diff options
| -rw-r--r-- | Documentation/lguest/lguest.c | 833 |
1 files changed, 259 insertions, 574 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 02fa524cf4ad..5470b8ed2149 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -16,6 +16,7 @@ #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> +#include <sys/eventfd.h> #include <fcntl.h> #include <stdbool.h> #include <errno.h> @@ -59,7 +60,6 @@ typedef uint8_t u8; /*:*/ #define PAGE_PRESENT 0x7 /* Present, RW, Execute */ -#define NET_PEERNUM 1 #define BRIDGE_PFX "bridge:" #ifndef SIOCBRADDIF #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ @@ -76,18 +76,10 @@ static bool verbose; do { if (verbose) printf(args); } while(0) /*:*/ -/* File descriptors for the Waker. */ -struct { - int pipe[2]; -} waker_fds; - /* The pointer to the start of guest memory. */ static void *guest_base; /* The maximum guest physical address allowed, and maximum possible. */ static unsigned long guest_limit, guest_max; -/* The pipe for signal hander to write to. */ -static int timeoutpipe[2]; -static unsigned int timeout_usec = 500; /* The /dev/lguest file descriptor. */ static int lguest_fd; @@ -97,11 +89,6 @@ static unsigned int __thread cpu_id; /* This is our list of devices. */ struct device_list { - /* Summary information about the devices in our list: ready to pass to - * select() to ask which need servicing.*/ - fd_set infds; - int max_infd; - /* Counter to assign interrupt numbers. */ unsigned int next_irq; @@ -137,16 +124,11 @@ struct device /* The name of this device, for --verbose. */ const char *name; - /* If handle_input is set, it wants to be called when this file - * descriptor is ready. */ - int fd; - bool (*handle_input)(struct device *me); - /* Any queues attached to this device */ struct virtqueue *vq; - /* Handle status being finalized (ie. feature bits stable). */ - void (*ready)(struct device *me); + /* Is it operational */ + bool running; /* Device-specific data. */ void *priv; @@ -169,16 +151,20 @@ struct virtqueue /* Last available index we saw. */ u16 last_avail_idx; - /* The routine to call when the Guest pings us, or timeout. */ - void (*handle_output)(struct virtqueue *me, bool timeout); + /* Eventfd where Guest notifications arrive. */ + int eventfd; - /* Is this blocked awaiting a timer? */ - bool blocked; + /* Function for the thread which is servicing this virtqueue. */ + void (*service)(struct virtqueue *vq); + pid_t thread; }; /* Remember the arguments to the program so we can "reboot" */ static char **main_args; +/* The original tty settings to restore on exit. */ +static struct termios orig_term; + /* We have to be careful with barriers: our devices are all run in separate * threads and so we need to make sure that changes visible to the Guest happen * in precise order. */ @@ -521,78 +507,6 @@ static void tell_kernel(unsigned long start) } /*:*/ -static void add_device_fd(int fd) -{ - FD_SET(fd, &devices.infds); - if (fd > devices.max_infd) - devices.max_infd = fd; -} - -/*L:200 - * The Waker. - * - * With console, block and network devices, we can have lots of input which we - * need to process. We could try to tell the kernel what file descriptors to - * watch, but handing a file descriptor mask through to the kernel is fairly - * icky. - * - * Instead, we clone off a thread which watches the file descriptors and writes - * the LHREQ_BREAK command to the /dev/lguest file descriptor to tell the Host - * stop running the Guest. This causes the Launcher to return from the - * /dev/lguest read with -EAGAIN, where it will write to /dev/lguest to reset - * the LHREQ_BREAK and wake us up again. - * - * This, of course, is merely a different *kind* of icky. - * - * Given my well-known antipathy to threads, I'd prefer to use processes. But - * it's easier to share Guest memory with threads, and trivial to share the - * devices.infds as the Launcher changes it. - */ -static int waker(void *unused) -{ - /* Close the write end of the pipe: only the Launcher has it open. */ - close(waker_fds.pipe[1]); - - for (;;) { - fd_set rfds = devices.infds; - unsigned long args[] = { LHREQ_BREAK, 1 }; - unsigned int maxfd = devices.max_infd; - - /* We also listen to the pipe from the Launcher. */ - FD_SET(waker_fds.pipe[0], &rfds); - if (waker_fds.pipe[0] > maxfd) - maxfd = waker_fds.pipe[0]; - - /* Wait until input is ready from one of the devices. */ - select(maxfd+1, &rfds, NULL, NULL, NULL); - - /* Message from Launcher? */ - if (FD_ISSET(waker_fds.pipe[0], &rfds)) { - char c; - /* If this fails, then assume Launcher has exited. - * Don't do anything on exit: we're just a thread! */ - if (read(waker_fds.pipe[0], &c, 