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 "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)