[PATCH v3 2/4] KVM: selftests: add is_cpu_online() utility function

[Ricardo Koller <ricarkol@google.com>]

Add is_cpu_online() utility function: a wrapper for
"/sys/devices/system/cpu/cpu%d/online".

Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
 tools/testing/selftests/kvm/include/test_util.h |  2 ++
 tools/testing/selftests/kvm/lib/test_util.c     | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index 99e0dcdc923f..14084dc4e152 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -143,4 +143,6 @@ static inline void *align_ptr_up(void *x, size_t size)
 	return (void *)align_up((unsigned long)x, size);
 }
 
+bool is_cpu_online(int pcpu);
+
 #endif /* SELFTEST_KVM_TEST_UTIL_H */
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 6d23878bbfe1..81950e6b6d10 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -334,3 +334,19 @@ long get_run_delay(void)
 
 	return val[1];
 }
+
+bool is_cpu_online(int pcpu)
+{
+	char p[128];
+	FILE *fp;
+	int ret;
+
+	snprintf(p, sizeof(p), "/sys/devices/system/cpu/cpu%d/online", pcpu);
+	fp = fopen(p, "r");
+	if (!fp)
+		return false;
+	assert(fscanf(fp, "%d ", &ret) == 1);
+	fclose(fp);
+
+	return !!ret;
+}
-- 
2.35.1.894.gb6a874cedc-goog