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

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Message-Id: <20250325015741.2478906-3-mlevitsk@redhat.com>
Date: Mon, 24 Mar 2025 21:57:41 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: kvm@...r.kernel.org
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>,
	linux-kernel@...r.kernel.org,
	Sean Christopherson <seanjc@...gle.com>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	James Houghton <jthoughton@...gle.com>,
	Shuah Khan <shuah@...nel.org>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Paolo Bonzini <pbonzini@...hat.com>,
	linux-kselftest@...r.kernel.org,
	Anup Patel <anup@...infault.org>
Subject: [PATCH v2 2/2] KVM: selftests: access_tracking_perf_test: add option to skip the sanity check

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@...hat.com>
---
 .../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