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 "qemu/error-report.h"
  22 #include "sysemu/sysemu.h"
  23 #include "sysemu/device_tree.h"
  24 #include "sysemu/rng.h"
  25 #include "hw/ppc/spapr.h"
  26 #include "kvm_ppc.h"
  27
  28 #define SPAPR_RNG(obj) \
  29     OBJECT_CHECK(sPAPRRngState, (obj), TYPE_SPAPR_RNG)
  30
  31 struct sPAPRRngState {
  32     /*< private >*/
  33     DeviceState ds;
  34     RngBackend *backend;
  35     bool use_kvm;
  36 };
  37 typedef struct sPAPRRngState sPAPRRngState;
  38
  39 struct HRandomData {
  40     QemuSemaphore sem;
  41     union {
  42         uint64_t v64;
  43         uint8_t v8[8];
  44     } val;
  45     int received;
  46 };
  47 typedef struct HRandomData HRandomData;
  48
  49 /* Callback function for the RngBackend */
  50 static void random_recv(void *dest, const void *src, size_t size)
  51 {
  52     HRandomData *hrdp = dest;
  53
  54     if (src && size > 0) {
  55         assert(size + hrdp->received <= sizeof(hrdp->val.v8));
  56         memcpy(&hrdp->val.v8[hrdp->received], src, size);
  57         hrdp->received += size;
  58     }
  59
  60     qemu_sem_post(&hrdp->sem);
  61 }
  62
  63 /* Handler for the H_RANDOM hypercall */
  64 static target_ulong h_random(PowerPCCPU *cpu, sPAPRMachineState *spapr,
  65                              target_ulong opcode, target_ulong *args)
  66 {
  67     sPAPRRngState *rngstate;
  68     HRandomData hrdata;
  69
  70     rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL));
  71
  72     if (!rngstate || !rngstate->backend) {
  73         return H_HARDWARE;
  74     }
  75
  76     qemu_sem_init(&hrdata.sem, 0);
  77     hrdata.val.v64 = 0;
  78     hrdata.received = 0;
  79
  80     while (hrdata.received < 8) {
  81         rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received,
  82                                     random_recv, &hrdata);
  83         qemu_mutex_unlock_iothread();
  84         qemu_sem_wait(&hrdata.sem);
  85         qemu_mutex_lock_iothread();
  86     }
  87
  88     qemu_sem_destroy(&hrdata.sem);
  89     args[0] = hrdata.val.v64;
  90
  91     return H_SUCCESS;
  92 }
  93
  94 static void spapr_rng_instance_init(Object *obj)
  95 {
  96     sPAPRRngState *rngstate = SPAPR_RNG(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_add_link(obj, "rng", TYPE_RNG_BACKEND,
 104                              (Object **)&rngstate->backend,
 105                              object_property_allow_set_link,
 106                              OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL);
 107     object_property_set_description(obj, "rng",
 108                                     "ID of the random number generator backend",
 109                                     NULL);
 110 }
 111
 112 static void spapr_rng_realize(DeviceState *dev, Error **errp)
 113 {
 114
 115     sPAPRRngState *rngstate = SPAPR_RNG(dev);
 116
 117     if (rngstate->use_kvm) {
 118         if (kvmppc_enable_hwrng() == 0) {
 119             return;
 120         }
 121         /*
 122          * If user specified both, use-kvm and a backend, we fall back to
 123          * the backend now. If not, provide an appropriate error message.
 124          */
 125         if (!rngstate->backend) {
 126             error_setg(errp, "Could not initialize in-kernel H_RANDOM call!");
 127             return;
 128         }
 129     }
 130
 131     if (rngstate->backend) {
 132         spapr_register_hypercall(H_RANDOM, h_random);
 133     } else {
 134         error_setg(errp, "spapr-rng needs an RNG backend!");
 135     }
 136 }
 137
 138 int spapr_rng_populate_dt(void *fdt)
 139 {
 140     int node;
 141     int ret;
 142
 143     node = qemu_fdt_add_subnode(fdt, "/ibm,platform-facilities");
 144     if (node <= 0) {
 145         return -1;
 146     }
 147     ret = fdt_setprop_string(fdt, node, "device_type",
 148                              "ibm,platform-facilities");
 149     ret |= fdt_setprop_cell(fdt, node, "#address-cells", 0x1);
 150     ret |= fdt_setprop_cell(fdt, node, "#size-cells", 0x0);
 151
 152     node = fdt_add_subnode(fdt, node, "ibm,random-v1");
 153     if (node <= 0) {
 154         return -1;
 155     }
 156     ret |= fdt_setprop_string(fdt, node, "compatible", "ibm,random");
 157
 158     return ret ? -1 : 0;
 159 }
 160
 161 static Property spapr_rng_properties[] = {
 162     DEFINE_PROP_BOOL("use-kvm", sPAPRRngState, use_kvm, false),
 163     DEFINE_PROP_END_OF_LIST(),
 164 };
 165
 166 static void spapr_rng_class_init(ObjectClass *oc, void *data)
 167 {
 168     DeviceClass *dc = DEVICE_CLASS(oc);
 169
 170     dc->realize = spapr_rng_realize;
 171     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 172     dc->props = spapr_rng_properties;
 173     dc->hotpluggable = false;
 174 }
 175
 176 static const TypeInfo spapr_rng_info = {
 177     .name          = TYPE_SPAPR_RNG,
 178     .parent        = TYPE_DEVICE,
 179     .instance_size = sizeof(sPAPRRngState),
 180     .instance_init = spapr_rng_instance_init,
 181     .class_init    = spapr_rng_class_init,
 182 };
 183
 184 static void spapr_rng_register_type(void)
 185 {
 186     type_register_static(&spapr_rng_info);
 187 }
 188 type_init(spapr_rng_register_type)