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virtio: simplify config mechanism.

Browse source 
Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2008-02-04 23:49:56 -05:00
parent f35d9d8aae
commit a586d4f601
11 changed files with 278 additions and 279 deletions
Download patch file Download diff file Expand all files Collapse all files

178
Documentation/lguest/lguest.c
View file

@ -34,6 +34,8 @@
#include <zlib.h> #include <zlib.h>
#include <assert.h> #include <assert.h>
#include <sched.h> #include <sched.h>
#include <limits.h>
#include <stddef.h>
#include "linux/lguest_launcher.h" #include "linux/lguest_launcher.h"
#include "linux/virtio_config.h" #include "linux/virtio_config.h"
#include "linux/virtio_net.h" #include "linux/virtio_net.h"
@ -99,13 +101,11 @@ struct device_list
/* The descriptor page for the devices. */ /* The descriptor page for the devices. */
u8 *descpage; u8 *descpage;
/* The tail of the last descriptor. */
unsigned int desc_used;
/* A single linked list of devices. */ /* A single linked list of devices. */
struct device *dev; struct device *dev;
/* ... And an end pointer so we can easily append new devices */ /* And a pointer to the last device for easy append and also for
struct device **lastdev; * configuration appending. */
struct device *lastdev;
}; };
/* The list of Guest devices, based on command line arguments. */ /* The list of Guest devices, based on command line arguments. */
@ -191,7 +191,7 @@ static void *_convert(struct iovec *iov, size_t size, size_t align,
#define cpu_to_le64(v64) (v64) #define cpu_to_le64(v64) (v64)
#define le16_to_cpu(v16) (v16) #define le16_to_cpu(v16) (v16)
#define le32_to_cpu(v32) (v32) #define le32_to_cpu(v32) (v32)
#define le64_to_cpu(v32) (v64) #define le64_to_cpu(v64) (v64)
/*L:100 The Launcher code itself takes us out into userspace, that scary place /*L:100 The Launcher code itself takes us out into userspace, that scary place
* where pointers run wild and free! Unfortunately, like most userspace * where pointers run wild and free! Unfortunately, like most userspace
@ -986,54 +986,44 @@ static void handle_input(int fd)
* *
* All devices need a descriptor so the Guest knows it exists, and a "struct * All devices need a descriptor so the Guest knows it exists, and a "struct
* device" so the Launcher can keep track of it. We have common helper * device" so the Launcher can keep track of it. We have common helper
* routines to allocate them. * routines to allocate and manage them. */
*
* This routine allocates a new "struct lguest_device_desc" from descriptor /* The layout of the device page is a "struct lguest_device_desc" followed by a
* table just above the Guest's normal memory. It returns a pointer to that * number of virtqueue descriptors, then two sets of feature bits, then an
* descriptor. */ * array of configuration bytes. This routine returns the configuration
* pointer. */
static u8 *device_config(const struct device *dev)
{
return (void *)(dev->desc + 1)
+ dev->desc->num_vq * sizeof(struct lguest_vqconfig)
+ dev->desc->feature_len * 2;
}
/* This routine allocates a new "struct lguest_device_desc" from descriptor
* table page just above the Guest's normal memory. It returns a pointer to
* that descriptor. */
static struct lguest_device_desc *new_dev_desc(u16 type) static struct lguest_device_desc *new_dev_desc(u16 type)
{ {
struct lguest_device_desc *d; struct lguest_device_desc d = { .type = type };
void *p;
/* Figure out where the next device config is, based on the last one. */
if (devices.lastdev)
p = device_config(devices.lastdev)
+ devices.lastdev->desc->config_len;
else
p = devices.descpage;
/* We only have one page for all the descriptors. */ /* We only have one page for all the descriptors. */
if (devices.desc_used + sizeof(*d) > getpagesize()) if (p + sizeof(d) > (void *)devices.descpage + getpagesize())
errx(1, "Too many devices"); errx(1, "Too many devices");
/* We don't need to set config_len or status: page is 0 already. */ /* p might not be aligned, so we memcpy in. */
d = (void *)devices.descpage + devices.desc_used; return memcpy(p, &d, sizeof(d));
d->type = type;
devices.desc_used += sizeof(*d);
return d;
} }
/* Each device descriptor is followed by some configuration information. /* Each device descriptor is followed by the description of its virtqueues. We
* Each configuration field looks like: u8 type, u8 len, [... len bytes...]. * specify how many descriptors the virtqueue is to have. */
*
* This routine adds a new field to an existing device's descriptor. It only
* works for the last device, but that's OK because that's how we use it. */
