diff options
Diffstat (limited to 'Documentation/lguest')
| -rw-r--r-- | Documentation/lguest/lguest.c | 106 |
1 files changed, 93 insertions, 13 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 46f4c5b09e9e..018472cee151 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -36,6 +36,7 @@ #include <sched.h> #include <limits.h> #include <stddef.h> +#include <signal.h> #include "linux/lguest_launcher.h" #include "linux/virtio_config.h" #include "linux/virtio_net.h" @@ -81,6 +82,8 @@ static int waker_fd; 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]; /* a per-cpu variable indicating whose vcpu is currently running */ static unsigned int __thread cpu_id; @@ -156,11 +159,14 @@ struct virtqueue /* Last available index we saw. */ u16 last_avail_idx; - /* The routine to call when the Guest pings us. */ - void (*handle_output)(int fd, struct virtqueue *me); + /* The routine to call when the Guest pings us, or timeout. */ + void (*handle_output)(int fd, struct virtqueue *me, bool timeout); /* Outstanding buffers */ unsigned int inflight; + + /* Is this blocked awaiting a timer? */ + bool blocked; }; /* Remember the arguments to the program so we can "reboot" */ @@ -874,7 +880,7 @@ static bool handle_console_input(int fd, struct device *dev) /* Handling output for console is simple: we just get all the output buffers * and write them to stdout. */ -static void handle_console_output(int fd, struct virtqueue *vq) +static void handle_console_output(int fd, struct virtqueue *vq, bool timeout) { unsigned int head, out, in; int len; @@ -889,6 +895,21 @@ static void handle_console_output(int fd, struct virtqueue *vq) } } +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 = 500; + + setitimer(ITIMER_REAL, &itm, NULL); +} + /* * The Network * @@ -896,9 +917,9 @@ static void handle_console_output(int fd, struct virtqueue *vq) * and write them (ignoring the first element) to this device's file descriptor * (/dev/net/tun). */ -static void handle_net_output(int fd, struct virtqueue *vq) +static void handle_net_output(int fd, struct virtqueue *vq, bool timeout) { - unsigned int head, out, in; + unsigned int head, out, in, num = 0; int len; struct iovec iov[vq->vring.num]; @@ -912,7 +933,12 @@ static void handle_net_output(int fd, struct virtqueue *vq) (void)convert(&iov[0], struct virtio_net_hdr); len = writev(vq->dev->fd, iov+1, out-1); add_used_and_trigger(fd, vq, head, len); + num++; } + + /* Block further kicks and set up a timer if we saw anything. */ + if (!timeout && num) + block_vq(vq); } /* This is where we handle a packet coming in from the tun device to our @@ -967,18 +993,18 @@ static bool handle_tun_input(int fd, struct device *dev) /*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(int fd, struct virtqueue *vq) +static void enable_fd(int fd, struct virtqueue *vq, bool timeout) { add_device_fd(vq->dev->fd); /* Tell waker to listen to it again */ write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd)); } -static void net_enable_fd(int fd, struct virtqueue *vq) +static void net_enable_fd(int fd, struct virtqueue *vq, bool timeout) { /* We don't need to know again when Guest refills receive buffer. */ vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; - enable_fd(fd, vq); + enable_fd(fd, vq, timeout); } /* When the Guest tells us they updated the status field, we handle it. */ @@ -1047,7 +1073,7 @@ static void handle_output(int fd, unsigned long addr) if (strcmp(vq->dev->name, "console") != 0) verbose("Output to %s\n", vq->dev->name); if (vq->handle_output) - vq->handle_output(fd, vq); + vq->handle_output(fd, vq, false); return; } } @@ -1061,6 +1087,29 @@ static void handle_output(int fd, unsigned long addr) strnlen(from_guest_phys(addr), guest_limit - addr)); } +static void handle_timeout(int fd) +{ + 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(fd, vq, true); + } + } +} + /* This is called when the Waker wakes us up: check for incoming file * descriptors. */ static void handle_input(int fd) @@ -1071,9 +1120,14 @@ static void handle_input(int fd) 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 (select(devices.max_infd+1, &fds, NULL, NULL, &poll) == 0) + if (num == 0) break; /* Otherwise, call the device(s) which have readable file @@ -1097,6 +1151,10 @@ static void handle_input(int fd) write(waker_fd, &dev_fd, sizeof(dev_fd)); } } + + /* Is this the timeout fd? */ + if (FD_ISSET(timeoutpipe[0], &fds)) + handle_timeout(fd); } } @@ -1145,7 +1203,7 @@ 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)(int fd, struct virtqueue *me)) + void (*handle_output)(int, struct virtqueue *, bool)) { unsigned int pages; struct virtqueue **i, *vq = malloc(sizeof(*vq)); @@ -1161,6 +1219,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, vq->last_avail_idx = 0; vq->dev = dev; vq->inflight = 0; + vq->blocked = false; /* Initialize the configuration. */ vq->config.num = num_descs; @@ -1293,6 +1352,24 @@ static void setup_console(void) } /*:*/ +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. @@ -1653,7 +1730,7 @@ static bool handle_io_finish(int fd, struct device *dev) } /* When the Guest submits some I/O, we just need to wake the I/O thread. */ -static void handle_virtblk_output(int fd, struct virtqueue *vq) +static void handle_virtblk_output(int fd, struct virtqueue *vq, bool timeout) { struct vblk_info *vblk = vq->dev->priv; char c = 0; @@ -1824,7 +1901,7 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) /* ERESTART means that we need to reboot the guest */ } else if (errno == ERESTART) { restart_guest(); - /* EAGAIN means the Waker wanted us to look at some input. + /* EAGAIN means a signal (timeout). * Anything else means a bug or incompatible change. */ } else if (errno != EAGAIN) err(1, "Running guest failed"); @@ -1948,6 +2025,9 @@ 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)); |