068380d..dd8e1ea6e6f2 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
@@ -190,9 +190,13 @@ void print_results(int topology_depth, int cpu)
                         }
                 }
         }
-        /* cpu offline */
-        if (cpu_top.core_info[cpu].pkg == -1 ||
-            cpu_top.core_info[cpu].core == -1) {
+        /*
+         * The monitor could still provide useful data, for example
+         * AMD HW counters partly sit in PCI config space.
+         * It's up to the monitor plug-in to check .is_online, this one
+         * is just for additional info.
+         */
+        if (!cpu_top.core_info[cpu].is_online) {
                 printf(_(" *is offline\n"));
                 return;
         } else