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/error-report.h"
  21 #include "sysemu/sysemu.h"
  22 #include "sysemu/device_tree.h"
  23 #include "sysemu/rng.h"
  24 #include "hw/ppc/spapr.h"
  25 #include "kvm_ppc.h"
  26
  27 #define SPAPR_RNG(obj) \
  28     OBJECT_CHECK(sPAPRRngState, (obj), TYPE_SPAPR_RNG)
  29
  30 struct sPAPRRngState {
  31     /*< private >*/
  32     DeviceState ds;
  33     RngBackend *backend;
  34     bool use_kvm;
  35 };
  36 typedef struct sPAPRRngState sPAPRRngState;
  37
  38 struct HRandomData {
  39     QemuSemaphore sem;
  40     union {
  41         uint64_t v64;
  42         uint8_t v8[8];
  43     } val;
  44     int received;
  45 };
  46 typedef struct HRandomData HRandomData;
  47
  48 /* Callback function for the RngBackend */
  49 static void random_recv(void *dest, const void *src, size_t size)
  50 {
  51     HRandomData *hrdp = dest;
  52
  53     if (src && size > 0) {
  54         assert(size + hrdp->received <= sizeof(hrdp->val.v8));
  55         memcpy(&hrdp->val.v8[hrdp->received], src, size);
  56         hrdp->received += size;
  57     }
  58
  59     qemu_sem_post(&hrdp->sem);
  60 }
  61
  62 /* Handler for the H_RANDOM hypercall */
  63 static target_ulong h_random(PowerPCCPU *cpu, sPAPRMachineState *spapr,
  64                              target_ulong opcode, target_ulong *args)
  65 {
  66     sPAPRRngState *rngstate;
  67     HRandomData hrdata;
  68
  69     rngstate = SPAPR_RNG(object_resolve_path_type("", TYPE_SPAPR_RNG, NULL));
  70
  71     if (!rngstate || !rngstate->backend) {
  72         return H_HARDWARE;
  73     }
  74
  75     qemu_sem_init(&hrdata.sem, 0);
  76     hrdata.val.v64 = 0;
  77     hrdata.received = 0;
  78
  79     qemu_mutex_unlock_iothread();
  80     while (hrdata.received < 8) {
  81         rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received,
  82                                     random_recv, &hrdata);
  83         qemu_sem_wait(&hrdata.sem);
  84     }
  85     qemu_mutex_lock_iothread();
  86
  87     qemu_sem_destroy(&hrdata.sem);
  88     args[0] = hrdata.val.v64;
  89
  90     return H_SUCCESS;
  91 }
  92
  93 static void spapr_rng_instance_init(Object *obj)
  94 {
  95     sPAPRRngState *rngstate = SPAPR_RNG(obj);
  96
  97     if (object_resolve_path_type("", TYPE_SPAPR_RNG, NULL) != NULL) {
  98         error_report("spapr-rng can not be instantiated twice!");
  99         return;
 100     }
 101
 102     object_property_add_link(obj, "rng", TYPE_RNG_BACKEND,
 103                              (Object **)&rngstate->backend,
 104                              object_property_allow_set_link,
 105                              OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL);
 106     object_property_set_description(obj, "rng",
 107                                     "ID of the random number generator backend",
 108                                     NULL);
 109 }
 110
 111 static void spapr_rng_realize(DeviceState *dev, Error **errp)
 112 {
 113
 114     sPAPRRngState *rngstate = SPAPR_RNG(dev);
 115
 116     if (rngstate->use_kvm) {
 117         if (kvmppc_enable_hwrng() == 0) {
 118             return;
 119         }
 120         /*
 121          * If user specified both, use-kvm and a backend, we fall back to
 122          * the backend now. If not, provide an appropriate error message.
 123          */
 124         if (!rngstate->backend) {
 125             error_setg(errp, "Could not initialize in-kernel H_RANDOM call!");
 126             return;
 127         }
 128     }
 129
 130     if (rngstate->backend) {
 131         spapr_register_hypercall(H_RANDOM, h_random);
 132     } else {
 133         error_setg(errp, "spapr-rng needs an RNG backend!");
 134     }
 135 }
 136
 137 int spapr_rng_populate_dt(void *fdt)
 138 {
 139     int node;
 140     int ret;
 141
 142     node = qemu_fdt_add_subnode(fdt, "/ibm,platform-facilities");
 143     if (node <= 0) {
 144         return -1;
 145     }
 146     ret = fdt_setprop_string(fdt, node, "device_type",
 147                              "ibm,platform-facilities");
 148     ret |= fdt_setprop_cell(fdt, node, "#address-cells", 0x1);
 149     ret |= fdt_setprop_cell(fdt, node, "#size-cells", 0x0);
 150
 151     node = fdt_add_subnode(fdt, node, "ibm,random-v1");
 152     if (node <= 0) {
 153         return -1;
 154     }
 155     ret |= fdt_setprop_string(fdt, node, "compatible", "ibm,random");
 156
 157     return ret ? -1 : 0;
 158 }
 159
 160 static Property spapr_rng_properties[] = {
 161     DEFINE_PROP_BOOL("use-kvm", sPAPRRngState, use_kvm, false),
 162     DEFINE_PROP_END_OF_LIST(),
 163 };
 164
 165 static void spapr_rng_class_init(ObjectClass *oc, void *data)
 166 {
 167     DeviceClass *dc = DEVICE_CLASS(oc);
 168
 169     dc->realize = spapr_rng_realize;
 170     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 171     dc->props = spapr_rng_properties;
 172 }
 173
 174 static const TypeInfo spapr_rng_info = {
 175     .name          = TYPE_SPAPR_RNG,
 176     .parent        = TYPE_DEVICE,
 177     .instance_size = sizeof(sPAPRRngState),
 178     .instance_init = spapr_rng_instance_init,
 179     .class_init    = spapr_rng_class_init,
 180 };
 181
 182 static void spapr_rng_register_type(void)
 183 {
 184     type_register_static(&spapr_rng_info);
 185 }
 186 type_init(spapr_rng_register_type)