libxl, minios: stubdom console based save/restore

Add two "special" PV consoles to stubdoms that are going to be used
to send and receive the qemu-xen save files on save/restore.

Use the second PV console to send the qemu-xen save file and the third
PV console to receive the qemu-xen save file on restore.

Fix the console shutdown function free_consfront that is called when the
qemu save file is closed.

Stubdom save/restore is still broken with xend.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

3 files changed, 72 insertions, 7 deletions

diff --git a/extras/mini-os/console/xencons_ring.c b/extras/mini-os/console/xencons_ring.c
index bfe5cb663c..22fd6187bc 100644
--- a/extras/mini-os/console/xencons_ring.c
+++ b/extras/mini-os/console/xencons_ring.c
@@ -184,16 +184,43 @@ struct consfront_dev *xencons_ring_init(void)
 
 void free_consfront(struct consfront_dev *dev)
 {
-    mask_evtchn(dev->evtchn);
+    char* err = NULL;
+    XenbusState state;
 
-    free(dev->backend);
+    char path[strlen(dev->backend) + 1 + 5 + 1];
+    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
 
-    gnttab_end_access(dev->ring_ref);
-    free_page(dev->ring);
+    snprintf(path, sizeof(path), "%s/state", dev->backend);
+    snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
 
-    unbind_evtchn(dev->evtchn);
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosing)) != NULL) {
+        printk("free_consfront: error changing state to %d: %s\n",
+                XenbusStateClosing, err);
+        goto close;
+    }
+    state = xenbus_read_integer(path);
+    while (err == NULL && state < XenbusStateClosing)
+        err = xenbus_wait_for_state_change(path, &state, &dev->events);
+    if (err) free(err);
+
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosed)) != NULL) {
+        printk("free_consfront: error changing state to %d: %s\n",
+                XenbusStateClosed, err);
+        goto close;
+    }
 
+close:
+    if (err) free(err);
+    xenbus_unwatch_path_token(XBT_NIL, path, path);
+
+    mask_evtchn(dev->evtchn);
+    unbind_evtchn(dev->evtchn);
+    free(dev->backend);
     free(dev->nodename);
+
+    gnttab_end_access(dev->ring_ref);
+
+    free_page(dev->ring);
     free(dev);
 }
 
@@ -206,7 +233,7 @@ struct consfront_dev *init_consfront(char *_nodename)
     char* msg = NULL;
     char nodename[256];
     char path[256];
-    static int consfrontends = 1;
+    static int consfrontends = 3;
     struct consfront_dev *dev;
     int res;
 
diff --git a/extras/mini-os/include/lib.h b/extras/mini-os/include/lib.h
index 9102d55b81..84e4de2bfe 100644
--- a/extras/mini-os/include/lib.h
+++ b/extras/mini-os/include/lib.h
@@ -146,6 +146,7 @@ enum fd_type {
     FTYPE_KBD,
     FTYPE_FB,
     FTYPE_MEM,
+    FTYPE_SAVEFILE,
 };
 
 #define MAX_EVTCHN_PORTS 16
diff --git a/extras/mini-os/lib/sys.c b/extras/mini-os/lib/sys.c
index 51a801f0ca..7a49886e2d 100644
--- a/extras/mini-os/lib/sys.c
+++ b/extras/mini-os/lib/sys.c
@@ -154,6 +154,9 @@ char *getcwd(char *buf, size_t size)
 }
 
 #define LOG_PATH "/var/log/"
+#define SAVE_PATH "/var/lib/xen"
+#define SAVE_CONSOLE 1
+#define RESTORE_CONSOLE 2
 
 int mkdir(const char *pathname, mode_t mode)
 {
@@ -175,6 +178,21 @@ int posix_openpt(int flags)
     return(dev->fd);
 }
 
+int open_savefile(char *path, int save)
+{
+    struct consfront_dev *dev;
+    char *nodename[64];
+
+    snprintf(nodename, sizeof(nodename), "device/console/%d", save ? SAVE_CONSOLE : RESTORE_CONSOLE);
+
+    dev = init_consfront(nodename);
+    dev->fd = alloc_fd(FTYPE_SAVEFILE);
+    files[dev->fd].cons.dev = dev;
+
+    printk("fd(%d) = open_savefile\n", dev->fd);
+    return(dev->fd);
+}
+
 int open(const char *pathname, int flags, ...)
 {
     int fd;
@@ -191,6 +209,8 @@ int open(const char *pathname, int flags, ...)
     }
     if (!strncmp(pathname, "/dev/ptmx", strlen("/dev/ptmx")))
         return posix_openpt(flags);
+    if (!strncmp(pathname,SAVE_PATH,strlen(SAVE_PATH)))
+        return open_savefile(pathname, flags & O_WRONLY);
     errno = EIO;
     return -1;
 }
@@ -203,6 +223,7 @@ int isatty(int fd)
 int read(int fd, void *buf, size_t nbytes)
 {
     switch (files[fd].type) {
+        case FTYPE_SAVEFILE:
 	case FTYPE_CONSOLE: {
 	    int ret;
             DEFINE_WAIT(w);
@@ -260,6 +281,15 @@ int read(int fd, void *buf, size_t nbytes)
 int write(int fd, const void *buf, size_t nbytes)
 {
     switch (files[fd].type) {
+        case FTYPE_SAVEFILE: {
+                int ret = 0, tot = nbytes;
+                while (nbytes > 0) {
+                    ret = xencons_ring_send(files[fd].cons.dev, (char *)buf, nbytes);
+                    nbytes -= ret;
+                    buf += ret;
+                }
+                return tot - nbytes;
+            }
 	case FTYPE_CONSOLE:
 	    console_print(files[fd].cons.dev, (char *)buf, nbytes);
 	    return nbytes;
@@ -331,6 +361,7 @@ int close(int fd)
             shutdown_fbfront(files[fd].fb.dev);
             files[fd].type = FTYPE_NONE;
             return 0;
+        case FTYPE_SAVEFILE:
         case FTYPE_CONSOLE:
             fini_console(files[fd].cons.dev);
             files[fd].type = FTYPE_NONE;
@@ -364,9 +395,15 @@ int fstat(int fd, struct stat *buf)
 {
     init_stat(buf);
     switch (files[fd].type) {
+	case FTYPE_SAVEFILE:
 	case FTYPE_CONSOLE:
 	case FTYPE_SOCKET: {
-	    buf->st_mode = (files[fd].type == FTYPE_CONSOLE?S_IFCHR:S_IFSOCK) | S_IRUSR|S_IWUSR;
+            if (files[fd].type == FTYPE_CONSOLE)
+                buf->st_mode = S_IFCHR|S_IRUSR|S_IWUSR;
+            else if (files[fd].type == FTYPE_SOCKET)
+                buf->st_mode = S_IFSOCK|S_IRUSR|S_IWUSR;
+            else if (files[fd].type == FTYPE_SAVEFILE)
+                buf->st_mode = S_IFREG|S_IRUSR|S_IWUSR;
 	    buf->st_uid = 0;
 	    buf->st_gid = 0;
 	    buf->st_size = 0;