s390/diag: Add memory topology information via diag310

Introduce diag310 and memory topology related subcodes.
Provide memory topology information obtanied from diag310 to userspace
via diag ioctl.

Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

8 files changed, 301 insertions, 1 deletions

diff --git a/arch/s390/include/asm/diag.h b/arch/s390/include/asm/diag.h
index c1050f4a7107..5790630e31f0 100644
--- a/arch/s390/include/asm/diag.h
+++ b/arch/s390/include/asm/diag.h
@@ -36,6 +36,7 @@ enum diag_stat_enum {
 	DIAG_STAT_X2FC,
 	DIAG_STAT_X304,
 	DIAG_STAT_X308,
+	DIAG_STAT_X310,
 	DIAG_STAT_X318,
 	DIAG_STAT_X320,
 	DIAG_STAT_X324,
diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
index 8ec6e436bf4c..4da3b2956285 100644
--- a/arch/s390/include/asm/sclp.h
+++ b/arch/s390/include/asm/sclp.h
@@ -92,6 +92,7 @@ struct sclp_info {
 	unsigned char has_kss : 1;
 	unsigned char has_diag204_bif : 1;
 	unsigned char has_gisaf : 1;
+	unsigned char has_diag310 : 1;
 	unsigned char has_diag318 : 1;
 	unsigned char has_diag320 : 1;
 	unsigned char has_diag324 : 1;
diff --git a/arch/s390/include/uapi/asm/diag.h b/arch/s390/include/uapi/asm/diag.h
index 361c9ba9d4f5..b7e6ccb4ff6e 100644
--- a/arch/s390/include/uapi/asm/diag.h
+++ b/arch/s390/include/uapi/asm/diag.h
@@ -17,8 +17,16 @@ struct diag324_pib {
 	__u64 sequence;
 };
 
+struct diag310_memtop {
+	__u64 address;
+	__u64 nesting_lvl;
+};
+
 /* Diag ioctl definitions */
 #define DIAG324_GET_PIBBUF	_IOWR(DIAG_MAGIC_STR, 0x77, struct diag324_pib)
 #define DIAG324_GET_PIBLEN	_IOR(DIAG_MAGIC_STR, 0x78, size_t)
+#define DIAG310_GET_STRIDE	_IOR(DIAG_MAGIC_STR, 0x79, size_t)
+#define DIAG310_GET_MEMTOPLEN	_IOWR(DIAG_MAGIC_STR, 0x7a, size_t)
+#define DIAG310_GET_MEMTOPBUF	_IOWR(DIAG_MAGIC_STR, 0x7b, struct diag310_memtop)
 
