From 2334d90a3b9f8b9207163e9e0fad714e88a28771 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Date: Wed, 7 Nov 2007 21:02:22 +1100
Subject: [PATCH] virtio: An entropy device, as suggested by hpa.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
Documentation/lguest/lguest.c | 53 +++++++++++++++
drivers/char/hw_random/Kconfig | 10 +++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/virtio-rng.c | 124
+++++++++++++++++++++++++++++++++++
include/linux/virtio_rng.h | 8 ++
5 files changed, 196 insertions(+), 0 deletions(-)
create mode 100644 drivers/char/hw_random/virtio-rng.c
create mode 100644 include/linux/virtio_rng.h
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 029cc7c..314e977 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -41,6 +41,7 @@
#include "linux/virtio_net.h"
#include "linux/virtio_blk.h"
#include "linux/virtio_console.h"
+#include "linux/virtio_rng.h"
#include "linux/virtio_ring.h"
#include "asm-x86/bootparam.h"
/*L:110 We can ignore the 38 include files we need for this program,
but I do
@@ -1535,6 +1536,54 @@ static void setup_block_file(const char *filename)
}
/* That's the end of device setup. */
+/* This is the routine which handles console input (ie. stdin). */
+static bool handle_rng_input(int fd, struct device *dev)
+{
+ int len;
+ unsigned int head, in_num, out_num;
+ struct iovec iov[dev->vq->vring.num];
+
+ printf("Got input on rng fd!\n");
+ /* First we need a buffer from the Guests's virtqueue. */
+ head = get_vq_desc(dev->vq, iov, &out_num, &in_num);
+
+ /* If they're not ready for input, stop listening to this file
+ * descriptor. We'll start again once they add an input buffer. */
+ if (head == dev->vq->vring.num) {
+ printf("But no buffer!\n");
+ return false;
+ }
+
+ if (out_num)
+ errx(1, "Output buffers in rng?");
+
+ /* This is why we convert to iovecs: the readv() call uses them, and so
+ * it reads straight into the Guest's buffer. */
+ len = readv(dev->fd, iov, in_num);
+ /* Tell the Guest about the new input. */
+ add_used_and_trigger(fd, dev->vq, head, len);
+
+ /* Everything went OK! */
+ return true;
+}
+
+static void setup_rng(void)
+{
+ struct device *dev;
+ int fd;
+
+ fd = open_or_die("/dev/urandom", O_RDONLY);
+
+ /* The device responds to return from I/O thread. */
+ dev = new_device("rng", VIRTIO_ID_RNG, fd, handle_rng_input);
+
+ /* The device has one virtqueue, where the Guest places inbufs. */
+ add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd);
+
+ verbose("device %u: rng\n", devices.device_num);
+}
+/* That's the end of device setup. */
+
/*L:220 Finally we reach the core of the Launcher, which runs the
Guest, serves
* its input and output, and finally, lays it to rest. */
static void __attribute__((noreturn)) run_guest(int lguest_fd)
@@ -1581,6 +1630,7 @@ static struct option opts[] = {
{ "verbose", 0, NULL, 'v' },
{ "tunnet", 1, NULL, 't' },
{ "block", 1, NULL, 'b' },
+ { "rng", 0, NULL, 'r' },
{ "initrd", 1, NULL, 'i' },
{ NULL },
};
@@ -1648,6 +1698,9 @@ int main(int argc, char *argv[])
case 'b':
setup_block_file(optarg);
break;
+ case 'r':
+ setup_rng();
+ break;
case 'i':
initrd_name = optarg;
break;
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 2d7cd48..de20022 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -105,3 +105,13 @@ config HW_RANDOM_PASEMI
If unsure, say Y.
+config HW_RANDOM_VIRTIO
+ tristate "VirtIO Random Number Generator support"
+ depends on HW_RANDOM && VIRTIO
+ ---help---
+ This driver provides kernel-side support for the virtual Random
Number
+ Generator hardware.