static void add_desc_field(struct device *dev, u8 type, u8 len, const void *c)
{
/* This is the last descriptor, right? */
assert(devices.descpage + devices.desc_used
== (u8 *)(dev->desc + 1) + dev->desc->config_len);
/* We only have one page of device descriptions. */
if (devices.desc_used + 2 + len > getpagesize())
errx(1, "Too many devices");
/* Copy in the new config header: type then length. */
devices.descpage[devices.desc_used++] = type;
devices.descpage[devices.desc_used++] = len;
memcpy(devices.descpage + devices.desc_used, c, len);
devices.desc_used += len;
/* Update the device descriptor length: two byte head then data. */
dev->desc->config_len += 2 + len;
}
/* This routine adds a virtqueue to a device. We specify how many descriptors
* the virtqueue is to have. */
static void add_virtqueue(struct device *dev, unsigned int num_descs, static void add_virtqueue(struct device *dev, unsigned int num_descs,
void (*handle_output)(int fd, struct virtqueue *me)) void (*handle_output)(int fd, struct virtqueue *me))
{ {
@ -1059,9 +1049,15 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
/* Initialize the vring. */ /* Initialize the vring. */
vring_init(&vq->vring, num_descs, p, getpagesize()); vring_init(&vq->vring, num_descs, p, getpagesize());
/* Add the configuration information to this device's descriptor. */ /* Append virtqueue to this device's descriptor. We use
add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE, * device_config() to get the end of the device's current virtqueues;
sizeof(vq->config), &vq->config); * we check that we haven't added any config or feature information
* yet, otherwise we'd be overwriting them. */
assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0);
memcpy(device_config(dev), &vq->config, sizeof(vq->config));
dev->desc->num_vq++;
verbose("Virtqueue page %#lx\n", to_guest_phys(p));
/* Add to tail of list, so dev->vq is first vq, dev->vq->next is /* Add to tail of list, so dev->vq is first vq, dev->vq->next is
* second. */ * second. */
@ -1077,6 +1073,37 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
vq->vring.used->flags = VRING_USED_F_NO_NOTIFY; vq->vring.used->flags = VRING_USED_F_NO_NOTIFY;
} }
/* The virtqueue descriptors are followed by feature bytes. */
static void add_feature(struct device *dev, unsigned bit)
{
u8 *features;
/* We can't extend the feature bits once we've added config bytes */
if (dev->desc->feature_len <= bit / CHAR_BIT) {
assert(dev->desc->config_len == 0);
dev->desc->feature_len = (bit / CHAR_BIT) + 1;
}
features = (u8 *)(dev->desc + 1)
+ dev->desc->num_vq * sizeof(struct lguest_vqconfig);
features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT));
}
/* This routine sets the configuration fields for an existing device's
* descriptor. It only works for the last device, but that's OK because that's
* how we use it. */
static void set_config(struct device *dev, unsigned len, const void *conf)
{
/* Check we haven't overflowed our single page. */
if (device_config(dev) + len > devices.descpage + getpagesize())
errx(1, "Too many devices");
/* Copy in the config information, and store the length. */
memcpy(device_config(dev), conf, len);
dev->desc->config_len = len;
}
/* This routine does all the creation and setup of a new device, including /* This routine does all the creation and setup of a new device, including
* calling new_dev_desc() to allocate the descriptor and device memory. */ * calling new_dev_desc() to allocate the descriptor and device memory. */
static struct device *new_device(const char *name, u16 type, int fd, static struct device *new_device(const char *name, u16 type, int fd,
@ -1084,14 +1111,6 @@ static struct device *new_device(const char *name, u16 type, int fd,
{ {
struct device *dev = malloc(sizeof(*dev)); struct device *dev = malloc(sizeof(*dev));
/* Append to device list. Prepending to a single-linked list is
* easier, but the user expects the devices to be arranged on the bus
* in command-line order. The first network device on the command line
* is eth0, the first block device /dev/vda, etc. */
*devices.lastdev = dev;
dev->next = NULL;
devices.lastdev = &dev->next;
/* Now we populate the fields one at a time. */ /* Now we populate the fields one at a time. */
dev->fd = fd; dev->fd = fd;
/* If we have an input handler for this file descriptor, then we add it /* If we have an input handler for this file descriptor, then we add it
@ -1102,6 +1121,17 @@ static struct device *new_device(const char *name, u16 type, int fd,
dev->handle_input = handle_input; dev->handle_input = handle_input;
dev->name = name; dev->name = name;
dev->vq = NULL; dev->vq = NULL;
