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/module.h" 25 #include "sysemu/sysemu.h" 26 #include "sysemu/device_tree.h" 27 #include "sysemu/rng.h" 28 #include "hw/ppc/spapr.h" 29 #include "kvm_ppc.h" 30 31 #define SPAPR_RNG(obj) \ 32 OBJECT_CHECK(SpaprRngState, (obj), TYPE_SPAPR_RNG) 33 34 struct SpaprRngState { 35 /*< private >*/ 36 DeviceState ds; 37 RngBackend *backend; 38 bool use_kvm; 39 }; 40 typedef struct SpaprRngState SpaprRngState; 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 NULL); 107 } 108 109 static void spapr_rng_realize(DeviceState *dev, Error **errp) 110 { 111 112 SpaprRngState *rngstate = SPAPR_RNG(dev); 113 114 if (rngstate->use_kvm) { 115 if (kvmppc_enable_hwrng() == 0) { 116 return; 117 } 118 /* 119 * If user specified both, use-kvm and a backend, we fall back to 120 * the backend now. If not, provide an appropriate error message. 121 */ 122 if (!rngstate->backend) { 123 error_setg(errp, "Could not initialize in-kernel H_RANDOM call!"); 124 return; 125 } 126 } 127 128 if (rngstate->backend) { 129 spapr_register_hypercall(H_RANDOM, h_random); 130 } else { 131 error_setg(errp, "spapr-rng needs an RNG backend!"); 132 } 133 } 134 135 static Property spapr_rng_properties[] = { 136 DEFINE_PROP_BOOL("use-kvm", SpaprRngState, use_kvm, false), 137 DEFINE_PROP_LINK("rng", SpaprRngState, backend, TYPE_RNG_BACKEND, 138 RngBackend *), 139 DEFINE_PROP_END_OF_LIST(), 140 }; 141 142 static void spapr_rng_class_init(ObjectClass *oc, void *data) 143 { 144 DeviceClass *dc = DEVICE_CLASS(oc); 145 146 dc->realize = spapr_rng_realize; 147 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 148 dc->props = spapr_rng_properties; 149 dc->hotpluggable = false; 150 } 151 152 static const TypeInfo spapr_rng_info = { 153 .name = TYPE_SPAPR_RNG, 154 .parent = TYPE_DEVICE, 155 .instance_size = sizeof(SpaprRngState), 156 .instance_init = spapr_rng_instance_init, 157 .class_init = spapr_rng_class_init, 158 }; 159 160 static void spapr_rng_register_type(void) 161 { 162 type_register_static(&spapr_rng_info); 163 } 164 type_init(spapr_rng_register_type) 165