1// SPDX-License-Identifier: GPL-2.0
2/*
3 *    Hypervisor filesystem for Linux on s390. Diag 204 and 224
4 *    implementation.
5 *
6 *    Copyright IBM Corp. 2006, 2008
7 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
8 */
9
10#define KMSG_COMPONENT "hypfs"
11#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
12
13#include <linux/types.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/string.h>
17#include <linux/vmalloc.h>
18#include <linux/mm.h>
19#include <asm/diag.h>
20#include <asm/ebcdic.h>
21#include "hypfs_diag.h"
22#include "hypfs.h"
23
24#define DBFS_D204_HDR_VERSION	0
25
26static enum diag204_sc diag204_store_sc;	/* used subcode for store */
27static enum diag204_format diag204_info_type;	/* used diag 204 data format */
28
29static void *diag204_buf;		/* 4K aligned buffer for diag204 data */
30static int diag204_buf_pages;		/* number of pages for diag204 data */
31
32static struct dentry *dbfs_d204_file;
33
34enum diag204_format diag204_get_info_type(void)
35{
36	return diag204_info_type;
37}
38
39static void diag204_set_info_type(enum diag204_format type)
40{
41	diag204_info_type = type;
42}
43
44/* Diagnose 204 functions */
45/*
46 * For the old diag subcode 4 with simple data format we have to use real
47 * memory. If we use subcode 6 or 7 with extended data format, we can (and
48 * should) use vmalloc, since we need a lot of memory in that case. Currently
49 * up to 93 pages!
50 */
51
52static void diag204_free_buffer(void)
53{
54	vfree(diag204_buf);
55	diag204_buf = NULL;
56}
57
58void *diag204_get_buffer(enum diag204_format fmt, int *pages)
59{
60	if (diag204_buf) {
61		*pages = diag204_buf_pages;
62		return diag204_buf;
63	}
64	if (fmt == DIAG204_INFO_SIMPLE) {
65		*pages = 1;
66	} else {/* DIAG204_INFO_EXT */
67		*pages = diag204((unsigned long)DIAG204_SUBC_RSI |
68				 (unsigned long)DIAG204_INFO_EXT, 0, NULL);
69		if (*pages <= 0)
70			return ERR_PTR(-EOPNOTSUPP);
71	}
72	diag204_buf = __vmalloc_node(array_size(*pages, PAGE_SIZE),
73				     PAGE_SIZE, GFP_KERNEL, NUMA_NO_NODE,
74				     __builtin_return_address(0));
75	if (!diag204_buf)
76		return ERR_PTR(-ENOMEM);
77	diag204_buf_pages = *pages;
78	return diag204_buf;
79}
80
81/*
82 * diag204_probe() has to find out, which type of diagnose 204 implementation
83 * we have on our machine. Currently there are three possible scanarios:
84 *   - subcode 4   + simple data format (only one page)
85 *   - subcode 4-6 + extended data format
86 *   - subcode 4-7 + extended data format
87 *
88 * Subcode 5 is used to retrieve the size of the data, provided by subcodes
89 * 6 and 7. Subcode 7 basically has the same function as subcode 6. In addition
90 * to subcode 6 it provides also information about secondary cpus.
91 * In order to get as much information as possible, we first try
92 * subcode 7, then 6 and if both fail, we use subcode 4.