/* Append to device list. Prepending to a single-linked list is
* easier, but the user expects the devices to be arranged on the bus
* in command-line order. The first network device on the command line
* is eth0, the first block device /dev/vda, etc. */
if (devices.lastdev)
devices.lastdev->next = dev;
else
devices.dev = dev;
devices.lastdev = dev;
return dev; return dev;
} }
@ -1226,7 +1256,7 @@ static void setup_tun_net(const char *arg)
int netfd, ipfd; int netfd, ipfd;
u32 ip; u32 ip;
const char *br_name = NULL; const char *br_name = NULL;
u8 hwaddr[6]; struct virtio_net_config conf;
/* We open the /dev/net/tun device and tell it we want a tap device. A /* We open the /dev/net/tun device and tell it we want a tap device. A
* tap device is like a tun device, only somehow different. To tell * tap device is like a tun device, only somehow different. To tell
@ -1265,12 +1295,13 @@ static void setup_tun_net(const char *arg)
ip = str2ip(arg); ip = str2ip(arg);
/* Set up the tun device, and get the mac address for the interface. */ /* Set up the tun device, and get the mac address for the interface. */
configure_device(ipfd, ifr.ifr_name, ip, hwaddr); configure_device(ipfd, ifr.ifr_name, ip, conf.mac);
/* Tell Guest what MAC address to use. */ /* Tell Guest what MAC address to use. */
add_desc_field(dev, VIRTIO_CONFIG_NET_MAC_F, sizeof(hwaddr), hwaddr); add_feature(dev, VIRTIO_NET_F_MAC);
set_config(dev, sizeof(conf), &conf);
/* We don't seed the socket any more; setup is done. */ /* We don't need the socket any more; setup is done. */
close(ipfd); close(ipfd);
verbose("device %u: tun net %u.%u.%u.%u\n", verbose("device %u: tun net %u.%u.%u.%u\n",
@ -1458,8 +1489,7 @@ static void setup_block_file(const char *filename)
struct device *dev; struct device *dev;
struct vblk_info *vblk; struct vblk_info *vblk;
void *stack; void *stack;
u64 cap; struct virtio_blk_config conf;
unsigned int val;
/* This is the pipe the I/O thread will use to tell us I/O is done. */ /* This is the pipe the I/O thread will use to tell us I/O is done. */
pipe(p); pipe(p);
@ -1477,14 +1507,18 @@ static void setup_block_file(const char *filename)
vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
vblk->len = lseek64(vblk->fd, 0, SEEK_END); vblk->len = lseek64(vblk->fd, 0, SEEK_END);
/* We support barriers. */
add_feature(dev, VIRTIO_BLK_F_BARRIER);
/* Tell Guest how many sectors this device has. */ /* Tell Guest how many sectors this device has. */
cap = cpu_to_le64(vblk->len / 512); conf.capacity = cpu_to_le64(vblk->len / 512);
add_desc_field(dev, VIRTIO_CONFIG_BLK_F_CAPACITY, sizeof(cap), &cap);
/* Tell Guest not to put in too many descriptors at once: two are used /* Tell Guest not to put in too many descriptors at once: two are used
* for the in and out elements. */ * for the in and out elements. */
val = cpu_to_le32(VIRTQUEUE_NUM - 2); add_feature(dev, VIRTIO_BLK_F_SEG_MAX);
add_desc_field(dev, VIRTIO_CONFIG_BLK_F_SEG_MAX, sizeof(val), &val); conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
set_config(dev, sizeof(conf), &conf);
/* The I/O thread writes to this end of the pipe when done. */ /* The I/O thread writes to this end of the pipe when done. */
vblk->done_fd = p[1]; vblk->done_fd = p[1];
@ -1505,7 +1539,7 @@ static void setup_block_file(const char *filename)
close(vblk->workpipe[0]); close(vblk->workpipe[0]);
verbose("device %u: virtblock %llu sectors\n", verbose("device %u: virtblock %llu sectors\n",
devices.device_num, cap); devices.device_num, le64_to_cpu(conf.capacity));
} }
/* That's the end of device setup. :*/ /* That's the end of device setup. :*/
@ -1610,12 +1644,12 @@ int main(int argc, char *argv[])
/* First we initialize the device list. Since console and network /* First we initialize the device list. Since console and network
* device receive input from a file descriptor, we keep an fdset * device receive input from a file descriptor, we keep an fdset
* (infds) and the maximum fd number (max_infd) with the head of the * (infds) and the maximum fd number (max_infd) with the head of the
* list. We also keep a pointer to the last device, for easy appending * list. We also keep a pointer to the last device. Finally, we keep
* to the list. Finally, we keep the next interrupt number to hand out * the next interrupt number to hand out (1: remember that 0 is used by
* (1: remember that 0 is used by the timer). */ * the timer). */
FD_ZERO(&devices.infds); FD_ZERO(&devices.infds);
devices.max_infd = -1; devices.max_infd = -1;
devices.lastdev = &devices.dev; devices.lastdev = NULL;
devices.next_irq = 1; devices.next_irq = 1;
cpu_id = 0; cpu_id = 0;

