[kvm-unit-tests PATCH v2 0/2] s390x: test CMM during migration

[kvm-unit-tests PATCH v2 0/2] s390x: test CMM during migration

[Nico Boehr]

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              |  90 ++++++++++++++++++++++++++
 lib/s390x/cmm.h              |  31 +++++++++
 s390x/Makefile               |   2 +
 s390x/migration-cmm.c        |  34 +++-------
 s390x/migration-during-cmm.c | 121 +++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg          |   5 ++
 6 files changed, 257 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 v2 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>
---
 lib/s390x/cmm.c       | 90 +++++++++++++++++++++++++++++++++++++++++++
 lib/s390x/cmm.h       | 31 +++++++++++++++
 s390x/Makefile        |  1 +
 s390x/migration-cmm.c | 34 ++++------------
 4 files changed, 130 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..5da02fe628f9
--- /dev/null
+++ b/lib/s390x/cmm.c
@@ -0,0 +1,90 @@
+/* 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.
+ */
+const 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 */
+};
+
+/*
+ * 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, int page_count)
+{
+	unsigned long addr = (unsigned long)pagebuf;
+	int 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, int page_count)
+{
+	struct cmm_verify_result result = {
+		.verify_failed = true
+	};
+	int i, expected_mask, actual_mask;
+	unsigned long addr;
+
+	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;
+			result.verify_failed = true;
+			return result;
+		}
+	}
+
+	result.verify_failed = false;
+	return result;
+}
+
+void cmm_report_verify(struct cmm_verify_result const *result)
+{
+	if (result->verify_failed)
+		report_fail("page state mismatch: first page idx = %d, 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..41dcc2f953fd
--- /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;
+	int page_mismatch_idx;
+	unsigned long page_mismatch_addr;
+};
+
+void cmm_set_page_states(uint8_t *pagebuf, int page_count);
+
+struct cmm_verify_result cmm_verify_page_states(uint8_t *pagebuf, int page_count);
+
+void cmm_report_verify(struct cmm_verify_result const *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..720ef9fb9799 100644
--- a/s390x/migration-cmm.c
+++ b/s390x/migration-cmm.c
@@ -14,41 +14,23 @@
 #include <asm/cmm.h>
 #include <bitops.h>
 
+#include "cmm.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 v2 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>
---
 s390x/Makefile               |   1 +
 s390x/migration-during-cmm.c | 121 +++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg          |   5 ++
 3 files changed, 127 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..afe1f73605ba
--- /dev/null
+++ b/s390x/migration-during-cmm.c
@@ -0,0 +1,121 @@
+/* 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 <asm-generic/barrier.h>
+
+#include "cmm.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 on the console, otherwise it will race with
+	 * the primary CPU on the SCLP buffer.
+	 */
+	while (!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)
+			goto out;
+	}
+
+out:
+	WRITE_ONCE(thread_exited, 1);
+}
+
+int main(void)
+{
+	bool has_essa = check_essa_available();
+	struct psw psw;
+
+	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;
+	}
+
+	psw.mask = extract_psw_mask();
+	psw.addr = (unsigned long)test_cmm_during_migration;
+	smp_cpu_setup(1, psw);
+
+	puts("Please migrate me, then press return\n");
+	(void)getchar();
+
+	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();
+
+	goto done;
+
+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 alltogether.
+	 */
+	puts("Please migrate me, then press return\n");
+	(void)getchar();
+
+done:
+	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

Re: [kvm-unit-tests PATCH v2 1/2] s390x: add a library for CMM-related functions

[Thomas Huth]

On 24/11/2022 14.44, Nico Boehr wrote:
> 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>
> ---
>   lib/s390x/cmm.c       | 90 +++++++++++++++++++++++++++++++++++++++++++
>   lib/s390x/cmm.h       | 31 +++++++++++++++
>   s390x/Makefile        |  1 +
>   s390x/migration-cmm.c | 34 ++++------------
>   4 files changed, 130 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..5da02fe628f9
> --- /dev/null
> +++ b/lib/s390x/cmm.c
> @@ -0,0 +1,90 @@
> +/* 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.
> + */
> +const int allowed_essa_state_masks[4] = {

Could be declared as "static const int ...", I guess?

Apart from that nit:
Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [kvm-unit-tests PATCH v2 2/2] s390x: add CMM test during migration

[Thomas Huth]

On 24/11/2022 14.44, Nico Boehr wrote:
> Add a test which modifies CMM page states while migration is in
> progress.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   s390x/Makefile               |   1 +
>   s390x/migration-during-cmm.c | 121 +++++++++++++++++++++++++++++++++++
>   s390x/unittests.cfg          |   5 ++
>   3 files changed, 127 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..afe1f73605ba
> --- /dev/null
> +++ b/s390x/migration-during-cmm.c
> @@ -0,0 +1,121 @@
> +/* 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 <asm-generic/barrier.h>
> +
> +#include "cmm.h"
> +
> +#define NUM_PAGES 128
> +
> +/*
> + * Allocate 3 pages more than we need so we can start at different offsets. This ensures page states

I'd suggest to break the line after "offsets.", that's better to read.

