lguest: Reboot support
Reboot Implemented
(Prevent fd leak, fix style and fix documentation --RR)
Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 9b0e322..86cac3e 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -153,6 +153,9 @@
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 @@
/* 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 @@
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 @@
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 @@
/* 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
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 92c5611..d6b18e2 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -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 @@
* 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 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 @@
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 @@
* 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();
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index f10abc8..c1069bc 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -235,6 +235,8 @@
lguest_arch_handle_trap(lg);
}
+ if (lg->dead == ERR_PTR(-ERESTART))
+ return -ERESTART;
/* The Guest is dead => "No such file or directory" */
return -ENOENT;
}
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index b478aff..05fad6f 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -41,8 +41,8 @@
* 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 @@
__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:
diff --git a/include/asm-x86/lguest_hcall.h b/include/asm-x86/lguest_hcall.h
index 2091779..758b9a5 100644
--- a/include/asm-x86/lguest_hcall.h
+++ b/include/asm-x86/lguest_hcall.h
@@ -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>