diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 56d5c90..2f902e3 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -247,3 +247,9 @@ uint64_t get_max_ram_size(void)
 {
 	return max_ram_size;
 }
+
+uint64_t sclp_get_stsi_mnest(void)
+{
+	assert(read_info);
+	return read_info->stsi_parm;
+}
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 853529b..6a611bc 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -150,7 +150,8 @@ typedef struct ReadInfo {
 	SCCBHeader h;
 	uint16_t rnmax;
 	uint8_t rnsize;
-	uint8_t  _reserved1[16 - 11];       /* 11-15 */
+	uint8_t  _reserved1[15 - 11];       /* 11-14 */
+	uint8_t stsi_parm;                  /* 15-15 */
 	uint16_t entries_cpu;               /* 16-17 */
 	uint16_t offset_cpu;                /* 18-19 */
 	uint8_t  _reserved2[24 - 20];       /* 20-23 */
@@ -341,5 +342,6 @@ int sclp_service_call(unsigned int command, void *sccb);
 void sclp_memory_setup(void);
 uint64_t get_ram_size(void);
 uint64_t get_max_ram_size(void);
+uint64_t sclp_get_stsi_mnest(void);
 
 #endif /* _S390X_SCLP_H_ */
diff --git a/lib/s390x/stsi.h b/lib/s390x/stsi.h
index bebc492..1351a6f 100644
--- a/lib/s390x/stsi.h
+++ b/lib/s390x/stsi.h
@@ -29,4 +29,40 @@ struct sysinfo_3_2_2 {
 	uint8_t ext_names[8][256];
 };
 
+#define CPUS_TLE_RES_BITS 0x00fffffff8000000UL
+struct topology_core {
+	uint8_t nl;
+	uint8_t reserved1[3];
+	uint8_t reserved4:5;
+	uint8_t d:1;
+	uint8_t pp:2;
+	uint8_t type;
+	uint16_t origin;
+	uint64_t mask;
+};
+
+#define CONTAINER_TLE_RES_BITS 0x00ffffffffffff00UL
+struct topology_container {
+	uint8_t nl;
+	uint8_t reserved[6];
+	uint8_t id;
+};
+
+union topology_entry {
+	uint8_t nl;
+	struct topology_core cpu;
+	struct topology_container container;
+};
+
+#define CPU_TOPOLOGY_MAX_LEVEL 6
+struct sysinfo_15_1_x {
+	uint8_t reserved0[2];
+	uint16_t length;
+	uint8_t mag[CPU_TOPOLOGY_MAX_LEVEL];
+	uint8_t reserved0a;
+	uint8_t mnest;
+	uint8_t reserved0c[4];
+	union topology_entry tle[];
+};
+
 #endif  /* _S390X_STSI_H_ */
diff --git a/s390x/topology.c b/s390x/topology.c
index 7e1bbf9..9974f33 100644
--- a/s390x/topology.c
+++ b/s390x/topology.c
@@ -17,6 +17,20 @@
 #include <smp.h>
 #include <sclp.h>
 #include <s390x/hardware.h>
+#include <s390x/stsi.h>
+
+static uint8_t pagebuf[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
+static int max_nested_lvl;
+static int number_of_cpus;
+static int cpus_in_masks;
+static int max_cpus;
+
+/*
+ * Topology level as defined by architecture, all levels exists with
+ * a single container unless overwritten by the QEMU -smp parameter.
+ */
+static int expected_topo_lvl[CPU_TOPOLOGY_MAX_LEVEL] = { 1, 1, 1, 1, 1, 1 };
 
 #define PTF_REQ_HORIZONTAL	0
 #define PTF_REQ_VERTICAL	1
@@ -157,11 +171,321 @@ static void test_ptf(void)
 	check_polarization_change();
 }
 
