1// SPDX-License-Identifier: GPL-2.0
2/*
3 *    Hypervisor filesystem for Linux on s390. z/VM implementation.
4 *
5 *    Copyright IBM Corp. 2006
6 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
7 */
8
9#include <linux/types.h>
10#include <linux/errno.h>
11#include <linux/string.h>
12#include <linux/vmalloc.h>
13#include <asm/extable.h>
14#include <asm/diag.h>
15#include <asm/ebcdic.h>
16#include <asm/timex.h>
17#include "hypfs_vm.h"
18#include "hypfs.h"
19
20#define DBFS_D2FC_HDR_VERSION 0
21
22static char local_guest[] = "        ";
23static char all_guests[] = "*       ";
24static char *all_groups = all_guests;
25char *diag2fc_guest_query;
26
27static int diag2fc(int size, char* query, void *addr)
28{
29	unsigned long residual_cnt;
30	unsigned long rc;
31	struct diag2fc_parm_list parm_list;
32
33	memcpy(parm_list.userid, query, DIAG2FC_NAME_LEN);
34	ASCEBC(parm_list.userid, DIAG2FC_NAME_LEN);
35	memcpy(parm_list.aci_grp, all_groups, DIAG2FC_NAME_LEN);
36	ASCEBC(parm_list.aci_grp, DIAG2FC_NAME_LEN);
37	parm_list.addr = (unsigned long)addr;
38	parm_list.size = size;
39	parm_list.fmt = 0x02;
40	rc = -1;
41
42	diag_stat_inc(DIAG_STAT_X2FC);
43	asm volatile(
44		"	diag    %0,%1,0x2fc\n"
45		"0:	nopr	%%r7\n"
46		EX_TABLE(0b,0b)
47		: "=d" (residual_cnt), "+d" (rc) : "0" (&parm_list) : "memory");
48
49	if ((rc != 0 ) && (rc != -2))
50		return rc;
51	else
52		return -residual_cnt;
53}
54
55/*
56 * Allocate buffer for "query" and store diag 2fc at "offset"
57 */
58void *diag2fc_store(char *query, unsigned int *count, int offset)
59{
60	void *data;
61	int size;
62
63	do {
64		size = diag2fc(0, query, NULL);
65		if (size < 0)
66			return ERR_PTR(-EACCES);
67		data = vmalloc(size + offset);
68		if (!data)
69			return ERR_PTR(-ENOMEM);
70		if (diag2fc(size, query, data + offset) == 0)
71			break;
72		vfree(data);
73	} while (1);
74	*count = (size / sizeof(struct diag2fc_data));
75
76	return data;
77}
78
79void diag2fc_free(const void *data)
80{
81	vfree(data);
82}
83
84struct dbfs_d2fc_hdr {
85	u64	len;		/* Length of d2fc buffer without header */
86	u16	version;	/* Version of header */
87	union tod_clock tod_ext; /* TOD clock for d2fc */
88	u64	count;		/* Number of VM guests in d2fc buffer */
89	char	reserved[30];
90} __attribute__ ((packed));
91
92struct dbfs_d2fc {
93	struct dbfs_d2fc_hdr	hdr;	/* 64 byte header */
94	char			buf[];	/* d2fc buffer */
95} __attribute__ ((packed));
96
97static int dbfs_diag2fc_create(void **data, void **data_free_ptr, size_t *size)
98{
99	struct dbfs_d2fc *d2fc;
100	unsigned int count;
101
102	d2fc = diag2fc_store(diag2fc_guest_query, &count, sizeof(d2fc->hdr));
103	if (IS_ERR(d2fc))
104		return PTR_ERR(d2fc);
105	store_tod_clock_ext(&d2fc->hdr.tod_ext);
106	d2fc->hdr.len = count * sizeof(struct diag2fc_data);
107	d2fc->hdr.version = DBFS_D2FC_HDR_VERSION;
108	d2fc->hdr.count = count;
109	memset(&d2fc->hdr.reserved, 0, sizeof(d2fc->hdr.reserved));
110	*data = d2fc;
111	*data_free_ptr = d2fc;
112	*size = d2fc->hdr.len + sizeof(struct dbfs_d2fc_hdr);
113	return 0;
114}
115
116static struct hypfs_dbfs_file dbfs_file_2fc = {
117	.name		= "diag_2fc",
118	.data_create	= dbfs_diag2fc_create,
119	.data_free	= diag2fc_free,
120};
121
122int hypfs_vm_init(void)
123{
124	if (!MACHINE_IS_VM)
125		return 0;
126	if (diag2fc(0, all_guests, NULL) > 0)
127		diag2fc_guest_query = all_guests;
128	else if (diag2fc(0, local_guest, NULL) > 0)
129		diag2fc_guest_query = local_guest;
130	else
131		return -EACCES;
132	hypfs_dbfs_create_file(&dbfs_file_2fc);
133	return 0;
134}
135
136void hypfs_vm_exit(void)
137{
138	if (!MACHINE_IS_VM)
139		return;
140	hypfs_dbfs_remove_file(&dbfs_file_2fc);
141}
142