diff options
Diffstat (limited to 'drivers/lguest/lguest_device.c')
| -rw-r--r-- | drivers/lguest/lguest_device.c | 48 |
1 files changed, 28 insertions, 20 deletions
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c index 2bc9bf7e88e5..7a643a6ee9a1 100644 --- a/drivers/lguest/lguest_device.c +++ b/drivers/lguest/lguest_device.c @@ -85,27 +85,34 @@ static unsigned desc_size(const struct lguest_device_desc *desc) + desc->config_len; } -/* This tests (and acknowleges) a feature bit. */ -static bool lg_feature(struct virtio_device *vdev, unsigned fbit) +/* This gets the device's feature bits. */ +static u32 lg_get_features(struct virtio_device *vdev) { + unsigned int i; + u32 features = 0; + struct lguest_device_desc *desc = to_lgdev(vdev)->desc; + u8 *in_features = lg_features(desc); + + /* We do this the slow but generic way. */ + for (i = 0; i < min(desc->feature_len * 8, 32); i++) + if (in_features[i / 8] & (1 << (i % 8))) + features |= (1 << i); + + return features; +} + +static void lg_set_features(struct virtio_device *vdev, u32 features) +{ + unsigned int i; struct lguest_device_desc *desc = to_lgdev(vdev)->desc; - u8 *features; - - /* Obviously if they ask for a feature off the end of our feature - * bitmap, it's not set. */ - if (fbit / 8 > desc->feature_len) - return false; - - /* The feature bitmap comes after the virtqueues. */ - features = lg_features(desc); - if (!(features[fbit / 8] & (1 << (fbit % 8)))) - return false; - - /* We set the matching bit in the other half of the bitmap to tell the - * Host we want to use this feature. We don't use this yet, but we - * could in future. */ - features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8)); - return true; + /* Second half of bitmap is features we accept. */ + u8 *out_features = lg_features(desc) + desc->feature_len; + + memset(out_features, 0, desc->feature_len); + for (i = 0; i < min(desc->feature_len * 8, 32); i++) { + if (features & (1 << i)) + out_features[i / 8] |= (1 << (i % 8)); + } } /* Once they've found a field, getting a copy of it is easy. */ @@ -286,7 +293,8 @@ static void lg_del_vq(struct virtqueue *vq) /* The ops structure which hooks everything together. */ static struct virtio_config_ops lguest_config_ops = { - .feature = lg_feature, + .get_features = lg_get_features, + .set_features = lg_set_features, .get = lg_get, .set = lg_set, .get_status = lg_get_status, |