+/*
+ * stsi_check_maxcpus
+ * @info: Pointer to the stsi information
+ *
+ * The product of the numbers of containers per level
+ * is the maximum number of CPU allowed by the machine.
+ */
+static void stsi_check_maxcpus(struct sysinfo_15_1_x *info)
+{
+	int n, i;
+
+	for (i = 0, n = 1; i < CPU_TOPOLOGY_MAX_LEVEL; i++)
+		n *= info->mag[i] ?: 1;
+
+	report(n == max_cpus, "Calculated max CPUs: %d", n);
+}
+
+/*
+ * stsi_check_mag
+ * @info: Pointer to the stsi information
+ *
+ * MAG field should match the architecture defined containers
+ * when MNEST as returned by SCLP matches MNEST of the SYSIB.
+ */
+static void stsi_check_mag(struct sysinfo_15_1_x *info)
+{
+	int i;
+
+	report_prefix_push("MAG");
+
+	stsi_check_maxcpus(info);
+
+	/*
+	 * It is not clear how the MAG fields are calculated when mnest
+	 * in the SYSIB 15.x is different from the maximum nested level
+	 * in the SCLP info, so we skip here for now.
+	 */
+	if (max_nested_lvl != info->mnest) {
+		report_skip("No specification on layer aggregation");
+		goto done;
+	}
+
+	/*
+	 * MAG up to max_nested_lvl must match the architecture
+	 * defined containers.
+	 */
+	for (i = 0; i < max_nested_lvl; i++)
+		report(info->mag[CPU_TOPOLOGY_MAX_LEVEL - i - 1] == expected_topo_lvl[i],
+		       "MAG %d field match %d == %d",
+		       i + 1,
+		       info->mag[CPU_TOPOLOGY_MAX_LEVEL - i - 1],
+		       expected_topo_lvl[i]);
+
+	/* Above max_nested_lvl the MAG field must be null */
+	for (; i < CPU_TOPOLOGY_MAX_LEVEL; i++)
+		report(info->mag[CPU_TOPOLOGY_MAX_LEVEL - i - 1] == 0,
+		       "MAG %d field match %d == %d", i + 1,
+		       info->mag[CPU_TOPOLOGY_MAX_LEVEL - i - 1], 0);
+
+done:
+	report_prefix_pop();
+}
+
+/**
+ * check_tle:
+ * @tc: pointer to first TLE
+ *
+ * Recursively check the containers TLEs until we
+ * find a CPU TLE.
+ */
+static uint8_t *check_tle(void *tc)
+{
+	struct topology_container *container = tc;
+	struct topology_core *cpus;
+	int n;
+
+	if (container->nl) {
+		report_info("NL: %d id: %d", container->nl, container->id);
+
+		report(!(*(uint64_t *)tc & CONTAINER_TLE_RES_BITS),
+		       "reserved bits %016lx",
+		       *(uint64_t *)tc & CONTAINER_TLE_RES_BITS);
+
+		return check_tle(tc + sizeof(*container));
+	}
+
+	report_info("NL: %d", container->nl);
+	cpus = tc;
+
+	report(!(*(uint64_t *)tc & CPUS_TLE_RES_BITS), "reserved bits %016lx",
+	       *(uint64_t *)tc & CPUS_TLE_RES_BITS);
+
+	report(cpus->type == 0x03, "type IFL");
+
+	report_info("origin: %d", cpus->origin);
+	report_info("mask: %016lx", cpus->mask);
+	report_info("dedicated: %d entitlement: %d", cpus->d, cpus->pp);
+
+	n = __builtin_popcountl(cpus->mask);
+	report(n <= expected_topo_lvl[0], "CPUs per mask: %d out of max %d",
+	       n, expected_topo_lvl[0]);
+	cpus_in_masks += n;
+
+	if (!cpus->d)
+		report_skip("Not dedicated");
+	else
+		report(cpus->pp == 3 || cpus->pp == 0, "Dedicated CPUs are either vertically polarized or have high entitlement");
+
+	return tc + sizeof(*cpus);
+}
+
+/**
+ * stsi_check_tle_coherency:
+ * @info: Pointer to the stsi information
+ *
+ * We verify that we get the expected number of Topology List Entry
+ * containers for a specific level.
+ */
+static void stsi_check_tle_coherency(struct sysinfo_15_1_x *info)
+{
+	void *tc, *end;
+
+	report_prefix_push("TLE");
+	cpus_in_masks = 0;
+
+	tc = info->tle;
+	end = (void *)info + info->length;
+
+	while (tc < end)
+		tc = check_tle(tc);
+
+	report(cpus_in_masks == number_of_cpus, "CPUs in mask %d",
+	       cpus_in_masks);
+
+	report_prefix_pop();
+}
+
+/**
+ * stsi_get_sysib:
+ * @info: pointer to the STSI info structure
+ * @sel2: the selector giving the topology level to check
+ *
+ * Fill the sysinfo_15_1_x info structure and check the
+ * SYSIB header.
+ *
+ * Returns instruction validity.
+ */
+static int stsi_get_sysib(struct sysinfo_15_1_x *info, int sel2)
+{
+	int ret;
+
+	report_prefix_pushf("SYSIB");
+
+	ret = stsi(pagebuf, 15, 1, sel2);
+
+	if (max_nested_lvl >= sel2) {
+		report(!ret, "Valid instruction");
+		report(sel2 == info->mnest, "Valid mnest");
+	} else {
+		report(ret, "Invalid instruction");
+	}
+
+	report_prefix_pop();
+
+	return ret;
+}
+
+/**
+ * check_sysinfo_15_1_x:
+ * @info: pointer to the STSI info structure
+ * @sel2: the selector giving the topology level to check
+ *