+
+ To compile this driver as a module, choose M here: the
+ module will be called virtio-rng. If unsure, say N.
+
diff --git a/drivers/char/hw_random/Makefile
b/drivers/char/hw_random/Makefile
index c8b7300..b4940dd 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_HW_RANDOM_VIA) += via-rng.o
obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o
+obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o
diff --git a/drivers/char/hw_random/virtio-rng.c
b/drivers/char/hw_random/virtio-rng.c
new file mode 100644
index 0000000..f723cc3
--- /dev/null
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -0,0 +1,124 @@
+/*
+ * Randomness driver for virtio
+ * Copyright (C) 2007 Rusty Russell IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301 USA
+ */
+#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>
+
+static struct virtqueue *vq;
+static u32 random_data;
+static bool have_data;
+
+static bool random_recv_done(struct virtqueue *vq)
+{
+ have_data = true;
+
+ /* Don't suppress callbacks: there can't be any more since we
+ * have used up the only buffer. */
+ return true;
+}
+
+static void register_buffer(void)
+{
+ struct scatterlist sg;
+
+ sg_init_one(&sg, &random_data, sizeof(random_data));
+ /* There should always be room for one buffer. */
+ if (vq->vq_ops->add_buf(vq, &sg, 0, 1, &random_data) != 0)
+ BUG();
+ vq->vq_ops->kick(vq);
+}
+
+static int virtio_data_present(struct hwrng *rng)
+{
+ return have_data;
+}
+
+static int virtio_data_read(struct hwrng *rng, u32 *data)
+{
+ BUG_ON(!have_data);
+ *data = random_data;
+
+ have_data = false;
+ register_buffer();
+ return sizeof(*data);
+}
+
+static struct hwrng virtio_hwrng = {
+ .name = "virtio",
+ .data_present = virtio_data_present,
+ .data_read = virtio_data_read,
+};
+
+static int virtrng_probe(struct virtio_device *vdev)
+{
+ int err;
+
+ /* We expect a single virtqueue. */
+ vq = vdev->config->find_vq(vdev, 0, random_recv_done);
+ if (IS_ERR(vq))
+ return PTR_ERR(vq);
+
+ err = hwrng_register(&virtio_hwrng);
+ if (err) {
+ vdev->config->del_vq(vq);
+ return err;
+ }
+
+ register_buffer();
+ return 0;
+}
+
+static void virtrng_remove(struct virtio_device *vdev)
+{
+ hwrng_unregister(&virtio_hwrng);
+ vq->vq_ops->shutdown(vq);
+ vdev->config->del_vq(vq);
+}
+
+static struct virtio_device_id id_table[] = {
+ { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
+ { 0 },
+};
+
+static struct virtio_driver virtio_rng = {
+ .driver.name = KBUILD_MODNAME,
+ .driver.owner = THIS_MODULE,
+ .id_table = id_table,
+ .probe = virtrng_probe,
+ .remove = __devexit_p(virtrng_remove),
+};
+
+static int __init init(void)
+{
+ return register_virtio_driver(&virtio_rng);
+}
+
+static void __exit fini(void)
+{
+ unregister_virtio_driver(&virtio_rng);
+}
+module_init(init);
+module_exit(fini);
+
+MODULE_DEVICE_TABLE(virtio, id_table);
+MODULE_DESCRIPTION("Virtio random number driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio_rng.h b/include/linux/virtio_rng.h
new file mode 100644
index 0000000..331afb6
--- /dev/null
+++ b/include/linux/virtio_rng.h
@@ -0,0 +1,8 @@
+#ifndef _LINUX_VIRTIO_RNG_H
+#define _LINUX_VIRTIO_RNG_H
+#include <linux/virtio_config.h>
+
+/* The ID for virtio_rng */
+#define VIRTIO_ID_RNG 4
+
+#endif /* _LINUX_VIRTIO_RNG_H */
--
1.5.3.3
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/virtualization
