hypfs_vm.c

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