diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/lguest/Makefile | 3 | ||||
| -rw-r--r-- | Documentation/lguest/lguest.c | 1008 | ||||
| -rw-r--r-- | Documentation/lguest/lguest.txt | 1 |
3 files changed, 375 insertions, 637 deletions
diff --git a/Documentation/lguest/Makefile b/Documentation/lguest/Makefile index 1f4f9e888bd..28c8cdfcafd 100644 --- a/Documentation/lguest/Makefile +++ b/Documentation/lguest/Makefile @@ -1,6 +1,5 @@ # This creates the demonstration utility "lguest" which runs a Linux guest. -CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include -I../../arch/x86/include -U_FORTIFY_SOURCE -LDLIBS:=-lz +CFLAGS:=-m32 -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include -I../../arch/x86/include -U_FORTIFY_SOURCE all: lguest diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index d36fcc0f271..9ebcd6ef361 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 */ @@ -76,19 +76,12 @@ static bool verbose; do { if (verbose) printf(args); } while(0) /*:*/ -/* File descriptors for the Waker. */ -struct { - int pipe[2]; - int lguest_fd; -} 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; /* a per-cpu variable indicating whose vcpu is currently running */ static unsigned int __thread cpu_id; @@ -96,11 +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; @@ -126,22 +114,21 @@ struct device /* The linked-list pointer. */ struct device *next; - /* The this device's descriptor, as mapped into the Guest. */ + /* The device's descriptor, as mapped into the Guest. */ struct lguest_device_desc *desc; + /* We can't trust desc values once Guest has booted: we use these. */ + unsigned int feature_len; + unsigned int num_vq; + /* 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)(int fd, 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; @@ -164,22 +151,28 @@ 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)(int fd, struct virtqueue *me, bool timeout); + /* How many are used since we sent last irq? */ + unsigned int pending_used; - /* Outstanding buffers */ - unsigned int inflight; + /* 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; -/* Since guest is UP and we don't run at the same time, we don't need barriers. - * But I include them in the code in case others copy it. */ -#define wmb() +/* 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. */ +#define wmb() __asm__ __volatile__("" : : : "memory") +#define mb() __asm__ __volatile__("" : : : "memory") /* Convert an iovec element to the given type. * @@ -245,7 +238,7 @@ static void iov_consume(struct iovec iov[], unsigned num_iov, unsigned len) static u8 *get_feature_bits(struct device *dev) { return (u8 *)(dev->desc + 1) - + dev->desc->num_vq * sizeof(struct lguest_vqconfig); + + dev->num_vq * sizeof(struct lguest_vqconfig); } /*L:100 The Launcher code itself takes us out into userspace, that scary place @@ -505,99 +498,19 @@ static void concat(char *dst, char *args[]) * saw the arguments it expects when we looked at initialize() in lguest_user.c: * the base of Guest "physical" memory, the top physical page to allow and the * entry point for the Guest. */ -static int tell_kernel(unsigned long start) +static void tell_kernel(unsigned long start) { unsigned long args[] = { LHREQ_INITIALIZE, (unsigned long)guest_base, guest_limit / getpagesize(), start }; - int fd; - verbose("Guest: %p - %p (%#lx)\n", guest_base, guest_base + guest_limit, guest_limit); - fd = open_or_die("/dev/lguest", O_RDWR); - if (write(fd, args, sizeof(args)) < 0) + lguest_fd = open_or_die("/dev/lguest", O_RDWR); + if (write(lguest_fd, args, sizeof(args)) < 0) err(1, "Writing to /dev/lguest"); - - /* We return the /dev/lguest file descriptor to control this Guest */ - return fd; } /*:*/ -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(waker_fds.lguest_fd, args, sizeof(args), cpu_id); - } - return 0; -} - -/* This routine just sets up a pipe to the Waker process. */ -static void setup_waker(int lguest_fd) -{ - /* This pipe is closed when Launcher dies, telling Waker. */ - if (pipe(waker_fds.pipe) != 0) - err(1, "Creating pipe for Waker"); - - /* Waker also needs to know the lguest fd */ - waker_fds.lguest_fd = lguest_fd; - - if (clone(waker, malloc(4096) + 4096, CLONE_VM | SIGCHLD, NULL) == -1) - err(1, "Creating Waker"); -} - /* * Device Handling. * @@ -623,49 +536,90 @@ static void *_check_pointer(unsigned long addr, unsigned int size, /* Each buffer in the virtqueues is actually a chain of descriptors. This * function returns the next descriptor in the chain, or vq->vring.num if we're * at the end. */ -static unsigned next_desc(struct virtqueue *vq, unsigned int i) +static unsigned next_desc(struct vring_desc *desc, + unsigned int i, unsigned int max) { unsigned int next; /* If this descriptor says it doesn't chain, we're done. */ - if (!(vq->vring.desc[i].flags & VRING_DESC_F_NEXT)) - return vq->vring.num; + if (!