35
drivers/block/virtio_blk.c
View file

@ -162,8 +162,6 @@ static int virtblk_probe(struct virtio_device *vdev)
{ {
struct virtio_blk *vblk; struct virtio_blk *vblk;
int err, major; int err, major;
void *token;
unsigned int len;
u64 cap; u64 cap;
u32 v; u32 v;
@ -178,7 +176,7 @@ static int virtblk_probe(struct virtio_device *vdev)
vblk->vdev = vdev; vblk->vdev = vdev;
/* We expect one virtqueue, for output. */ /* We expect one virtqueue, for output. */
vblk->vq = vdev->config->find_vq(vdev, blk_done); vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);
if (IS_ERR(vblk->vq)) { if (IS_ERR(vblk->vq)) {
err = PTR_ERR(vblk->vq); err = PTR_ERR(vblk->vq);
goto out_free_vblk; goto out_free_vblk;
@ -216,15 +214,12 @@ static int virtblk_probe(struct virtio_device *vdev)
vblk->disk->fops = &virtblk_fops; vblk->disk->fops = &virtblk_fops;
/* If barriers are supported, tell block layer that queue is ordered */ /* If barriers are supported, tell block layer that queue is ordered */
token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len); if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))
if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap); /* Host must always specify the capacity. */
if (err) { __virtio_config_val(vdev, offsetof(struct virtio_blk_config, capacity),
dev_err(&vdev->dev, "Bad/missing capacity in config\n"); &cap);
goto out_cleanup_queue;
}
/* If capacity is too big, truncate with warning. */ /* If capacity is too big, truncate with warning. */
if ((sector_t)cap != cap) { if ((sector_t)cap != cap) {
@ -234,27 +229,23 @@ static int virtblk_probe(struct virtio_device *vdev)
} }
set_capacity(vblk->disk, cap); set_capacity(vblk->disk, cap);
err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v); /* Host can optionally specify maximum segment size and number of
* segments. */
err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
offsetof(struct virtio_blk_config, size_max),
&v);
if (!err) if (!err)
blk_queue_max_segment_size(vblk->disk->queue, v); blk_queue_max_segment_size(vblk->disk->queue, v);
else if (err != -ENOENT) {
dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");
goto out_cleanup_queue;
}
err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v); err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
offsetof(struct virtio_blk_config, seg_max),
&v);
if (!err) if (!err)
blk_queue_max_hw_segments(vblk->disk->queue, v); blk_queue_max_hw_segments(vblk->disk->queue, v);
else if (err != -ENOENT) {
dev_err(&vdev->dev, "Bad SEG_MAX in config\n");
goto out_cleanup_queue;
}
add_disk(vblk->disk); add_disk(vblk->disk);
return 0; return 0;
out_cleanup_queue:
blk_cleanup_queue(vblk->disk->queue);
out_put_disk: out_put_disk:
put_disk(vblk->disk); put_disk(vblk->disk);
out_unregister_blkdev: out_unregister_blkdev:

