From e7d4c1c5a54648fd5b787a4a0f81521ec7260bcd Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 8 Jul 2025 17:54:49 +0200 Subject: virtio: introduce extended features The virtio specifications allows for up to 128 bits for the device features. Soon we are going to use some of the 'extended' bits features (above 64) for the virtio_net driver. Introduce extended features as a fixed size array of u64. To minimize the diffstat allows legacy driver to access the low 64 bits via a transparent union. Introduce an extended get_extended_features configuration callback that devices supporting the extended features range must implement in place of the traditional one. Note that legacy and transport features don't need any change, as they are always in the low 64 bit range. Acked-by: Jason Wang Signed-off-by: Paolo Abeni --- drivers/virtio/virtio.c | 43 ++++++++++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 17 deletions(-) (limited to 'drivers/virtio/virtio.c') diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index 95d5d7993e5b..5c48788cdbec 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -53,7 +53,7 @@ static ssize_t features_show(struct device *_d, /* We actually represent this as a bitstring, as it could be * arbitrary length in future. */ - for (i = 0; i < sizeof(dev->features)*8; i++) + for (i = 0; i < VIRTIO_FEATURES_MAX; i++) len += sysfs_emit_at(buf, len, "%c", __virtio_test_bit(dev, i) ? '1' : '0'); len += sysfs_emit_at(buf, len, "\n"); @@ -272,22 +272,22 @@ static int virtio_dev_probe(struct device *_d) int err, i; struct virtio_device *dev = dev_to_virtio(_d); struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); - u64 device_features; - u64 driver_features; + u64 device_features[VIRTIO_FEATURES_DWORDS]; + u64 driver_features[VIRTIO_FEATURES_DWORDS]; u64 driver_features_legacy; /* We have a driver! */ virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); /* Figure out what features the device supports. */ - device_features = dev->config->get_features(dev); + virtio_get_features(dev, device_features); /* Figure out what features the driver supports. */ - driver_features = 0; + virtio_features_zero(driver_features); for (i = 0; i < drv->feature_table_size; i++) { unsigned int f = drv->feature_table[i]; - BUG_ON(f >= 64); - driver_features |= (1ULL << f); + if (!WARN_ON_ONCE(f >= VIRTIO_FEATURES_MAX)) + virtio_features_set_bit(driver_features, f); } /* Some drivers have a separate feature table for virtio v1.0 */ @@ -295,24 +295,29 @@ static int virtio_dev_probe(struct device *_d) driver_features_legacy = 0; for (i = 0; i < drv->feature_table_size_legacy; i++) { unsigned int f = drv->feature_table_legacy[i]; - BUG_ON(f >= 64); - driver_features_legacy |= (1ULL << f); + if (!WARN_ON_ONCE(f >= 64)) + driver_features_legacy |= (1ULL << f); } } else { - driver_features_legacy = driver_features; + driver_features_legacy = driver_features[0]; } - if (device_features & (1ULL << VIRTIO_F_VERSION_1)) - dev->features = driver_features & device_features; - else - dev->features = driver_features_legacy & device_features; + if (virtio_features_test_bit(device_features, VIRTIO_F_VERSION_1)) { + for (i = 0; i < VIRTIO_FEATURES_DWORDS; ++i) + dev->features_array[i] = driver_features[i] & + device_features[i]; + } else { + virtio_features_from_u64(dev->features_array, + driver_features_legacy & + device_features[0]); + } /* When debugging, user may filter some features by hand. */ virtio_debug_device_filter_features(dev); /* Transport features always preserved to pass to finalize_features. */ for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) - if (device_features & (1ULL << i)) + if (virtio_features_test_bit(device_features, i)) __virtio_set_bit(dev, i); err = dev->config->finalize_features(dev); @@ -320,14 +325,15 @@ static int virtio_dev_probe(struct device *_d) goto err; if (drv->validate) { - u64 features = dev->features; + u64 features[VIRTIO_FEATURES_DWORDS]; + virtio_features_copy(features, dev->features_array); err = drv->validate(dev); if (err) goto err; /* Did validation change any features? Then write them again. */ - if (features != dev->features) { + if (!virtio_features_equal(features, dev->features_array)) { err = dev->config->finalize_features(dev); if (err) goto err; @@ -701,6 +707,9 @@ EXPORT_SYMBOL_GPL(virtio_device_reset_done); static int virtio_init(void) { + BUILD_BUG_ON(offsetof(struct virtio_device, features) != + offsetof(struct virtio_device, features_array[0])); + if (bus_register(&virtio_bus) != 0) panic("virtio bus registration failed"); virtio_debug_init(); -- cgit v1.2.3