> + * 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 on the console, otherwise it will race with

"print to the console" ? ... no clue, I'm not a native speaker ;-)

> +	 * the primary CPU on the SCLP buffer.
> +	 */
> +	while (!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)
> +			goto out;

A "break" would be nicer than a goto.

> +	}
> +
> +out:
> +	WRITE_ONCE(thread_exited, 1);
> +}
> +
> +int main(void)
> +{
> +	bool has_essa = check_essa_available();
> +	struct psw psw;
> +
> +	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;
> +	}
> +
> +	psw.mask = extract_psw_mask();
> +	psw.addr = (unsigned long)test_cmm_during_migration;
> +	smp_cpu_setup(1, psw);
> +
> +	puts("Please migrate me, then press return\n");
> +	(void)getchar();
> +
> +	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();
> +
> +	goto done;
> +
> +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 alltogether.

s/alltogether/all together/

> +	 */
> +	puts("Please migrate me, then press return\n");
> +	(void)getchar();
> +
> +done:
> +	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

With the nits fixed:
Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [kvm-unit-tests PATCH v2 1/2] s390x: add a library for CMM-related functions

[Claudio Imbrenda]

On Thu, 24 Nov 2022 14:44:28 +0100
Nico Boehr <nrb@linux.ibm.com> wrote:

> 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>
> ---
>  lib/s390x/cmm.c       | 90 +++++++++++++++++++++++++++++++++++++++++++
>  lib/s390x/cmm.h       | 31 +++++++++++++++
>  s390x/Makefile        |  1 +
>  s390x/migration-cmm.c | 34 ++++------------
>  4 files changed, 130 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..5da02fe628f9
> --- /dev/null
> +++ b/lib/s390x/cmm.c
> @@ -0,0 +1,90 @@
> +/* 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.
> + */
> +const 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 */
> +};
> +
> +/*
> + * 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, int page_count)

this could be an unsigned int (but maybe unsigned long would be better)

> +{
> +	unsigned long addr = (unsigned long)pagebuf;
> +	int 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, int page_count)

same here

> +{
> +	struct cmm_verify_result result = {
> +		.verify_failed = true
> +	};
> +	int i, expected_mask, actual_mask;
> +	unsigned long addr;
> +
> +	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;
> +			result.verify_failed = true;

it's already true, you don't need to set it again

> +			return result;
> +		}
> +	}
> +
> +	result.verify_failed = false;
> +	return result;
> +}
> +
> +void cmm_report_verify(struct cmm_verify_result const *result)
> +{
> +	if (result->verify_failed)
> +		report_fail("page state mismatch: first page idx = %d, addr = %lx, expected_mask = 0x%x, actual_mask = 0x%x", result->page_mismatch_idx, result->page_mismatch_addr, result->expected_mask, result->actual_mask);

this line looks longer than 120 columns

> +	else
> +		report_pass("page states match");
> +}
> diff --git a/lib/s390x/cmm.h b/lib/s390x/cmm.h
> new file mode 100644
> index 000000000000..41dcc2f953fd
> --- /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;
> +	int page_mismatch_idx;

maybe also unsigned long to be consistent with
cmm_set_page_states

> +	unsigned long page_mismatch_addr;
> +};
> +
> +void cmm_set_page_states(uint8_t *pagebuf, int page_count);
> +
> +struct cmm_verify_result cmm_verify_page_states(uint8_t *pagebuf, int page_count);
> +
> +void cmm_report_verify(struct cmm_verify_result const *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..720ef9fb9799 100644
> --- a/s390x/migration-cmm.c
> +++ b/s390x/migration-cmm.c
> @@ -14,41 +14,23 @@
>  #include <asm/cmm.h>
>  #include <bitops.h>
>  
> +#include "cmm.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)

Re: [kvm-unit-tests PATCH v2 2/2] s390x: add CMM test during migration

[Claudio Imbrenda]

On Fri, 25 Nov 2022 14:58:35 +0100
Thomas Huth <thuth@redhat.com> wrote:

[...]

> > +	/*
> > +	 * 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 alltogether.  
> 
> s/alltogether/all together/

nope, it's "altogether"

Re: [kvm-unit-tests PATCH v2 2/2] s390x: add CMM test during migration

[Thomas Huth]

On 25/11/2022 15.05, Claudio Imbrenda wrote:
> On Fri, 25 Nov 2022 14:58:35 +0100
> Thomas Huth <thuth@redhat.com> wrote:
> 
> [...]
> 
>>> +	/*
>>> +	 * 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 alltogether.
>>
>> s/alltogether/all together/
> 
> nope, it's "altogether"

Drat, it must be close to the weekend already ;-)

  Thomas

Re: [kvm-unit-tests PATCH v2 2/2] s390x: add CMM test during migration

[Claudio Imbrenda]

