[PATCH v2 2/2] KVM: selftests: access_tracking_perf_test: add option to skip the sanity check

[Maxim Levitsky]

Add an option to skip sanity check of number of still idle pages,
and set it by default to skip, in case hypervisor or NUMA balancing
is detected.

Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
 .../selftests/kvm/access_tracking_perf_test.c | 33 ++++++++++++++++---
 .../testing/selftests/kvm/include/test_util.h |  1 +
 tools/testing/selftests/kvm/lib/test_util.c   |  7 ++++
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
index 3c7defd34f56..6d50c829f00c 100644
--- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
+++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
@@ -65,6 +65,8 @@ static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
 /* Whether to overlap the regions of memory vCPUs access. */
 static bool overlap_memory_access;
 
+static int warn_on_too_many_idle_pages = -1;
+
 struct test_params {
 	/* The backing source for the region of memory. */
 	enum vm_mem_backing_src_type backing_src;
@@ -184,11 +186,10 @@ static void mark_vcpu_memory_idle(struct kvm_vm *vm,
 	 * are cached and the guest won't see the "idle" bit cleared.
 	 */
 	if (still_idle >= pages / 10) {
-#ifdef __x86_64__
-		TEST_ASSERT(this_cpu_has(X86_FEATURE_HYPERVISOR),
+		TEST_ASSERT(warn_on_too_many_idle_pages,
 			    "vCPU%d: Too many pages still idle (%lu out of %lu)",
 			    vcpu_idx, still_idle, pages);
-#endif
+
 		printf("WARNING: vCPU%d: Too many pages still idle (%lu out of %lu), "
 		       "this will affect performance results.\n",
 		       vcpu_idx, still_idle, pages);
@@ -342,6 +343,8 @@ static void help(char *name)
 	printf(" -v: specify the number of vCPUs to run.\n");
 	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 	       "     them into a separate region of memory for each vCPU.\n");
+	printf(" -w: Skip or force enable the check that after dirtying the guest memory, most (90%%) of \n"
+	       "it is reported as dirty again (0/1)");
 	backing_src_help("-s");
 	puts("");
 	exit(0);
@@ -359,7 +362,7 @@ int main(int argc, char *argv[])
 
 	guest_modes_append_default();
 
-	while ((opt = getopt(argc, argv, "hm:b:v:os:")) != -1) {
+	while ((opt = getopt(argc, argv, "hm:b:v:os:w:")) != -1) {
 		switch (opt) {
 		case 'm':
 			guest_modes_cmdline(optarg);
@@ -376,6 +379,11 @@ int main(int argc, char *argv[])
 		case 's':
 			params.backing_src = parse_backing_src_type(optarg);
 			break;
+		case 'w':
+			warn_on_too_many_idle_pages =
+				atoi_non_negative("1 - enable warning, 0 - disable",
+						  optarg);
+			break;
 		case 'h':
 		default:
 			help(argv[0]);
@@ -386,6 +394,23 @@ int main(int argc, char *argv[])
 	page_idle_fd = open("/sys/kernel/mm/page_idle/bitmap", O_RDWR);
 	__TEST_REQUIRE(page_idle_fd >= 0,
 		       "CONFIG_IDLE_PAGE_TRACKING is not enabled");
+	if (warn_on_too_many_idle_pages == -1) {
+#ifdef __x86_64__
+		if (this_cpu_has(X86_FEATURE_HYPERVISOR)) {
+			printf("Skipping idle page count sanity check, because the test is run nested\n");
+			warn_on_too_many_idle_pages = 0;
+		} else
+#endif
+		if (is_numa_balancing_enabled()) {
+			printf("Skipping idle page count sanity check, because NUMA balance is enabled\n");
+			warn_on_too_many_idle_pages = 0;
+		} else {
+			warn_on_too_many_idle_pages = 1;
+		}
+	} else if (!warn_on_too_many_idle_pages) {
+		printf("Skipping idle page count sanity check, because this was requested by the user\n");
+	}
+
 	close(page_idle_fd);
 
 	for_each_guest_mode(run_test, &params);
diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index 3e473058849f..1bc9b0a92427 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -153,6 +153,7 @@ bool is_backing_src_hugetlb(uint32_t i);
 void backing_src_help(const char *flag);
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
 long get_run_delay(void);
+bool is_numa_balancing_enabled(void);
 
 /*
  * Whether or not the given source type is shared memory (as opposed to
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 3dc8538f5d69..03eb99af9b8d 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -176,6 +176,13 @@ size_t get_trans_hugepagesz(void)
 	return get_sysfs_val("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size");
 }
 
+bool is_numa_balancing_enabled(void)
+{
+	if (!test_sysfs_path("/proc/sys/kernel/numa_balancing"))
+		return false;
+	return get_sysfs_val("/proc/sys/kernel/numa_balancing") == 1;
+}
+
 size_t get_def_hugetlb_pagesz(void)
 {
 	char buf[64];
-- 
2.26.3