lguest: Tell Guest net not to notify us on every packet xmit (a161883a) · Commits · 戴 / test

Documentation/lguest/lguest.c

+93 −13

Original line number	Diff line number	Diff line
		@@ -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));

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