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)
