lguest: make Launcher see device status updates

This brings us closer to Real Life, where we'd examine the device
features once it's set the DRIVER_OK status bit.

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

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 5cd705c..3be8ab2 100644 (file)
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -131,6 +131,9 @@ struct device
        /* Any queues attached to this device */
        struct virtqueue *vq;
 
+       /* Handle status being finalized (ie. feature bits stable). */
+       void (*ready)(struct device *me);
+
        /* Device-specific data. */
        void *priv;
 };
@@ -925,24 +928,40 @@ static void enable_fd(int fd, struct virtqueue *vq)
        write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd));
 }
 
-/* When the Guest asks us to reset a device, it's is fairly easy. */
-static void reset_device(struct device *dev)
+/* When the Guest tells us they updated the status field, we handle it. */
+static void update_device_status(struct device *dev)
 {
        struct virtqueue *vq;
 
-       verbose("Resetting device %s\n", dev->name);
-       /* Clear the status. */
-       dev->desc->status = 0;
+       /* This is a reset. */
+       if (dev->desc->status == 0) {
+               verbose("Resetting device %s\n", dev->name);
 
-       /* Clear any features they've acked. */
-       memset(get_feature_bits(dev) + dev->desc->feature_len, 0,
-              dev->desc->feature_len);
+               /* 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;
+               /* 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;
+               }
+       } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) {
+               warnx("Device %s configuration FAILED", dev->name);
+       } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) {
+               unsigned int i;
+
+               verbose("Device %s OK: offered", dev->name);
+               for (i = 0; i < dev->desc->feature_len; i++)
+                       verbose(" %08x", get_feature_bits(dev)[i]);
+               verbose(", accepted");
+               for (i = 0; i < dev->desc->feature_len; i++)
+                       verbose(" %08x", get_feature_bits(dev)
+                               [dev->desc->feature_len+i]);
+
+               if (dev->ready)
+                       dev->ready(dev);
        }
 }
 
@@ -954,9 +973,9 @@ static void handle_output(int fd, unsigned long addr)
 
        /* Check each device and virtqueue. */
        for (i = devices.dev; i; i = i->next) {
-               /* Notifications to device descriptors reset the device. */
+               /* Notifications to device descriptors update device status. */
                if (from_guest_phys(addr) == i->desc) {
-                       reset_device(i);
+                       update_device_status(i);
                        return;
                }
 
@@ -1170,6 +1189,7 @@ static struct device *new_device(const char *name, u16 type, int fd,
        dev->handle_input = handle_input;
        dev->name = name;
        dev->vq = NULL;
+       dev->ready = NULL;
 
        /* Append to device list.  Prepending to a single-linked list is
         * easier, but the user expects the devices to be arranged on the bus

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 7a643a6..8080249 100644 (file)
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -144,20 +144,26 @@ static u8 lg_get_status(struct virtio_device *vdev)
        return to_lgdev(vdev)->desc->status;
 }
 
+/* To notify on status updates, we (ab)use the NOTIFY hypercall, with the
+ * descriptor address of the device.  A zero status means "reset". */
+static void set_status(struct virtio_device *vdev, u8 status)
+{
+       unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+       /* We set the status. */
+       to_lgdev(vdev)->desc->status = status;
+       hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0);
+}
+
 static void lg_set_status(struct virtio_device *vdev, u8 status)
 {
        BUG_ON(!status);
-       to_lgdev(vdev)->desc->status = status;
+       set_status(vdev, 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);
+       set_status(vdev, 0);
 }
 
 /*