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/device_tree.h" 27 #include "sysemu/rng.h" 28 #include "hw/ppc/spapr.h" 29 #include "hw/qdev-properties.h" 30 #include "kvm_ppc.h" 31 #include "qom/object.h" 32 33 OBJECT_DECLARE_SIMPLE_TYPE(SpaprRngState, SPAPR_RNG) 34 35 struct SpaprRngState { 36 /*< private >*/ 37 DeviceState ds; 38 RngBackend *backend; 39 bool use_kvm; 40 }; 41 42 struct HRandomData { 43 QemuSemaphore sem; 44 union { 45 uint64_t v64; 46 uint8_t v8[8]; 47 } val; 48 int received; 49 }; 50 typedef struct HRandomData HRandomData; 51 52 /* Callback function for the RngBackend */ 53 static void random_recv(void *dest, const void *src, size_t size) 54 { 55 HRandomData *hrdp = dest; 56 57 if (src && size > 0) { 58 assert(size + hrdp->received <= sizeof(hrdp->val.v8)); 59 memcpy(&hrdp->val.v8[hrdp->received], src, size); 60 hrdp->received += size; 61 } 62 63 qemu_sem_post(&hrdp->sem); 64 } 65 66 /* Handler for the H_RANDOM hypercall */ 67 static target_ulong h_random(PowerPCCPU *cpu, SpaprMachineState *spapr, 68 target_ulong opcode, target_ulong *args) 69 { 70 SpaprRngState *rngstate; 71 HRandomData hrdata; 72 73 rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL)); 74 75 if (!rngstate || !rngstate->backend) { 76 return H_HARDWARE; 77 } 78 79 qemu_sem_init(&hrdata.sem, 0); 80 hrdata.val.v64 = 0; 81 hrdata.received = 0; 82 83 while (hrdata.received < 8) { 84 rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received, 85 random_recv, &hrdata); 86 qemu_mutex_unlock_iothread(); 87 qemu_sem_wait(&hrdata.sem); 88 qemu_mutex_lock_iothread(); 89 } 90 91 qemu_sem_destroy(&hrdata.sem); 92 args[0] = hrdata.val.v64; 93 94 return H_SUCCESS; 95 } 96 97 static void spapr_rng_instance_init(Object *obj) 98 { 99 if (object_resolve_path_type("", TYPE_SPAPR_RNG, NULL) != NULL) { 100 error_report("spapr-rng can not be instantiated twice!"); 101 return; 102 } 103 104 object_property_set_description(obj, "rng", 105 "ID of the random number generator backend"); 106 } 107 108 static void spapr_rng_realize(DeviceState *dev, Error **errp) 109 { 110 111 SpaprRngState *rngstate = SPAPR_RNG(dev); 112 113 if (rngstate->use_kvm) { 114 if (kvmppc_enable_hwrng() == 0) { 115 return; 116 } 117 /* 118 * If user specified both, use-kvm and a backend, we fall back to 119 * the backend now. If not, provide an appropriate error message. 120 */ 121 if (!rngstate->backend) { 122 error_setg(errp, "Could not initialize in-kernel H_RANDOM call!"); 123 return; 124 } 125 } 126 127 if (rngstate->backend) { 128 spapr_register_hypercall(H_RANDOM, h_random); 129 } else { 130 error_setg(errp, "spapr-rng needs an RNG backend!"); 131 } 132 } 133 134 static Property spapr_rng_properties[] = { 135 DEFINE_PROP_BOOL("use-kvm", SpaprRngState, use_kvm, false), 136 DEFINE_PROP_LINK("rng", SpaprRngState, backend, TYPE_RNG_BACKEND, 137 RngBackend *), 138 DEFINE_PROP_END_OF_LIST(), 139 }; 140 141 static void spapr_rng_class_init(ObjectClass *oc, void *data) 142 { 143 DeviceClass *dc = DEVICE_CLASS(oc); 144 145 dc->realize = spapr_rng_realize; 146 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 147 device_class_set_props(dc, spapr_rng_properties); 148 dc->hotpluggable = false; 149 } 150 151 static const TypeInfo spapr_rng_info = { 152 .name = TYPE_SPAPR_RNG, 153 .parent = TYPE_DEVICE, 154 .instance_size = sizeof(SpaprRngState), 155 .instance_init = spapr_rng_instance_init, 156 .class_init = spapr_rng_class_init, 157 }; 158 159 static void spapr_rng_register_type(void) 160 { 161 type_register_static(&spapr_rng_info); 162 } 163 type_init(spapr_rng_register_type) 164