lguest: notify on empty

[linux-2.6-omap-h63xx.git] / Documentation / lguest / lguest.c

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 4c1fc65a8b3d1c946965db4afc2a2dc08f82c44e..82fafe0429fed8dc441411059be52b33154dd8a8 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;
 };
@@ -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;
                }
        }