hw/ppc/spapr_rng.c

   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         qemu_mutex_unlock_iothread();
  86         qemu_sem_wait(&hrdata.sem);
  87         qemu_mutex_lock_iothread();
  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)