LXR qemu/hw/ppc/spapr

   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
  34struct SpaprRngState {
  35    /*< private >*/
  36    DeviceState ds;
  37    RngBackend *backend;
  38    bool use_kvm;
  39};
  40typedef struct SpaprRngState SpaprRngState;
  41
  42struct HRandomData {
  43    QemuSemaphore sem;
  44    union {
  45        uint64_t v64;
  46        uint8_t v8[8];
  47    } val;
  48    int received;
  49};
  50typedef struct HRandomData HRandomData;
  51
  52/* Callback function for the RngBackend */
  53static 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 */
  67static 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
  97static 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
 109static 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
 135static 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
 142static 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
 152static 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
 160static void spapr_rng_register_type(void)
 161{
 162    type_register_static(&spapr_rng_info);
 163}
 164type_init(spapr_rng_register_type)
 165