1 // SPDX-License-Identifier: GPL-2.0
2 /* hvapi.c: Hypervisor API management.
3  *
4  * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
5  */
6 #include <linux/kernel.h>
7 #include <linux/export.h>
8 #include <linux/init.h>
9 
10 #include <asm/hypervisor.h>
11 #include <asm/oplib.h>
12 
13 /* If the hypervisor indicates that the API setting
14  * calls are unsupported, by returning HV_EBADTRAP or
15  * HV_ENOTSUPPORTED, we assume that API groups with the
16  * PRE_API flag set are major 1 minor 0.
17  */
18 struct api_info {
19 	unsigned long group;
20 	unsigned long major;
21 	unsigned long minor;
22 	unsigned int refcnt;
23 	unsigned int flags;
24 #define FLAG_PRE_API		0x00000001
25 };
26 
27 static struct api_info api_table[] = {
28 	{ .group = HV_GRP_SUN4V,	.flags = FLAG_PRE_API	},
29 	{ .group = HV_GRP_CORE,		.flags = FLAG_PRE_API	},
30 	{ .group = HV_GRP_INTR,					},
31 	{ .group = HV_GRP_SOFT_STATE,				},
32 	{ .group = HV_GRP_TM,					},
33 	{ .group = HV_GRP_PCI,		.flags = FLAG_PRE_API	},
34 	{ .group = HV_GRP_LDOM,					},
35 	{ .group = HV_GRP_SVC_CHAN,	.flags = FLAG_PRE_API	},
36 	{ .group = HV_GRP_NCS,		.flags = FLAG_PRE_API	},
37 	{ .group = HV_GRP_RNG,					},
38 	{ .group = HV_GRP_PBOOT,				},
39 	{ .group = HV_GRP_TPM,					},
40 	{ .group = HV_GRP_SDIO,					},
41 	{ .group = HV_GRP_SDIO_ERR,				},
42 	{ .group = HV_GRP_REBOOT_DATA,				},
43 	{ .group = HV_GRP_ATU,		.flags = FLAG_PRE_API	},
44 	{ .group = HV_GRP_DAX,					},
45 	{ .group = HV_GRP_NIAG_PERF,	.flags = FLAG_PRE_API	},
46 	{ .group = HV_GRP_FIRE_PERF,				},
47 	{ .group = HV_GRP_N2_CPU,				},
48 	{ .group = HV_GRP_NIU,					},
49 	{ .group = HV_GRP_VF_CPU,				},
50 	{ .group = HV_GRP_KT_CPU,				},
51 	{ .group = HV_GRP_VT_CPU,				},
52 	{ .group = HV_GRP_T5_CPU,				},
53 	{ .group = HV_GRP_DIAG,		.flags = FLAG_PRE_API	},
54 	{ .group = HV_GRP_M7_PERF,				},
55 };
56 
57 static DEFINE_SPINLOCK(hvapi_lock);
58 
__get_info(unsigned long group)59 static struct api_info *__get_info(unsigned long group)
60 {
61 	int i;
62 
63 	for (i = 0; i < ARRAY_SIZE(api_table); i++) {
64 		if (api_table[i].group == group)
65 			return &api_table[i];
66 	}
67 	return NULL;
68 }
69 
__get_ref(struct api_info * p)70 static void __get_ref(struct api_info *p)
71 {
72 	p->refcnt++;
73 }
74 
__put_ref(struct api_info * p)75 static void __put_ref(struct api_info *p)
76 {
77 	if (--p->refcnt == 0) {
78 		unsigned long ignore;
79 
80 		sun4v_set_version(p->group, 0, 0, &ignore);
81 		p->major = p->minor = 0;
82 	}
83 }
84 
85 /* Register a hypervisor API specification.  It indicates the
86  * API group and desired major+minor.
87  *
88  * If an existing API registration exists '0' (success) will
89  * be returned if it is compatible with the one being registered.
90  * Otherwise a negative error code will be returned.