1) != 1) - _exit(0); - continue; - } - - /* Send LHREQ_BREAK command to snap the Launcher out of it. */ - pwrite(lguest_fd, args, sizeof(args), cpu_id); - } - return 0; -} - -/* This routine just sets up a pipe to the Waker process. */ -static void setup_waker(void) -{ - /* This pipe is closed when Launcher dies, telling Waker. */ - if (pipe(waker_fds.pipe) != 0) - err(1, "Creating pipe for Waker"); - - if (clone(waker, malloc(4096) + 4096, CLONE_VM | SIGCHLD, NULL) == -1) - err(1, "Creating Waker"); -} - /* * Device Handling. * @@ -642,25 +556,27 @@ static unsigned next_desc(struct virtqueue *vq, unsigned int i) * number of output then some number of input descriptors, it's actually two * iovecs, but we pack them into one and note how many of each there were. * - * This function returns the descriptor number found, or vq->vring.num (which - * is never a valid descriptor number) if none was found. */ -static unsigned get_vq_desc(struct virtqueue *vq, - struct iovec iov[], - unsigned int *out_num, unsigned int *in_num) + * This function returns the descriptor number found. */ +static unsigned wait_for_vq_desc(struct virtqueue *vq, + struct iovec iov[], + unsigned int *out_num, unsigned int *in_num) { unsigned int i, head; - u16 last_avail; + u16 last_avail = lg_last_avail(vq); + + while (last_avail == vq->vring.avail->idx) { + u64 event; + + /* Nothing new? Wait for eventfd to tell us they refilled. */ + if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) + errx(1, "Event read failed?"); + } /* Check it isn't doing very strange things with descriptor numbers. */ - last_avail = lg_last_avail(vq); if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) errx(1, "Guest moved used index from %u to %u", last_avail, vq->vring.avail->idx); - /* If there's nothing new since last we looked, return invalid. */ - if (vq->vring.avail->idx == last_avail) - return vq->vring.num; - /* Grab the next descriptor number they're advertising, and increment * the index we've seen. */ head = vq->vring.avail->ring[last_avail % vq->vring.num]; @@ -740,15 +656,7 @@ static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) /* * The Console * - * Here is the input terminal setting we save, and the routine to restore them - * on exit so the user gets their terminal back. */ -static struct termios orig_term; -static void restore_term(void) -{ - tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); -} - -/* We associate some data with the console for our exit hack. */ + * We associate some data with the console for our exit hack. */ struct console_abort { /* How many times have they hit ^C? */ @@ -758,245 +666,235 @@ struct console_abort }; /* This is the routine which handles console input (ie. stdin). */ -static bool handle_console_input(struct device *dev) +static void console_input(struct virtqueue *vq) { int len; unsigned int head, in_num, out_num; - struct iovec iov[dev->vq->vring.num]; - struct console_abort *abort = dev->priv; - - /* First we need a console buffer from the Guests's input 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) - return false; + struct console_abort *abort = vq->dev->priv; + struct iovec iov[vq->vring.num]; + /* Make sure there's a descriptor waiting. */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); if (out_num) errx(1, "Output buffers in console in queue?"); - /* 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); + /* Read it in. */ + len = readv(STDIN_FILENO, iov, in_num); if (len <= 0) { - /* This implies that the console is closed, is /dev/null, or - * something went terribly wrong. */ + /* Ran out of input? */ warnx("Failed to get console input, ignoring console."); - /* Put the input terminal back. */ - restore_term(); - /* Remove callback from input vq, so it doesn't restart us. */ - dev->vq->handle_output = NULL; - /* Stop listening to this fd: don't call us again. */ - return false; + /* For simplicity, dying threads kill the whole Launcher. So + * just nap here. */ + for (;;) + pause(); } - /* Tell the Guest about the new input. */ - add_used_and_trigger(dev->vq, head, len); + add_used_and_trigger(vq, head, len); /* Three ^C within one second? Exit. * - * This is such a hack, but works surprisingly well. Each ^C has to be - * in a buffer by itself, so they can't be too fast. But we check that - * we get three within about a second, so they can't be too slow. */ - if (len == 1 && ((char *)iov[0].iov_base)[0] == 3) { - if (!abort->count++) - gettimeofday(&abort->start, NULL); - else if (abort->count == 3) { - struct timeval now; - gettimeofday(&now, NULL); - if (now.tv_sec <= abort->start.tv_sec+1) { - unsigned