mini-os/tpm{back, front}: Allow device repoens

Allow the vtpm device to be disconnected and reconnected so that a
bootloader (like pv-grub) can submit measurements and return the vtpm
device to its initial state before booting the target kernel.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>

1 files changed, 12 insertions, 2 deletions

diff --git a/extras/mini-os/tpmfront.c b/extras/mini-os/tpmfront.c
index 9f930b5c6f..95d86f6fcc 100644
--- a/extras/mini-os/tpmfront.c
+++ b/extras/mini-os/tpmfront.c
@@ -156,6 +156,9 @@ static int wait_for_backend_closed(xenbus_event_queue* events, char* path)
 	 case XenbusStateClosed:
 	    TPMFRONT_LOG("Backend Closed\n");
 	    return 0;
+	 case XenbusStateInitWait:
+	    TPMFRONT_LOG("Backend Closed (waiting for reconnect)\n");
+	    return 0;
 	 default:
 	    xenbus_wait_for_watch(events);
       }
@@ -339,10 +342,10 @@ void shutdown_tpmfront(struct tpmfront_dev* dev)
    TPMFRONT_LOG("Shutting down tpmfront\n");
    /* disconnect */
    if(dev->state == XenbusStateConnected) {
-      dev->state = XenbusStateClosing;
-      //FIXME: Transaction for this?
       /* Tell backend we are closing */
+      dev->state = XenbusStateClosing;
       if((err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%u", (unsigned int) dev->state))) {
+	 TPMFRONT_ERR("Unable to write to %s, error was %s", dev->nodename, err);
 	 free(err);
       }
 
@@ -366,6 +369,13 @@ void shutdown_tpmfront(struct tpmfront_dev* dev)
       /* Wait for the backend to close and unmap shared pages, ignore any errors */
       wait_for_backend_state_changed(dev, XenbusStateClosed);
 
+      /* Prepare for a later reopen (possibly by a kexec'd kernel) */
+      dev->state = XenbusStateInitialising;
+      if((err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%u", (unsigned int) dev->state))) {
+	 TPMFRONT_ERR("Unable to write to %s, error was %s", dev->nodename, err);
+	 free(err);
+      }
+
       /* Close event channel and unmap shared page */
       mask_evtchn(dev->evtchn);
       unbind_evtchn(dev->evtchn);