+ * Check if the validity of the STSI instruction and then
+ * calls specific checks on the information buffer.
+ */
+static void check_sysinfo_15_1_x(struct sysinfo_15_1_x *info, int sel2)
+{
+	int ret;
+	int cc;
+	unsigned long rc;
+
+	report_prefix_pushf("15_1_%d", sel2);
+
+	ret = stsi_get_sysib(info, sel2);
+	if (ret) {
+		report_skip("Selector 2 not supported by architecture");
+		goto end;
+	}
+
+	report_prefix_pushf("H");
+	cc = ptf(PTF_REQ_HORIZONTAL, &rc);
+	if (cc != 0 && rc != PTF_ERR_ALRDY_POLARIZED) {
+		report_fail("Unable to set horizontal polarization");
+		goto vertical;
+	}
+
+	stsi_check_mag(info);
+	stsi_check_tle_coherency(info);
+
+vertical:
+	report_prefix_pop();
+	report_prefix_pushf("V");
+
+	cc = ptf(PTF_REQ_VERTICAL, &rc);
+	if (cc != 0 && rc != PTF_ERR_ALRDY_POLARIZED) {
+		report_fail("Unable to set vertical polarization");
+		goto end;
+	}
+
+	stsi_check_mag(info);
+	stsi_check_tle_coherency(info);
+	report_prefix_pop();
+
+end:
+	report_prefix_pop();
+}
+
+/*
+ * The Maximum Nested level is given by SCLP READ_SCP_INFO if the MNEST facility
+ * is available.
+ * If the MNEST facility is not available, sclp_get_stsi_mnest  returns 0 and the
+ * Maximum Nested level is 2
+ */
+#define S390_DEFAULT_MNEST	2
+static int sclp_get_mnest(void)
+{
+	return sclp_get_stsi_mnest() ?: S390_DEFAULT_MNEST;
+}
+
+static int expected_num_cpus(void)
+{
+	int i;
+	int ncpus = 1;
+
+	for (i = 0; i < CPU_TOPOLOGY_MAX_LEVEL; i++)
+		ncpus *= expected_topo_lvl[i] ?: 1;
+
+	return ncpus;
+}
+
+/**
+ * test_stsi:
+ *
+ * Retrieves the maximum nested topology level supported by the architecture
+ * and the number of CPUs.
+ * Calls the checking for the STSI instruction in sel2 reverse level order
+ * from 6 (CPU_TOPOLOGY_MAX_LEVEL) to 2 to have the most interesting level,
+ * the one triggering a topology-change-report-pending condition, level 2,
+ * at the end of the report.
+ *
+ */
+static void test_stsi(void)
+{
+	int sel2;
+
+	max_cpus = expected_num_cpus();
+	report_info("Architecture max CPUs: %d", max_cpus);
+
+	max_nested_lvl = sclp_get_mnest();
+	report_info("SCLP maximum nested level : %d", max_nested_lvl);
+
+	number_of_cpus = sclp_get_cpu_num();
+	report_info("SCLP number of CPU: %d", number_of_cpus);
+
+	/* STSI selector 2 can takes values between 2 and 6 */
+	for (sel2 = 6; sel2 >= 2; sel2--)
+		check_sysinfo_15_1_x((struct sysinfo_15_1_x *)pagebuf, sel2);
+}
+
+/**
+ * parse_topology_args:
+ * @argc: number of arguments
+ * @argv: argument array
+ *
+ * This function initialize the architecture topology levels
+ * which should be the same as the one provided by the hypervisor.
+ *
+ * We use the current names found in IBM/Z literature, Linux and QEMU:
+ * cores, sockets/packages, books, drawers and nodes to facilitate the
+ * human machine interface but store the result in a machine abstract
+ * array of architecture topology levels.
+ * Note that when QEMU uses socket as a name for the topology level 1
+ * Linux uses package or physical_package.
+ */
+static void parse_topology_args(int argc, char **argv)
+{
+	int i;
+	static const char * const levels[] = { "cores", "sockets",
+					       "books", "drawers" };
+
+	for (i = 1; i < argc; i++) {
+		char *flag = argv[i];
+		int level;
+
+		if (flag[0] != '-')
+			report_abort("Argument is expected to begin with '-'");
+		flag++;
+		for (level = 0; ARRAY_SIZE(levels); level++) {
+			if (!strcmp(levels[level], flag))
+				break;
+		}
+		if (level == ARRAY_SIZE(levels))
+			report_abort("Unknown parameter %s", flag);
+
+		expected_topo_lvl[level] = atol(argv[++i]);
+		report_info("%s: %d", levels[level], expected_topo_lvl[level]);
+	}
+}
+
 static struct {
 	const char *name;
 	void (*func)(void);
 } tests[] = {
 	{ "PTF", test_ptf },
+	{ "STSI", test_stsi },
 	{ NULL, NULL }
 };
 
@@ -171,6 +495,8 @@ int main(int argc, char *argv[])
 
 	report_prefix_push("CPU Topology");
 
+	parse_topology_args(argc, argv);
+
 	if (!test_facility(11)) {
 		report_skip("Topology facility not present");
 		goto end;
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index fc3666b..a90ad24 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -221,3 +221,7 @@ file = ex.elf
 
 [topology]
 file = topology.elf
+
+[topology-2]
+file = topology.elf
+extra_params = -cpu max,ctop=on -smp sockets=31,cores=8,maxcpus=248  -append '-sockets 31 -cores 8'
