[kvm-unit-tests PATCH v4 0/2] s390x: test CMM during migration

[kvm-unit-tests PATCH v4 0/2] s390x: test CMM during migration

[Nico Boehr]

v3->v4:
---
* rebase on top of Claudio's series
    [kvm-unit-tests PATCH v3 0/2] lib: s390x: add PSW and
    PSW_WITH_CUR_MASK macros
    https://lore.kernel.org/kvm/20221130154038.70492-1-imbrenda@linux.ibm.com/
* switch cmm.h to system includes
* move const qualifier before struct keyword

v2->v3:
---
* make allowed_essa_state_masks static (thanks Thomas)
* change several variables to unsigned (thanks Claudio)
* remove unneeded assignment (thanks Claudio)
* fix line length (thanks Claudio)
* fix some spellings, line wraps (thanks Thomas)
* remove unneeded goto (thanks Thomas)
* add migrate_once (thanks Claudio)
  I introduce migrate_once() only in migration-during-cmm.c for now, but
  I plan to send a future patch to move it to the library.
* add missing READ_ONCE (thanks Claudio)

v1->v2:
---
* cmm lib: return struct instead of passing in a pointer (thanks Claudio)
* cmm lib: remove get_page_addr() (thanks Claudio)
* cmm lib: print address of mismatch (thanks Claudio)
* cmm lib: misc comments reworked, added and variables renamed
* make sure page states change on every iteration (thanks Claudio)
* add WRITE_ONCE even when not strictly needed (thanks Claudio)

Add a test which changes CMM page states while VM is being migrated.

Nico Boehr (2):
  s390x: add a library for CMM-related functions
  s390x: add CMM test during migration

 lib/s390x/cmm.c              |  92 ++++++++++++++++++++++++++
 lib/s390x/cmm.h              |  31 +++++++++
 s390x/Makefile               |   2 +
 s390x/migration-cmm.c        |  33 ++--------
 s390x/migration-during-cmm.c | 123 +++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg          |   5 ++
 6 files changed, 260 insertions(+), 26 deletions(-)
 create mode 100644 lib/s390x/cmm.c
 create mode 100644 lib/s390x/cmm.h
 create mode 100644 s390x/migration-during-cmm.c

-- 
2.36.1

[kvm-unit-tests PATCH v4 1/2] s390x: add a library for CMM-related functions

[Nico Boehr]

Upcoming changes will add a test which is very similar to the existing
CMM migration test. To reduce code duplication, move the common function
to a library which can be re-used by both tests.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 lib/s390x/cmm.c       | 92 +++++++++++++++++++++++++++++++++++++++++++
 lib/s390x/cmm.h       | 31 +++++++++++++++
 s390x/Makefile        |  1 +
 s390x/migration-cmm.c | 33 ++++------------
 4 files changed, 131 insertions(+), 26 deletions(-)
 create mode 100644 lib/s390x/cmm.c
 create mode 100644 lib/s390x/cmm.h

