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Commit 56739c80 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: cleanup passing of /dev/lguest fd around example launcher. 



We hand the /dev/lguest fd everywhere; it's far neater to just make it
a global (it already is, in fact, hidden in the waker_fds struct).

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 713b15b3

Documentation/lguest/lguest.c

+47 −55
Original line number Diff line number Diff line
@@ -79,7 +79,6 @@ static bool verbose; 
/* File descriptors for the Waker. */

struct {

	int pipe[2];

	int lguest_fd;

} waker_fds;



/* The pointer to the start of guest memory. */
@@ -89,6 +88,8 @@ 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;
@@ -139,7 +140,7 @@ struct device 
	/* 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);

	bool (*handle_input)(struct device *me);



	/* Any queues attached to this device */

	struct virtqueue *vq;
@@ -169,7 +170,7 @@ struct virtqueue 
	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);

	void (*handle_output)(struct virtqueue *me, bool timeout);



	/* Outstanding buffers */

	unsigned int inflight;
@@ -509,21 +510,16 @@ 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;

}

/*:*/
@@ -583,21 +579,18 @@ static int waker(void *unused) 
		}



		/* Send LHREQ_BREAK command to snap the Launcher out of it. */

		pwrite(waker_fds.lguest_fd, args, sizeof(args), cpu_id);

		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(int lguest_fd)

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");



	/* 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");

}
@@ -727,7 +720,7 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len) 
}



/* This actually sends the interrupt for this virtqueue */

static void trigger_irq(int fd, struct virtqueue *vq)

static void trigger_irq(struct virtqueue *vq)

{

	unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
@@ -737,16 +730,15 @@ static void trigger_irq(int fd, struct virtqueue *vq) 
		return;



	/* Send the Guest an interrupt tell them we used something up. */

	if (write(fd, buf, sizeof(buf)) != 0)

	if (write(lguest_fd, buf, sizeof(buf)) != 0)

		err(1, "Triggering irq %i", vq->config.irq);

}



/* 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);

}



/*
@@ -770,7 +762,7 @@ struct console_abort 
};



/* This is the routine which handles console input (ie. stdin). */

static bool handle_console_input(int fd, struct device *dev)

static bool handle_console_input(struct device *dev)

{

	int len;

	unsigned int head, in_num, out_num;
@@ -804,7 +796,7 @@ static bool handle_console_input(int fd, struct device *dev) 
	}



	/* Tell the Guest about the new input. */

	add_used_and_trigger(fd, dev->vq, head, len);

	add_used_and_trigger(dev->vq, head, len);



	/* Three ^C within one second?  Exit.

	 *
@@ -824,7 +816,7 @@ static bool handle_console_input(int fd, struct device *dev) 
				close(waker_fds.pipe[1]);

				/* Just in case Waker is blocked in BREAK, send

				 * unbreak now. */

				write(fd, args, sizeof(args));

				write(lguest_fd, args, sizeof(args));

				exit(2);

			}

			abort->count = 0;
@@ -839,7 +831,7 @@ 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, bool timeout)

static void handle_console_output(struct virtqueue *vq, bool timeout)

{

	unsigned int head, out, in;

	int len;
@@ -850,7 +842,7 @@ static void handle_console_output(int fd, struct virtqueue *vq, bool timeout) 
		if (in)

			errx(1, "Input buffers in output queue?");

		len = writev(STDOUT_FILENO, iov, out);

		add_used_and_trigger(fd, vq, head, len);

		add_used_and_trigger(vq, head, len);

	}

}
@@ -879,7 +871,7 @@ static void block_vq(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, bool timeout)

static void handle_net_output(struct virtqueue *vq, bool timeout)

{

	unsigned int head, out, in, num = 0;

	int len;
@@ -893,7 +885,7 @@ static void handle_net_output(int fd, struct virtqueue *vq, bool timeout) 
		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);

		add_used_and_trigger(vq, head, len);

		num++;

	}
@@ -917,7 +909,7 @@ static void handle_net_output(int fd, struct virtqueue *vq, bool timeout) 


/* This is where we handle a packet coming in from the tun device to our

 * Guest. */

static bool handle_tun_input(int fd, struct device *dev)

static bool handle_tun_input(struct device *dev)

{

	unsigned int head, in_num, out_num;

	int len;
@@ -946,7 +938,7 @@ static bool handle_tun_input(int fd, struct device *dev) 
		err(1, "reading network");



	/* Tell the Guest about the new packet. */

	add_used_and_trigger(fd, dev->vq, head, len);

	add_used_and_trigger(dev->vq, head, len);



	verbose("tun input packet len %i [%02x %02x] (%s)\n", len,

		((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1],
@@ -959,18 +951,18 @@ 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, bool timeout)

static void enable_fd(struct virtqueue *vq, bool timeout)

{

	add_device_fd(vq->dev->fd);

	/* Snap the Waker out of its select loop. */

	write(waker_fds.pipe[1], "", 1);

}



static void net_enable_fd(int fd, struct virtqueue *vq, bool timeout)

static void net_enable_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, timeout);

	enable_fd(vq, timeout);

}



/* When the Guest tells us they updated the status field, we handle it. */
@@ -1011,7 +1003,7 @@ static void update_device_status(struct 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;
@@ -1039,7 +1031,7 @@ 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, false);

				vq->handle_output(vq, false);

			return;

