diff options
Diffstat (limited to 'sys/dev/pv/viornd.c')
| -rw-r--r-- | sys/dev/pv/viornd.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/sys/dev/pv/viornd.c b/sys/dev/pv/viornd.c new file mode 100644 index 00000000000..dc0a43738b7 --- /dev/null +++ b/sys/dev/pv/viornd.c @@ -0,0 +1,201 @@ +/* $OpenBSD: viornd.c,v 1.1 2017/01/21 11:22:48 reyk Exp $ */ + +/* + * Copyright (c) 2014 Stefan Fritsch <sf@sfritsch.de> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/timeout.h> +#include <machine/bus.h> +#include <sys/device.h> +#include <sys/pool.h> +#include <dev/rndvar.h> +#include <dev/pv/virtioreg.h> +#include <dev/pv/virtiovar.h> + +/* + * The host may not have an unlimited supply of entropy. Therefore, we must + * not blindly get as much entropy as we can. Instead, we just request + * VIORND_BUFSIZE bytes at boot and every 15 * (1 << interval_shift) seconds. + * XXX There should be an API to check if we actually need more entropy. + * + * The lowest byte in the flags is used for transport specific settings. + * Therefore we use the second byte. + */ +#define VIORND_INTERVAL_SHIFT(f) ((f >> 8) & 0xf) +#define VIORND_INTERVAL_SHIFT_DEFAULT 5 +#define VIORND_ONESHOT 0x1000 +#define VIORND_BUFSIZE 16 + +#define VIORND_DEBUG 0 + +struct viornd_softc { + struct device sc_dev; + struct virtio_softc *sc_virtio; + + struct virtqueue sc_vq; + int *sc_buf; + bus_dmamap_t sc_dmamap; + + unsigned int sc_interval; + struct timeout sc_tick; +}; + +int viornd_match(struct device *, void *, void *); +void viornd_attach(struct device *, struct device *, void *); +int viornd_vq_done(struct virtqueue *); +void viornd_tick(void *); + +struct cfattach viornd_ca = { + sizeof(struct viornd_softc), + viornd_match, + viornd_attach, + NULL +}; + +struct cfdriver viornd_cd = { + NULL, "viornd", DV_DULL +}; + + +int viornd_match(struct device *parent, void *match, void *aux) +{ + struct virtio_softc *va = aux; + if (va->sc_childdevid == PCI_PRODUCT_VIRTIO_ENTROPY) + return 1; + return 0; +} + +void +viornd_attach(struct device *parent, struct device *self, void *aux) +{ + struct viornd_softc *sc = (struct viornd_softc *)self; + struct virtio_softc *vsc = (struct virtio_softc *)parent; + unsigned int shift; + + vsc->sc_vqs = &sc->sc_vq; + vsc->sc_nvqs = 1; + vsc->sc_config_change = 0; + if (vsc->sc_child != NULL) + panic("already attached to something else"); + vsc->sc_child = self; + vsc->sc_ipl = IPL_NET; + sc->sc_virtio = vsc; + + virtio_negotiate_features(vsc, 0, NULL); + + if (sc->sc_dev.dv_cfdata->cf_flags & VIORND_ONESHOT) { + sc->sc_interval = 0; + } else { + shift = VIORND_INTERVAL_SHIFT(sc->sc_dev.dv_cfdata->cf_flags); + if (shift == 0) + shift = VIORND_INTERVAL_SHIFT_DEFAULT; + sc->sc_interval = 15 * (1 << shift); + } +#if VIORND_DEBUG + printf(": request interval: %us\n", sc->sc_interval); +#endif + + sc->sc_buf = dma_alloc(VIORND_BUFSIZE, PR_NOWAIT|PR_ZERO); + if (sc->sc_buf == NULL) { + printf(": Can't alloc dma buffer\n"); + goto err; + } + if (bus_dmamap_create(sc->sc_virtio->sc_dmat, VIORND_BUFSIZE, 1, + VIORND_BUFSIZE, 0, BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, + &sc->sc_dmamap)) { + printf(": Can't alloc dmamap\n"); + goto err; + } + if (bus_dmamap_load(sc->sc_virtio->sc_dmat, sc->sc_dmamap, + sc->sc_buf, VIORND_BUFSIZE, NULL, BUS_DMA_NOWAIT|BUS_DMA_READ)) { + printf(": Can't load dmamap\n"); + goto err2; + } + + if (virtio_alloc_vq(vsc, &sc->sc_vq, 0, VIORND_BUFSIZE, 1, + "Entropy request") != 0) { + printf(": Can't alloc virtqueue\n"); + goto err2; + } + + sc->sc_vq.vq_done = viornd_vq_done; + virtio_start_vq_intr(vsc, &sc->sc_vq); + timeout_set(&sc->sc_tick, viornd_tick, sc); + timeout_add(&sc->sc_tick, 1); + + printf("\n"); + return; +err2: + bus_dmamap_destroy(vsc->sc_dmat, sc->sc_dmamap); +err: + vsc->sc_child = VIRTIO_CHILD_ERROR; + if (sc->sc_buf != NULL) { + dma_free(sc->sc_buf, VIORND_BUFSIZE); + sc->sc_buf = NULL; + } + return; +} + +int +viornd_vq_done(struct virtqueue *vq) +{ + struct virtio_softc *vsc = vq->vq_owner; + struct viornd_softc *sc = (struct viornd_softc *)vsc->sc_child; + int slot, len, i; + + if (virtio_dequeue(vsc, vq, &slot, &len) != 0) + return 0; + bus_dmamap_sync(vsc->sc_dmat, sc->sc_dmamap, 0, VIORND_BUFSIZE, + BUS_DMASYNC_POSTREAD); + if (len > VIORND_BUFSIZE) { + printf("%s: inconsistent descriptor length %d > %d\n", + sc->sc_dev.dv_xname, len, VIORND_BUFSIZE); + goto out; + } + +#if VIORND_DEBUG + printf("%s: got %d bytes of entropy\n", __func__, len); +#endif + for (i = 0; (i + 1) * sizeof(int) <= len; i++) + add_true_randomness(sc->sc_buf[i]); + + if (sc->sc_interval) + timeout_add_sec(&sc->sc_tick, sc->sc_interval); + +out: + virtio_dequeue_commit(vq, slot); + return 1; +} + +void +viornd_tick(void *arg) +{ + struct viornd_softc *sc = arg; + struct virtio_softc *vsc = sc->sc_virtio; + struct virtqueue *vq = &sc->sc_vq; + int slot; + + bus_dmamap_sync(vsc->sc_dmat, sc->sc_dmamap, 0, VIORND_BUFSIZE, + BUS_DMASYNC_PREREAD); + if (virtio_enqueue_prep(vq, &slot) != 0 || + virtio_enqueue_reserve(vq, slot, 1) != 0) { + panic("%s: virtqueue enqueue failed", sc->sc_dev.dv_xname); + } + virtio_enqueue(vq, slot, sc->sc_dmamap, 0); + virtio_enqueue_commit(vsc, vq, slot, 1); +} |