diff options
Diffstat (limited to 'Documentation/lguest')
| -rw-r--r-- | Documentation/lguest/lguest.c | 107 |
1 files changed, 57 insertions, 50 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 7418f852e40c..cbf4becd2667 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -598,15 +598,17 @@ static void wake_parent(int pipefd, int lguest_fd) select(devices.max_infd+1, &rfds, NULL, NULL, NULL); /* Is it a message from the Launcher? */ if (FD_ISSET(pipefd, &rfds)) { - int ignorefd; + int fd; /* If read() returns 0, it means the Launcher has * exited. We silently follow. */ - if (read(pipefd, &ignorefd, sizeof(ignorefd)) == 0) + if (read(pipefd, &fd, sizeof(fd)) == 0) exit(0); - /* Otherwise it's telling us there's a problem with one - * of the devices, and we should ignore that file - * descriptor from now on. */ - FD_CLR(ignorefd, &devices.infds); + /* Otherwise it's telling us to change what file + * descriptors we're to listen to. */ + if (fd >= 0) + FD_SET(fd, &devices.infds); + else + FD_CLR(-fd - 1, &devices.infds); } else /* Send LHREQ_BREAK command. */ write(lguest_fd, args, sizeof(args)); } @@ -658,18 +660,6 @@ static void *_check_pointer(unsigned long addr, unsigned int size, /* A macro which transparently hands the line number to the real function. */ #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) -/* This simply sets up an iovec array where we can put data to be discarded. - * This happens when the Guest doesn't want or can't handle the input: we have - * to get rid of it somewhere, and if we bury it in the ceiling space it will - * start to smell after a week. */ -static void discard_iovec(struct iovec *iov, unsigned int *num) -{ - static char discard_buf[1024]; - *num = 1; - iov->iov_base = discard_buf; - iov->iov_len = sizeof(discard_buf); -} - /* This function returns the next descriptor in the chain, or vq->vring.num. */ static unsigned next_desc(struct virtqueue *vq, unsigned int i) { @@ -812,12 +802,13 @@ static bool handle_console_input(int fd, struct device *dev) /* First we need a console buffer from the Guests's input virtqueue. */ head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - if (head == dev->vq->vring.num) { - /* If they're not ready for input, we warn and set up to - * discard. */ - warnx("console: no dma buffer!"); - discard_iovec(iov, &in_num); - } else if (out_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; + + 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 @@ -827,15 +818,16 @@ static bool handle_console_input(int fd, struct device *dev) /* This implies that the console is closed, is /dev/null, or * something went terribly wrong. */ warnx("Failed to get console input, ignoring console."); - /* Put the input terminal back and return failure (meaning, - * don't call us again). */ + /* 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; } - /* If we actually read the data into the Guest, tell them about it. */ - if (head != dev->vq->vring.num) - add_used_and_trigger(fd, dev->vq, head, len); + /* Tell the Guest about the new input. */ + add_used_and_trigger(fd, dev->vq, head, len); /* Three ^C within one second? Exit. * @@ -924,7 +916,8 @@ static bool handle_tun_input(int fd, struct device *dev) /* FIXME: Actually want DRIVER_ACTIVE here. */ if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) warn("network: no dma buffer!"); - discard_iovec(iov, &in_num); + /* 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?"); @@ -938,9 +931,8 @@ static bool handle_tun_input(int fd, struct device *dev) if (len <= 0) err(1, "reading network"); - /* If we actually read the data into the Guest, tell them about it. */ - if (head != dev->vq->vring.num) - add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len); + /* Tell the Guest about the new packet. */ + add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len); verbose("tun input packet len %i [%02x %02x] (%s)\n", len, ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1], @@ -950,6 +942,15 @@ static bool handle_tun_input(int fd, struct device *dev) return true; } +/* This callback 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) +{ + add_device_fd(vq->dev->fd); + /* Tell waker to listen to it again */ + write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd)); +} + /* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */ static void handle_output(int fd, unsigned long addr) { @@ -996,17 +997,22 @@ static void handle_input(int fd) * 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)) { + int dev_fd; + if (i->handle_input(fd, i)) + continue; + /* If handle_input() returns false, it means we - * should no longer service it. - * handle_console_input() does this. */ - if (!i->handle_input(fd, i)) { - /* Clear it from the set of input file - * descriptors kept at the head of the - * device list. */ - FD_CLR(i->fd, &devices.infds); - /* Tell waker to ignore it too... */ - write(waker_fd, &i->fd, sizeof(i->fd)); - } + * 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); + /* Tell waker to ignore it too, by sending a + * negative fd number (-1, since 0 is a valid + * FD number). */ + dev_fd = -i->fd - 1; + write(waker_fd, &dev_fd, sizeof(dev_fd)); } } } @@ -1154,11 +1160,11 @@ static void setup_console(void) dev->priv = malloc(sizeof(struct console_abort)); ((struct console_abort *)dev->priv)->count = 0; - /* The console needs two virtqueues: the input then the output. We - * don't care when they refill the input queue, since we don't hold - * data waiting for them. That's why the input queue's callback is - * NULL. */ - add_virtqueue(dev, VIRTQUEUE_NUM, NULL); + /* The console needs two virtqueues: the input then the output. When + * 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); verbose("device %u: console\n", devices.device_num++); @@ -1270,8 +1276,9 @@ static void setup_tun_net(const char *arg) /* First we create a new network device. */ dev = new_device("net", VIRTIO_ID_NET, netfd, handle_tun_input); - /* Network devices need a receive and a send queue. */ - add_virtqueue(dev, VIRTQUEUE_NUM, NULL); + /* Network devices need a receive and a send queue, just like + * console. */ + add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output); /* We need a socket to perform the magic network ioctls to bring up the |