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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /drivers/char/hw_random/virtio-rng.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/char/hw_random/virtio-rng.c')
-rw-r--r-- | drivers/char/hw_random/virtio-rng.c | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c new file mode 100644 index 0000000000..e41a84e6b4 --- /dev/null +++ b/drivers/char/hw_random/virtio-rng.c @@ -0,0 +1,264 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Randomness driver for virtio + * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation + */ + +#include <asm/barrier.h> +#include <linux/err.h> +#include <linux/hw_random.h> +#include <linux/scatterlist.h> +#include <linux/spinlock.h> +#include <linux/virtio.h> +#include <linux/virtio_rng.h> +#include <linux/module.h> +#include <linux/slab.h> + +static DEFINE_IDA(rng_index_ida); + +struct virtrng_info { + struct hwrng hwrng; + struct virtqueue *vq; + char name[25]; + int index; + bool hwrng_register_done; + bool hwrng_removed; + /* data transfer */ + struct completion have_data; + unsigned int data_avail; + unsigned int data_idx; + /* minimal size returned by rng_buffer_size() */ +#if SMP_CACHE_BYTES < 32 + u8 data[32]; +#else + u8 data[SMP_CACHE_BYTES]; +#endif +}; + +static void random_recv_done(struct virtqueue *vq) +{ + struct virtrng_info *vi = vq->vdev->priv; + unsigned int len; + + /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ + if (!virtqueue_get_buf(vi->vq, &len)) + return; + + smp_store_release(&vi->data_avail, len); + complete(&vi->have_data); +} + +static void request_entropy(struct virtrng_info *vi) +{ + struct scatterlist sg; + + reinit_completion(&vi->have_data); + vi->data_idx = 0; + + sg_init_one(&sg, vi->data, sizeof(vi->data)); + + /* There should always be room for one buffer. */ + virtqueue_add_inbuf(vi->vq, &sg, 1, vi->data, GFP_KERNEL); + + virtqueue_kick(vi->vq); +} + +static unsigned int copy_data(struct virtrng_info *vi, void *buf, + unsigned int size) +{ + size = min_t(unsigned int, size, vi->data_avail); + memcpy(buf, vi->data + vi->data_idx, size); + vi->data_idx += size; + vi->data_avail -= size; + if (vi->data_avail == 0) + request_entropy(vi); + return size; +} + +static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) +{ + int ret; + struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + unsigned int chunk; + size_t read; + + if (vi->hwrng_removed) + return -ENODEV; + + read = 0; + + /* copy available data */ + if (smp_load_acquire(&vi->data_avail)) { + chunk = copy_data(vi, buf, size); + size -= chunk; + read += chunk; + } + + if (!wait) + return read; + + /* We have already copied available entropy, + * so either size is 0 or data_avail is 0 + */ + while (size != 0) { + /* data_avail is 0 but a request is pending */ + ret = wait_for_completion_killable(&vi->have_data); + if (ret < 0) + return ret; + /* if vi->data_avail is 0, we have been interrupted + * by a cleanup, but buffer stays in the queue + */ + if (vi->data_avail == 0) + return read; + + chunk = copy_data(vi, buf + read, size); + size -= chunk; + read += chunk; + } + + return read; +} + +static void virtio_cleanup(struct hwrng *rng) +{ + struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + + complete(&vi->have_data); +} + +static int probe_common(struct virtio_device *vdev) +{ + int err, index; + struct virtrng_info *vi = NULL; + + vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL); + if (!vi) + return -ENOMEM; + + vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL); + if (index < 0) { + err = index; + goto err_ida; + } + sprintf(vi->name, "virtio_rng.%d", index); + init_completion(&vi->have_data); + + vi->hwrng = (struct hwrng) { + .read = virtio_read, + .cleanup = virtio_cleanup, + .priv = (unsigned long)vi, + .name = vi->name, + }; + vdev->priv = vi; + + /* We expect a single virtqueue. */ + vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); + if (IS_ERR(vi->vq)) { + err = PTR_ERR(vi->vq); + goto err_find; + } + + virtio_device_ready(vdev); + + /* we always have a pending entropy request */ + request_entropy(vi); + + return 0; + +err_find: + ida_simple_remove(&rng_index_ida, index); +err_ida: + kfree(vi); + return err; +} + +static void remove_common(struct virtio_device *vdev) +{ + struct virtrng_info *vi = vdev->priv; + + vi->hwrng_removed = true; + vi->data_avail = 0; + vi->data_idx = 0; + complete(&vi->have_data); + if (vi->hwrng_register_done) + hwrng_unregister(&vi->hwrng); + virtio_reset_device(vdev); + vdev->config->del_vqs(vdev); + ida_simple_remove(&rng_index_ida, vi->index); + kfree(vi); +} + +static int virtrng_probe(struct virtio_device *vdev) +{ + return probe_common(vdev); +} + +static void virtrng_remove(struct virtio_device *vdev) +{ + remove_common(vdev); +} + +static void virtrng_scan(struct virtio_device *vdev) +{ + struct virtrng_info *vi = vdev->priv; + int err; + + err = hwrng_register(&vi->hwrng); + if (!err) + vi->hwrng_register_done = true; +} + +#ifdef CONFIG_PM_SLEEP +static int virtrng_freeze(struct virtio_device *vdev) +{ + remove_common(vdev); + return 0; +} + +static int virtrng_restore(struct virtio_device *vdev) +{ + int err; + + err = probe_common(vdev); + if (!err) { + struct virtrng_info *vi = vdev->priv; + + /* + * Set hwrng_removed to ensure that virtio_read() + * does not block waiting for data before the + * registration is complete. + */ + vi->hwrng_removed = true; + err = hwrng_register(&vi->hwrng); + if (!err) { + vi->hwrng_register_done = true; + vi->hwrng_removed = false; + } + } + + return err; +} +#endif + +static const struct virtio_device_id id_table[] = { + { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static struct virtio_driver virtio_rng_driver = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = virtrng_probe, + .remove = virtrng_remove, + .scan = virtrng_scan, +#ifdef CONFIG_PM_SLEEP + .freeze = virtrng_freeze, + .restore = virtrng_restore, +#endif +}; + +module_virtio_driver(virtio_rng_driver); +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio random number driver"); +MODULE_LICENSE("GPL"); |