(desc[i].flags & VRING_DESC_F_NEXT)) + return max; /* Check they're not leading us off end of descriptors. */ - next = vq->vring.desc[i].next; + next = desc[i].next; /* Make sure compiler knows to grab that: we don't want it changing! */ wmb(); - if (next >= vq->vring.num) + if (next >= max) errx(1, "Desc next is %u", next); return next; } +/* This actually sends the interrupt for this virtqueue */ +static void trigger_irq(struct virtqueue *vq) +{ + unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; + + /* Don't inform them if nothing used. */ + if (!vq->pending_used) + return; + vq->pending_used = 0; + + /* If they don't want an interrupt, don't send one, unless empty. */ + if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) + && lg_last_avail(vq) != vq->vring.avail->idx) + return; + + /* Send the Guest an interrupt tell them we used something up. */ + if (write(lguest_fd, buf, sizeof(buf)) != 0) + err(1, "Triggering irq %i", vq->config.irq); +} + /* This looks in the virtqueue and for the first available buffer, and converts * it to an iovec for convenient access. Since descriptors consist of some * 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; + unsigned int i, head, max; + struct vring_desc *desc; + u16 last_avail = lg_last_avail(vq); + + while (last_avail == vq->vring.avail->idx) { + u64 event; + + /* OK, tell Guest about progress up to now. */ + trigger_irq(vq); + + /* OK, now we need to know about added descriptors. */ + vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; + + /* They could have slipped one in as we were doing that: make + * sure it's written, then check again. */ + mb(); + if (last_avail != vq->vring.avail->idx) { + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + break; + } + + /* Nothing new? Wait for eventfd to tell us they refilled. */ + if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) + errx(1, "Event read failed?"); + + /* We don't need to be notified again. */ + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + } /* 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]; @@ -678,15 +632,28 @@ static unsigned get_vq_desc(struct virtqueue *vq, /* When we start there are none of either input nor output. */ *out_num = *in_num = 0; + max = vq->vring.num; + desc = vq->vring.desc; i = head; + + /* If this is an indirect entry, then this buffer contains a descriptor + * table which we handle as if it's any normal descriptor chain. */ + if (desc[i].flags & VRING_DESC_F_INDIRECT) { + if (desc[i].len % sizeof(struct vring_desc)) + errx(1, "Invalid size for indirect buffer table"); + + max = desc[i].len / sizeof(struct vring_desc); + desc = check_pointer(desc[i].addr, desc[i].len); + i = 0; + } + do { /* Grab the first descriptor, and check it's OK. */ - iov[*out_num + *in_num].iov_len = vq->vring.desc[i].len; + iov[*out_num + *in_num].iov_len = desc[i].len; iov[*out_num + *in_num].iov_base - = check_pointer(vq->vring.desc[i].addr, - vq->vring.desc[i].len); + = check_pointer(desc[i].addr, desc[i].len); /* If this is an input descriptor, increment that count. */ - if (vq->vring.desc[i].flags & VRING_DESC_F_WRITE) + if (desc[i].flags & VRING_DESC_F_WRITE) (*in_num)++; else { /* If it's an output descriptor, they're all supposed @@ -697,11 +664,10 @@ static unsigned get_vq_desc(struct virtqueue *vq, } /* If we've got too many, that implies a descriptor loop. */ - if (*out_num + *in_num > vq->vring.num) + if (*out_num + *in_num > max) errx(1, "Looped descriptor"); - } while ((i = next_desc(vq, i)) != vq->vring.num); + } while ((i = next_desc(desc, i, max)) != max); - vq->inflight++; return head; } @@ -719,44 +685,20 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len) /* Make sure buffer is written before we update index. */ wmb(); vq->vring.used->idx++; - vq->inflight--; -} - -/* This actually sends the interrupt for this virtqueue */ -static void trigger_irq(int fd, struct virtqueue *vq) -{ - unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; - - /* If they don't want an interrupt, don't send one, unless empty. */ - if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && vq->inflight) - return; - - /* Send the Guest an interrupt tell them we used something up. */ - if (write(fd, buf, sizeof(buf)) != 0) - err(1, "Triggering irq %i", vq->config.irq); + vq->pending_used++; } /* And here's the combo meal deal. Supersize me! */ -static void add_used_and_trigger(int fd, struct virtqueue *vq, - unsigned int head, int len) +static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) { add_used(vq, head, len); - trigger_irq(fd, vq); + trigger_irq(vq); } /* * 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? */ @@ -766,276 +708,275 @@ struct console_abort }; /* This is the routine which handles console input (ie. stdin). */ -static bool handle_console_input(int fd, 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(fd, 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(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(int fd, 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; - int len; 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?"); - len = writev(STDOUT_FILENO, iov, out); - add_used_and_trigger(fd, vq, head, len); + 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(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(int fd, struct virtqueue *vq, bool timeout) +struct net_info { + int tunfd; +}; + +static void net_output(struct virtqueue *vq) { - unsigned int head, out, in, num = 0; - int len; + 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?"); - len = writev(vq->dev->fd, iov, out); - if (len < 0) - err(1, "Writing network packet to