[V2 PATCH 5/6] KVM: selftests: Add get_free_huge_2m_pages

[Vishal Annapurve <vannapurve@google.com>]

Add an API to query free 2MB hugepages in the system.

Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 .../testing/selftests/kvm/include/test_util.h  |  1 +
 tools/testing/selftests/kvm/lib/test_util.c    | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index aea80071f2b8..3d1cc215940a 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -122,6 +122,7 @@ struct vm_mem_backing_src_alias {
 bool thp_configured(void);
 size_t get_trans_hugepagesz(void);
 size_t get_def_hugetlb_pagesz(void);
+size_t get_free_huge_2mb_pages(void);
 const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i);
 size_t get_backing_src_pagesz(uint32_t i);
 bool is_backing_src_hugetlb(uint32_t i);
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index d33b98bfe8a3..745573023b57 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -162,6 +162,24 @@ size_t get_trans_hugepagesz(void)
 	return size;
 }
 
+size_t get_free_huge_2mb_pages(void)
+{
+	size_t free_pages;
+	FILE *f;
+	int ret;
+
+	f = fopen("/sys/kernel/mm/hugepages/hugepages-2048kB/free_hugepages", "r");
+	TEST_ASSERT(f != NULL, "Error in opening hugepages-2048kB/free_hugepages");
+
+	do {
+		ret = fscanf(f, "%ld", &free_pages);
+	} while (errno == EINTR);
+	TEST_ASSERT(ret < 1, "Error reading hugepages-2048kB/free_hugepages");
+	fclose(f);
+
+	return free_pages;
+}
+
 size_t get_def_hugetlb_pagesz(void)
 {
 	char buf[64];
-- 
2.39.0.rc0.267.gcb52ba06e7-goog