mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
4476987a9a
No use waiting for input from host when the module is being removed. We're going to remove the vq in the next step anyway, so just perform any other steps for cleanup (currently none). Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
145 lines
3.2 KiB
C
145 lines
3.2 KiB
C
/*
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* Randomness driver for virtio
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* Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <linux/err.h>
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#include <linux/hw_random.h>
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#include <linux/scatterlist.h>
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#include <linux/spinlock.h>
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#include <linux/virtio.h>
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#include <linux/virtio_rng.h>
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#include <linux/module.h>
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static struct virtqueue *vq;
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static unsigned int data_avail;
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static DECLARE_COMPLETION(have_data);
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static bool busy;
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static void random_recv_done(struct virtqueue *vq)
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{
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/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
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if (!virtqueue_get_buf(vq, &data_avail))
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return;
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complete(&have_data);
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}
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/* The host will fill any buffer we give it with sweet, sweet randomness. */
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static void register_buffer(u8 *buf, size_t size)
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{
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struct scatterlist sg;
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sg_init_one(&sg, buf, size);
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/* There should always be room for one buffer. */
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if (virtqueue_add_buf(vq, &sg, 0, 1, buf, GFP_KERNEL) < 0)
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BUG();
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virtqueue_kick(vq);
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}
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static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
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{
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int ret;
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if (!busy) {
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busy = true;
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init_completion(&have_data);
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register_buffer(buf, size);
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}
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if (!wait)
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return 0;
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ret = wait_for_completion_killable(&have_data);
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if (ret < 0)
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return ret;
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busy = false;
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return data_avail;
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}
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static void virtio_cleanup(struct hwrng *rng)
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{
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if (busy)
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wait_for_completion(&have_data);
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}
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static struct hwrng virtio_hwrng = {
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.name = "virtio",
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.cleanup = virtio_cleanup,
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.read = virtio_read,
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};
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static int virtrng_probe(struct virtio_device *vdev)
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{
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int err;
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/* We expect a single virtqueue. */
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vq = virtio_find_single_vq(vdev, random_recv_done, "input");
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if (IS_ERR(vq))
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return PTR_ERR(vq);
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err = hwrng_register(&virtio_hwrng);
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if (err) {
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vdev->config->del_vqs(vdev);
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return err;
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}
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return 0;
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}
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static void __devexit virtrng_remove(struct virtio_device *vdev)
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{
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vdev->config->reset(vdev);
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busy = false;
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hwrng_unregister(&virtio_hwrng);
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vdev->config->del_vqs(vdev);
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}
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
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{ 0 },
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};
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static struct virtio_driver virtio_rng_driver = {
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.driver.name = KBUILD_MODNAME,
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.driver.owner = THIS_MODULE,
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.id_table = id_table,
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.probe = virtrng_probe,
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.remove = __devexit_p(virtrng_remove),
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};
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static int __init init(void)
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{
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return register_virtio_driver(&virtio_rng_driver);
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}
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static void __exit fini(void)
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{
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unregister_virtio_driver(&virtio_rng_driver);
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}
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module_init(init);
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module_exit(fini);
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MODULE_DEVICE_TABLE(virtio, id_table);
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MODULE_DESCRIPTION("Virtio random number driver");
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MODULE_LICENSE("GPL");
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