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author | Rusty Russell <rusty@rustcorp.com.au> | 2008-05-03 06:50:50 +0400 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-05-02 15:50:50 +0400 |
commit | c45a6816c19dee67b8f725e6646d428901a6dc24 (patch) | |
tree | 096e3263fd14e140685bcc3082394ff15f5aeddb /drivers | |
parent | 72e61eb40b55dd57031ec5971e810649f82b0259 (diff) | |
download | linux-c45a6816c19dee67b8f725e6646d428901a6dc24.tar.xz |
virtio: explicit advertisement of driver features
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.
There is nothing in the API to require this, however, and even I
didn't notice when it was violated.
So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core. The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.
Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.
Drivers can still remove feature bits in their probe routine if they
really have to.
API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/block/virtio_blk.c | 8 | ||||
-rw-r--r-- | drivers/lguest/lguest_device.c | 48 | ||||
-rw-r--r-- | drivers/net/virtio_net.c | 22 | ||||
-rw-r--r-- | drivers/virtio/virtio.c | 38 | ||||
-rw-r--r-- | drivers/virtio/virtio_balloon.c | 6 | ||||
-rw-r--r-- | drivers/virtio/virtio_pci.c | 30 |
6 files changed, 106 insertions, 46 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index cc6d39383a3f..78be6b8c89e0 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -242,7 +242,7 @@ static int virtblk_probe(struct virtio_device *vdev) index++; /* If barriers are supported, tell block layer that queue is ordered */ - if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER)) + if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); /* Host must always specify the capacity. */ @@ -308,7 +308,13 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static unsigned int features[] = { + VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, +}; + static struct virtio_driver virtio_blk = { + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, 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, diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ad43421ab6f1..f926b5ab3d09 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -378,26 +378,26 @@ static int virtnet_probe(struct virtio_device *vdev) SET_NETDEV_DEV(dev, &vdev->dev); /* Do we support "hardware" checksums? */ - if (csum && vdev->config->feature(vdev, VIRTIO_NET_F_CSUM)) { + if (csum && virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) { /* This opens up the world of extra features. */ dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST; - if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_GSO)) { + if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) { dev->features |= NETIF_F_TSO | NETIF_F_UFO | NETIF_F_TSO_ECN | NETIF_F_TSO6; } /* Individual feature bits: what can host handle? */ - if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_TSO4)) + if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4)) dev->features |= NETIF_F_TSO; - if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_TSO6)) + if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6)) dev->features |= NETIF_F_TSO6; - if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_ECN)) + if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN)) dev->features |= NETIF_F_TSO_ECN; - if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_UFO)) + if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO)) dev->features |= NETIF_F_UFO; } /* Configuration may specify what MAC to use. Otherwise random. */ - if (vdev->config->feature(vdev, VIRTIO_NET_F_MAC)) { + if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) { vdev->config->get(vdev, offsetof(struct virtio_net_config, mac), dev->dev_addr, dev->addr_len); @@ -486,7 +486,15 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static unsigned int features[] = { + VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC, + VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, + VIRTIO_NET_F_HOST_ECN, +}; + static struct virtio_driver virtio_net = { + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index b535483bc556..13866789b356 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -80,19 +80,51 @@ static void add_status(struct virtio_device *dev, unsigned status) dev->config->set_status(dev, dev->config->get_status(dev) | status); } +void virtio_check_driver_offered_feature(const struct virtio_device *vdev, + unsigned int fbit) +{ + unsigned int i; + struct virtio_driver *drv = container_of(vdev->dev.driver, + struct virtio_driver, driver); + + for (i = 0; i < drv->feature_table_size; i++) + if (drv->feature_table[i] == fbit) + return; + BUG(); +} +EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature); + static int virtio_dev_probe(struct device *_d) { - int err; + int err, i; struct virtio_device *dev = container_of(_d,struct virtio_device,dev); struct virtio_driver *drv = container_of(dev->dev.driver, struct virtio_driver, driver); + u32 device_features; + /* We have a driver! */ add_status(dev, VIRTIO_CONFIG_S_DRIVER); + + /* Figure out what features the device supports. */ + device_features = dev->config->get_features(dev); + + /* Features supported by both device and driver into dev->features. */ + memset(dev->features, 0, sizeof(dev->features)); + for (i = 0; i < drv->feature_table_size; i++) { + unsigned int f = drv->feature_table[i]; + BUG_ON(f >= 32); + if (device_features & (1 << f)) + set_bit(f, dev->features); + } + err = drv->probe(dev); if (err) add_status(dev, VIRTIO_CONFIG_S_FAILED); - else + else { add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); + /* They should never have set feature bits beyond 32 */ + dev->config->set_features(dev, dev->features[0]); + } return err; } @@ -114,6 +146,8 @@ static int virtio_dev_remove(struct device *_d) int register_virtio_driver(struct virtio_driver *driver) { + /* Catch this early. */ + BUG_ON(driver->feature_table_size && !driver->feature_table); driver->driver.bus = &virtio_bus; driver->driver.probe = virtio_dev_probe; driver->driver.remove = virtio_dev_remove; diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index fef88d84cef6..bfef604160d1 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -227,7 +227,7 @@ static int virtballoon_probe(struct virtio_device *vdev) } vb->tell_host_first - = vdev->config->feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); + = virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); return 0; @@ -259,7 +259,11 @@ static void virtballoon_remove(struct virtio_device *vdev) kfree(vb); } +static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST }; + static struct virtio_driver virtio_balloon = { + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index de102a614e97..27e9fc9117cd 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -87,23 +87,22 @@ static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev) return container_of(vdev, struct virtio_pci_device, vdev); } -/* virtio config->feature() implementation */ -static bool vp_feature(struct virtio_device *vdev, unsigned bit) +/* virtio config->get_features() implementation */ +static u32 vp_get_features(struct virtio_device *vdev) +{ + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + /* When someone needs more than 32 feature bits, we'll need to + * steal a bit to indicate that the rest are somewhere else. */ + return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES); +} + +/* virtio config->set_features() implementation */ +static void vp_set_features(struct virtio_device *vdev, u32 features) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); - u32 mask; - - /* Since this function is supposed to have the side effect of - * enabling a queried feature, we simulate that by doing a read - * from the host feature bitmask and then writing to the guest - * feature bitmask */ - mask = ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES); - if (mask & (1 << bit)) { - mask |= (1 << bit); - iowrite32(mask, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES); - } - return !!(mask & (1 << bit)); + iowrite32(features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES); } /* virtio config->get() implementation */ @@ -293,7 +292,6 @@ static void vp_del_vq(struct virtqueue *vq) } static struct virtio_config_ops virtio_pci_config_ops = { - .feature = vp_feature, .get = vp_get, .set = vp_set, .get_status = vp_get_status, @@ -301,6 +299,8 @@ static struct virtio_config_ops virtio_pci_config_ops = { .reset = vp_reset, .find_vq = vp_find_vq, .del_vq = vp_del_vq, + .get_features = vp_get_features, + .set_features = vp_set_features, }; /* the PCI probing function */ |