4
drivers/char/virtio_console.c
View file

@ -158,13 +158,13 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
/* Find the input queue. */ /* Find the input queue. */
/* FIXME: This is why we want to wean off hvc: we do nothing /* FIXME: This is why we want to wean off hvc: we do nothing
* when input comes in. */ * when input comes in. */
in_vq = vdev->config->find_vq(vdev, NULL); in_vq = vdev->config->find_vq(vdev, 0, NULL);
if (IS_ERR(in_vq)) { if (IS_ERR(in_vq)) {
err = PTR_ERR(in_vq); err = PTR_ERR(in_vq);
goto free; goto free;
} }
out_vq = vdev->config->find_vq(vdev, NULL); out_vq = vdev->config->find_vq(vdev, 1, NULL);
if (IS_ERR(out_vq)) { if (IS_ERR(out_vq)) {
err = PTR_ERR(out_vq); err = PTR_ERR(out_vq);
goto free_in_vq; goto free_in_vq;

128
drivers/lguest/lguest_device.c
View file

@ -52,57 +52,82 @@ struct lguest_device {
/*D:130 /*D:130
* Device configurations * Device configurations
* *
* The configuration information for a device consists of a series of fields. * The configuration information for a device consists of one or more
* We don't really care what they are: the Launcher set them up, and the driver * virtqueues, a feature bitmaks, and some configuration bytes. The
* will look at them during setup. * configuration bytes don't really matter to us: the Launcher set them up, and
* the driver will look at them during setup.
* *
* For us these fields come immediately after that device's descriptor in the * A convenient routine to return the device's virtqueue config array:
* lguest_devices page. * immediately after the descriptor. */
* static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
* Each field starts with a "type" byte, a "length" byte, then that number of {
* bytes of configuration information. The device descriptor tells us the return (void *)(desc + 1);
* total configuration length so we know when we've reached the last field. */ }
/* type + length bytes */ /* The features come immediately after the virtqueues. */
#define FHDR_LEN 2 static u8 *lg_features(const struct lguest_device_desc *desc)
{
return (void *)(lg_vq(desc) + desc->num_vq);
}
/* This finds the first field of a given type for a device's configuration. */ /* The config space comes after the two feature bitmasks. */
static void *lg_find(struct virtio_device *vdev, u8 type, unsigned int *len) static u8 *lg_config(const struct lguest_device_desc *desc)
{
return lg_features(desc) + desc->feature_len * 2;
}
/* The total size of the config page used by this device (incl. desc) */
static unsigned desc_size(const struct lguest_device_desc *desc)
{
return sizeof(*desc)
+ desc->num_vq * sizeof(struct lguest_vqconfig)
+ desc->feature_len * 2
+ desc->config_len;
}
/* This tests (and acknowleges) a feature bit. */
static bool lg_feature(struct virtio_device *vdev, unsigned fbit)
{ {
struct lguest_device_desc *desc = to_lgdev(vdev)->desc; struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
int i; u8 *features;
for (i = 0; i < desc->config_len; i += FHDR_LEN + desc->config[i+1]) { /* Obviously if they ask for a feature off the end of our feature
if (desc->config[i] == type) { * bitmap, it's not set. */
/* Mark it used, so Host can know we looked at it, and if (fbit / 8 > desc->feature_len)
* also so we won't find the same one twice. */ return false;
desc->config[i] |= 0x80;
/* Remember, the second byte is the length. */
*len = desc->config[i+1];
/* We return a pointer to the field header. */
return desc->config + i;
}
}
/* Not found: return NULL for failure. */ /* The feature bitmap comes after the virtqueues. */
return NULL; features = lg_features(desc);
if (!(features[fbit / 8] & (1 << (fbit % 8))))
return false;
/* We set the matching bit in the other half of the bitmap to tell the
* Host we want to use this feature. We don't use this yet, but we
* could in future. */
features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8));
return true;
} }
/* Once they've found a field, getting a copy of it is easy. */ /* Once they've found a field, getting a copy of it is easy. */
static void lg_get(struct virtio_device *vdev, void *token, static void lg_get(struct virtio_device *vdev, unsigned int offset,
void *buf, unsigned len) void *buf, unsigned len)
{ {
/* Check they didn't ask for more than the length of the field! */ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
BUG_ON(len > ((u8 *)token)[1]);
memcpy(buf, token + FHDR_LEN, len); /* Check they didn't ask for more than the length of the config! */
BUG_ON(offset + len > desc->config_len);
memcpy(buf, lg_config(desc) + offset, len);
} }
/* Setting the contents is also trivial. */ /* Setting the contents is also trivial. */
static void lg_set(struct virtio_device *vdev, void *token, static void lg_set(struct virtio_device *vdev, unsigned int offset,
const void *buf, unsigned len) const void *buf, unsigned len)
{ {
BUG_ON(len > ((u8 *)token)[1]); struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
memcpy(token + FHDR_LEN, buf, len);
/* Check they didn't ask for more than the length of the config! */
BUG_ON(offset + len > desc->config_len);
memcpy(lg_config(desc) + offset, buf, len);
} }
/* The operations to get and set the status word just access the status field /* The operations to get and set the status word just access the status field
@ -165,39 +190,29 @@ static void lg_notify(struct virtqueue *vq)
* *
* So we provide devices with a "find virtqueue and set it up" function. */ * So we provide devices with a "find virtqueue and set it up" function. */
static struct virtqueue *lg_find_vq(struct virtio_device *vdev, static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
unsigned index,
bool (*callback)(struct virtqueue *vq)) bool (*callback)(struct virtqueue *vq))
{ {
struct lguest_device *ldev = to_lgdev(vdev);
struct lguest_vq_info *lvq; struct lguest_vq_info *lvq;
struct virtqueue *vq; struct virtqueue *vq;
unsigned int len;
void *token;
int err; int err;
/* Look for a field of the correct type to mark a virtqueue. Note that /* We must have this many virtqueues. */
* if this succeeds, then the type will be changed so it won't be found if (index >= ldev->desc->num_vq)
* again, and future lg_find_vq() calls will find the next
* virtqueue (if any). */
token = vdev->config->find(vdev, VIRTIO_CONFIG_F_VIRTQUEUE, &len);
if (!token)
return ERR_PTR(-ENOENT); return ERR_PTR(-ENOENT);
lvq = kmalloc(sizeof(*lvq), GFP_KERNEL); lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
if (!lvq) if (!lvq)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
/* Note: we could use a configuration space inside here, just like we /* Make a copy of the "struct lguest_vqconfig" entry, which sits after
* do for the device. This would allow expansion in future, because * the descriptor. We need a copy because the config space might not
* our configuration system is designed to be expansible. But this is * be aligned correctly. */
* way easier. */ memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
if (len != sizeof(lvq->config)) {
dev_err(&vdev->dev, "Unexpected virtio config len %u\n", len);
err = -EIO;
goto free_lvq;
}
/* Make a copy of the "struct lguest_vqconfig" field. We need a copy
* because the config space might not be aligned correctly. */
vdev->config->get(vdev, token, &lvq->config, sizeof(lvq->config));
printk("Mapping virtqueue %i addr %lx\n", index,
(unsigned long)lvq->config.pfn << PAGE_SHIFT);
/* Figure out how many pages the ring will take, and map that memory */ /* Figure out how many pages the ring will take, and map that memory */
lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT, lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
DIV_ROUND_UP(vring_size(lvq->config.num, DIV_ROUND_UP(vring_size(lvq->config.num,
@ -259,7 +274,7 @@ static void lg_del_vq(struct virtqueue *vq)
/* The ops structure which hooks everything together. */ /* The ops structure which hooks everything together. */
static struct virtio_config_ops lguest_config_ops = { static struct virtio_config_ops lguest_config_ops = {
.find = lg_find, .feature = lg_feature,
.get = lg_get, .get = lg_get,
.set = lg_set, .set = lg_set,
.get_status = lg_get_status, .get_status = lg_get_status,
@ -329,13 +344,14 @@ static void scan_devices(void)
struct lguest_device_desc *d; struct lguest_device_desc *d;
/* We start at the page beginning, and skip over each entry. */ /* We start at the page beginning, and skip over each entry. */
for (i = 0; i < PAGE_SIZE; i += sizeof(*d) + d->config_len) { for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
d = lguest_devices + i; d = lguest_devices + i;
/* Once we hit a zero, stop. */ /* Once we hit a zero, stop. */
if (d->type == 0) if (d->type == 0)
break; break;
printk("Device at %i has size %u\n", i, desc_size(d));
add_lguest_device(d); add_lguest_device(d);
} }
} }

