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 "qemu/error-report.h" 23 #include "qemu/main-loop.h" 24 #include "qemu/module.h" 25 #include "sysemu/device_tree.h" 26 #include "sysemu/rng.h" 27 #include "hw/ppc/spapr.h" 28 #include "hw/qdev-properties.h" 29 #include "kvm_ppc.h" 30 #include "qom/object.h" 31 32 OBJECT_DECLARE_SIMPLE_TYPE(SpaprRngState, SPAPR_RNG) 33 34 struct SpaprRngState { 35 /*< private >*/ 36 DeviceState ds; 37 RngBackend *backend; 38 bool use_kvm; 39 }; 40 41 struct HRandomData { 42 QemuSemaphore sem; 43 union { 44 uint64_t v64; 45 uint8_t v8[8]; 46 } val; 47 int received; 48 }; 49 typedef struct HRandomData HRandomData; 50 51 /* Callback function for the RngBackend */ 52 static void random_recv(void *dest, const void *src, size_t size) 53 { 54 HRandomData *hrdp = dest; 55 56 if (src && size > 0) { 57 assert(size + hrdp->received <= sizeof(hrdp->val.v8)); 58 memcpy(&hrdp->val.v8[hrdp->received], src, size); 59 hrdp->received += size; 60 } 61 62 qemu_sem_post(&hrdp->sem); 63 } 64 65 /* Handler for the H_RANDOM hypercall */ 66 static target_ulong h_random(PowerPCCPU *cpu, SpaprMachineState *spapr, 67 target_ulong opcode, target_ulong *args) 68 { 69 SpaprRngState *rngstate; 70 HRandomData hrdata; 71 72 rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL)); 73 74 if (!rngstate || !rngstate->backend) { 75 return H_HARDWARE; 76 } 77 78 qemu_sem_init(&hrdata.sem, 0); 79 hrdata.val.v64 = 0; 80 hrdata.received = 0; 81 82 while (hrdata.received < 8) { 83 rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received, 84 random_recv, &hrdata); 85 bql_unlock(); 86 qemu_sem_wait(&hrdata.sem); 87 bql_lock(); 88 } 89 90 qemu_sem_destroy(&hrdata.sem); 91 args[0] = hrdata.val.v64; 92 93 return H_SUCCESS; 94 } 95 96 static void spapr_rng_instance_init(Object *obj) 97 { 98 if (object_resolve_path_type("", TYPE_SPAPR_RNG, NULL) != NULL) { 99 error_report("spapr-rng can not be instantiated twice!"); 100 return; 101 } 102 103 object_property_set_description(obj, "rng", 104 "ID of the random number generator backend"); 105 } 106 107 static void spapr_rng_realize(DeviceState *dev, Error **errp) 108 { 109 110 SpaprRngState *rngstate = SPAPR_RNG(dev); 111 112 if (rngstate->use_kvm) { 113 if (kvmppc_enable_hwrng() == 0) { 114 return; 115 } 116 /* 117 * If user specified both, use-kvm and a backend, we fall back to 118 * the backend now. If not, provide an appropriate error message. 119 */ 120 if (!rngstate->backend) { 121 error_setg(errp, "Could not initialize in-kernel H_RANDOM call!"); 122 return; 123 } 124 } 125 126 if (rngstate->backend) { 127 spapr_register_hypercall(H_RANDOM, h_random); 128 } else { 129 error_setg(errp, "spapr-rng needs an RNG backend!"); 130 } 131 } 132 133 static Property spapr_rng_properties[] = { 134 DEFINE_PROP_BOOL("use-kvm", SpaprRngState, use_kvm, false), 135 DEFINE_PROP_LINK("rng", SpaprRngState, backend, TYPE_RNG_BACKEND, 136 RngBackend *), 137 DEFINE_PROP_END_OF_LIST(), 138 }; 139 140 static void spapr_rng_class_init(ObjectClass *oc, void *data) 141 { 142 DeviceClass *dc = DEVICE_CLASS(oc); 143 144 dc->realize = spapr_rng_realize; 145 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 146 device_class_set_props(dc, spapr_rng_properties); 147 dc->hotpluggable = false; 148 } 149 150 static const TypeInfo spapr_rng_info = { 151 .name = TYPE_SPAPR_RNG, 152 .parent = TYPE_DEVICE, 153 .instance_size = sizeof(SpaprRngState), 154 .instance_init = spapr_rng_instance_init, 155 .class_init = spapr_rng_class_init, 156 }; 157 158 static void spapr_rng_register_type(void) 159 { 160 type_register_static(&spapr_rng_info); 161 } 162 type_init(spapr_rng_register_type) 163