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 32 #define SPAPR_RNG(obj) \ 33 OBJECT_CHECK(SpaprRngState, (obj), TYPE_SPAPR_RNG) 34 35 struct SpaprRngState { 36 /*< private >*/ 37 DeviceState ds; 38 RngBackend *backend; 39 bool use_kvm; 40 }; 41 typedef struct SpaprRngState SpaprRngState; 42 43 struct HRandomData { 44 QemuSemaphore sem; 45 union { 46 uint64_t v64; 47 uint8_t v8[8]; 48 } val; 49 int received; 50 }; 51 typedef struct HRandomData HRandomData; 52 53 /* Callback function for the RngBackend */ 54 static void random_recv(void *dest, const void *src, size_t size) 55 { 56 HRandomData *hrdp = dest; 57 58 if (src && size > 0) { 59 assert(size + hrdp->received <= sizeof(hrdp->val.v8)); 60 memcpy(&hrdp->val.v8[hrdp->received], src, size); 61 hrdp->received += size; 62 } 63 64 qemu_sem_post(&hrdp->sem); 65 } 66 67 /* Handler for the H_RANDOM hypercall */ 68 static target_ulong h_random(PowerPCCPU *cpu, SpaprMachineState *spapr, 69 target_ulong opcode, target_ulong *args) 70 { 71 SpaprRngState *rngstate; 72 HRandomData hrdata; 73 74 rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL)); 75 76 if (!rngstate || !rngstate->backend) { 77 return H_HARDWARE; 78 } 79 80 qemu_sem_init(&hrdata.sem, 0); 81 hrdata.val.v64 = 0; 82 hrdata.received = 0; 83 84 while (hrdata.received < 8) { 85 rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received, 86 random_recv, &hrdata); 87 qemu_mutex_unlock_iothread(); 88 qemu_sem_wait(&hrdata.sem); 89 qemu_mutex_lock_iothread(); 90 } 91 92 qemu_sem_destroy(&hrdata.sem); 93 args[0] = hrdata.val.v64; 94 95 return H_SUCCESS; 96 } 97 98 static void spapr_rng_instance_init(Object *obj) 99 { 100 if (object_resolve_path_type("", TYPE_SPAPR_RNG, NULL) != NULL) { 101 error_report("spapr-rng can not be instantiated twice!"); 102 return; 103 } 104 105 object_property_set_description(obj, "rng", 106 "ID of the random number generator backend", 107 NULL); 108 } 109 110 static void spapr_rng_realize(DeviceState *dev, Error **errp) 111 { 112 113 SpaprRngState *rngstate = SPAPR_RNG(dev); 114 115 if (rngstate->use_kvm) { 116 if (kvmppc_enable_hwrng() == 0) { 117 return; 118 } 119 /* 120 * If user specified both, use-kvm and a backend, we fall back to 121 * the backend now. If not, provide an appropriate error message. 122 */ 123 if (!rngstate->backend) { 124 error_setg(errp, "Could not initialize in-kernel H_RANDOM call!"); 125 return; 126 } 127 } 128 129 if (rngstate->backend) { 130 spapr_register_hypercall(H_RANDOM, h_random); 131 } else { 132 error_setg(errp, "spapr-rng needs an RNG backend!"); 133 } 134 } 135 136 static Property spapr_rng_properties[] = { 137 DEFINE_PROP_BOOL("use-kvm", SpaprRngState, use_kvm, false), 138 DEFINE_PROP_LINK("rng", SpaprRngState, backend, TYPE_RNG_BACKEND, 139 RngBackend *), 140 DEFINE_PROP_END_OF_LIST(), 141 }; 142 143 static void spapr_rng_class_init(ObjectClass *oc, void *data) 144 { 145 DeviceClass *dc = DEVICE_CLASS(oc); 146 147 dc->realize = spapr_rng_realize; 148 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 149 dc->props = spapr_rng_properties; 150 dc->hotpluggable = false; 151 } 152 153 static const TypeInfo spapr_rng_info = { 154 .name = TYPE_SPAPR_RNG, 155 .parent = TYPE_DEVICE, 156 .instance_size = sizeof(SpaprRngState), 157 .instance_init = spapr_rng_instance_init, 158 .class_init = spapr_rng_class_init, 159 }; 160 161 static void spapr_rng_register_type(void) 162 { 163 type_register_static(&spapr_rng_info); 164 } 165 type_init(spapr_rng_register_type) 166