25
drivers/net/virtio_net.c
View file

@ -311,10 +311,8 @@ static int virtnet_close(struct net_device *dev)
static int virtnet_probe(struct virtio_device *vdev) static int virtnet_probe(struct virtio_device *vdev)
{ {
int err; int err;
unsigned int len;
struct net_device *dev; struct net_device *dev;
struct virtnet_info *vi; struct virtnet_info *vi;
void *token;
/* Allocate ourselves a network device with room for our info */ /* Allocate ourselves a network device with room for our info */
dev = alloc_etherdev(sizeof(struct virtnet_info)); dev = alloc_etherdev(sizeof(struct virtnet_info));
@ -330,25 +328,24 @@ static int virtnet_probe(struct virtio_device *vdev)
SET_NETDEV_DEV(dev, &vdev->dev); SET_NETDEV_DEV(dev, &vdev->dev);
/* Do we support "hardware" checksums? */ /* Do we support "hardware" checksums? */
token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_F, &len); if (vdev->config->feature(vdev, VIRTIO_NET_F_NO_CSUM)) {
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_NO_CSUM)) {
/* This opens up the world of extra features. */ /* This opens up the world of extra features. */
dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST; dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4)) if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4))
dev->features |= NETIF_F_TSO; dev->features |= NETIF_F_TSO;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_UFO)) if (vdev->config->feature(vdev, VIRTIO_NET_F_UFO))
dev->features |= NETIF_F_UFO; dev->features |= NETIF_F_UFO;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4_ECN)) if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4_ECN))
dev->features |= NETIF_F_TSO_ECN; dev->features |= NETIF_F_TSO_ECN;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO6)) if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO6))
dev->features |= NETIF_F_TSO6; dev->features |= NETIF_F_TSO6;
} }
/* Configuration may specify what MAC to use. Otherwise random. */ /* Configuration may specify what MAC to use. Otherwise random. */
token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_MAC_F, &len); if (vdev->config->feature(vdev, VIRTIO_NET_F_MAC)) {
if (token) { vdev->config->get(vdev,
dev->addr_len = len; offsetof(struct virtio_net_config, mac),
vdev->config->get(vdev, token, dev->dev_addr, len); dev->dev_addr, dev->addr_len);
} else } else
random_ether_addr(dev->dev_addr); random_ether_addr(dev->dev_addr);
@ -359,13 +356,13 @@ static int virtnet_probe(struct virtio_device *vdev)
vi->vdev = vdev; vi->vdev = vdev;
/* We expect two virtqueues, receive then send. */ /* We expect two virtqueues, receive then send. */
vi->rvq = vdev->config->find_vq(vdev, skb_recv_done); vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
if (IS_ERR(vi->rvq)) { if (IS_ERR(vi->rvq)) {
err = PTR_ERR(vi->rvq); err = PTR_ERR(vi->rvq);
goto free; goto free;
} }
vi->svq = vdev->config->find_vq(vdev, skb_xmit_done); vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
if (IS_ERR(vi->svq)) { if (IS_ERR(vi->svq)) {
err = PTR_ERR(vi->svq); err = PTR_ERR(vi->svq);
goto free_recv; goto free_recv;

45
drivers/virtio/virtio.c
View file

@ -148,51 +148,6 @@ void unregister_virtio_device(struct virtio_device *dev)
} }
EXPORT_SYMBOL_GPL(unregister_virtio_device); EXPORT_SYMBOL_GPL(unregister_virtio_device);
int __virtio_config_val(struct virtio_device *vdev,
u8 type, void *val, size_t size)
{
void *token;
unsigned int len;
token = vdev->config->find(vdev, type, &len);
if (!token)
return -ENOENT;
if (len != size)
return -EIO;
vdev->config->get(vdev, token, val, size);
return 0;
}
EXPORT_SYMBOL_GPL(__virtio_config_val);
int virtio_use_bit(struct virtio_device *vdev,
void *token, unsigned int len, unsigned int bitnum)
{
unsigned long bits[16];
/* This makes it convenient to pass-through find() results. */
if (!token)
return 0;
/* bit not in range of this bitfield? */
if (bitnum * 8 >= len / 2)
return 0;
/* Giant feature bitfields are silly. */
BUG_ON(len > sizeof(bits));
vdev->config->get(vdev, token, bits, len);
if (!test_bit(bitnum, bits))
return 0;
/* Set acknowledge bit, and write it back. */
set_bit(bitnum + len * 8 / 2, bits);
vdev->config->set(vdev, token, bits, len);
return 1;
}
EXPORT_SYMBOL_GPL(virtio_use_bit);
static int virtio_init(void) static int virtio_init(void)
{ {
if (bus_register(&virtio_bus) != 0) if (bus_register(&virtio_bus) != 0)

9
include/linux/lguest_launcher.h
View file

@ -23,7 +23,12 @@
struct lguest_device_desc { struct lguest_device_desc {
/* The device type: console, network, disk etc. Type 0 terminates. */ /* The device type: console, network, disk etc. Type 0 terminates. */
__u8 type; __u8 type;
/* The number of bytes of the config array. */ /* The number of virtqueues (first in config array) */
__u8 num_vq;
/* The number of bytes of feature bits. Multiply by 2: one for host
* features and one for guest acknowledgements. */
__u8 feature_len;
/* The number of bytes of the config array after virtqueues. */
__u8 config_len; __u8 config_len;
/* A status byte, written by the Guest. */ /* A status byte, written by the Guest. */
__u8 status; __u8 status;
@ -31,7 +36,7 @@ struct lguest_device_desc {
}; };
/*D:135 This is how we expect the device configuration field for a virtqueue /*D:135 This is how we expect the device configuration field for a virtqueue
* (type VIRTIO_CONFIG_F_VIRTQUEUE) to be laid out: */ * to be laid out in config space. */
struct lguest_vqconfig { struct lguest_vqconfig {
/* The number of entries in the virtio_ring */ /* The number of entries in the virtio_ring */
__u16 num; __u16 num;

