Merge branch 'for-linus' of git://linux-nfs.org/~bfields/linux

[powerpc.git] / Documentation / lguest / lguest.c

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 9b0e322..6c8a238 100644 (file)
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -79,6 +79,9 @@ static void *guest_base;
 /* The maximum guest physical address allowed, and maximum possible. */
 static unsigned long guest_limit, guest_max;
 
+/* a per-cpu variable indicating whose vcpu is currently running */
+static unsigned int __thread cpu_id;
+
 /* This is our list of devices. */
 struct device_list
 {
@@ -153,6 +156,9 @@ 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()
@@ -554,7 +560,7 @@ static void wake_parent(int pipefd, int lguest_fd)
                        else
                                FD_CLR(-fd - 1, &devices.infds);
                } else /* Send LHREQ_BREAK command. */
-                       write(lguest_fd, args, sizeof(args));
+                       pwrite(lguest_fd, args, sizeof(args), cpu_id);
        }
 }
 
@@ -1489,7 +1495,9 @@ 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 +1507,21 @@ 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. */
@@ -1511,7 +1533,8 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd)
                int readval;
 
                /* We read from the /dev/lguest device to run the Guest. */
-               readval = read(lguest_fd, &notify_addr, sizeof(notify_addr));
+               readval = pread(lguest_fd, &notify_addr,
+                               sizeof(notify_addr), cpu_id);
 
                /* One unsigned long means the Guest did HCALL_NOTIFY */
                if (readval == sizeof(notify_addr)) {
@@ -1521,16 +1544,23 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd)
                /* ENOENT means the Guest died.  Reading tells us why. */
                } else if (errno == ENOENT) {
                        char reason[1024] = { 0 };
-                       read(lguest_fd, reason, sizeof(reason)-1);
+                       pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
                        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)
                        err(1, "Running guest failed");
 
+               /* Only service input on thread for CPU 0. */
+               if (cpu_id != 0)
+                       continue;
+
                /* Service input, then unset the BREAK to release the Waker. */
                handle_input(lguest_fd);
-               if (write(lguest_fd, args, sizeof(args)) < 0)
+               if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
                        err(1, "Resetting break");
        }
 }
@@ -1571,6 +1601,12 @@ 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
@@ -1582,6 +1618,7 @@ int main(int argc, char *argv[])
        devices.lastdev = &devices.dev;
        devices.next_irq = 1;
 
+       cpu_id = 0;
        /* We need to know how much memory so we can set up the device
         * descriptor and memory pages for the devices as we parse the command
         * line.  So we quickly look through the arguments to find the amount