On Thu, 24 Nov 2022 14:44:29 +0100
Nico Boehr <nrb@linux.ibm.com> wrote:

> Add a test which modifies CMM page states while migration is in
> progress.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>  s390x/Makefile               |   1 +
>  s390x/migration-during-cmm.c | 121 +++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg          |   5 ++
>  3 files changed, 127 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..afe1f73605ba
> --- /dev/null
> +++ b/s390x/migration-during-cmm.c
> @@ -0,0 +1,121 @@
> +/* 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 <asm-generic/barrier.h>
> +
> +#include "cmm.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 on the console, otherwise it will race with
> +	 * the primary CPU on the SCLP buffer.
> +	 */
> +	while (!thread_should_exit) {

I don't see any mb()s here, maybe use READ_ONCE

> +		/*
> +		 * 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)
> +			goto out;
> +	}
> +
> +out:
> +	WRITE_ONCE(thread_exited, 1);
> +}
> +
> +int main(void)
> +{
> +	bool has_essa = check_essa_available();
> +	struct psw psw;
> +
> +	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;
> +	}
> +
> +	psw.mask = extract_psw_mask();
> +	psw.addr = (unsigned long)test_cmm_during_migration;
> +	smp_cpu_setup(1, psw);
> +
> +	puts("Please migrate me, then press return\n");
> +	(void)getchar();
> +
> +	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();
> +
> +	goto done;
> +
> +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 alltogether.
> +	 */
> +	puts("Please migrate me, then press return\n");
> +	(void)getchar();
> +

I wonder if this can be made easier to review and less error prone... 

maybe something like:

static void migrate_once(void)
{
	static bool migrated = false;

	if (migrated)
		return;
	puts("Please migrate me, then press return\n");
	migrated = true;
	(void)getchar();
}

then you can put it where needed in the code _and_ unconditionally at the end

> +done:
> +	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

Re: [kvm-unit-tests PATCH v2 1/2] s390x: add a library for CMM-related functions

[Nico Boehr]

Quoting Thomas Huth (2022-11-25 14:45:53)
> On 24/11/2022 14.44, Nico Boehr wrote:
[...]
> > diff --git a/lib/s390x/cmm.c b/lib/s390x/cmm.c
> > new file mode 100644
> > index 000000000000..5da02fe628f9
[...]
> > +/*
> > + * Maps ESSA actions to states the page is allowed to be in after the
> > + * respective action was executed.
> > + */
> > +const int allowed_essa_state_masks[4] = {
> 
> Could be declared as "static const int ...", I guess?

Yes, done.

> Apart from that nit:
> Reviewed-by: Thomas Huth <thuth@redhat.com>

Thanks.

Re: [kvm-unit-tests PATCH v2 1/2] s390x: add a library for CMM-related functions

[Nico Boehr]

Quoting Claudio Imbrenda (2022-11-25 15:03:48)
> On Thu, 24 Nov 2022 14:44:28 +0100
> Nico Boehr <nrb@linux.ibm.com> wrote:
[...]
> > diff --git a/lib/s390x/cmm.c b/lib/s390x/cmm.c
> > new file mode 100644
> > index 000000000000..5da02fe628f9
> > --- /dev/null
> > +++ b/lib/s390x/cmm.c
[...]
> > +/*
> > + * 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, int page_count)
> 
> this could be an unsigned int (but maybe unsigned long would be better)

Yes, changed to unsigned long.

[...]
> > +/*
> > + * 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, int page_count)
> 
> same here

Yes, done.
> 
> > +{
> > +     struct cmm_verify_result result = {
> > +             .verify_failed = true
> > +     };
> > +     int i, expected_mask, actual_mask;
> > +     unsigned long addr;
> > +
> > +     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);

Oh, essa() returns unsigned long, so let's make actual_mask, expected_mask etc. unsigned long, too.

> > +             /* 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;
> > +                     result.verify_failed = true;
> 
> it's already true, you don't need to set it again

OK, removed. 

[...]
> > +void cmm_report_verify(struct cmm_verify_result const *result)
> > +{
> > +     if (result->verify_failed)
> > +             report_fail("page state mismatch: first page idx = %d, addr = %lx, expected_mask = 0x%x, actual_mask = 0x%x", result->page_mismatch_idx, result->page_mismatch_addr, result->expected_mask, result->actual_mask);
> 
> this line looks longer than 120 columns

Yes, wrapped it.

> > diff --git a/lib/s390x/cmm.h b/lib/s390x/cmm.h
> > new file mode 100644
> > index 000000000000..41dcc2f953fd
> > --- /dev/null
> > +++ b/lib/s390x/cmm.h
[...]
> > +struct cmm_verify_result {
> > +     bool verify_failed;
> > +     char expected_mask;
> > +     char actual_mask;
> > +     int page_mismatch_idx;
> 
> maybe also unsigned long to be consistent with
> cmm_set_page_states

Yes, done.