1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2013, Bryan Venteicher <bryanv@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $FreeBSD: head/sys/dev/virtio/random/virtio_random.c 338324 2018-08-26 12:51:46Z markm $ 29 */ 30 31 /* Driver for VirtIO entropy device. */ 32 33 #include <sys/param.h> 34 #include <sys/kernel.h> 35 #include <sys/module.h> 36 #include <sys/thread.h> 37 #include <sys/sglist.h> 38 #include <sys/callout.h> 39 #include <sys/random.h> 40 #include <sys/systm.h> 41 #include <sys/bus.h> 42 43 #include <dev/virtual/virtio/virtio/virtio.h> 44 #include <dev/virtual/virtio/virtio/virtqueue.h> 45 46 struct vtrnd_softc { 47 device_t vtrnd_dev; 48 uint64_t vtrnd_features; 49 struct callout vtrnd_callout; 50 struct virtqueue *vtrnd_vq; 51 }; 52 53 static int vtrnd_modevent(module_t, int, void *); 54 55 static int vtrnd_probe(device_t); 56 static int vtrnd_attach(device_t); 57 static int vtrnd_detach(device_t); 58 59 static void vtrnd_negotiate_features(struct vtrnd_softc *); 60 static int vtrnd_alloc_virtqueue(struct vtrnd_softc *); 61 static void vtrnd_harvest(struct vtrnd_softc *); 62 static void vtrnd_timer(void *); 63 64 #define VTRND_FEATURES 0 65 66 static struct virtio_feature_desc vtrnd_feature_desc[] = { 67 { 0, NULL } 68 }; 69 70 static device_method_t vtrnd_methods[] = { 71 /* Device methods. */ 72 DEVMETHOD(device_probe, vtrnd_probe), 73 DEVMETHOD(device_attach, vtrnd_attach), 74 DEVMETHOD(device_detach, vtrnd_detach), 75 76 DEVMETHOD_END 77 }; 78 79 static driver_t vtrnd_driver = { 80 "vtrnd", 81 vtrnd_methods, 82 sizeof(struct vtrnd_softc) 83 }; 84 static devclass_t vtrnd_devclass; 85 86 DRIVER_MODULE(virtio_random, virtio_pci, vtrnd_driver, vtrnd_devclass, 87 vtrnd_modevent, NULL); 88 MODULE_VERSION(virtio_random, 1); 89 MODULE_DEPEND(virtio_random, virtio, 1, 1, 1); 90 91 static int 92 vtrnd_modevent(module_t mod, int type, void *unused) 93 { 94 int error; 95 96 switch (type) { 97 case MOD_LOAD: 98 case MOD_UNLOAD: 99 case MOD_SHUTDOWN: 100 error = 0; 101 break; 102 default: 103 error = EOPNOTSUPP; 104 break; 105 } 106 107 return (error); 108 } 109 110 static int 111 vtrnd_probe(device_t dev) 112 { 113 114 if (virtio_get_device_type(dev) != VIRTIO_ID_ENTROPY) 115 return (ENXIO); 116 117 device_set_desc(dev, "VirtIO Entropy Adapter"); 118 119 return (BUS_PROBE_DEFAULT); 120 } 121 122 static int 123 vtrnd_attach(device_t dev) 124 { 125 struct vtrnd_softc *sc; 126 int error; 127 128 sc = device_get_softc(dev); 129 sc->vtrnd_dev = dev; 130 131 callout_init_mp(&sc->vtrnd_callout); 132 133 virtio_set_feature_desc(dev, vtrnd_feature_desc); 134 vtrnd_negotiate_features(sc); 135 136 error = vtrnd_alloc_virtqueue(sc); 137 if (error) { 138 device_printf(dev, "cannot allocate virtqueue\n"); 139 goto fail; 140 } 141 142 callout_reset(&sc->vtrnd_callout, 5 * hz, vtrnd_timer, sc); 143 144 fail: 145 if (error) 146 vtrnd_detach(dev); 147 148 return (error); 149 } 150 151 static int 152 vtrnd_detach(device_t dev) 153 { 154 struct vtrnd_softc *sc; 155 156 sc = device_get_softc(dev); 157 158 callout_terminate(&sc->vtrnd_callout); 159 160 return (0); 161 } 162 163 static void 164 vtrnd_negotiate_features(struct vtrnd_softc *sc) 165 { 166 device_t dev; 167 uint64_t features; 168 169 dev = sc->vtrnd_dev; 170 features = VTRND_FEATURES; 171 172 sc->vtrnd_features = virtio_negotiate_features(dev, features); 173 } 174 175 static int 176 vtrnd_alloc_virtqueue(struct vtrnd_softc *sc) 177 { 178 device_t dev; 179 struct vq_alloc_info vq_info; 180 181 dev = sc->vtrnd_dev; 182 183 VQ_ALLOC_INFO_INIT(&vq_info, 0, &sc->vtrnd_vq, 184 "%s request", device_get_nameunit(dev)); 185 186 return (virtio_alloc_virtqueues(dev, 1, &vq_info)); 187 } 188 189 static void 190 vtrnd_harvest(struct vtrnd_softc *sc) 191 { 192 struct sglist_seg segs[1]; 193 struct sglist sg; 194 struct virtqueue *vq; 195 uint32_t value; 196 int error; 197 198 vq = sc->vtrnd_vq; 199 200 sglist_init(&sg, 1, segs); 201 error = sglist_append(&sg, &value, sizeof(value)); 202 KASSERT(error == 0 && sg.sg_nseg == 1, 203 ("%s: error %d adding buffer to sglist", __func__, error)); 204 205 if (!virtqueue_empty(vq)) 206 return; 207 if (virtqueue_enqueue(vq, &value, &sg, 0, 1) != 0) 208 return; 209 210 /* 211 * Poll for the response, but the command is likely already 212 * done when we return from the notify. 213 */ 214 virtqueue_notify(vq, NULL); 215 virtqueue_poll(vq, NULL); 216 217 add_buffer_randomness_src((const char *)&value, sizeof(value), 218 RAND_SRC_VIRTIO); 219 } 220 221 static void 222 vtrnd_timer(void *xsc) 223 { 224 struct vtrnd_softc *sc; 225 226 sc = xsc; 227 228 vtrnd_harvest(sc); 229 callout_reset(&sc->vtrnd_callout, 5 * hz, vtrnd_timer, sc); 230 } 231