 #endif /* __S390_UAPI_ASM_DIAG_H */
diff --git a/arch/s390/kernel/diag/Makefile b/arch/s390/kernel/diag/Makefile
index 44d3e0471151..956aee6c4090 100644
--- a/arch/s390/kernel/diag/Makefile
+++ b/arch/s390/kernel/diag/Makefile
@@ -1 +1 @@
-obj-y	:= diag_misc.o diag324.o diag.o
+obj-y	:= diag_misc.o diag324.o diag.o diag310.o
diff --git a/arch/s390/kernel/diag/diag.c b/arch/s390/kernel/diag/diag.c
index 91161f09299f..e15b8dee3228 100644
--- a/arch/s390/kernel/diag/diag.c
+++ b/arch/s390/kernel/diag/diag.c
@@ -51,6 +51,7 @@ static const struct diag_desc diag_map[NR_DIAG_STAT] = {
 	[DIAG_STAT_X2FC] = { .code = 0x2fc, .name = "Guest Performance Data" },
 	[DIAG_STAT_X304] = { .code = 0x304, .name = "Partition-Resource Service" },
 	[DIAG_STAT_X308] = { .code = 0x308, .name = "List-Directed IPL" },
+	[DIAG_STAT_X310] = { .code = 0x310, .name = "Memory Topology Information" },
 	[DIAG_STAT_X318] = { .code = 0x318, .name = "CP Name and Version Codes" },
 	[DIAG_STAT_X320] = { .code = 0x320, .name = "Certificate Store" },
 	[DIAG_STAT_X324] = { .code = 0x324, .name = "Power Information Block" },
diff --git a/arch/s390/kernel/diag/diag310.c b/arch/s390/kernel/diag/diag310.c
new file mode 100644
index 000000000000..d6a34454aa5a
--- /dev/null
+++ b/arch/s390/kernel/diag/diag310.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Request memory topology information via diag0x310.
+ *
+ * Copyright IBM Corp. 2025
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <asm/diag.h>
+#include <asm/sclp.h>
+#include <uapi/asm/diag.h>
+#include "diag_ioctl.h"
+
+#define DIAG310_LEVELMIN 1
+#define DIAG310_LEVELMAX 6
+
+enum diag310_sc {
+	DIAG310_SUBC_0 = 0,
+	DIAG310_SUBC_1 = 1,
+	DIAG310_SUBC_4 = 4,
+	DIAG310_SUBC_5 = 5
+};
+
+enum diag310_retcode {
+	DIAG310_RET_SUCCESS	= 0x0001,
+	DIAG310_RET_BUSY	= 0x0101,
+	DIAG310_RET_OPNOTSUPP	= 0x0102,
+	DIAG310_RET_SC4_INVAL	= 0x0401,
+	DIAG310_RET_SC4_NODATA	= 0x0402,
+	DIAG310_RET_SC5_INVAL	= 0x0501,
+	DIAG310_RET_SC5_NODATA	= 0x0502,
+	DIAG310_RET_SC5_ESIZE	= 0x0503
+};
+
+union diag310_response {
+	u64 response;
+	struct {
+		u64 result	: 32;
+		u64		: 16;
+		u64 rc		: 16;
+	};
+};
+
+union diag310_req_subcode {
+	u64 subcode;
+	struct {
+		u64		: 48;
+		u64 st		: 8;
+		u64 sc		: 8;
+	};
+};
+
+union diag310_req_size {
+	u64 size;
+	struct {
+		u64 page_count	: 32;
+		u64		: 32;
+	};
+};
+
+static inline unsigned long diag310(unsigned long subcode, unsigned long size, void *addr)
+{
+	union register_pair rp = { .even = (unsigned long)addr, .odd = size };
+
+	diag_stat_inc(DIAG_STAT_X310);
+	asm volatile("diag	%[rp],%[subcode],0x310\n"
+		     : [rp] "+d" (rp.pair)
+		     : [subcode] "d" (subcode)
+		     : "memory");
+	return rp.odd;
+}
+
+static int diag310_result_to_errno(unsigned int result)
+{
+	switch (result) {
+	case DIAG310_RET_BUSY:
+		return -EBUSY;
+	case DIAG310_RET_OPNOTSUPP:
+		return -EOPNOTSUPP;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int diag310_get_subcode_mask(unsigned long *mask)
+{
+	union diag310_response res;
+
+	res.response = diag310(DIAG310_SUBC_0, 0, NULL);
+	if (res.rc != DIAG310_RET_SUCCESS)
+		return diag310_result_to_errno(res.rc);
+	*mask = res.response;
+	return 0;
+}
+
+static int diag310_get_memtop_stride(unsigned long *stride)
+{
+	union diag310_response res;
+
+	res.response = diag310(DIAG310_SUBC_1, 0, NULL);
+	if (res.rc != DIAG310_RET_SUCCESS)
+		return diag310_result_to_errno(res.rc);
+	*stride = res.result;
+	return 0;
+}
+
+static int diag310_get_memtop_size(unsigned long *pages, unsigned long level)
+{
+	union diag310_req_subcode req = { .sc = DIAG310_SUBC_4, .st = level };
+	union diag310_response res;
+
+	res.response = diag310(req.subcode, 0, NULL);
+	switch (res.rc) {
+	case DIAG310_RET_SUCCESS:
+		*pages = res.result;
+		return 0;
+	case DIAG310_RET_SC4_NODATA:
+		return -ENODATA;
+	case DIAG310_RET_SC4_INVAL:
+		return -EINVAL;
+	default:
+		return diag310_result_to_errno(res.rc);
+	}
+}
+
+static int diag310_store_topology_map(void *buf, unsigned long pages, unsigned long level)
+{
+	union diag310_req_subcode req_sc = { .sc = DIAG310_SUBC_5, .st = level };
+	union diag310_req_size req_size = { .page_count = pages };
+	union diag310_response res;
+
+	res.response = diag310(req_sc.subcode, req_size.size, buf);
