This is a basic implementation of packed virtqueues as specified in the Virtio 1.1 draft. A compiled version of the current draft is available at https://github.com/oasis-tcs/virtio-docs.git (or as .pdf at https://github.com/oasis-tcs/virtio-docs/blob/master/virtio-v1.1-packed-wd10.pdf
A packed virtqueue is different from a split virtqueue in that it consists of only a single descriptor ring that replaces available and used ring, index and descriptor pointers. Each descriptor is readable and writable and has a flags field. These flags will mark if a descriptor is available or used. To detect new available descriptors even after the ring has wrapped, device and driver each have a single-bit wrap counter that is flipped from 0 to 1 and vice versa every time the last descriptor in the ring is used/made available. v9-v10: * don't mix index into buffer list and descriptors * whitespace and formatting issues * remove "VQ:" in dump virtqueue patch * add extra packed vring struct to virtqueue and change function prototypes and code accordingly * move wrap_counters to virtqueue * make if-conditions for packed and !packed more clear in set_rxtx_funcs() * initialize wrap counters in first patch, instead of rx and tx implementation patch * make virtio-user not supported with packed virtqueues, to be fixed in other patch set? v8-v9: * fix virtio_ring_free_chain_packed() to handle descriptors correctly in case of out-of-order * fix check in virtqueue_xmit_cleanup_packed() to improve performance v7->v8: * move desc_is_used change to correct patch * remove trailing newline * correct xmit code, flags update and memory barrier * move packed desc init to dedicated function, split and packed variant Jens Freimann (9): net/virtio: vring init for packed queues net/virtio: add packed virtqueue defines net/virtio: add packed virtqueue helpers net/virtio: dump packed virtqueue data net/virtio: implement transmit path for packed queues net/virtio: implement receive path for packed queues net/virtio: add virtio send command packed queue support net/virtio: enable packed virtqueues by default net/virtio-user: disable packed virtqueues when CTRL_VQ enabled drivers/net/virtio/virtio_ethdev.c | 202 +++++-- drivers/net/virtio/virtio_ethdev.h | 5 + drivers/net/virtio/virtio_pci.h | 7 + drivers/net/virtio/virtio_ring.h | 64 +- drivers/net/virtio/virtio_rxtx.c | 561 +++++++++++++++++- .../net/virtio/virtio_user/virtio_user_dev.c | 1 + drivers/net/virtio/virtqueue.c | 22 + drivers/net/virtio/virtqueue.h | 69 ++- 8 files changed, 859 insertions(+), 72 deletions(-) -- 2.17.1
