lguest: Reboot support (ec04b13f) · Commits · git / linux-net

Documentation/lguest/lguest.c

+30 −2

Original line number	Diff line number	Diff line
		@@ -153,6 +153,9 @@ struct virtqueue
		void (handle_output)(int fd, struct virtqueue me);
		};

		/* 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()
		@@ -1489,7 +1492,9 @@ static void setup_block_file(const char *filename)

		/* Create stack for thread and run it */
		stack = malloc(32768);
		if (clone(io_thread, stack + 32768, CLONE_VM, dev) == -1)
		/* SIGCHLD - We dont "wait" for our cloned thread, so prevent it from
		* becoming a zombie. */
		if (clone(io_thread, stack + 32768, CLONE_VM \| SIGCHLD, dev) == -1)
		err(1, "Creating clone");

		/* We don't need to keep the I/O thread's end of the pipes open. */
		@@ -1499,7 +1504,21 @@ static void setup_block_file(const char *filename)
		verbose("device %u: virtblock %llu sectors\n",
		devices.device_num, cap);
		}
		/* That's the end of device setup. */
		/* That's the end of device setup. :*/

		/* Reboot */
		static void __attribute__((noreturn)) restart_guest(void)
		{
		unsigned int i;

		/* Closing pipes causes the waker thread and io_threads to die, and
		* closing /dev/lguest cleans up the Guest. Since we don't track all
		* open fds, we simply close everything beyond stderr. */
		for (i = 3; i < FD_SETSIZE; i++)
		close(i);
		execv(main_args[0], main_args);
		err(1, "Could not exec %s", main_args[0]);
		}

		/*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. */
		@@ -1523,6 +1542,9 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd)
		char reason[1024] = { 0 };
		read(lguest_fd, reason, sizeof(reason)-1);
		errx(1, "%s", reason);
		/* 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.
		* Anything else means a bug or incompatible change. */
		} else if (errno != EAGAIN)
		@@ -1571,6 +1593,12 @@ int main(int argc, char *argv[])
		/* If they specify an initrd file to load. */
		const char *initrd_name = NULL;

		/* Save the args: we "reboot" by execing ourselves again. */
		main_args = argv;
		/* We don't "wait" for the children, so prevent them from becoming
		* zombies. */
		signal(SIGCHLD, SIG_IGN);

		/* First we initialize the device list. Since console and network
		* device receive input from a file descriptor, we keep an fdset
		* (infds) and the maximum fd number (max_infd) with the head of the

arch/x86/lguest/boot.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -67,6 +67,7 @@
		#include <asm/mce.h>
		#include <asm/io.h>
		#include <asm/i387.h>
		#include <asm/reboot.h> /* for struct machine_ops */

		/*G:010 Welcome to the Guest!
		*
		@@ -812,7 +813,7 @@ static void lguest_safe_halt(void)
		* rather than virtual addresses, so we use __pa() here. */
		static void lguest_power_off(void)
		{
		hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
		hcall(LHCALL_SHUTDOWN, __pa("Power down"), LGUEST_SHUTDOWN_POWEROFF, 0);
		}

		/*
		@@ -822,7 +823,7 @@ static void lguest_power_off(void)
		*/
		static int lguest_panic(struct notifier_block nb, unsigned long l, void p)
		{
		hcall(LHCALL_CRASH, __pa(p), 0, 0);
		hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0);
		/* The hcall won't return, but to keep gcc happy, we're "done". */
		return NOTIFY_DONE;
		}
		@@ -926,6 +927,11 @@ static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf,
		return insn_len;
		}

		static void lguest_restart(char *reason)
		{
		hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0);
		}

		/*G:030 Once we get to lguest_init(), we know we're a Guest. The pv_ops
		* structures in the kernel provide points for (almost) every routine we have
		* to override to avoid privileged instructions. */
		@@ -1059,6 +1065,7 @@ __init void lguest_init(void)
		* the Guest routine to power off. */
		pm_power_off = lguest_power_off;

		machine_ops.restart = lguest_restart;
		/* Now we're set up, call start_kernel() in init/main.c and we proceed
		* to boot as normal. It never returns. */
		start_kernel();

drivers/lguest/core.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -235,6 +235,8 @@ int run_guest(struct lguest lg, unsigned long __user user)
		lguest_arch_handle_trap(lg);
		}

		if (lg->dead == ERR_PTR(-ERESTART))
		return -ERESTART;
		/* The Guest is dead => "No such file or directory" */
		return -ENOENT;
		}

drivers/lguest/hypercalls.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -41,8 +41,8 @@ static void do_hcall(struct lguest lg, struct hcall_args args)
		* do that. */
		kill_guest(lg, "already have lguest_data");
		break;
		case LHCALL_CRASH: {
		/* Crash is such a trivial hypercall that we do it in four
		case LHCALL_SHUTDOWN: {
		/* Shutdown is such a trivial hypercall that we do it in four
		* lines right here. */
		char msg[128];
		/* If the lgread fails, it will call kill_guest() itself; the
		@@ -50,6 +50,8 @@ static void do_hcall(struct lguest lg, struct hcall_args args)
		__lgread(lg, msg, args->arg1, sizeof(msg));
		msg[sizeof(msg)-1] = '\0';
		kill_guest(lg, "CRASH: %s", msg);
		if (args->arg2 == LGUEST_SHUTDOWN_RESTART)
		lg->dead = ERR_PTR(-ERESTART);
		break;
		}
		case LHCALL_FLUSH_TLB:

include/asm-x86/lguest_hcall.h

+5 −1

Original line number	Diff line number	Diff line
		@@ -4,7 +4,7 @@

		#define LHCALL_FLUSH_ASYNC 0
		#define LHCALL_LGUEST_INIT 1
		#define LHCALL_CRASH 2
		#define LHCALL_SHUTDOWN 2
		#define LHCALL_LOAD_GDT 3
		#define LHCALL_NEW_PGTABLE 4
		#define LHCALL_FLUSH_TLB 5
		@@ -20,6 +20,10 @@

		#define LGUEST_TRAP_ENTRY 0x1F

		/* Argument number 3 to LHCALL_LGUEST_SHUTDOWN */
		#define LGUEST_SHUTDOWN_POWEROFF 1
		#define LGUEST_SHUTDOWN_RESTART 2

		#ifndef __ASSEMBLY__
		#include <asm/hw_irq.h>