93 */
94
95static int diag204_probe(void)
96{
97	void *buf;
98	int pages, rc;
99
100	buf = diag204_get_buffer(DIAG204_INFO_EXT, &pages);
101	if (!IS_ERR(buf)) {
102		if (diag204((unsigned long)DIAG204_SUBC_STIB7 |
103			    (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
104			diag204_store_sc = DIAG204_SUBC_STIB7;
105			diag204_set_info_type(DIAG204_INFO_EXT);
106			goto out;
107		}
108		if (diag204((unsigned long)DIAG204_SUBC_STIB6 |
109			    (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
110			diag204_store_sc = DIAG204_SUBC_STIB6;
111			diag204_set_info_type(DIAG204_INFO_EXT);
112			goto out;
113		}
114		diag204_free_buffer();
115	}
116
117	/* subcodes 6 and 7 failed, now try subcode 4 */
118
119	buf = diag204_get_buffer(DIAG204_INFO_SIMPLE, &pages);
120	if (IS_ERR(buf)) {
121		rc = PTR_ERR(buf);
122		goto fail_alloc;
123	}
124	if (diag204((unsigned long)DIAG204_SUBC_STIB4 |
125		    (unsigned long)DIAG204_INFO_SIMPLE, pages, buf) >= 0) {
126		diag204_store_sc = DIAG204_SUBC_STIB4;
127		diag204_set_info_type(DIAG204_INFO_SIMPLE);
128		goto out;
129	} else {
130		rc = -EOPNOTSUPP;
131		goto fail_store;
132	}
133out:
134	rc = 0;
135fail_store:
136	diag204_free_buffer();
137fail_alloc:
138	return rc;
139}
140
141int diag204_store(void *buf, int pages)
142{
143	int rc;
144
145	rc = diag204((unsigned long)diag204_store_sc |
146		     (unsigned long)diag204_get_info_type(), pages, buf);
147	return rc < 0 ? -EOPNOTSUPP : 0;
148}
149
150struct dbfs_d204_hdr {
151	u64	len;		/* Length of d204 buffer without header */
152	u16	version;	/* Version of header */
153	u8	sc;		/* Used subcode */
154	char	reserved[53];
155} __attribute__ ((packed));
156
157struct dbfs_d204 {
158	struct dbfs_d204_hdr	hdr;	/* 64 byte header */
159	char			buf[];	/* d204 buffer */
160} __attribute__ ((packed));
161
162static int dbfs_d204_create(void **data, void **data_free_ptr, size_t *size)
163{
164	struct dbfs_d204 *d204;
165	int rc, buf_size;
166	void *base;
167
168	buf_size = PAGE_SIZE * (diag204_buf_pages + 1) + sizeof(d204->hdr);
169	base = vzalloc(buf_size);
170	if (!base)
171		return -ENOMEM;
172	d204 = PTR_ALIGN(base + sizeof(d204->hdr), PAGE_SIZE) - sizeof(d204->hdr);
173	rc = diag204_store(d204->buf, diag204_buf_pages);
174	if (rc) {
175		vfree(base);
176		return rc;
177	}
178	d204->hdr.version = DBFS_D204_HDR_VERSION;
179	d204->hdr.len = PAGE_SIZE * diag204_buf_pages;
180	d204->hdr.sc = diag204_store_sc;
181	*data = d204;
182	*data_free_ptr = base;
183	*size = d204->hdr.len + sizeof(struct dbfs_d204_hdr);
184	return 0;
185}
186
187static struct hypfs_dbfs_file dbfs_file_d204 = {
188	.name		= "diag_204",
189	.data_create	= dbfs_d204_create,
190	.data_free	= vfree,
191};
192
193__init int hypfs_diag_init(void)
194{
195	int rc;
196
197	if (diag204_probe()) {
198		pr_info("The hardware system does not support hypfs\n");
199		return -ENODATA;
200	}
201
202	if (diag204_get_info_type() == DIAG204_INFO_EXT)
203		hypfs_dbfs_create_file(&dbfs_file_d204);
204
205	rc = hypfs_diag_fs_init();
206	if (rc) {
207		pr_err("The hardware system does not provide all functions required by hypfs\n");
208		debugfs_remove(dbfs_d204_file);
209	}
210	return rc;
211}
212
213void hypfs_diag_exit(void)
214{
215	debugfs_remove(dbfs_d204_file);
216	hypfs_diag_fs_exit();
217	diag204_free_buffer();
218	hypfs_dbfs_remove_file(&dbfs_file_d204);
219}
220