		}

	}
@@ -1053,7 +1045,7 @@ static void handle_output(int fd, unsigned long addr) 
	      strnlen(from_guest_phys(addr), guest_limit - addr));

}



static void handle_timeout(int fd)

static void handle_timeout(void)

{

	char buf[32];

	struct device *i;
@@ -1071,14 +1063,14 @@ static void handle_timeout(int fd) 
			vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;

			vq->blocked = false;

			if (vq->handle_output)

				vq->handle_output(fd, vq, true);

				vq->handle_output(vq, true);

		}

	}

}



/* This is called when the Waker wakes us up: check for incoming file

 * descriptors. */

static void handle_input(int fd)

static void handle_input(void)

{

	/* select() wants a zeroed timeval to mean "don't wait". */

	struct timeval poll = { .tv_sec = 0, .tv_usec = 0 };
@@ -1100,7 +1092,7 @@ static void handle_input(int fd) 
		 * 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))

				if (i->handle_input(i))

					continue;



				/* If handle_input() returns false, it means we
@@ -1114,7 +1106,7 @@ static void handle_input(int fd) 


		/* Is this the timeout fd? */

		if (FD_ISSET(timeoutpipe[0], &fds))

			handle_timeout(fd);

			handle_timeout();

	}

}
@@ -1163,7 +1155,7 @@ 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 (*handle_output)(struct virtqueue *, bool))

{

	unsigned int pages;

	struct virtqueue **i, *vq = malloc(sizeof(*vq));
@@ -1249,7 +1241,7 @@ static void set_config(struct device *dev, unsigned len, const void *conf) 
 *

 * See what I mean about userspace being boring? */

static struct device *new_device(const char *name, u16 type, int fd,

				 bool (*handle_input)(int, struct device *))

				 bool (*handle_input)(struct device *))

{

	struct device *dev = malloc(sizeof(*dev));
@@ -1678,7 +1670,7 @@ static int io_thread(void *_dev) 


/* 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(int fd, struct device *dev)

static bool handle_io_finish(struct device *dev)

{

	char c;
@@ -1688,12 +1680,12 @@ static bool handle_io_finish(int fd, struct device *dev) 
		exit(1);



	/* It did some work, so trigger the irq. */

	trigger_irq(fd, dev->vq);

	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(int fd, struct virtqueue *vq, bool timeout)

static void handle_virtblk_output(struct virtqueue *vq, bool timeout)

{

	struct vblk_info *vblk = vq->dev->priv;

	char c = 0;
@@ -1771,7 +1763,7 @@ static void setup_block_file(const char *filename) 
 * console is the reverse.

 *

 * The same logic applies, however. */

static bool handle_rng_input(int fd, struct device *dev)

static bool handle_rng_input(struct device *dev)

{

	int len;

	unsigned int head, in_num, out_num, totlen = 0;
@@ -1800,7 +1792,7 @@ static bool handle_rng_input(int fd, struct device *dev) 
	}



	/* Tell the Guest about the new input. */

	add_used_and_trigger(fd, dev->vq, head, totlen);

	add_used_and_trigger(dev->vq, head, totlen);



	/* Everything went OK! */

	return true;
@@ -1841,7 +1833,7 @@ static void __attribute__((noreturn)) restart_guest(void) 


/*L:220 Finally we reach the core of the Launcher which runs the Guest, serves

 * its input and output, and finally, lays it to rest. */

static void __attribute__((noreturn)) run_guest(int lguest_fd)

static void __attribute__((noreturn)) run_guest(void)

{

	for (;;) {

		unsigned long args[] = { LHREQ_BREAK, 0 };
@@ -1855,7 +1847,7 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) 
		/* One unsigned long means the Guest did HCALL_NOTIFY */

		if (readval == sizeof(notify_addr)) {

			verbose("Notify on address %#lx\n", notify_addr);

			handle_output(lguest_fd, notify_addr);

			handle_output(notify_addr);

			continue;

		/* ENOENT means the Guest died.  Reading tells us why. */

		} else if (errno == ENOENT) {
@@ -1875,7 +1867,7 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) 
			continue;



		/* Service input, then unset the BREAK to release the Waker. */

		handle_input(lguest_fd);

		handle_input();

		if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)

			err(1, "Resetting break");

	}
@@ -1911,8 +1903,8 @@ int main(int argc, char *argv[]) 
	/* Memory, top-level pagetable, code startpoint and size of the

	 * (optional) initrd. */

	unsigned long mem = 0, start, initrd_size = 0;

	/* Two temporaries and the /dev/lguest file descriptor. */

	int i, c, lguest_fd;

	/* Two temporaries. */

	int i, c;

	/* The boot information for the Guest. */

	struct boot_params *boot;

	/* If they specify an initrd file to load. */
@@ -2030,15 +2022,15 @@ int main(int argc, char *argv[]) 


	/* We tell the kernel to initialize the Guest: this returns the open

	 * /dev/lguest file descriptor. */

	lguest_fd = tell_kernel(start);

	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(lguest_fd);

	setup_waker();



	/* Finally, run the Guest.  This doesn't return. */

	run_guest(lguest_fd);

	run_guest();

}

/*:*/