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1 /*
2 * QEMU sPAPR random number generator "device" for H_RANDOM hypercall
3 *
4 * Copyright 2015 Thomas Huth, Red Hat Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License,
9 * or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "qapi/error.h"
22 #include "cpu.h"
23 #include "qemu/error-report.h"
24 #include "qemu/main-loop.h"
25 #include "qemu/module.h"
26 #include "sysemu/sysemu.h"
27 #include "sysemu/device_tree.h"
28 #include "sysemu/rng.h"
29 #include "hw/ppc/spapr.h"
30 #include "hw/qdev-properties.h"
31 #include "kvm_ppc.h"
32
33 #define SPAPR_RNG(obj) \
34 OBJECT_CHECK(SpaprRngState, (obj), TYPE_SPAPR_RNG)
35
36 struct SpaprRngState {
37 /*< private >*/
38 DeviceState ds;
39 RngBackend *backend;
40 bool use_kvm;
41 };
42 typedef struct SpaprRngState SpaprRngState;
43
44 struct HRandomData {
45 QemuSemaphore sem;
46 union {
47 uint64_t v64;
48 uint8_t v8[8];
49 } val;
50 int received;
51 };
52 typedef struct HRandomData HRandomData;
53
54 /* Callback function for the RngBackend */
55 static void random_recv(void *dest, const void *src, size_t size)
56 {
57 HRandomData *hrdp = dest;
58
59 if (src && size > 0) {
60 assert(size + hrdp->received <= sizeof(hrdp->val.v8));
61 memcpy(&hrdp->val.v8[hrdp->received], src, size);
62 hrdp->received += size;
63 }
64
65 qemu_sem_post(&hrdp->sem);
66 }
67
68 /* Handler for the H_RANDOM hypercall */
69 static target_ulong h_random(PowerPCCPU *cpu, SpaprMachineState *spapr,
70 target_ulong opcode, target_ulong *args)
71 {
72 SpaprRngState *rngstate;
73 HRandomData hrdata;
74
75 rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL));
76
77 if (!rngstate || !rngstate->backend) {
78 return H_HARDWARE;
79 }
80
81 qemu_sem_init(&hrdata.sem, 0);
82 hrdata.val.v64 = 0;
83 hrdata.received = 0;
84
85 while (hrdata.received < 8) {
86 rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received,
87 random_recv, &hrdata);
88 qemu_mutex_unlock_iothread();
89 qemu_sem_wait(&hrdata.sem);
90 qemu_mutex_lock_iothread();
91 }
92
93 qemu_sem_destroy(&hrdata.sem);
94 args[0] = hrdata.val.v64;
95
96 return H_SUCCESS;
97 }
98
99 static void spapr_rng_instance_init(Object *obj)
100 {
101 if (object_resolve_path_type("", TYPE_SPAPR_RNG, NULL) != NULL) {
102 error_report("spapr-rng can not be instantiated twice!");
103 return;
104 }
105
106 object_property_set_description(obj, "rng",
107 "ID of the random number generator backend",
108 NULL);
109 }
110
111 static void spapr_rng_realize(DeviceState *dev, Error **errp)
112 {
113
114 SpaprRngState *rngstate = SPAPR_RNG(dev);
115
116 if (rngstate->use_kvm) {
117 if (kvmppc_enable_hwrng() == 0) {
118 return;
119 }
120 /*
121 * If user specified both, use-kvm and a backend, we fall back to
122 * the backend now. If not, provide an appropriate error message.
123 */
124 if (!rngstate->backend) {
125 error_setg(errp, "Could not initialize in-kernel H_RANDOM call!");
126 return;
127 }
128 }
129
130 if (rngstate->backend) {
131 spapr_register_hypercall(H_RANDOM, h_random);
132 } else {
133 error_setg(errp, "spapr-rng needs an RNG backend!");
134 }
135 }
136
137 static Property spapr_rng_properties[] = {
138 DEFINE_PROP_BOOL("use-kvm", SpaprRngState, use_kvm, false),
139 DEFINE_PROP_LINK("rng", SpaprRngState, backend, TYPE_RNG_BACKEND,
140 RngBackend *),
141 DEFINE_PROP_END_OF_LIST(),
142 };
143
144 static void spapr_rng_class_init(ObjectClass *oc, void *data)
145 {
146 DeviceClass *dc = DEVICE_CLASS(oc);
147
148 dc->realize = spapr_rng_realize;
149 set_bit(DEVICE_CATEGORY_MISC, dc->categories);
150 dc->props = spapr_rng_properties;
151 dc->hotpluggable = false;
152 }
153
154 static const TypeInfo spapr_rng_info = {
155 .name = TYPE_SPAPR_RNG,
156 .parent = TYPE_DEVICE,
157 .instance_size = sizeof(SpaprRngState),
158 .instance_init = spapr_rng_instance_init,
159 .class_init = spapr_rng_class_init,
160 };
161
162 static void spapr_rng_register_type(void)
163 {
164 type_register_static(&spapr_rng_info);
165 }
166 type_init(spapr_rng_register_type)