tun"); - 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); - - /* 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(vq, head, 0); +} + +/* Will reading from this file descriptor block? */ +static bool will_block(int fd) +{ + fd_set fdset; + struct timeval zero = { 0, 0 }; + FD_ZERO(&fdset); + FD_SET(fd, &fdset); + return select(fd+1, &fdset, NULL, NULL, &zero) != 1; } -/* 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(int fd, 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); - if (len <= 0) - err(1, "reading network"); + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + struct net_info *net_info = vq->dev->priv; - /* Tell the Guest about the new packet. */ - add_used_and_trigger(fd, dev->vq, head, len); + head = wait_for_vq_desc(vq, iov, &out, &in); + if (out) + errx(1, "Output buffers in net input queue?"); - 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"); + /* Deliver interrupt now, since we're about to sleep. */ + if (vq->pending_used && will_block(net_info->tunfd)) + trigger_irq(vq); - /* All good. */ - return true; + len = readv(net_info->tunfd, iov, in); + if (len <= 0) + err(1, "Failed to read from tun."); + add_used(vq, head, len); } -/*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, bool timeout) +/* This is the helper to create threads. */ +static int do_thread(void *_vq) { - add_device_fd(vq->dev->fd); - /* Snap the Waker out of its select loop. */ - write(waker_fds.pipe[1], "", 1); + struct virtqueue *vq = _vq; + + for (;;) + vq->service(vq); + return 0; } -static void net_enable_fd(int fd, struct virtqueue *vq, bool timeout) +/* 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) { - /* 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, timeout); + kill(0, SIGTERM); } -/* When the Guest tells us they updated the status field, we handle it. */ -static void update_device_status(struct device *dev) +static void reset_device(struct device *dev) { struct virtqueue *vq; - /* This is a reset. */ - if (dev->desc->status == 0) { - verbose("Resetting device %s\n", dev->name); + verbose("Resetting device %s\n", dev->name); - /* Clear any features they've acked. */ - memset(get_feature_bits(dev) + dev->desc->feature_len, 0, - dev->desc->feature_len); + /* Clear any features they've acked. */ + memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len); - /* 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; + /* 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; } - } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { + 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 create_thread(struct virtqueue *vq) +{ + /* 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); +} + +static void start_device(struct device *dev) +{ + unsigned int i; + struct virtqueue *vq; + + 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); + + /* 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); +} + +/* 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->desc->feature_len; i++) - verbose(" %02x", get_feature_bits(dev)[i]); - verbose(", accepted"); - for (i = 0; i < dev->desc->feature_len; i++) - verbose(" %02x", get_feature_bits(dev) - [dev->desc->feature_len+i]); - - if (dev->ready) - dev->ready(dev); + if (!dev->running) + start_device(dev); } } /* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */ -static void handle_output(int fd, unsigned long addr) +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(fd, vq, false); + if (i->running) + errx(1, "Notification on running %s", i->name); + start_device(i); return; } } @@ -1049,71 +990,6 @@ 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) -{ - /* 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(fd, 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(fd); - } -} - /*L:190 * Device Setup * @@ -1129,8 +1005,8 @@ static void handle_input(int fd) 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; + + dev->num_vq * sizeof(struct lguest_vqconfig) + + dev->feature_len * 2; } /* This routine allocates a new "struct lguest_device_desc" from descriptor @@ -1159,7 +1035,7 @@ 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, struct virtqueue *, bool)) + void (*service)(struct virtqueue *)) { unsigned int pages; struct virtqueue **i, *vq = malloc(sizeof(*vq)); @@ -1174,8 +1050,8 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, vq->next = NULL; vq->last_avail_idx = 0; vq->dev = dev; - vq->inflight = 0; - vq->blocked = false; + vq->service = service; + vq->thread = (pid_t)-1; /* Initialize the configuration. */ vq->config.num = num_descs; @@ -1191,6 +1067,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, * 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->num_vq++; dev->desc->num_vq++; verbose("Virtqueue page %#lx\n", to_guest_phys(p)); @@ -1199,15 +1076,6 @@ 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 @@ -1219,7 +1087,7 @@ static void add_feature(struct device *dev, unsigned bit) /* 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; + dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1; } features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT)); @@ -1243,22 +1111,17 @@ static void set_config(struct device *dev, unsigned len, const void *conf) * calling new_dev_desc() to allocate the descriptor and device m |