diff options
Diffstat (limited to 'Documentation/lguest/lguest.c')
| -rw-r--r-- | Documentation/lguest/lguest.c | 231 |
1 files changed, 154 insertions, 77 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 6c8a238..0f23d67 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -34,6 +34,8 @@ #include <zlib.h> #include <assert.h> #include <sched.h> +#include <limits.h> +#include <stddef.h> #include "linux/lguest_launcher.h" #include "linux/virtio_config.h" #include "linux/virtio_net.h" @@ -99,13 +101,11 @@ struct device_list /* The descriptor page for the devices. */ u8 *descpage; - /* The tail of the last descriptor. */ - unsigned int desc_used; - /* A single linked list of devices. */ struct device *dev; - /* ... And an end pointer so we can easily append new devices */ - struct device **lastdev; + /* And a pointer to the last device for easy append and also for + * configuration appending. */ + struct device *lastdev; }; /* The list of Guest devices, based on command line arguments. */ @@ -191,7 +191,14 @@ static void *_convert(struct iovec *iov, size_t size, size_t align, #define cpu_to_le64(v64) (v64) #define le16_to_cpu(v16) (v16) #define le32_to_cpu(v32) (v32) -#define le64_to_cpu(v32) (v64) +#define le64_to_cpu(v64) (v64) + +/* The device virtqueue descriptors are followed by feature bitmasks. */ +static u8 *get_feature_bits(struct device *dev) +{ + return (u8 *)(dev->desc + 1) + + dev->desc->num_vq * sizeof(struct lguest_vqconfig); +} /*L:100 The Launcher code itself takes us out into userspace, that scary place * where pointers run wild and free! Unfortunately, like most userspace @@ -914,21 +921,58 @@ static void enable_fd(int fd, struct virtqueue *vq) write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd)); } +/* Resetting a device is fairly easy. */ +static void reset_device(struct device *dev) +{ + struct virtqueue *vq; + + verbose("Resetting device %s\n", dev->name); + /* Clear the status. */ + dev->desc->status = 0; + + /* Clear any features they've acked. */ + memset(get_feature_bits(dev) + dev->desc->feature_len, 0, + dev->desc->feature_len); + + /* Zero out the virtqueues. */ + for (vq = dev->vq; vq; vq = vq->next) { + memset(vq->vring.desc, 0, + vring_size(vq->config.num, getpagesize())); + vq->last_avail_idx = 0; + } +} + /* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */ static void handle_output(int fd, unsigned long addr) { struct device *i; struct virtqueue *vq; - /* Check each virtqueue. */ + /* Check each device and virtqueue. */ for (i = devices.dev; i; i = i->next) { + /* Notifications to device descriptors reset the device. */ + if (from_guest_phys(addr) == i->desc) { + reset_device(i); + return; + } + + /* Notifications to virtqueues mean output has occurred. */ for (vq = i->vq; vq; vq = vq->next) { - if (vq->config.pfn == addr/getpagesize() - && vq->handle_output) { - verbose("Output to %s\n", vq->dev->name); - vq->handle_output(fd, vq); + if (vq->config.pfn != addr/getpagesize()) + continue; + + /* Guest should acknowledge (and set features!) before + * using the device. */ + if (i->desc->status == 0) { + warnx("%s gave early output", i->name); return; } + + if (strcmp(vq->dev->name, "console") != 0) + verbose("Output to %s\n", vq->dev->name); + if (vq->handle_output) + vq->handle_output(fd, vq); + return; } } @@ -986,54 +1030,44 @@ static void handle_input(int fd) * * 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 - * routines to allocate them. - * - * This routine allocates a new "struct lguest_device_desc" from descriptor - * table just above the Guest's normal memory. It returns a pointer to that - * descriptor. */ -static struct lguest_device_desc *new_dev_desc(u16 type) -{ - struct lguest_device_desc *d; + * routines to allocate and manage them. */ - /* We only have one page for all the descriptors. */ - if (devices.desc_used + sizeof(*d) > getpagesize()) - errx(1, "Too many devices"); - - /* We don't need to set config_len or status: page is 0 already. */ - d = (void *)devices.descpage + devices.desc_used; - d->type = type; - devices.desc_used += sizeof(*d); - - return d; +/* The layout of the device page is a "struct lguest_device_desc" followed by a + * number of virtqueue descriptors, then two sets of feature bits, then an + * 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; } -/* Each device descriptor is followed by some configuration information. - * Each configuration field looks like: u8 type, u8 len, [... len bytes...]