[PATCH v4 2/4] KVM: selftests: add is_cpu_eligible_to_run() utility function

[Ricardo Koller <ricarkol@xxxxxxxxxx>]

Add is_cpu_eligible_to_run() utility function, which checks whether the current
process, or one of its threads, is eligible to run on a particular CPU.
This information is obtained using sched_getaffinity.

Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
---
 .../testing/selftests/kvm/include/test_util.h |  2 ++
 tools/testing/selftests/kvm/lib/test_util.c   | 20 ++++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index 99e0dcdc923f..a7653f369b6c 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_eligible_to_run(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..7813a68333c0 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -4,6 +4,7 @@
  *
  * Copyright (C) 2020, Google LLC.
  */
+#define _GNU_SOURCE
 
 #include <assert.h>
 #include <ctype.h>
@@ -13,7 +14,9 @@
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <linux/mman.h>
-#include "linux/kernel.h"
+#include <linux/kernel.h>
+#include <sched.h>
+#include <sys/sysinfo.h>
 
 #include "test_util.h"
 
@@ -334,3 +337,18 @@ long get_run_delay(void)
 
 	return val[1];
 }
+
+bool is_cpu_eligible_to_run(int pcpu)
+{
+	cpu_set_t cpuset;
+	long i, nprocs;
+
+	nprocs = get_nprocs_conf();
+	sched_getaffinity(0, sizeof(cpu_set_t), &cpuset);
+	for (i = 0; i < nprocs; i++) {
+		if (i == pcpu)
+			return CPU_ISSET(i, &cpuset);
+	}
+
+	return false;
+}
-- 
2.35.1.1094.g7c7d902a7c-goog