20
include/linux/virtio_blk.h
View file

@ -6,15 +6,19 @@
#define VIRTIO_ID_BLOCK 2 #define VIRTIO_ID_BLOCK 2
/* Feature bits */ /* Feature bits */
#define VIRTIO_CONFIG_BLK_F 0x40 #define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
#define VIRTIO_BLK_F_BARRIER 1 /* Does host support barriers? */ #define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
/* The capacity (in 512-byte sectors). */ struct virtio_blk_config
#define VIRTIO_CONFIG_BLK_F_CAPACITY 0x41 {
/* The maximum segment size. */ /* The capacity (in 512-byte sectors). */
#define VIRTIO_CONFIG_BLK_F_SIZE_MAX 0x42 __le64 capacity;
/* The maximum number of segments. */ /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
#define VIRTIO_CONFIG_BLK_F_SEG_MAX 0x43 __le32 size_max;
/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
__le32 seg_max;
} __attribute__((packed));
/* These two define direction. */ /* These two define direction. */
#define VIRTIO_BLK_T_IN 0 #define VIRTIO_BLK_T_IN 0

98
include/linux/virtio_config.h
View file

@ -5,7 +5,7 @@
* store and access that space differently. */ * store and access that space differently. */
#include <linux/types.h> #include <linux/types.h>
/* Status byte for guest to report progress, and synchronize config. */ /* Status byte for guest to report progress, and synchronize features. */
/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */ /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1 #define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
/* We have found a driver for the device. */ /* We have found a driver for the device. */
@ -15,34 +15,27 @@
/* We've given up on this device. */ /* We've given up on this device. */
#define VIRTIO_CONFIG_S_FAILED 0x80 #define VIRTIO_CONFIG_S_FAILED 0x80
/* Feature byte (actually 7 bits availabe): */
/* Requirements/features of the virtio implementation. */
#define VIRTIO_CONFIG_F_VIRTIO 1
/* Requirements/features of the virtqueue (may have more than one). */
#define VIRTIO_CONFIG_F_VIRTQUEUE 2
#ifdef __KERNEL__ #ifdef __KERNEL__
struct virtio_device; struct virtio_device;
/** /**
* virtio_config_ops - operations for configuring a virtio device * virtio_config_ops - operations for configuring a virtio device
* @find: search for the next configuration field of the given type. * @feature: search for a feature in this config
* vdev: the virtio_device * vdev: the virtio_device
* type: the feature type * bit: the feature bit
* len: the (returned) length of the field if found. * Returns true if the feature is supported. Acknowledges the feature
* Returns a token if found, or NULL. Never returnes the same field twice * so the host can see it.
* (ie. it's used up). * @get: read the value of a configuration field
* @get: read the value of a configuration field after find().
* vdev: the virtio_device * vdev: the virtio_device
* token: the token returned from find(). * offset: the offset of the configuration field
* buf: the buffer to write the field value into. * buf: the buffer to write the field value into.
* len: the length of the buffer (given by find()). * len: the length of the buffer
* Note that contents are conventionally little-endian. * Note that contents are conventionally little-endian.
* @set: write the value of a configuration field after find(). * @set: write the value of a configuration field
* vdev: the virtio_device * vdev: the virtio_device
* token: the token returned from find(). * offset: the offset of the configuration field
* buf: the buffer to read the field value from. * buf: the buffer to read the field value from.
* len: the length of the buffer (given by find()). * len: the length of the buffer
* Note that contents are conventionally little-endian. * Note that contents are conventionally little-endian.
* @get_status: read the status byte * @get_status: read the status byte
* vdev: the virtio_device * vdev: the virtio_device
@ -50,62 +43,63 @@ struct virtio_device;
* @set_status: write the status byte * @set_status: write the status byte
* vdev: the virtio_device * vdev: the virtio_device
* status: the new status byte * status: the new status byte
* @find_vq: find the first VIRTIO_CONFIG_F_VIRTQUEUE and create a virtqueue. * @find_vq: find a virtqueue and instantiate it.
* vdev: the virtio_device * vdev: the virtio_device
* index: the 0-based virtqueue number in case there's more than one.
* callback: the virqtueue callback * callback: the virqtueue callback
* Returns the new virtqueue or ERR_PTR(). * Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
* @del_vq: free a virtqueue found by find_vq(). * @del_vq: free a virtqueue found by find_vq().
*/ */
struct virtio_config_ops struct virtio_config_ops
{ {
void *(*find)(struct virtio_device *vdev, u8 type, unsigned *len); bool (*feature)(struct virtio_device *vdev, unsigned bit);
void (*get)(struct virtio_device *vdev, void *token, void (*get)(struct virtio_device *vdev, unsigned offset,
void *buf, unsigned len); void *buf, unsigned len);
void (*set)(struct virtio_device *vdev, void *token, void (*set)(struct virtio_device *vdev, unsigned offset,
const void *buf, unsigned len); const void *buf, unsigned len);
u8 (*get_status)(struct virtio_device *vdev); u8 (*get_status)(struct virtio_device *vdev);
void (*set_status)(struct virtio_device *vdev, u8 status); void (*set_status)(struct virtio_device *vdev, u8 status);
struct virtqueue *(*find_vq)(struct virtio_device *vdev, struct virtqueue *(*find_vq)(struct virtio_device *vdev,
unsigned index,
bool (*callback)(struct virtqueue *)); bool (*callback)(struct virtqueue *));
void (*del_vq)(struct virtqueue *vq); void (*del_vq)(struct virtqueue *vq);
}; };
/** /**
* virtio_config_val - get a single virtio config and mark it used. * virtio_config_val - look for a feature and get a single virtio config.
* @config: the virtio config space * @vdev: the virtio device
* @type: the type to search for. * @fbit: the feature bit
* @offset: the type to search for.
* @val: a pointer to the value to fill in. * @val: a pointer to the value to fill in.
* *
* Once used, the config type is marked with VIRTIO_CONFIG_F_USED so it can't * The return value is -ENOENT if the feature doesn't exist. Otherwise
* be found again. This version does endian conversion. */ * the value is endian-corrected and returned in v. */
#define virtio_config_val(vdev, type, v) ({ \ #define virtio_config_val(vdev, fbit, offset, v) ({ \
int _err = __virtio_config_val((vdev),(type),(v),sizeof(*(v))); \ int _err; \
\ if ((vdev)->config->feature((vdev), (fbit))) { \
BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \ __virtio_config_val((vdev), (offset), (v)); \
&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \ _err = 0; \
if (!_err) { \ } else \
switch (sizeof(*(v))) { \ _err = -ENOENT; \
case 2: le16_to_cpus((__u16 *) v); break; \
case 4: le32_to_cpus((__u32 *) v); break; \
case 8: le64_to_cpus((__u64 *) v); break; \
} \
} \
_err; \ _err; \
}) })
int __virtio_config_val(struct virtio_device *dev,
u8 type, void *val, size_t size);
/** /**
* virtio_use_bit - helper to use a feature bit in a bitfield value. * __virtio_config_val - get a single virtio config without feature check.
* @dev: the virtio device * @vdev: the virtio device
* @token: the token as returned from vdev->config->find(). * @offset: the type to search for.
* @len: the length of the field. * @val: a pointer to the value to fill in.
* @bitnum: the bit to test.
* *
* If handed a NULL token, it returns false, otherwise returns bit status. * The value is endian-corrected and returned in v. */
* If it's one, it sets the mirroring acknowledgement bit. */ #define __virtio_config_val(vdev, offset, v) do { \
int virtio_use_bit(struct virtio_device *vdev, BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
void *token, unsigned int len, unsigned int bitnum); && sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
(vdev)->config->get((vdev), (offset), (v), sizeof(*(v))); \
switch (sizeof(*(v))) { \
case 2: le16_to_cpus((__u16 *) v); break; \
case 4: le32_to_cpus((__u32 *) v); break; \
case 8: le64_to_cpus((__u64 *) v); break; \
} \
} while(0)
#endif /* __KERNEL__ */ #endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_CONFIG_H */ #endif /* _LINUX_VIRTIO_CONFIG_H */