91  *
92  * Otherwise an attempt will be made to negotiate the requested
93  * API group/major/minor with the hypervisor, and errors returned
94  * if that does not succeed.
95  */
sun4v_hvapi_register(unsigned long group,unsigned long major,unsigned long * minor)96 int sun4v_hvapi_register(unsigned long group, unsigned long major,
97 			 unsigned long *minor)
98 {
99 	struct api_info *p;
100 	unsigned long flags;
101 	int ret;
102 
103 	spin_lock_irqsave(&hvapi_lock, flags);
104 	p = __get_info(group);
105 	ret = -EINVAL;
106 	if (p) {
107 		if (p->refcnt) {
108 			ret = -EINVAL;
109 			if (p->major == major) {
110 				*minor = p->minor;
111 				ret = 0;
112 			}
113 		} else {
114 			unsigned long actual_minor;
115 			unsigned long hv_ret;
116 
117 			hv_ret = sun4v_set_version(group, major, *minor,
118 						   &actual_minor);
119 			ret = -EINVAL;
120 			if (hv_ret == HV_EOK) {
121 				*minor = actual_minor;
122 				p->major = major;
123 				p->minor = actual_minor;
124 				ret = 0;
125 			} else if (hv_ret == HV_EBADTRAP ||
126 				   hv_ret == HV_ENOTSUPPORTED) {
127 				if (p->flags & FLAG_PRE_API) {
128 					if (major == 1) {
129 						p->major = 1;
130 						p->minor = 0;
131 						*minor = 0;
132 						ret = 0;
133 					}
134 				}
135 			}
136 		}
137 
138 		if (ret == 0)
139 			__get_ref(p);
140 	}
141 	spin_unlock_irqrestore(&hvapi_lock, flags);
142 
143 	return ret;
144 }
145 EXPORT_SYMBOL(sun4v_hvapi_register);
146 
sun4v_hvapi_unregister(unsigned long group)147 void sun4v_hvapi_unregister(unsigned long group)
148 {
149 	struct api_info *p;
150 	unsigned long flags;
151 
152 	spin_lock_irqsave(&hvapi_lock, flags);
153 	p = __get_info(group);
154 	if (p)
155 		__put_ref(p);
156 	spin_unlock_irqrestore(&hvapi_lock, flags);
157 }
158 EXPORT_SYMBOL(sun4v_hvapi_unregister);
159 
sun4v_hvapi_get(unsigned long group,unsigned long * major,unsigned long * minor)160 int sun4v_hvapi_get(unsigned long group,
161 		    unsigned long *major,
162 		    unsigned long *minor)
163 {
164 	struct api_info *p;
165 	unsigned long flags;
166 	int ret;
167 
168 	spin_lock_irqsave(&hvapi_lock, flags);
169 	ret = -EINVAL;
170 	p = __get_info(group);
171 	if (p && p->refcnt) {
172 		*major = p->major;
173 		*minor = p->minor;
174 		ret = 0;
175 	}
176 	spin_unlock_irqrestore(&hvapi_lock, flags);
177 
178 	return ret;
179 }
180 EXPORT_SYMBOL(sun4v_hvapi_get);
181 
sun4v_hvapi_init(void)182 void __init sun4v_hvapi_init(void)
183 {
184 	unsigned long group, major, minor;
185 
186 	group = HV_GRP_SUN4V;
187 	major = 1;
188 	minor = 0;
189 	if (sun4v_hvapi_register(group, major, &minor))
190 		goto bad;
191 
192 	group = HV_GRP_CORE;
193 	major = 1;
194 	minor = 6;
195 	if (sun4v_hvapi_register(group, major, &minor))
196 		goto bad;
197 
198 	return;
199 
200 bad:
201 	prom_printf("HVAPI: Cannot register API group "
202 		    "%lx with major(%lu) minor(%lu)\n",
203 		    group, major, minor);
204 	prom_halt();
205 }
206