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>

2 files changed, 48 insertions, 22 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 5cd705c3d75b..3be8ab2a886a 100644
--- 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 7a643a6ee9a1..8080249957af 100644
--- 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);
 }
 
 /*