+	switch (res.rc) {
+	case DIAG310_RET_SUCCESS:
+		return 0;
+	case DIAG310_RET_SC5_NODATA:
+		return -ENODATA;
+	case DIAG310_RET_SC5_ESIZE:
+		return -EOVERFLOW;
+	case DIAG310_RET_SC5_INVAL:
+		return -EINVAL;
+	default:
+		return diag310_result_to_errno(res.rc);
+	}
+}
+
+static int diag310_check_features(void)
+{
+	static int features_available;
+	unsigned long mask;
+	int rc;
+
+	if (READ_ONCE(features_available))
+		return 0;
+	if (!sclp.has_diag310)
+		return -EOPNOTSUPP;
+	rc = diag310_get_subcode_mask(&mask);
+	if (rc)
+		return rc;
+	if (!test_bit_inv(DIAG310_SUBC_1, &mask))
+		return -EOPNOTSUPP;
+	if (!test_bit_inv(DIAG310_SUBC_4, &mask))
+		return -EOPNOTSUPP;
+	if (!test_bit_inv(DIAG310_SUBC_5, &mask))
+		return -EOPNOTSUPP;
+	WRITE_ONCE(features_available, 1);
+	return 0;
+}
+
+static int memtop_get_stride_len(unsigned long *res)
+{
+	static unsigned long memtop_stride;
+	unsigned long stride;
+	int rc;
+
+	stride = READ_ONCE(memtop_stride);
+	if (!stride) {
+		rc = diag310_get_memtop_stride(&stride);
+		if (rc)
+			return rc;
+		WRITE_ONCE(memtop_stride, stride);
+	}
+	*res = stride;
+	return 0;
+}
+
+static int memtop_get_page_count(unsigned long *res, unsigned long level)
+{
+	static unsigned long memtop_pages[DIAG310_LEVELMAX];
+	unsigned long pages;
+	int rc;
+
+	if (level > DIAG310_LEVELMAX || level < DIAG310_LEVELMIN)
+		return -EINVAL;
+	pages = READ_ONCE(memtop_pages[level - 1]);
+	if (!pages) {
+		rc = diag310_get_memtop_size(&pages, level);
+		if (rc)
+			return rc;
+		WRITE_ONCE(memtop_pages[level - 1], pages);
+	}
+	*res = pages;
+	return 0;
+}
+
+long diag310_memtop_stride(unsigned long arg)
+{
+	size_t __user *argp = (void __user *)arg;
+	unsigned long stride;
+	int rc;
+
+	rc = diag310_check_features();
+	if (rc)
+		return rc;
+	rc = memtop_get_stride_len(&stride);
+	if (rc)
+		return rc;
+	if (put_user(stride, argp))
+		return -EFAULT;
+	return 0;
+}
+
+long diag310_memtop_len(unsigned long arg)
+{
+	size_t __user *argp = (void __user *)arg;
+	unsigned long pages, level;
+	int rc;
+
+	rc = diag310_check_features();
+	if (rc)
+		return rc;
+	if (get_user(level, argp))
+		return -EFAULT;
+	rc = memtop_get_page_count(&pages, level);
+	if (rc)
+		return rc;
+	if (put_user(pages * PAGE_SIZE, argp))
+		return -EFAULT;
+	return 0;
+}
+
+long diag310_memtop_buf(unsigned long arg)
+{
+	struct diag310_memtop __user *udata = (struct diag310_memtop __user *)arg;
+	unsigned long level, pages, data_size;
+	u64 address;
+	void *buf;
+	int rc;
+
+	rc = diag310_check_features();
+	if (rc)
+		return rc;
+	if (get_user(level, &udata->nesting_lvl))
+		return -EFAULT;
+	if (get_user(address, &udata->address))
+		return -EFAULT;
+	rc = memtop_get_page_count(&pages, level);
+	if (rc)
+		return rc;
+	data_size = pages * PAGE_SIZE;
+	buf = __vmalloc_node(data_size, PAGE_SIZE, GFP_KERNEL | __GFP_ZERO | __GFP_ACCOUNT,
+			     NUMA_NO_NODE, __builtin_return_address(0));
+	if (!buf)
+		return -ENOMEM;
+	rc = diag310_store_topology_map(buf, pages, level);
+	if (rc)
+		goto out;
+	if (copy_to_user((void __user *)address, buf, data_size))
+		rc = -EFAULT;
+out:
+	vfree(buf);
+	return rc;
+}
diff --git a/arch/s390/kernel/diag/diag_ioctl.h b/arch/s390/kernel/diag/diag_ioctl.h
index de5365b23e11..7080be946785 100644
--- a/arch/s390/kernel/diag/diag_ioctl.h
+++ b/arch/s390/kernel/diag/diag_ioctl.h
@@ -7,4 +7,8 @@
 long diag324_pibbuf(unsigned long arg);
 long diag324_piblen(unsigned long arg);
 
+long diag310_memtop_stride(unsigned long arg);
+long diag310_memtop_len(unsigned long arg);
+long diag310_memtop_buf(unsigned long arg);
+
 #endif /* _DIAG_IOCTL_H */
diff --git a/arch/s390/kernel/diag/diag_misc.c b/arch/s390/kernel/diag/diag_misc.c
index 1f4f5c757329..efffe02ea02e 100644
--- a/arch/s390/kernel/diag/diag_misc.c
+++ b/arch/s390/kernel/diag/diag_misc.c
@@ -26,6 +26,15 @@ static long diag_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case DIAG324_GET_PIBBUF:
 		rc = diag324_pibbuf(arg);
 		break;
+	case DIAG310_GET_STRIDE:
+		rc = diag310_memtop_stride(arg);
+		break;
+	case DIAG310_GET_MEMTOPLEN:
+		rc = diag310_memtop_len(arg);
+		break;
+	case DIAG310_GET_MEMTOPBUF:
+		rc = diag310_memtop_buf(arg);
+		break;
 	default:
 		rc = -ENOIOCTLCMD;
 		break;