From 3ef536095446552823fc488fec1c5451aab1260d Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 16 May 2008 11:17:03 +0200 Subject: virtio_blk: allow read-only disks Hello Rusty, sometimes it is useful to share a disk (e.g. usr). To avoid file system corruption, the disk should be mounted read-only in that case. This patch adds a new feature flag, that allows the host to specify, if the disk should be considered read-only. Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell --- include/linux/virtio_blk.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h index d4695a3356d0..b80919fad0ef 100644 --- a/include/linux/virtio_blk.h +++ b/include/linux/virtio_blk.h @@ -10,6 +10,7 @@ #define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */ #define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */ #define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */ +#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */ struct virtio_blk_config { -- cgit v1.2.3 From f7f510ec195781c857ab76366a3e1c59e1caae42 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 30 May 2008 15:09:44 -0500 Subject: virtio: An entropy device, as suggested by hpa. Note that by itself, having a "hardware" random generator does very little: you should probably run "rngd" in your guest to feed this into the kernel entropy pool. Included: virtio_rng: dont use vmalloced addresses for virtio If virtio_rng is build as a module, random_data is an address in vmalloc space. As virtio expects guest real addresses, this can cause any kind of funny behaviour, so lets allocate random_data dynamically with kmalloc. Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell --- drivers/char/hw_random/Kconfig | 9 +++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/virtio-rng.c | 155 ++++++++++++++++++++++++++++++++++++ include/linux/virtio_rng.h | 8 ++ 4 files changed, 173 insertions(+) create mode 100644 drivers/char/hw_random/virtio-rng.c create mode 100644 include/linux/virtio_rng.h (limited to 'include/linux') diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index 8d6c2089d2a8..efd0b4db7c8e 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -112,3 +112,12 @@ 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 c8b7300e2fb1..b4940ddbb35f 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 000000000000..d0e563e4fc39 --- /dev/null +++ b/drivers/char/hw_random/virtio-rng.c @@ -0,0 +1,155 @@ +/* + * Randomness driver for virtio + * Copyright (C) 2007, 2008 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 +#include +#include +#include +#include +#include + +/* The host will fill any buffer we give it with sweet, sweet randomness. We + * give it 64 bytes at a time, and the hwrng framework takes it 4 bytes at a + * time. */ +#define RANDOM_DATA_SIZE 64 + +static struct virtqueue *vq; +static u32 *random_data; +static unsigned int data_left; +static DECLARE_COMPLETION(have_data); + +static void random_recv_done(struct virtqueue *vq) +{ + int len; + + /* We never get spurious callbacks. */ + if (!vq->vq_ops->get_buf(vq, &len)) + BUG(); + + data_left = len / sizeof(random_data[0]); + complete(&have_data); +} + +static void register_buffer(void) +{ + struct scatterlist sg; + + sg_init_one(&sg, random_data, RANDOM_DATA_SIZE); + /* 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); +} + +/* At least we don't udelay() in a loop like some other drivers. */ +static int virtio_data_present(struct hwrng *rng, int wait) +{ + if (data_left) + return 1; + + if (!wait) + return 0; + + wait_for_completion(&have_data); + return 1; +} + +/* virtio_data_present() must have succeeded before this is called. */ +static int virtio_data_read(struct hwrng *rng, u32 *data) +{ + BUG_ON(!data_left); + + *data = random_data[--data_left]; + + if (!data_left) { + init_completion(&have_data); + 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) +{ + vdev->config->reset(vdev); + hwrng_unregister(&virtio_hwrng); + 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) +{ + int err; + + random_data = kmalloc(RANDOM_DATA_SIZE, GFP_KERNEL); + if (!random_data) + return -ENOMEM; + + err = register_virtio_driver(&virtio_rng); + if (err) + kfree(random_data); + return err; +} + +static void __exit fini(void) +{ + kfree(random_data); + 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 000000000000..331afb6c9f62 --- /dev/null +++ b/include/linux/virtio_rng.h @@ -0,0 +1,8 @@ +#ifndef _LINUX_VIRTIO_RNG_H +#define _LINUX_VIRTIO_RNG_H +#include + +/* The ID for virtio_rng */ +#define VIRTIO_ID_RNG 4 + +#endif /* _LINUX_VIRTIO_RNG_H */ -- cgit v1.2.3 From 7f31fe05000af54e1af81f65a96cab90db8d7ed8 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 29 May 2008 11:08:01 +0200 Subject: virtio_config: fix len calculation of config elements Rusty, This patch is a prereq for the virtio_blk blocksize patch, please apply it first. Adding an u32 value to the virtio_blk_config unconvered a small bug the config space defintions: v is a pointer, to we have to use sizeof(*v) instead of sizeof(v). Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell --- include/linux/virtio_config.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 50db245c81ad..71d6c102497e 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -99,7 +99,7 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev, * The return value is -ENOENT if the feature doesn't exist. Otherwise * the config value is copied into whatever is pointed to by v. */ #define virtio_config_val(vdev, fbit, offset, v) \ - virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(v)) + virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v)) static inline int virtio_config_buf(struct virtio_device *vdev, unsigned int fbit, -- cgit v1.2.3 From 7757f09c70af87887dfc195e6d6ddd54f5cc7c39 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 29 May 2008 11:10:01 +0200 Subject: virtio_blk: fix endianess annotations Since commit 72e61eb40b55dd57031ec5971e810649f82b0259 (virtio: change config to guest endian) config space is no longer fixed endian. Lets change the virtio_blk_config variables. Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell --- include/linux/virtio_blk.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h index b80919fad0ef..5f79a5f9de79 100644 --- a/include/linux/virtio_blk.h +++ b/include/linux/virtio_blk.h @@ -15,14 +15,14 @@ struct virtio_blk_config { /* The capacity (in 512-byte sectors). */ - __le64 capacity; + __u64 capacity; /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */ - __le32 size_max; + __u32 size_max; /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */ - __le32 seg_max; + __u32 seg_max; /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */ struct virtio_blk_geometry { - __le16 cylinders; + __u16 cylinders; __u8 heads; __u8 sectors; } geometry; -- cgit v1.2.3 From b4f68be6c5d507afdcd74f5be3df0b1209cda503 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 30 May 2008 15:09:45 -0500 Subject: virtio: force callback on empty. virtio allows drivers to suppress callbacks (ie. interrupts) for efficiency (no locking, it's just an optimization). There's a similar mechanism for the host to suppress notifications coming from the guest: in that case, we ignore the suppression if the ring is completely full. It turns out that life is simpler if the host similarly ignores callback suppression when the ring is completely empty: the network driver wants to free up old packets in a timely manner, and otherwise has to use a timer to poll. We have to remove the code which ignores interrupts when the driver has disabled them (again, it had no locking and hence was unreliable anyway). Signed-off-by: Rusty Russell --- drivers/virtio/virtio_ring.c | 7 ------- include/linux/virtio_config.h | 4 ++++ 2 files changed, 4 insertions(+), 7 deletions(-) (limited to 'include/linux') diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 96d2567a7df8..72bf8bc09014 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -253,13 +253,6 @@ irqreturn_t vring_interrupt(int irq, void *_vq) if (unlikely(vq->broken)) return IRQ_HANDLED; - /* Other side may have missed us turning off the interrupt, - * but we should preserve disable semantic for virtio users. */ - if (unlikely(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) { - pr_debug("virtqueue interrupt after disable for %p\n", vq); - return IRQ_HANDLED; - } - pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); if (vq->vq.callback) vq->vq.callback(&vq->vq); diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 71d6c102497e..f364bbf63c34 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -15,6 +15,10 @@ /* We've given up on this device. */ #define VIRTIO_CONFIG_S_FAILED 0x80 +/* Do we get callbacks when the ring is completely used, even if we've + * suppressed them? */ +#define VIRTIO_F_NOTIFY_ON_EMPTY 24 + #ifdef __KERNEL__ #include -- cgit v1.2.3