diff --git a/lib/s390x/cmm.c b/lib/s390x/cmm.c
new file mode 100644
index 000000000000..f6c01b3467e8
--- /dev/null
+++ b/lib/s390x/cmm.c
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * CMM test library
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Nico Boehr <nrb@linux.ibm.com>
+ */
+#include <libcflat.h>
+#include <bitops.h>
+#include "cmm.h"
+
+/*
+ * Maps ESSA actions to states the page is allowed to be in after the
+ * respective action was executed.
+ */
+static const unsigned long allowed_essa_state_masks[4] = {
+	BIT(ESSA_USAGE_STABLE),					/* ESSA_SET_STABLE */
+	BIT(ESSA_USAGE_UNUSED),					/* ESSA_SET_UNUSED */
+	BIT(ESSA_USAGE_VOLATILE),				/* ESSA_SET_VOLATILE */
+	BIT(ESSA_USAGE_VOLATILE) | BIT(ESSA_USAGE_POT_VOLATILE) /* ESSA_SET_POT_VOLATILE */
+};
+
+/*
+ * Set CMM page states on pagebuf.
+ * pagebuf must point to page_count consecutive pages.
+ * page_count must be a multiple of 4.
+ */
+void cmm_set_page_states(uint8_t *pagebuf, unsigned long page_count)
+{
+	unsigned long addr = (unsigned long)pagebuf;
+	unsigned long i;
+
+	assert(page_count % 4 == 0);
+	for (i = 0; i < page_count; i += 4) {
+		essa(ESSA_SET_STABLE, addr + i * PAGE_SIZE);
+		essa(ESSA_SET_UNUSED, addr + (i + 1) * PAGE_SIZE);
+		essa(ESSA_SET_VOLATILE, addr + (i + 2) * PAGE_SIZE);
+		essa(ESSA_SET_POT_VOLATILE, addr + (i + 3) * PAGE_SIZE);
+	}
+}
+
+/*
+ * Verify CMM page states on pagebuf.
+ * Page states must have been set by cmm_set_page_states on pagebuf before.
+ * page_count must be a multiple of 4.
+ *
+ * If page states match the expected result, will return a cmm_verify_result
+ * with verify_failed false. All other fields are then invalid.
+ * If there is a mismatch, the returned struct will have verify_failed true
+ * and will be filled with details on the first mismatch encountered.
+ */
+struct cmm_verify_result cmm_verify_page_states(uint8_t *pagebuf, unsigned long page_count)
+{
+	struct cmm_verify_result result = {
+		.verify_failed = true
+	};
+	unsigned long expected_mask, actual_mask;
+	unsigned long addr, i;
+
+	assert(page_count % 4 == 0);
+
+	for (i = 0; i < page_count; i++) {
+		addr = (unsigned long)(pagebuf + i * PAGE_SIZE);
+		actual_mask = essa(ESSA_GET_STATE, addr);
+		/* usage state in bits 60 and 61 */
+		actual_mask = BIT((actual_mask >> 2) & 0x3);
+		expected_mask = allowed_essa_state_masks[i % ARRAY_SIZE(allowed_essa_state_masks)];
+		if (!(actual_mask & expected_mask)) {
+			result.page_mismatch_idx = i;
+			result.page_mismatch_addr = addr;
+			result.expected_mask = expected_mask;
+			result.actual_mask = actual_mask;
+			return result;
+		}
+	}
+
+	result.verify_failed = false;
+	return result;
+}
+
+void cmm_report_verify(const struct cmm_verify_result *result)
+{
+	if (result->verify_failed)
+		report_fail("page state mismatch: first page idx = %lu, addr = %lx, "
+			"expected_mask = 0x%x, actual_mask = 0x%x",
+			result->page_mismatch_idx, result->page_mismatch_addr,
+			result->expected_mask, result->actual_mask);
+	else
+		report_pass("page states match");
+}
diff --git a/lib/s390x/cmm.h b/lib/s390x/cmm.h
new file mode 100644
index 000000000000..a14e6afe809c
--- /dev/null
+++ b/lib/s390x/cmm.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * CMM test library
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Nico Boehr <nrb@linux.ibm.com>
+ */
+#ifndef S390X_CMM_H
+#define S390X_CMM_H
+
+#include <libcflat.h>
+#include <asm/page.h>
+#include <asm/cmm.h>
+
+struct cmm_verify_result {
+	bool verify_failed;
+	char expected_mask;
+	char actual_mask;
+	unsigned long page_mismatch_idx;
+	unsigned long page_mismatch_addr;
+};
+
+void cmm_set_page_states(uint8_t *pagebuf, unsigned long page_count);
+
+struct cmm_verify_result cmm_verify_page_states(uint8_t *pagebuf, unsigned long page_count);
+
+void cmm_report_verify(const struct cmm_verify_result *result);
+
+#endif /* S390X_CMM_H */
diff --git a/s390x/Makefile b/s390x/Makefile
index bf1504f9d58c..401cb6371cee 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -99,6 +99,7 @@ cflatobjs += lib/s390x/malloc_io.o
 cflatobjs += lib/s390x/uv.o
 cflatobjs += lib/s390x/sie.o
 cflatobjs += lib/s390x/fault.o
+cflatobjs += lib/s390x/cmm.o
 
 OBJDIRS += lib/s390x
 
diff --git a/s390x/migration-cmm.c b/s390x/migration-cmm.c
index aa7910ca76bf..541abd31f46a 100644
--- a/s390x/migration-cmm.c
+++ b/s390x/migration-cmm.c
@@ -9,46 +9,27 @@
  */
 
 #include <libcflat.h>
+#include <cmm.h>
 #include <asm/interrupt.h>
 #include <asm/page.h>
 #include <asm/cmm.h>
 #include <bitops.h>
 
 #define NUM_PAGES 128
-static uint8_t pagebuf[NUM_PAGES][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
+static uint8_t pagebuf[NUM_PAGES * PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
 
 static void test_migration(void)
 {
-	int i, state_mask, actual_state;
-	/*
-	 * Maps ESSA actions to states the page is allowed to be in after the
-	 * respective action was executed.
-	 */
-	int allowed_essa_state_masks[4] = {
-		BIT(ESSA_USAGE_STABLE),					/* ESSA_SET_STABLE */
-		BIT(ESSA_USAGE_UNUSED),					/* ESSA_SET_UNUSED */
-		BIT(ESSA_USAGE_VOLATILE),				/* ESSA_SET_VOLATILE */
-		BIT(ESSA_USAGE_VOLATILE) | BIT(ESSA_USAGE_POT_VOLATILE) /* ESSA_SET_POT_VOLATILE */
-	};
+	struct cmm_verify_result result;
 
-	assert(NUM_PAGES % 4 == 0);
-	for (i = 0; i < NUM_PAGES; i += 4) {
-		essa(ESSA_SET_STABLE, (unsigned long)pagebuf[i]);
-		essa(ESSA_SET_UNUSED, (unsigned long)pagebuf[i + 1]);
-		essa(ESSA_SET_VOLATILE, (unsigned long)pagebuf[i + 2]);
-		essa(ESSA_SET_POT_VOLATILE, (unsigned long)pagebuf[i + 3]);
-	}
+	cmm_set_page_states(pagebuf, NUM_PAGES);
 
 	puts("Please migrate me, then press return\n");
 	(void)getchar();
 
-	for (i = 0; i < NUM_PAGES; i++) {
-		actual_state = essa(ESSA_GET_STATE, (unsigned long)pagebuf[i]);
-		/* extract the usage state in bits 60 and 61 */
-		actual_state = (actual_state >> 2) & 0x3;
-		state_mask = allowed_essa_state_masks[i % ARRAY_SIZE(allowed_essa_state_masks)];
-		report(BIT(actual_state) & state_mask, "page %d state: expected_mask=0x%x actual_mask=0x%lx", i, state_mask, BIT(actual_state));
-	}
+	result = cmm_verify_page_states(pagebuf, NUM_PAGES);
+	cmm_report_verify(&result);
 }
 
 int main(void)
-- 
2.36.1

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

[Nico Boehr]

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