diff options
Diffstat (limited to 'Documentation/lguest/lguest.c')
| -rw-r--r-- | Documentation/lguest/lguest.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 950cde6d6e5..ba9373f82ab 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -42,6 +42,7 @@ #include <signal.h> #include "linux/lguest_launcher.h" #include "linux/virtio_config.h" +#include <linux/virtio_ids.h> #include "linux/virtio_net.h" #include "linux/virtio_blk.h" #include "linux/virtio_console.h" @@ -133,6 +134,9 @@ struct device { /* Is it operational */ bool running; + /* Does Guest want an intrrupt on empty? */ + bool irq_on_empty; + /* Device-specific data. */ void *priv; }; @@ -623,10 +627,13 @@ static void trigger_irq(struct virtqueue *vq) return; vq->pending_used = 0; - /* If they don't want an interrupt, don't send one, unless empty. */ - if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && lg_last_avail(vq) != vq->vring.avail->idx) - return; + /* If they don't want an interrupt, don't send one... */ + if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) { + /* ... unless they've asked us to force one on empty. */ + if (!vq->dev->irq_on_empty + || lg_last_avail(vq) != vq->vring.avail->idx) + return; + } /* Send the Guest an interrupt tell them we used something up. */ if (write(lguest_fd, buf, sizeof(buf)) != 0) @@ -1042,6 +1049,15 @@ static void create_thread(struct virtqueue *vq) close(vq->eventfd); } +static bool accepted_feature(struct device *dev, unsigned int bit) +{ + const u8 *features = get_feature_bits(dev) + dev->feature_len; + + if (dev->feature_len < bit / CHAR_BIT) + return false; + return features[bit / CHAR_BIT] & (1 << (bit % CHAR_BIT)); +} + static void start_device(struct device *dev) { unsigned int i; @@ -1055,6 +1071,8 @@ static void start_device(struct device *dev) verbose(" %02x", get_feature_bits(dev) [dev->feature_len+i]); + dev->irq_on_empty = accepted_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY); + for (vq = dev->vq; vq; vq = vq->next) { if (vq->service) create_thread(vq); |