11
include/linux/virtio_net.h
View file

@ -5,16 +5,19 @@
/* The ID for virtio_net */ /* The ID for virtio_net */
#define VIRTIO_ID_NET 1 #define VIRTIO_ID_NET 1
/* The bitmap of config for virtio net */ /* The feature bitmap for virtio net */
#define VIRTIO_CONFIG_NET_F 0x40
#define VIRTIO_NET_F_NO_CSUM 0 #define VIRTIO_NET_F_NO_CSUM 0
#define VIRTIO_NET_F_TSO4 1 #define VIRTIO_NET_F_TSO4 1
#define VIRTIO_NET_F_UFO 2 #define VIRTIO_NET_F_UFO 2
#define VIRTIO_NET_F_TSO4_ECN 3 #define VIRTIO_NET_F_TSO4_ECN 3
#define VIRTIO_NET_F_TSO6 4 #define VIRTIO_NET_F_TSO6 4
#define VIRTIO_NET_F_MAC 5
/* The config defining mac address. */ struct virtio_net_config
#define VIRTIO_CONFIG_NET_MAC_F 0x41 {
/* The config defining mac address (if VIRTIO_NET_F_MAC) */
__u8 mac[6];
} __attribute__((packed));
/* This is the first element of the scatter-gather list. If you don't /* This is the first element of the scatter-gather list. If you don't
* specify GSO or CSUM features, you can simply ignore the header. */ * specify GSO or CSUM features, you can simply ignore the header. */

4
net/9p/trans_virtio.c
View file

@ -236,13 +236,13 @@ static int p9_virtio_probe(struct virtio_device *dev)
/* Find the input queue. */ /* Find the input queue. */
dev->priv = chan; dev->priv = chan;
chan->in_vq = dev->config->find_vq(dev, p9_virtio_intr); chan->in_vq = dev->config->find_vq(dev, 0, p9_virtio_intr);
if (IS_ERR(chan->in_vq)) { if (IS_ERR(chan->in_vq)) {
err = PTR_ERR(chan->in_vq); err = PTR_ERR(chan->in_vq);
goto free; goto free;
} }
chan->out_vq = dev->config->find_vq(dev, NULL); chan->out_vq = dev->config->find_vq(dev, 1, NULL);
if (IS_ERR(chan->out_vq)) { if (IS_ERR(chan->out_vq)) {
err = PTR_ERR(chan->out_vq); err = PTR_ERR(chan->out_vq);
goto free_in_vq; goto free_in_vq;