[PATCH] KVM: selftests: skip hugetlb tests if huge pages are not available

[Paolo Bonzini]

Right now, if KVM memory stress tests are run with hugetlb sources but hugetlb is
not available (either in the kernel or because /proc/sys/vm/nr_hugepages is 0)
the test will fail with a memory allocation error.

This makes it impossible to add tests that default to hugetlb-backed memory,
because on a machine with a default configuration they will fail.  Therefore,
check HugePages_Total as well and, if zero, direct the user to enable hugepages
in procfs.  Furthermore, return KSFT_SKIP whenever hugetlb is not available.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/lib/test_util.c | 25 +++++++++++++--------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 5c22fa4c2825..b772193f6c18 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -165,26 +165,33 @@ size_t get_trans_hugepagesz(void)
 size_t get_def_hugetlb_pagesz(void)
 {
 	char buf[64];
-	const char *tag = "Hugepagesize:";
+	const char *hugepagesize = "Hugepagesize:";
+	const char *hugepages_total = "HugePages_Total:";
 	FILE *f;
 
 	f = fopen("/proc/meminfo", "r");
 	TEST_ASSERT(f != NULL, "Error in opening /proc/meminfo");
 
 	while (fgets(buf, sizeof(buf), f) != NULL) {
-		if (strstr(buf, tag) == buf) {
+		if (strstr(buf, hugepages_total) == buf) {
+			unsigned long long total = strtoull(buf + strlen(hugepages_total), NULL, 10);
+			if (!total) {
+				fprintf(stderr, "HUGETLB is not enabled in /proc/sys/vm/nr_hugepages\n");
+				exit(KSFT_SKIP);
+			}
+		}
+		if (strstr(buf, hugepagesize) == buf) {
 			fclose(f);
-			return strtoull(buf + strlen(tag), NULL, 10) << 10;
+			return strtoull(buf + strlen(hugepagesize), NULL, 10) << 10;
 		}
 	}
 
-	if (feof(f))
-		TEST_FAIL("HUGETLB is not configured in host kernel");
-	else
-		TEST_FAIL("Error in reading /proc/meminfo");
+	if (feof(f)) {
+		fprintf(stderr, "HUGETLB is not configured in host kernel");
+		exit(KSFT_SKIP);
+	}
 
-	fclose(f);
-	return 0;
+	TEST_FAIL("Error in reading /proc/meminfo");
 }
 
 #define ANON_FLAGS	(MAP_PRIVATE | MAP_ANONYMOUS)
-- 
2.39.1