tools/lguest: handle device reset correctly in example launcher.

The example launcher doesn't reset the queue_enable like the spec says
we have to.  Plus, we should reset the size in case they negotiated
a different (smaller) one.

This is easy to test by unloading and reloading a virtio module.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index 5d10432..60cabaf 100644 (file)
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -1037,6 +1037,12 @@ static void kill_launcher(int signal)
        kill(0, SIGTERM);
 }
 
+static void reset_vq_pci_config(struct virtqueue *vq)
+{
+       vq->pci_config.queue_size = VIRTQUEUE_NUM;
+       vq->pci_config.queue_enable = 0;
+}
+
 static void reset_device(struct device *dev)
 {
        struct virtqueue *vq;
@@ -1049,8 +1055,19 @@ static void reset_device(struct device *dev)
        /* We're going to be explicitly killing threads, so ignore them. */
        signal(SIGCHLD, SIG_IGN);
 
+       /*
+        * 4.1.4.3.1:
+        *
+        *   The device MUST present a 0 in queue_enable on reset. 
+        *
+        * This means we set it here, and reset the saved ones in every vq.
+        */
+       dev->mmio->cfg.queue_enable = 0;
+
        /* Get rid of the virtqueue threads */
        for (vq = dev->vq; vq; vq = vq->next) {
+               vq->last_avail_idx = 0;
+               reset_vq_pci_config(vq);
                if (vq->thread != (pid_t)-1) {
                        kill(vq->thread, SIGTERM);
                        waitpid(vq->thread, NULL, 0);
@@ -1952,8 +1969,7 @@ static void add_pci_virtqueue(struct device *dev,
        vq->thread = (pid_t)-1;
 
        /* Initialize the configuration. */
-       vq->pci_config.queue_size = VIRTQUEUE_NUM;
-       vq->pci_config.queue_enable = 0;
+       reset_vq_pci_config(vq);
        vq->pci_config.queue_notify_off = 0;
 
        /* Add one to the number of queues */