1 files changed, 51 insertions, 23 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 4c1fc65..82fafe0 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;
 };
@@ -154,6 +157,9 @@ struct virtqueue
 
 	/* The routine to call when the Guest pings us. */
 	void (*handle_output)(int fd, struct virtqueue *me);
+
+	/* Outstanding buffers */
+	unsigned int inflight;
 };
 
 /* Remember the arguments to the program so we can "reboot" */
@@ -699,6 +705,7 @@ static unsigned get_vq_desc(struct virtqueue *vq,
 			errx(1, "Looped descriptor");
 	} while ((i = next_desc(vq, i)) != vq->vring.num);
 
+	vq->inflight++;
 	return head;
 }
 
@@ -716,6 +723,7 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len)
 	/* Make sure buffer is written before we update index. */
 	wmb();
 	vq->vring.used->idx++;
+	vq->inflight--;
 }
 
 /* This actually sends the interrupt for this virtqueue */
@@ -723,8 +731,9 @@ static void trigger_irq(int fd, struct virtqueue *vq)
 {
 	unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
 
-	/* If they don't want an interrupt, don't send one. */
-	if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+	/* If they don't want an interrupt, don't send one, unless empty. */
+	if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+	    && vq->inflight)
 		return;
 
 	/* Send the Guest an interrupt tell them we used something up. */
@@ -925,24 +934,40 @@ 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 +979,9 @@ 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;
 		}
 
@@ -1088,6 +1113,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
 	vq->next = NULL;
 	vq->last_avail_idx = 0;
 	vq->dev = dev;
+	vq->inflight = 0;
 
 	/* Initialize the configuration. */
 	vq->config.num = num_descs;
@@ -1170,6 +1196,7 @@ 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
@@ -1348,6 +1375,7 @@ static void setup_tun_net(const char *arg)
 
 	/* Tell Guest what MAC address to use. */
 	add_feature(dev, VIRTIO_NET_F_MAC);
+	add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
 	set_config(dev, sizeof(conf), &conf);
 
 	/* We don't need the socket any more; setup is done. */
@@ -1398,7 +1426,7 @@ static bool service_io(struct device *dev)
 	struct vblk_info *vblk = dev->priv;
 	unsigned int head, out_num, in_num, wlen;
 	int ret;
-	struct virtio_blk_inhdr *in;
+	u8 *in;
 	struct virtio_blk_outhdr *out;
 	struct iovec iov[dev->vq->vring.num];
 	off64_t off;
@@ -1416,7 +1444,7 @@ static bool service_io(struct device *dev)
 		     head, out_num, in_num);
 
 	out = convert(&iov[0], struct virtio_blk_outhdr);
-	in = convert(&iov[out_num+in_num-1], struct virtio_blk_inhdr);
+	in = convert(&iov[out_num+in_num-1], u8);
 	off = out->sector * 512;
 
 	/* The block device implements "barriers", where the Guest indicates
@@ -1430,7 +1458,7 @@ static bool service_io(struct device *dev)
 	 * It'd be nice if we supported eject, for example, but we don't. */
 	if (out->type & VIRTIO_BLK_T_SCSI_CMD) {
 		fprintf(stderr, "Scsi commands unsupported\n");
-		in->status = VIRTIO_BLK_S_UNSUPP;
+		*in = VIRTIO_BLK_S_UNSUPP;
 		wlen = sizeof(*in);
 	} else if (out->type & VIRTIO_BLK_T_OUT) {
 		/* Write */
@@ -1453,7 +1481,7 @@ static bool service_io(struct device *dev)
 			errx(1, "Write past end %llu+%u", off, ret);
 		}
 		wlen = sizeof(*in);
-		in->status = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+		*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
 	} else {
 		/* Read */
 
@@ -1466,10 +1494,10 @@ static bool service_io(struct device *dev)
 		verbose("READ from sector %llu: %i\n", out->sector, ret);
 		if (ret >= 0) {
 			wlen = sizeof(*in) + ret;
-			in->status = VIRTIO_BLK_S_OK;
+			*in = VIRTIO_BLK_S_OK;
 		} else {
 			wlen = sizeof(*in);
-			in->status = VIRTIO_BLK_S_IOERR;
+			*in = VIRTIO_BLK_S_IOERR;
 		}
 	}