. - * - * 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 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) { - /* This is the last descriptor, right? */ - assert(devices.descpage + devices.desc_used - == (u8 *)(dev->desc + 1) + dev->desc->config_len); + struct lguest_device_desc d = { .type = type }; + void *p; - /* We only have one page of device descriptions. */ - if (devices.desc_used + 2 + len > getpagesize()) - errx(1, "Too many devices"); + /* 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; - /* 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; + /* We only have one page for all the descriptors. */ + if (p + sizeof(d) > (void *)devices.descpage + getpagesize()) + errx(1, "Too many devices"); - /* Update the device descriptor length: two byte head then data. */ - dev->desc->config_len += 2 + len; + /* p might not be aligned, so we memcpy in. */ + return memcpy(p, &d, sizeof(d)); } -/* This routine adds a virtqueue to a device. We specify how many descriptors - * the virtqueue is to have. */ +/* Each device descriptor is followed by the description of its virtqueues. We + * specify how many descriptors the virtqueue is to have. */ static void add_virtqueue(struct device *dev, unsigned int num_descs, void (*handle_output)(int fd, struct virtqueue *me)) { @@ -1059,9 +1093,15 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, /* Initialize the vring. */ vring_init(&vq->vring, num_descs, p, getpagesize()); - /* Add the configuration information to this device's descriptor. */ - add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE, - sizeof(vq->config), &vq->config); + /* Append virtqueue to this device's descriptor. We use + * device_config() to get the end of the device's current virtqueues; + * 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 * second. */ @@ -1072,11 +1112,41 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, * virtqueue. */ vq->handle_output = handle_output; - /* Set the "Don't Notify Me" flag if we don't have a handler */ + /* As an optimization, set the advisory "Don't Notify Me" flag if we + * don't have a handler */ if (!handle_output) vq->vring.used->flags = VRING_USED_F_NO_NOTIFY; } +/* The first half of the feature bitmask is for us to advertise features. The + * second half if for the Guest to accept features. */ +static void add_feature(struct device *dev, unsigned bit) +{ + u8 *features = get_feature_bits(dev); + + /* 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[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 * calling new_dev_desc() to allocate the descriptor and device memory. */ static struct device *new_device(const char *name, u16 type, int fd, @@ -1084,14 +1154,6 @@ static struct device *new_device(const char *name, u16 type, int fd, { 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. */ dev->fd = fd; /* If we have an input handler for this file descriptor, then we add it @@ -1102,6 +1164,17 @@ static struct device *new_device(const char *name, u16 type, int fd, dev->handle_input = handle_input; dev->name = name; 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; } @@ -1226,7 +1299,7 @@ static void setup_tun_net(const char *arg) int netfd, ipfd; u32 ip; 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 * tap device is like a tun device, only somehow different. To tell @@ -1265,12 +1338,13 @@ static void setup_tun_net(const char *arg) ip = str2ip(arg); /* 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. */ - 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); verbose("device %u: tun net %u.%u.%u.%u\n", @@ -1458,8 +1532,7 @@ static void setup_block_file(const char *filename) struct device *dev; struct vblk_info *vblk; void *stack; - u64 cap; - unsigned int val; + struct virtio_blk_config conf; /* This is the pipe the I/O thread will use to tell us I/O is done. */ pipe(p); @@ -1477,14 +1550,18 @@ static void setup_block_file(const char *filename) vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); 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. */ - cap = cpu_to_le64(vblk->len / 512); - add_desc_field(dev, VIRTIO_CONFIG_BLK_F_CAPACITY, sizeof(cap), &cap); + conf.capacity = cpu_to_le64(vblk->len / 512); /* Tell Guest not to put in too many descriptors at once: two are used * for the in and out elements. */ - val = cpu_to_le32(VIRTQUEUE_NUM - 2); - add_desc_field(dev, VIRTIO_CONFIG_BLK_F_SEG_MAX, sizeof(val), &val); + add_feature(dev, VIRTIO_BLK_F_SEG_MAX); + 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. */ vblk->done_fd = p[1]; @@ -1505,7 +1582,7 @@ static void setup_block_file(const char *filename) close(vblk->workpipe[0]); 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. :*/ @@ -1610,12 +1687,12 @@ int main(int argc, char *argv[]) /* First we initialize the device list. Since console and network * device receive input from a file descriptor, we keep an fdset * (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 - * to the list. Finally, we keep the next interrupt number to hand out - * (1: remember that 0 is used by the timer). */ + * list. We also keep a pointer to the last device. Finally, we keep + * the next interrupt number to hand out (1: remember that 0 is used by + * the timer). */ FD_ZERO(&devices.infds); devices.max_infd = -1; - devices.lastdev = &devices.dev; + devices.lastdev = NULL; devices.next_irq = 1; cpu_id = 0; |