8 files changed, 87 insertions, 32 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 8ff2d8bc690a..0f23d67f958f 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -193,6 +193,13 @@ static void *_convert(struct iovec *iov, size_t size, size_t align,
 #define le32_to_cpu(v32) (v32)
 #define le64_to_cpu(v64) (v64)
 
+/* The device virtqueue descriptors are followed by feature bitmasks. */
+static u8 *get_feature_bits(struct device *dev)
+{
+        return (u8 *)(dev->desc + 1)
+                + dev->desc->num_vq * sizeof(struct lguest_vqconfig);
+}
+
 /*L:100 The Launcher code itself takes us out into userspace, that scary place
  * where pointers run wild and free!  Unfortunately, like most userspace
  * programs, it's quite boring (which is why everyone likes to hack on the
@@ -914,21 +921,58 @@ static void enable_fd(int fd, struct virtqueue *vq)
         write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd));
 }
 
+/* Resetting a device is fairly easy. */
+static void reset_device(struct device *dev)
+{
+        struct virtqueue *vq;
+
+        verbose("Resetting device %s\n", dev->name);
+        /* Clear the status. */
+        dev->desc->status = 0;
+
+        /* Clear any features they've acked. */
+        memset(get_feature_bits(dev) + dev->desc->feature_len, 0,
+               dev->desc->feature_len);
+
+        /* Zero out the virtqueues. */
+        for (vq = dev->vq; vq; vq = vq->next) {
+                memset(vq->vring.desc, 0,
+                       vring_size(vq->config.num, getpagesize()));
+                vq->last_avail_idx = 0;
+        }
+}
+
 /* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */
 static void handle_output(int fd, unsigned long addr)
 {
         struct device *i;
         struct virtqueue *vq;
 
-        /* Check each virtqueue. */
+        /* Check each device and virtqueue. */
         for (i = devices.dev; i; i = i->next) {
+                /* Notifications to device descriptors reset the device. */
+                if (from_guest_phys(addr) == i->desc) {
+                        reset_device(i);
+                        return;
+                }
+
+                /* Notifications to virtqueues mean output has occurred. */
                 for (vq = i->vq; vq; vq = vq->next) {
-                        if (vq->config.pfn == addr/getpagesize()) {
-                                verbose("Output to %s\n", vq->dev->name);
-                                if (vq->handle_output)
-                                        vq->handle_output(fd, vq);
+                        if (vq->config.pfn != addr/getpagesize())
+                                continue;
+
+                        /* Guest should acknowledge (and set features!)  before
+                         * using the device. */
+                        if (i->desc->status == 0) {
+                                warnx("%s gave early output", i->name);
                                 return;
                         }
+
+                        if (strcmp(vq->dev->name, "console") != 0)
+                                verbose("Output to %s\n", vq->dev->name);
+                        if (vq->handle_output)
+                                vq->handle_output(fd, vq);
+                        return;
                 }
         }
 
@@ -1074,10 +1118,11 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
                 vq->vring.used->flags = VRING_USED_F_NO_NOTIFY;
 }
 
-/* The virtqueue descriptors are followed by feature bytes. */
+/* The first half of the feature bitmask is for us to advertise features.  The
+ * second half if for the Guest to accept features. */
 static void add_feature(struct device *dev, unsigned bit)
 {
-        u8 *features;
+        u8 *features = get_feature_bits(dev);
 
         /* We can't extend the feature bits once we've added config bytes */
         if (dev->desc->feature_len <= bit / CHAR_BIT) {
@@ -1085,9 +1130,6 @@ static void add_feature(struct device *dev, unsigned bit)
                 dev->desc->feature_len = (bit / CHAR_BIT) + 1;
         }
 
-        features = (u8 *)(dev->desc + 1)
-                + dev->desc->num_vq * sizeof(struct lguest_vqconfig);
-
         features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT));
 }
 
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 54a8017ad487..6143337527e7 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -264,12 +264,16 @@ static void virtblk_remove(struct virtio_device *vdev)
         struct virtio_blk *vblk = vdev->priv;
         int major = vblk->disk->major;
 
+        /* Nothing should be pending. */
         BUG_ON(!list_empty(&vblk->reqs));
+
+        /* Stop all the virtqueues. */
+        vdev->config->reset(vdev);
+
         blk_cleanup_queue(vblk->disk->queue);
         put_disk(vblk->disk);
         unregister_blkdev(major, "virtblk");
         mempool_destroy(vblk->pool);
-        /* There should be nothing in the queue now, so no need to shutdown */
         vdev->config->del_vq(vblk->vq);
         kfree(vblk);
 }
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index ced5b44cebce..84f85e23cca7 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -54,7 +54,7 @@ struct lguest_device {
  *
  * The configuration information for a device consists of one or more
  * virtqueues, a feature bitmaks, and some configuration bytes.  The
- * configuration bytes don't really matter to us: the Launcher set them up, and
+ * configuration bytes don't really matter to us: the Launcher sets them up, and
  * the driver will look at them during setup.
  *
  * A convenient routine to return the device's virtqueue config array:
@@ -139,9 +139,20 @@ static u8 lg_get_status(struct virtio_device *vdev)
 
 static void lg_set_status(struct virtio_device *vdev, u8 status)
 {
+        BUG_ON(!status);
         to_lgdev(vdev)->desc->status = status;
 }
 
+/* To reset the device, we (ab)use the NOTIFY hypercall, with the descriptor
+ * address of the device.  The Host will zero the status and all the
+ * features. */
+static void lg_reset(struct virtio_device *vdev)
+{
+        unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+        hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0);
+}
+
 /*
  * Virtqueues
  *
@@ -279,6 +290,7 @@ static struct virtio_config_ops lguest_config_ops = {
         .set = lg_set,
         .get_status = lg_get_status,