long args[] = { LHREQ_BREAK, 0 }; - /* Close the fd so Waker will know it has to - * exit. */ - close(waker_fds.pipe[1]); - /* Just in case Waker is blocked in BREAK, send - * unbreak now. */ - write(lguest_fd, args, sizeof(args)); - exit(2); - } - abort->count = 0; - } - } else - /* Any other key resets the abort counter. */ + * This is such a hack, but works surprisingly well. Each ^C has to + * be in a buffer by itself, so they can't be too fast. But we check + * that we get three within about a second, so they can't be too + * slow. */ + if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) { abort->count = 0; + return; + } - /* Everything went OK! */ - return true; + abort->count++; + if (abort->count == 1) + gettimeofday(&abort->start, NULL); + else if (abort->count == 3) { + struct timeval now; + gettimeofday(&now, NULL); + /* Kill all Launcher processes with SIGINT, like normal ^C */ + if (now.tv_sec <= abort->start.tv_sec+1) + kill(0, SIGINT); + abort->count = 0; + } } -/* Handling output for console is simple: we just get all the output buffers - * and write them to stdout. */ -static void handle_console_output(struct virtqueue *vq, bool timeout) +/* This is the routine which handles console output (ie. stdout). */ +static void console_output(struct virtqueue *vq) { unsigned int head, out, in; struct iovec iov[vq->vring.num]; - /* Keep getting output buffers from the Guest until we run out. */ - while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { - if (in) - errx(1, "Input buffers in output queue?"); - while (!iov_empty(iov, out)) { - int len = writev(STDOUT_FILENO, iov, out); - if (len <= 0) - err(1, "Write to stdout gave %i", len); - iov_consume(iov, out, len); - } - add_used_and_trigger(vq, head, 0); + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + errx(1, "Input buffers in console output queue?"); + while (!iov_empty(iov, out)) { + int len = writev(STDOUT_FILENO, iov, out); + if (len <= 0) + err(1, "Write to stdout gave %i", len); + iov_consume(iov, out, len); } -} - -/* This is called when we no longer want to hear about Guest changes to a - * virtqueue. This is more efficient in high-traffic cases, but it means we - * have to set a timer to check if any more changes have occurred. */ -static void block_vq(struct virtqueue *vq) -{ - struct itimerval itm; - - vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; - vq->blocked = true; - - itm.it_interval.tv_sec = 0; - itm.it_interval.tv_usec = 0; - itm.it_value.tv_sec = 0; - itm.it_value.tv_usec = timeout_usec; - - setitimer(ITIMER_REAL, &itm, NULL); + add_used_and_trigger(vq, head, 0); } /* * The Network * * Handling output for network is also simple: we get all the output buffers - * and write them (ignoring the first element) to this device's file descriptor - * (/dev/net/tun). + * and write them to /dev/net/tun. */ -static void handle_net_output(struct virtqueue *vq, bool timeout) +struct net_info { + int tunfd; +}; + +static void net_output(struct virtqueue *vq) { - unsigned int head, out, in, num = 0; + struct net_info *net_info = vq->dev->priv; + unsigned int head, out, in; struct iovec iov[vq->vring.num]; - static int last_timeout_num; - - /* Keep getting output buffers from the Guest until we run out. */ - while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { - if (in) - errx(1, "Input buffers in output queue?"); - if (writev(vq->dev->fd, iov, out) < 0) - err(1, "Writing network packet to tun"); - add_used_and_trigger(vq, head, 0); - num++; - } - /* Block further kicks and set up a timer if we saw anything. */ - if (!timeout && num) - block_vq(vq); - - /* We never quite know how long should we wait before we check the - * queue again for more packets. We start at 500 microseconds, and if - * we get fewer packets than last time, we assume we made the timeout - * too small and increase it by 10 microseconds. Otherwise, we drop it - * by one microsecond every time. It seems to work well enough. */ - if (timeout) { - if (num < last_timeout_num) - timeout_usec += 10; - else if (timeout_usec > 1) - timeout_usec--; - last_timeout_num = num; - } + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + errx(1, "Input buffers in net output queue?"); + if (writev(net_info->tunfd, iov, out) < 0) + errx(1, "Write to tun failed?"); + add_used_and_trigger(vq, head, 0); } -/* This is where we handle a packet coming in from the tun device to our +/* This is where we handle packets coming in from the tun device to our * Guest. */ -static bool handle_tun_input(struct device *dev) +static void net_input(struct virtqueue *vq) { - unsigned int head, in_num, out_num; int len; - struct iovec iov[dev->vq->vring.num]; - - /* First we need a network buffer from the Guests's recv virtqueue. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - if (head == dev->vq->vring.num) { - /* Now, it's expected that if we try to send a packet too - * early, the Guest won't be ready yet. Wait until the device - * status says it's ready. */ - /* FIXME: Actually want DRIVER_ACTIVE here. */ - - /* Now tell it we want to know if new things appear. */ - dev->vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; - wmb(); - - /* We'll turn this back on if input buffers are registered. */ - return false; - } else if (out_num) - errx(1, "Output buffers in network recv queue?"); - - /* Read the packet from the device directly into the Guest's buffer. */ - len = readv(dev->fd, iov, in_num); + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + struct net_info *net_info = vq->dev->priv; + + head = wait_for_vq_desc(vq, iov, &out, &in); + if (out) + errx(1, "Output buffers in net input queue?"); + len = readv(net_info->tunfd, iov, in); if (len <= 0) - err(1, "reading network"); + err(1, "Failed to read from tun."); + add_used_and_trigger(vq, head, len); +} - /* Tell the Guest about the new packet. */ - add_used_and_trigger(dev->vq, head, len); +/* This is the helper to create threads. */ +static int do_thread(void *_vq) +{ + struct virtqueue *vq = _vq; - verbose("tun input packet len %i [%02x %02x] (%s)\n", len, - ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1], - head != dev->vq->vring.num ? "sent" : "discarded"); + for (;;) + vq->service(vq); + return 0; +} - /* All good. */ - return true; +/* When a child dies, we kill our entire process group with SIGTERM. This + * also has the side effect that the shell restores the console for us! */ +static void kill_launcher(int signal) +{ + kill(0, SIGTERM); } -/*L:215 This is the callback attached to the network and console input - * virtqueues: it ensures we try again, in case we stopped console or net - * delivery because Guest didn't have any buffers. */ -static void enable_fd(struct virtqueue *vq, bool timeout) +static void reset_device(struct device *dev) { - add_device_fd(vq->dev->fd); - /* Snap the Waker out of its select loop. */ - write(waker_fds.pipe[1], "", 1); + struct virtqueue *vq; + + verbose("Resetting device %s\n", dev->name); + + /* Clear any features they've acked. */ + memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len); + + /* We're going to be explicitly killing threads, so ignore them. */ + signal(SIGCHLD, SIG_IGN); + + /* Zero out the virtqueues, get rid of their threads */ + for (vq = dev->vq; vq; vq = vq->next) { + if (vq->thread != (pid_t)-1) { + kill(vq->thread, SIGTERM); + waitpid(vq->thread, NULL, 0); + vq->thread = (pid_t)-1; + } + memset(vq->vring.desc, 0, + vring_size(vq->config.num, LGUEST_VRING_ALIGN)); + lg_last_avail(vq) = 0; + } + dev->running = false; + + /* Now we care if threads die. */ + signal(SIGCHLD, (void *)kill_launcher); } -static void net_enable_fd(struct virtqueue *vq, bool timeout) +static void create_thread(struct virtqueue *vq) { - /* We don't need to know again when Guest refills receive buffer. */ - vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; - enable_fd(vq, timeout); + /* Create stack for thread and run it. Since stack grows + * upwards, we point the stack pointer to the end of this + * region. */ + char *stack = malloc(32768); + unsigned long args[] = { LHREQ_EVENTFD, + vq->config.pfn*getpagesize(), 0 }; + + /* Create a zero-initialized eventfd. */ + vq->eventfd = eventfd(0, 0); + if (vq->eventfd < 0) + err(1, "Creating eventfd"); + args[2] = vq->eventfd; + + /* Attach an eventfd to this virtqueue: it will go off + * when the Guest does an LHCALL_NOTIFY for this vq. */ + if (write(lguest_fd, &args, sizeof(args)) != 0) + err(1, "Attaching eventfd"); + + /* CLONE_VM: because it has to access the Guest memory, and + * SIGCHLD so we get a signal if it dies. */ + vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq); + if (vq->thread == (pid_t)-1) + err(1, "Creating clone"); + /* We close our local copy, now the child has it. */ + close(vq->eventfd); } -/* When the Guest tells us they updated the status field, we handle it. */ -static void update_device_status(struct device *dev) +static void start_device(struct device *dev) { + unsigned int i; struct virtqueue *vq; - /* This is a reset. */ - if (dev->desc->status == 0) { - verbose("Resetting device %s\n", dev->name); + verbose("Device %s OK: offered", dev->name); + for (i = 0; i < dev->feature_len; i++) + verbose(" %02x", get_feature_bits(dev)[i]); + verbose(", accepted"); + for (i = 0; i < dev->feature_len; i++) + verbose(" %02x", get_feature_bits(dev) + [dev->feature_len+i]); + + for (vq = dev->vq; vq; vq = vq->next) { + if (vq->service) + create_thread(vq); + } + dev->running = true; +} + +static void cleanup_devices(void) +{ + struct device *dev; + + for (dev = devices.dev; dev; dev = dev->next) + reset_device(dev); - /* Clear any features they've acked. */ - memset(get_feature_bits(dev) + dev->feature_len, 0, - dev->feature_len); + /* If we saved off the original terminal settings, restore them now. */ + if (orig_term.c_lflag & (ISIG|ICANON|ECHO)) + tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); +} - /* Zero out the virtqueues. */ - for (vq = dev->vq; vq; vq = vq->next) { - memset(vq->vring.desc, 0, - vring_size(vq->config.num, LGUEST_VRING_ALIGN)); - lg_last_avail(vq) = 0; - } - } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { +/* When the Guest tells us they updated the status field, we handle it. */ +static void update_device_status(struct device *dev) +{ + /* A zero status is a reset, otherwise it's a set of flags. */ + if (dev->desc->status == 0) + reset_device(dev); + else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { warnx("Device %s configuration FAILED", dev->name); + if (dev->running) + reset_device(dev); } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) { - unsigned int i; - - verbose("Device %s OK: offered", dev->name); - for (i = 0; i < dev->feature_len; i++) - verbose(" %02x", get_feature_bits(dev)[i]); - verbose(", accepted"); - for (i = 0; i < dev->feature_len; i++) - verbose(" %02x", get_feature_bits(dev) - [dev->feature_len+i]); - - if (dev->ready) - dev->ready(dev); + if (!dev->running) + start_device(dev); } } @@ -1004,32 +902,24 @@ static void update_device_status(struct device *dev) static void handle_output(unsigned long addr) { struct device *i; - struct virtqueue *vq; - /* Check each device and virtqueue. */ + /* Check each device. */ for (i = devices.dev; i; i = i->next) { + struct virtqueue *vq; + /* Notifications to device descriptors update device status. */ if (from_guest_phys(addr) == i->desc) { update_device_status(i); return; } - /* Notifications to virtqueues mean output has occurred. */ + /* Devices *can* be used before status is set to DRIVER_OK. */ for (vq = i->vq; vq; vq = vq->next) { - if (vq->config.pfn != addr/getpagesize()) + if (addr != vq->config.pfn*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(vq, false); + if (i->running) + errx(1, "Notification on running %s", i->name); + start_device(i); return; } } @@ -1043,71 +933,6 @@ static void handle_output(unsigned long addr) strnlen(from_guest_phys(addr), guest_limit - addr)); } -static void handle_timeout(void) -{ - char buf[32]; - struct device *i; - struct virtqueue *vq; - - /* Clear the pipe */ - read(timeoutpipe[0], buf, sizeof(buf)); - - /* Check each device and virtqueue: flush blocked ones. */ - for (i = devices.dev; i; i = i->next) { - for (vq = i->vq; vq; vq = vq->next) { - if (!vq->blocked) - continue; - - vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; - vq->blocked = false; - if (vq->handle_output) - vq->handle_output(vq, true); - } - } -} - -/* This is called when the Waker wakes us up: check for incoming file - * descriptors. */ -static void handle_input(void) -{ - /* select() wants a zeroed timeval to mean "don't wait". */ - struct timeval poll = { .tv_sec = 0, .tv_usec = 0 }; - - for (;;) { - struct device *i; - fd_set fds = devices.infds; - int num; - - num = select(devices.max_infd+1, &fds, NULL, NULL, &poll); - /* Could get interrupted */ - if (num < 0) - continue; - /* If nothing is ready, we're done. */ - if (num == 0) - break; - - /* Otherwise, call the device(s) which have readable file - * descriptors and a method of handling them. */ - for (i = devices.dev; i; i = i->next) { - if (i->handle_input && FD_ISSET(i->fd, &fds)) { - if (i->handle_input(i)) - continue; - - /* If handle_input() returns false, it means we - * should no longer service it. Networking and - * console do this when there's no input - * buffers to deliver into. Console also uses - * it when it discovers that stdin is closed. */ - FD_CLR(i->fd, &devices.infds); - } - } - - /* Is this the timeout fd? */ - if (FD_ISSET(timeoutpipe[0], &fds)) - handle_timeout(); - } -} - /*L:190 * Device Setup * @@ -1153,7 +978,7 @@ static struct lguest_device_desc *new_dev_desc(u16 type) /* 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)(struct virtqueue *, bool)) + void (*service)(struct virtqueue *)) { unsigned int pages; struct virtqueue **i, *vq = malloc(sizeof(*vq)); @@ -1168,7 +993,8 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, vq->next = NULL; vq->last_avail_idx = 0; vq->dev = dev; - vq->blocked = false; + vq->service = service; + vq->thread = (pid_t)-1; /* Initialize the configuration. */ vq->config.num = num_descs; @@ -1193,15 +1019,6 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, * second. */ for (i = &dev->vq; *i; i = &(*i)->next); *i = vq; - - /* Set the routine to call when the Guest does something to this - * virtqueue. */ - vq->handle_output = handle_output; - - /* 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 @@ -1237,24 +1054,17 @@ static void set_config(struct device *dev, unsigned len, const void *conf) * calling new_dev_desc() to allocate the descriptor and device memory. * * See what I mean about userspace being boring? */ -static struct device *new_device(const char *name, u16 type, int fd, - bool (*handle_input)(struct device *)) +static struct device *new_device(const char *name, u16 type) { struct device *dev = malloc(sizeof(*dev)); /* 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 - * to the device_list's fdset and maxfd. */ - if (handle_input) - add_device_fd(dev->fd); dev->desc = new_dev_desc(type); - dev->handle_input = handle_input; dev->name = name; dev->vq = NULL; - dev->ready = NULL; dev->feature_len = 0; dev->num_vq = 0; + dev->running = false; /* Append to device list. Prepending to a single-linked list is * easier, but the user expects the devices to be arranged on the bus @@ -1282,13 +1092,10 @@ static void setup_console(void) * raw input stream to the Guest. */ term.c_lflag &= ~(ISIG|ICANON|ECHO); tcsetattr(STDIN_FILENO, TCSANOW, &term); - /* If we exit gracefully, the original settings will be - * restored so the user can see what they're typing. */ - atexit(restore_term); } - dev = new_device("console", VIRTIO_ID_CONSOLE, - STDIN_FILENO, handle_console_input); + dev = new_device("console", VIRTIO_ID_CONSOLE); + /* We store the console state in dev->priv, and initialize it. */ dev->priv = malloc(sizeof(struct console_abort)); ((struct console_abort *)dev->priv)->count = 0; @@ -1297,31 +1104,13 @@ static void setup_console(void) * they put something the input queue, we make sure we're listening to * stdin. When they put something in the output queue, we write it to * stdout. */ - add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); - add_virtqueue(dev, VIRTQUEUE_NUM, handle_console_output); + add_virtqueue(dev, VIRTQUEUE_NUM, console_input); + add_virtqueue(dev, VIRTQUEUE_NUM, console_output); - verbose("device %u: console\n", devices.device_num++); + verbose("device %u: console\n", ++devices.device_num); } /*:*/ -static void timeout_alarm(int sig) -{ - write(timeoutpipe[1], "", 1); -} - -static void setup_timeout(void) -{ - if (pipe(timeoutpipe) != 0) - err(1, "Creating timeout pipe"); - - if (fcntl(timeoutpipe[1], F_SETFL, - fcntl(timeoutpipe[1], F_GETFL) | O_NONBLOCK) != 0) - err(1, "Making timeout pipe nonblocking"); - - add_device_fd(timeoutpipe[0]); - signal(SIGALRM, timeout_alarm); -} - /*M:010 Inter-guest networking is an interesting area. Simplest is to have a * --sharenet=<name> option which opens or creates a named pipe. This can be * used to send packets to another guest in a 1:1 manner. @@ -1443,21 +1232,23 @@ static int get_tun_device(char tapif[IFNAMSIZ]) static void setup_tun_net(char *arg) { struct device *dev; - int netfd, ipfd; + struct net_info *net_info = malloc(sizeof(*net_info)); + int ipfd; u32 ip = INADDR_ANY; bool bridging = false; char tapif[IFNAMSIZ], *p; struct virtio_net_config conf; - netfd = get_tun_device(tapif); + net_info->tunfd = get_tun_device(tapif); /* First we create a new network device. */ - dev = new_device("net", VIRTIO_ID_NET, netfd, handle_tun_input); + dev = new_device("net", VIRTIO_ID_NET); + dev->priv = net_info; /* Network devices need a receive and a send queue, just like * console. */ - add_virtqueue(dev, VIRTQUEUE_NUM, net_enable_fd); - add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output); + add_virtqueue(dev, VIRTQUEUE_NUM, net_input); + add_virtqueue(dev, VIRTQUEUE_NUM, net_output); /* We need a socket to perform the magic network ioctls to bring up the * tap interface, connect to the bridge etc. Any socket will do! */ @@ -1546,20 +1337,18 @@ struct vblk_info * Remember that the block device is handled by a separate I/O thread. We head * straight into the core of that thread here: */ -static bool service_io(struct device *dev) +static void blk_request(struct virtqueue *vq) { - struct vblk_info *vblk = dev->priv; + struct vblk_info *vblk = vq->dev->priv; unsigned int head, out_num, in_num, wlen; int ret; u8 *in; struct virtio_blk_outhdr *out; - struct iovec iov[dev->vq->vring.num]; + struct iovec iov[vq->vring.num]; off64_t off; - /* See if there's a request waiting. If not, nothing to do. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - if (head == dev->vq->vring.num) - return false; + /* Get the next request. */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); /* Every block request should contain at least one output buffer * (detailing the location on disk and the type of request) and one @@ -1633,83 +1422,21 @@ static bool service_io(struct device *dev) if (out->type & VIRTIO_BLK_T_BARRIER) fdatasync(vblk->fd); - /* We can't trigger an IRQ, because we're not the Launcher. It does - * that when we tell it we're done. */ - add_used(dev->vq, head, wlen); - return true; -} - -/* This is the thread which actually services the I/O. */ -static int io_thread(void *_dev) -{ - struct device *dev = _dev; - struct vblk_info *vblk = dev->priv; - char c; - - /* Close other side of workpipe so we get 0 read when main dies. */ - close(vblk->workpipe[1]); - /* Close the other side of the done_fd pipe. */ - close(dev->fd); - - /* When this read fails, it means Launcher died, so we follow. */ - while (read(vblk->workpipe[0], &c, 1) == 1) { - /* We acknowledge each request immediately to reduce latency, - * rather than waiting until we've done them all. I haven't - * measured to see if it makes any difference. - * - * That would be an interesting test, wouldn't it? You could - * also try having more than one I/O thread. */ - while (service_io(dev)) - write(vblk->done_fd, &c, 1); - } - return 0; -} - -/* Now we've seen the I/O thread, we return to the Launcher to see what happens - * when that thread tells us it's completed some I/O. */ -static bool handle_io_finish(struct device *dev) -{ - char c; - - /* If the I/O thread died, presumably it printed the error, so we - * simply exit. */ - if (read(dev->fd, &c, 1) != 1) - exit(1); - - /* It did some work, so trigger the irq. */ - trigger_irq(dev->vq); - return true; -} - -/* When the Guest submits some I/O, we just need to wake the I/O thread. */ -static void handle_virtblk_output(struct virtqueue *vq, bool timeout) -{ - struct vblk_info *vblk = vq->dev->priv; - char c = 0; - - /* Wake up I/O thread and tell it to go to work! */ - if (write(vblk->workpipe[1], &c, 1) != 1) - /* Presumably it indicated why it died. */ - exit(1); + add_used_and_trigger(vq, head, wlen); } /*L:198 This actually sets up a virtual block device. */ static void setup_block_file(const char *filename) { - int p[2]; struct device *dev; struct vblk_info *vblk; - void *stack; struct virtio_blk_config conf; - /* This is the pipe the I/O thread will use to tell us I/O is done. */ - pipe(p); - /* The device responds to return from I/O thread. */ - dev = new_device("block", VIRTIO_ID_BLOCK, p[0], handle_io_finish); + dev = new_device("block", VIRTIO_ID_BLOCK); /* The device has one virtqueue, where the Guest places requests. */ - add_virtqueue(dev, VIRTQUEUE_NUM, handle_virtblk_output); + add_virtqueue(dev, VIRTQUEUE_NUM, blk_request); /* Allocate the room for our own bookkeeping */ vblk = dev->priv = malloc(sizeof(*vblk)); @@ -1731,49 +1458,29 @@ static void setup_block_file(const char *filename) set_config(dev, sizeof(conf), &conf); - /* The I/O thread writes to this end of the pipe when done. */ - vblk->done_fd = p[1]; - - /* This is the second pipe, which is how we tell the I/O thread about - * more work. */ - pipe(vblk->workpipe); - - /* Create stack for thread and run it. Since stack grows upwards, we - * point the stack pointer to the end of this region. */ - stack = malloc(32768); - /* SIGCHLD - We dont "wait" for our cloned thread, so prevent it from - * becoming a zombie. */ - if (clone(io_thread, stack + 32768, CLONE_VM | SIGCHLD, dev) == -1) - err(1, "Creating clone"); - - /* We don't need to keep the I/O thread's end of the pipes open. */ - close(vblk->done_fd); - close(vblk->workpipe[0]); - verbose("device %u: virtblock %llu sectors\n", - devices.device_num, le64_to_cpu(conf.capacity)); + ++devices.device_num, le64_to_cpu(conf.capacity)); } +struct rng_info { + int rfd; +}; + /* Our random number generator device reads from /dev/random into the Guest's * input buffers. The usual case is that the Guest doesn't want random numbers * and so has no buffers although /dev/random is still readable, whereas * console is the reverse. * * The same logic applies, however. */ -static bool handle_rng_input(struct device *dev) +static void rng_input(struct virtqueue *vq) { int len; unsigned int head, in_num, out_num, totlen = 0; - struct iovec iov[dev->vq->vring.num]; + struct rng_info *rng_info = vq->dev->priv; + struct iovec iov[vq->vring.num]; /* 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) - return false; - + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); if (out_num) errx(1, "Output buffers in rng?"); @@ -1781,7 +1488,7 @@ static bool handle_rng_input(struct device *dev) * it reads straight into the Guest's buffer. We loop to make sure we * fill it. */ while (!iov_empty(iov, in_num)) { - len = readv(dev->fd, iov, in_num); + len = readv(rng_info->rfd, iov, in_num); if (len <= 0) err(1, "Read from /dev/random gave %i", len); iov_consume(iov, in_num, len); @@ -1789,25 +1496,23 @@ static bool handle_rng_input(struct device *dev) } /* Tell the Guest about the new input. */ - add_used_and_trigger(dev->vq, head, totlen); - - /* Everything went OK! */ - return true; + add_used_and_trigger(vq, head, totlen); } /* And this creates a "hardware" random number device for the Guest. */ static void setup_rng(void) { struct device *dev; - int fd; + struct rng_info *rng_info = malloc(sizeof(*rng_info)); - fd = open_or_die("/dev/random", O_RDONLY); + rng_info->rfd = open_or_die("/dev/random", O_RDONLY); /* The device responds to return from I/O thread. */ - dev = new_device("rng", VIRTIO_ID_RNG, fd, handle_rng_input); + dev = new_device("rng", VIRTIO_ID_RNG); + dev->priv = rng_info; /* The device has one virtqueue, where the Guest places inbufs. */ - add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); + add_virtqueue(dev, VIRTQUEUE_NUM, rng_input); verbose("device %u: rng\n", devices.device_num++); } @@ -1823,7 +1528,9 @@ static void __attribute__((noreturn)) restart_guest(void) for (i = 3; i < FD_SETSIZE; i++) close(i); - /* The exec automatically gets rid of the I/O and Waker threads. */ + /* Reset all the devices (kills all threads). */ + cleanup_devices(); + execv(main_args[0], main_args); err(1, "Could not exec %s", main_args[0]); } @@ -1833,7 +1540,6 @@ static void __attribute__((noreturn)) restart_guest(void) static void __attribute__((noreturn)) run_guest(void) { for (;;) { - unsigned long args[] = { LHREQ_BREAK, 0 }; unsigned long notify_addr; int readval; @@ -1845,7 +1551,6 @@ static void __attribute__((noreturn)) run_guest(void) if (readval == sizeof(notify_addr)) { verbose("Notify on address %#lx\n", notify_addr); handle_output(notify_addr); - continue; /* ENOENT means the Guest died. Reading tells us why. */ } else if (errno == ENOENT) { char reason[1024] = { 0 }; @@ -1854,19 +1559,9 @@ static void __attribute__((noreturn)) run_guest(void) /* ERESTART means that we need to reboot the guest */ } else if (errno == ERESTART) { restart_guest(); - /* EAGAIN means a signal (timeout). - * Anything else means a bug or incompatible change. */ - } else if (errno != EAGAIN) + /* Anything else means a bug or incompatible change. */ + } else err(1, "Running guest failed"); - - /* Only service input on thread for CPU 0. */ - if (cpu_id != 0) - continue; - - /* Service input, then unset the BREAK to release the Waker. */ - handle_input(); - if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0) - err(1, "Resetting break"); } } /*L:240 @@ -1909,18 +1604,10 @@ int main(int argc, char *argv[]) /* Save the args: we "reboot" by execing ourselves again. */ main_args = argv; - /* We don't "wait" for the children, so prevent them from becoming - * zombies. */ - signal(SIGCHLD, SIG_IGN); - /* 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. Finally, we keep - * the next interrupt number to use for devices (1: remember that 0 is - * used by the timer). */ - FD_ZERO(&devices.infds); - devices.max_infd = -1; + /* First we initialize the device list. We keep a pointer to the last + * device, and the next interrupt number to use for devices (1: + * remember that 0 is used by the timer). */ devices.lastdev = NULL; devices.next_irq = 1; @@ -1978,9 +1665,6 @@ int main(int argc, char *argv[]) /* We always have a console device */ setup_console(); - /* We can timeout waiting for Guest network transmit. */ - setup_timeout(); - /* Now we load the kernel */ start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); @@ -2021,10 +1705,11 @@ int main(int argc, char *argv[]) * /dev/lguest file descriptor. */ tell_kernel(start); - /* We clone off a thread, which wakes the Launcher whenever one of the - * input file descriptors needs attention. We call this the Waker, and - * we'll cover it in a moment. */ - setup_waker(); + /* Ensure that we terminate if a child dies. */ + signal(SIGCHLD, kill_launcher); + + /* If we exit via err(), this kills all the threads, restores tty. */ + atexit(cleanup_devices); /* Finally, run the Guest. This doesn't return. */ run_guest(); |