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 */
18struct 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
27static 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
57static DEFINE_SPINLOCK(hvapi_lock);
58
59static 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
70static void __get_ref(struct api_info *p)
71{
72	p->refcnt++;
73}
74
75static 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 */
96int 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}
145EXPORT_SYMBOL(sun4v_hvapi_register);
146
147void 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}
158EXPORT_SYMBOL(sun4v_hvapi_unregister);
159
160int 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}
180EXPORT_SYMBOL(sun4v_hvapi_get);
181
182void __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
200bad:
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