1 /* $OpenBSD: viornd.c,v 1.11 2024/08/27 18:44:12 sf Exp $ */ 2 3 /* 4 * Copyright (c) 2014 Stefan Fritsch <sf@sfritsch.de> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/param.h> 20 #include <sys/systm.h> 21 #include <sys/timeout.h> 22 #include <machine/bus.h> 23 #include <sys/device.h> 24 #include <sys/pool.h> 25 #include <dev/pv/virtioreg.h> 26 #include <dev/pv/virtiovar.h> 27 28 /* 29 * The host may not have an unlimited supply of entropy. Therefore, we must 30 * not blindly get as much entropy as we can. Instead, we just request 31 * VIORND_BUFSIZE bytes at boot and every 15 * (1 << interval_shift) seconds. 32 * XXX There should be an API to check if we actually need more entropy. 33 * 34 * The lowest byte in the flags is used for transport specific settings. 35 * Therefore we use the second byte. 36 */ 37 #define VIORND_INTERVAL_SHIFT(f) ((f >> 8) & 0xf) 38 #define VIORND_INTERVAL_SHIFT_DEFAULT 5 39 #define VIORND_ONESHOT 0x1000 40 #define VIORND_BUFSIZE 16 41 42 #define VIORND_DEBUG 0 43 44 struct viornd_softc { 45 struct device sc_dev; 46 struct virtio_softc *sc_virtio; 47 48 struct virtqueue sc_vq; 49 int *sc_buf; 50 bus_dmamap_t sc_dmamap; 51 52 unsigned int sc_interval; 53 struct timeout sc_tick; 54 }; 55 56 int viornd_match(struct device *, void *, void *); 57 void viornd_attach(struct device *, struct device *, void *); 58 int viornd_vq_done(struct virtqueue *); 59 void viornd_tick(void *); 60 61 const struct cfattach viornd_ca = { 62 sizeof(struct viornd_softc), 63 viornd_match, 64 viornd_attach, 65 NULL 66 }; 67 68 struct cfdriver viornd_cd = { 69 NULL, "viornd", DV_DULL 70 }; 71 72 int 73 viornd_match(struct device *parent, void *match, void *aux) 74 { 75 struct virtio_attach_args *va = aux; 76 if (va->va_devid == PCI_PRODUCT_VIRTIO_ENTROPY) 77 return 1; 78 return 0; 79 } 80 81 void 82 viornd_attach(struct device *parent, struct device *self, void *aux) 83 { 84 struct viornd_softc *sc = (struct viornd_softc *)self; 85 struct virtio_softc *vsc = (struct virtio_softc *)parent; 86 unsigned int shift; 87 88 vsc->sc_vqs = &sc->sc_vq; 89 vsc->sc_nvqs = 1; 90 vsc->sc_config_change = NULL; 91 if (vsc->sc_child != NULL) 92 panic("already attached to something else"); 93 vsc->sc_child = self; 94 vsc->sc_ipl = IPL_NET; 95 sc->sc_virtio = vsc; 96 97 virtio_negotiate_features(vsc, NULL); 98 99 if (sc->sc_dev.dv_cfdata->cf_flags & VIORND_ONESHOT) { 100 sc->sc_interval = 0; 101 } else { 102 shift = VIORND_INTERVAL_SHIFT(sc->sc_dev.dv_cfdata->cf_flags); 103 if (shift == 0) 104 shift = VIORND_INTERVAL_SHIFT_DEFAULT; 105 sc->sc_interval = 15 * (1 << shift); 106 } 107 #if VIORND_DEBUG 108 printf(": request interval: %us\n", sc->sc_interval); 109 #endif 110 111 sc->sc_buf = dma_alloc(VIORND_BUFSIZE, PR_NOWAIT|PR_ZERO); 112 if (sc->sc_buf == NULL) { 113 printf(": Can't alloc dma buffer\n"); 114 goto err; 115 } 116 if (bus_dmamap_create(sc->sc_virtio->sc_dmat, VIORND_BUFSIZE, 1, 117 VIORND_BUFSIZE, 0, BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, 118 &sc->sc_dmamap)) { 119 printf(": Can't alloc dmamap\n"); 120 goto err; 121 } 122 if (bus_dmamap_load(sc->sc_virtio->sc_dmat, sc->sc_dmamap, 123 sc->sc_buf, VIORND_BUFSIZE, NULL, BUS_DMA_NOWAIT|BUS_DMA_READ)) { 124 printf(": Can't load dmamap\n"); 125 goto err2; 126 } 127 128 if (virtio_alloc_vq(vsc, &sc->sc_vq, 0, 1, "Entropy request") != 0) { 129 printf(": Can't alloc virtqueue\n"); 130 goto err2; 131 } 132 133 sc->sc_vq.vq_done = viornd_vq_done; 134 virtio_start_vq_intr(vsc, &sc->sc_vq); 135 timeout_set(&sc->sc_tick, viornd_tick, sc); 136 timeout_add(&sc->sc_tick, 1); 137 138 printf("\n"); 139 virtio_set_status(vsc, VIRTIO_CONFIG_DEVICE_STATUS_DRIVER_OK); 140 return; 141 err2: 142 bus_dmamap_destroy(vsc->sc_dmat, sc->sc_dmamap); 143 err: 144 vsc->sc_child = VIRTIO_CHILD_ERROR; 145 if (sc->sc_buf != NULL) { 146 dma_free(sc->sc_buf, VIORND_BUFSIZE); 147 sc->sc_buf = NULL; 148 } 149 return; 150 } 151 152 int 153 viornd_vq_done(struct virtqueue *vq) 154 { 155 struct virtio_softc *vsc = vq->vq_owner; 156 struct viornd_softc *sc = (struct viornd_softc *)vsc->sc_child; 157 int slot, len, i; 158 159 if (virtio_dequeue(vsc, vq, &slot, &len) != 0) 160 return 0; 161 bus_dmamap_sync(vsc->sc_dmat, sc->sc_dmamap, 0, VIORND_BUFSIZE, 162 BUS_DMASYNC_POSTREAD); 163 if (len > VIORND_BUFSIZE) { 164 printf("%s: inconsistent descriptor length %d > %d\n", 165 sc->sc_dev.dv_xname, len, VIORND_BUFSIZE); 166 goto out; 167 } 168 169 #if VIORND_DEBUG 170 printf("%s: got %d bytes of entropy\n", __func__, len); 171 #endif 172 for (i = 0; (i + 1) * sizeof(int) <= len; i++) 173 enqueue_randomness(sc->sc_buf[i]); 174 175 if (sc->sc_interval) 176 timeout_add_sec(&sc->sc_tick, sc->sc_interval); 177 178 out: 179 virtio_dequeue_commit(vq, slot); 180 return 1; 181 } 182 183 void 184 viornd_tick(void *arg) 185 { 186 struct viornd_softc *sc = arg; 187 struct virtio_softc *vsc = sc->sc_virtio; 188 struct virtqueue *vq = &sc->sc_vq; 189 int slot; 190 191 bus_dmamap_sync(vsc->sc_dmat, sc->sc_dmamap, 0, VIORND_BUFSIZE, 192 BUS_DMASYNC_PREREAD); 193 if (virtio_enqueue_prep(vq, &slot) != 0 || 194 virtio_enqueue_reserve(vq, slot, 1) != 0) { 195 panic("%s: virtqueue enqueue failed", sc->sc_dev.dv_xname); 196 } 197 virtio_enqueue(vq, slot, sc->sc_dmamap, 0); 198 virtio_enqueue_commit(vsc, vq, slot, 1); 199 } 200