[kvm-unit-tests PATCH v4 2/2] s390x: add CMM test during migration

[Nico Boehr <nrb@linux.ibm.com>]

Add a test which modifies CMM page states while migration is in
progress.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 s390x/Makefile               |   1 +
 s390x/migration-during-cmm.c | 123 +++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg          |   5 ++
 3 files changed, 129 insertions(+)
 create mode 100644 s390x/migration-during-cmm.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 401cb6371cee..64c7c04409ae 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -39,6 +39,7 @@ tests += $(TEST_DIR)/panic-loop-extint.elf
 tests += $(TEST_DIR)/panic-loop-pgm.elf
 tests += $(TEST_DIR)/migration-sck.elf
 tests += $(TEST_DIR)/exittime.elf
+tests += $(TEST_DIR)/migration-during-cmm.elf
 
 pv-tests += $(TEST_DIR)/pv-diags.elf
 
diff --git a/s390x/migration-during-cmm.c b/s390x/migration-during-cmm.c
new file mode 100644
index 000000000000..7e1f9590ae50
--- /dev/null
+++ b/s390x/migration-during-cmm.c
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Perform CMMA actions while migrating.
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Nico Boehr <nrb@linux.ibm.com>
+ */
+
+#include <libcflat.h>
+#include <smp.h>
+#include <cmm.h>
+#include <asm-generic/barrier.h>
+
+#define NUM_PAGES 128
+
+/*
+ * Allocate 3 pages more than we need so we can start at different offsets.
+ * This ensures page states change on every loop iteration.
+ */
+static uint8_t pagebuf[(NUM_PAGES + 3) * PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
+static unsigned int thread_iters;
+static int thread_should_exit;
+static int thread_exited;
+struct cmm_verify_result result;
+
+static void test_cmm_during_migration(void)
+{
+	uint8_t *pagebuf_start;
+	/*
+	 * The second CPU must not print to the console, otherwise it will race with
+	 * the primary CPU on the SCLP buffer.
+	 */
+	while (!READ_ONCE(thread_should_exit)) {
+		/*
+		 * Start on a offset different from the last iteration so page states change with
+		 * every iteration. This is why pagebuf has 3 extra pages.
+		 */
+		pagebuf_start = pagebuf + (thread_iters % 4) * PAGE_SIZE;
+		cmm_set_page_states(pagebuf_start, NUM_PAGES);
+
+		/*
+		 * Always increment even if the verify fails. This ensures primary CPU knows where
+		 * we left off and can do an additional verify round after migration finished.
+		 */
+		thread_iters++;
+
+		result = cmm_verify_page_states(pagebuf_start, NUM_PAGES);
+		if (result.verify_failed)
+			break;
+	}
+
+	WRITE_ONCE(thread_exited, 1);
+}
+
+static void migrate_once(void)
+{
+	static bool migrated;
+
+	if (migrated)
+		return;
+
+	migrated = true;
+	puts("Please migrate me, then press return\n");
+	(void)getchar();
+}
+
+int main(void)
+{
+	bool has_essa = check_essa_available();
+
+	report_prefix_push("migration-during-cmm");
+	if (!has_essa) {
+		report_skip("ESSA is not available");
+		goto error;
+	}
+
+	if (smp_query_num_cpus() == 1) {
+		report_skip("need at least 2 cpus for this test");
+		goto error;
+	}
+
+	smp_cpu_setup(1, PSW_WITH_CUR_MASK(test_cmm_during_migration));
+
+	migrate_once();
+
+	WRITE_ONCE(thread_should_exit, 1);
+
+	while (!thread_exited)
+		mb();
+
+	report_info("thread completed %u iterations", thread_iters);
+
+	report_prefix_push("during migration");
+	cmm_report_verify(&result);
+	report_prefix_pop();
+
+	/*
+	 * Verification of page states occurs on the thread. We don't know if we
+	 * were still migrating during the verification.
+	 * To be sure, make another verification round after the migration
+	 * finished to catch page states which might not have been migrated
+	 * correctly.
+	 */
+	report_prefix_push("after migration");
+	assert(thread_iters > 0);
+	result = cmm_verify_page_states(pagebuf + ((thread_iters - 1) % 4) * PAGE_SIZE, NUM_PAGES);
+	cmm_report_verify(&result);
+	report_prefix_pop();
+
+error:
+	/*
+	 * If we just exit and don't ask migrate_cmd to migrate us, it
+	 * will just hang forever. Hence, also ask for migration when we
+	 * skip this test altogether.
+	 */
+	migrate_once();
+
+	report_prefix_pop();
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index 3caf81eda396..f6889bd4da01 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -208,3 +208,8 @@ groups = migration
 [exittime]
 file = exittime.elf
 smp = 2
+
+[migration-during-cmm]
+file = migration-during-cmm.elf
+groups = migration
+smp = 2
-- 
2.36.1