On 09/08/2023 18:57, Mina Almasry wrote: > Add a netdev_dmabuf_binding struct which represents the > dma-buf-to-netdevice binding. The netlink API will bind the dma-buf to > an rx queue on the netdevice. On the binding, the dma_buf_attach > & dma_buf_map_attachment will occur. The entries in the sg_table from > mapping will be inserted into a genpool to make it ready > for allocation. > > The chunks in the genpool are owned by a dmabuf_chunk_owner struct which > holds the dma-buf offset of the base of the chunk and the dma_addr of > the chunk. Both are needed to use allocations that come from this chunk. > > We create a new type that represents an allocation from the genpool: > page_pool_iov. We setup the page_pool_iov allocation size in the > genpool to PAGE_SIZE for simplicity: to match the PAGE_SIZE normally > allocated by the page pool and given to the drivers. > > The user can unbind the dmabuf from the netdevice by closing the netlink > socket that established the binding. We do this so that the binding is > automatically unbound even if the userspace process crashes. > > The binding and unbinding leaves an indicator in struct netdev_rx_queue > that the given queue is bound, but the binding doesn't take effect until > the driver actually reconfigures its queues, and re-initializes its page > pool. This issue/weirdness is highlighted in the memory provider > proposal[1], and I'm hoping that some generic solution for all > memory providers will be discussed; this patch doesn't address that > weirdness again. > > The netdev_dmabuf_binding struct is refcounted, and releases its > resources only when all the refs are released. > > [1] https://lore.kernel.org/netdev/20230707183935.997267-1-k...@kernel.org/ > > Signed-off-by: Willem de Bruijn <will...@google.com> > Signed-off-by: Kaiyuan Zhang <kaiyu...@google.com> > > Signed-off-by: Mina Almasry <almasrym...@google.com> > --- > include/linux/netdevice.h | 57 ++++++++++++ > include/net/page_pool.h | 27 ++++++ > net/core/dev.c | 178 ++++++++++++++++++++++++++++++++++++++ > net/core/netdev-genl.c | 101 ++++++++++++++++++++- > 4 files changed, 361 insertions(+), 2 deletions(-) > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index 3800d0479698..1b7c5966d2ca 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -53,6 +53,8 @@ > #include <net/net_trackers.h> > #include <net/net_debug.h> > #include <net/dropreason-core.h> > +#include <linux/xarray.h> > +#include <linux/refcount.h> > > struct netpoll_info; > struct device; > @@ -782,6 +784,55 @@ bool rps_may_expire_flow(struct net_device *dev, u16 > rxq_index, u32 flow_id, > #endif > #endif /* CONFIG_RPS */ > > +struct netdev_dmabuf_binding { > + struct dma_buf *dmabuf; > + struct dma_buf_attachment *attachment; > + struct sg_table *sgt; > + struct net_device *dev; > + struct gen_pool *chunk_pool; > + > + /* The user holds a ref (via the netlink API) for as long as they want > + * the binding to remain alive. Each page pool using this binding holds > + * a ref to keep the binding alive. Each allocated page_pool_iov holds a > + * ref. > + * > + * The binding undos itself and unmaps the underlying dmabuf once all > + * those refs are dropped and the binding is no longer desired or in > + * use. > + */ > + refcount_t ref; > + > + /* The portid of the user that owns this binding. Used for netlink to > + * notify us of the user dropping the bind. > + */ > + u32 owner_nlportid; > + > + /* The list of bindings currently active. Used for netlink to notify us > + * of the user dropping the bind. > + */ > + struct list_head list; > + > + /* rxq's this binding is active on. */ > + struct xarray bound_rxq_list; > +}; > + > +void __netdev_devmem_binding_free(struct netdev_dmabuf_binding *binding); > + > +static inline void > +netdev_devmem_binding_get(struct netdev_dmabuf_binding *binding) > +{ > + refcount_inc(&binding->ref); > +} > + > +static inline void > +netdev_devmem_binding_put(struct netdev_dmabuf_binding *binding) > +{ > + if (!refcount_dec_and_test(&binding->ref)) > + return; > + > + __netdev_devmem_binding_free(binding); > +} > + > /* This structure contains an instance of an RX queue. */ > struct netdev_rx_queue { > struct xdp_rxq_info xdp_rxq; > @@ -796,6 +847,7 @@ struct netdev_rx_queue { > #ifdef CONFIG_XDP_SOCKETS > struct xsk_buff_pool *pool; > #endif > + struct netdev_dmabuf_binding *binding; > } ____cacheline_aligned_in_smp; > > /* > @@ -5026,6 +5078,11 @@ void netif_set_tso_max_segs(struct net_device *dev, > unsigned int segs); > void netif_inherit_tso_max(struct net_device *to, > const struct net_device *from); > > +void netdev_unbind_dmabuf_to_queue(struct netdev_dmabuf_binding *binding); > +int netdev_bind_dmabuf_to_queue(struct net_device *dev, unsigned int > dmabuf_fd, > + u32 rxq_idx, > + struct netdev_dmabuf_binding **out); > + > static inline bool netif_is_macsec(const struct net_device *dev) > { > return dev->priv_flags & IFF_MACSEC; > diff --git a/include/net/page_pool.h b/include/net/page_pool.h > index 364fe6924258..61b2066d32b5 100644 > --- a/include/net/page_pool.h > +++ b/include/net/page_pool.h > @@ -170,6 +170,33 @@ extern const struct pp_memory_provider_ops hugesp_ops; > extern const struct pp_memory_provider_ops huge_ops; > extern const struct pp_memory_provider_ops huge_1g_ops; > > +/* page_pool_iov support */ > + > +/* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist > + * entry from the dmabuf is inserted into the genpool as a chunk, and needs > + * this owner struct to keep track of some metadata necessary to create > + * allocations from this chunk. > + */ > +struct dmabuf_genpool_chunk_owner { > + /* Offset into the dma-buf where this chunk starts. */ > + unsigned long base_virtual; > + > + /* dma_addr of the start of the chunk. */ > + dma_addr_t base_dma_addr; > + > + /* Array of page_pool_iovs for this chunk. */ > + struct page_pool_iov *ppiovs; > + size_t num_ppiovs; > + > + struct netdev_dmabuf_binding *binding; > +}; > + > +struct page_pool_iov { > + struct dmabuf_genpool_chunk_owner *owner; > + > + refcount_t refcount; > +}; > +
Hi Mina, we're working on ZC RX to host memory [1] and have a similar need for a page pool memory provider (backed by userspace host memory instead of GPU memory) that hands out generic page_pool_iov buffers. The current differences are that we hold a page ptr and its dma_addr_t directly as we are backed by real pages; we still need a refcount for lifetime management. See struct io_zc_rx_buf in [2]. It would be great to align on page_pool_iov such that it will work for both of us. Would a union work here? [1] https://lore.kernel.org/io-uring/20230826011954.1801099-1...@davidwei.uk/ [2] https://lore.kernel.org/io-uring/20230826011954.1801099-6...@davidwei.uk/ > struct page_pool { > struct page_pool_params p; > > diff --git a/net/core/dev.c b/net/core/dev.c > index 8e7d0cb540cd..02a25ccf771a 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -151,6 +151,8 @@ > #include <linux/pm_runtime.h> > #include <linux/prandom.h> > #include <linux/once_lite.h> > +#include <linux/genalloc.h> > +#include <linux/dma-buf.h> > > #include "dev.h" > #include "net-sysfs.h" > @@ -2037,6 +2039,182 @@ static int call_netdevice_notifiers_mtu(unsigned long > val, > return call_netdevice_notifiers_info(val, &info.info); > } > > +/* Device memory support */ > + > +static void netdev_devmem_free_chunk_owner(struct gen_pool *genpool, > + struct gen_pool_chunk *chunk, > + void *not_used) > +{ > + struct dmabuf_genpool_chunk_owner *owner = chunk->owner; > + > + kvfree(owner->ppiovs); > + kfree(owner); > +} > + > +void __netdev_devmem_binding_free(struct netdev_dmabuf_binding *binding) > +{ > + size_t size, avail; > + > + gen_pool_for_each_chunk(binding->chunk_pool, > + netdev_devmem_free_chunk_owner, NULL); > + > + size = gen_pool_size(binding->chunk_pool); > + avail = gen_pool_avail(binding->chunk_pool); > + > + if (!WARN(size != avail, "can't destroy genpool. size=%lu, avail=%lu", > + size, avail)) > + gen_pool_destroy(binding->chunk_pool); > + > + dma_buf_unmap_attachment(binding->attachment, binding->sgt, > + DMA_BIDIRECTIONAL); > + dma_buf_detach(binding->dmabuf, binding->attachment); > + dma_buf_put(binding->dmabuf); > + kfree(binding); > +} > + > +void netdev_unbind_dmabuf_to_queue(struct netdev_dmabuf_binding *binding) > +{ > + struct netdev_rx_queue *rxq; > + unsigned long xa_idx; > + > + list_del_rcu(&binding->list); > + > + xa_for_each(&binding->bound_rxq_list, xa_idx, rxq) > + if (rxq->binding == binding) > + rxq->binding = NULL; > + > + netdev_devmem_binding_put(binding); > +} > + > +int netdev_bind_dmabuf_to_queue(struct net_device *dev, unsigned int > dmabuf_fd, > + u32 rxq_idx, struct netdev_dmabuf_binding **out) > +{ > + struct netdev_dmabuf_binding *binding; > + struct netdev_rx_queue *rxq; > + struct scatterlist *sg; > + struct dma_buf *dmabuf; > + unsigned int sg_idx, i; > + unsigned long virtual; > + u32 xa_idx; > + int err; > + > + rxq = __netif_get_rx_queue(dev, rxq_idx); > + > + if (rxq->binding) > + return -EEXIST; > + > + dmabuf = dma_buf_get(dmabuf_fd); > + if (IS_ERR_OR_NULL(dmabuf)) > + return -EBADFD; > + > + binding = kzalloc_node(sizeof(*binding), GFP_KERNEL, > + dev_to_node(&dev->dev)); > + if (!binding) { > + err = -ENOMEM; > + goto err_put_dmabuf; > + } > + > + xa_init_flags(&binding->bound_rxq_list, XA_FLAGS_ALLOC); > + > + refcount_set(&binding->ref, 1); > + > + binding->dmabuf = dmabuf; > + > + binding->attachment = dma_buf_attach(binding->dmabuf, dev->dev.parent); > + if (IS_ERR(binding->attachment)) { > + err = PTR_ERR(binding->attachment); > + goto err_free_binding; > + } > + > + binding->sgt = dma_buf_map_attachment(binding->attachment, > + DMA_BIDIRECTIONAL); > + if (IS_ERR(binding->sgt)) { > + err = PTR_ERR(binding->sgt); > + goto err_detach; > + } > + > + /* For simplicity we expect to make PAGE_SIZE allocations, but the > + * binding can be much more flexible than that. We may be able to > + * allocate MTU sized chunks here. Leave that for future work... > + */ > + binding->chunk_pool = gen_pool_create(PAGE_SHIFT, > + dev_to_node(&dev->dev)); > + if (!binding->chunk_pool) { > + err = -ENOMEM; > + goto err_unmap; > + } > + > + virtual = 0; > + for_each_sgtable_dma_sg(binding->sgt, sg, sg_idx) { > + dma_addr_t dma_addr = sg_dma_address(sg); > + struct dmabuf_genpool_chunk_owner *owner; > + size_t len = sg_dma_len(sg); > + struct page_pool_iov *ppiov; > + > + owner = kzalloc_node(sizeof(*owner), GFP_KERNEL, > + dev_to_node(&dev->dev)); > + owner->base_virtual = virtual; > + owner->base_dma_addr = dma_addr; > + owner->num_ppiovs = len / PAGE_SIZE; > + owner->binding = binding; > + > + err = gen_pool_add_owner(binding->chunk_pool, dma_addr, > + dma_addr, len, dev_to_node(&dev->dev), > + owner); > + if (err) { > + err = -EINVAL; > + goto err_free_chunks; > + } > + > + owner->ppiovs = kvmalloc_array(owner->num_ppiovs, > + sizeof(*owner->ppiovs), > + GFP_KERNEL); > + if (!owner->ppiovs) { > + err = -ENOMEM; > + goto err_free_chunks; > + } > + > + for (i = 0; i < owner->num_ppiovs; i++) { > + ppiov = &owner->ppiovs[i]; > + ppiov->owner = owner; > + refcount_set(&ppiov->refcount, 1); > + } > + > + dma_addr += len; > + virtual += len; > + } > + > + /* TODO: need to be able to bind to multiple rx queues on the same > + * netdevice. The code should already be able to handle that with > + * minimal changes, but the netlink API currently allows for 1 rx > + * queue. > + */ > + err = xa_alloc(&binding->bound_rxq_list, &xa_idx, rxq, xa_limit_32b, > + GFP_KERNEL); > + if (err) > + goto err_free_chunks; > + > + rxq->binding = binding; > + *out = binding; > + > + return 0; > + > +err_free_chunks: > + gen_pool_for_each_chunk(binding->chunk_pool, > + netdev_devmem_free_chunk_owner, NULL); > + gen_pool_destroy(binding->chunk_pool); > +err_unmap: > + dma_buf_unmap_attachment(binding->attachment, binding->sgt, > + DMA_BIDIRECTIONAL); > +err_detach: > + dma_buf_detach(dmabuf, binding->attachment); > +err_free_binding: > + kfree(binding); > +err_put_dmabuf: > + dma_buf_put(dmabuf); > + return err; > +} > + > #ifdef CONFIG_NET_INGRESS > static DEFINE_STATIC_KEY_FALSE(ingress_needed_key); > > diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c > index bf7324dd6c36..288ed0112995 100644 > --- a/net/core/netdev-genl.c > +++ b/net/core/netdev-genl.c > @@ -141,10 +141,74 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, > struct netlink_callback *cb) > return skb->len; > } > > -/* Stub */ > +static LIST_HEAD(netdev_rbinding_list); > + > int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info) > { > - return 0; > + struct netdev_dmabuf_binding *out_binding; > + u32 ifindex, dmabuf_fd, rxq_idx; > + struct net_device *netdev; > + struct sk_buff *rsp; > + int err = 0; > + void *hdr; > + > + if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_DEV_IFINDEX) || > + GENL_REQ_ATTR_CHECK(info, NETDEV_A_BIND_DMABUF_DMABUF_FD) || > + GENL_REQ_ATTR_CHECK(info, NETDEV_A_BIND_DMABUF_QUEUE_IDX)) > + return -EINVAL; > + > + ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]); > + dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_BIND_DMABUF_DMABUF_FD]); > + rxq_idx = nla_get_u32(info->attrs[NETDEV_A_BIND_DMABUF_QUEUE_IDX]); > + > + rtnl_lock(); > + > + netdev = __dev_get_by_index(genl_info_net(info), ifindex); > + if (!netdev) { > + err = -ENODEV; > + goto err_unlock; > + } > + > + if (rxq_idx >= netdev->num_rx_queues) { > + err = -ERANGE; > + goto err_unlock; > + } > + > + if (netdev_bind_dmabuf_to_queue(netdev, dmabuf_fd, rxq_idx, > + &out_binding)) { > + err = -EINVAL; > + goto err_unlock; > + } > + > + out_binding->owner_nlportid = info->snd_portid; > + list_add_rcu(&out_binding->list, &netdev_rbinding_list); > + > + rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL); > + if (!rsp) { > + err = -ENOMEM; > + goto err_unbind; > + } > + > + hdr = genlmsg_put(rsp, info->snd_portid, info->snd_seq, > + &netdev_nl_family, 0, info->genlhdr->cmd); > + if (!hdr) { > + err = -EMSGSIZE; > + goto err_genlmsg_free; > + } > + > + genlmsg_end(rsp, hdr); > + > + rtnl_unlock(); > + > + return genlmsg_reply(rsp, info); > + > +err_genlmsg_free: > + nlmsg_free(rsp); > +err_unbind: > + netdev_unbind_dmabuf_to_queue(out_binding); > +err_unlock: > + rtnl_unlock(); > + return err; > } > > static int netdev_genl_netdevice_event(struct notifier_block *nb, > @@ -167,10 +231,37 @@ static int netdev_genl_netdevice_event(struct > notifier_block *nb, > return NOTIFY_OK; > } > > +static int netdev_netlink_notify(struct notifier_block *nb, unsigned long > state, > + void *_notify) > +{ > + struct netlink_notify *notify = _notify; > + struct netdev_dmabuf_binding *rbinding; > + > + if (state != NETLINK_URELEASE || notify->protocol != NETLINK_GENERIC) > + return NOTIFY_DONE; > + > + rcu_read_lock(); > + > + list_for_each_entry_rcu(rbinding, &netdev_rbinding_list, list) { > + if (rbinding->owner_nlportid == notify->portid) { > + netdev_unbind_dmabuf_to_queue(rbinding); > + break; > + } > + } > + > + rcu_read_unlock(); > + > + return NOTIFY_OK; > +} > + > static struct notifier_block netdev_genl_nb = { > .notifier_call = netdev_genl_netdevice_event, > }; > > +static struct notifier_block netdev_netlink_notifier = { > + .notifier_call = netdev_netlink_notify, > +}; > + > static int __init netdev_genl_init(void) > { > int err; > @@ -183,8 +274,14 @@ static int __init netdev_genl_init(void) > if (err) > goto err_unreg_ntf; > > + err = netlink_register_notifier(&netdev_netlink_notifier); > + if (err) > + goto err_unreg_family; > + > return 0; > > +err_unreg_family: > + genl_unregister_family(&netdev_nl_family); > err_unreg_ntf: > unregister_netdevice_notifier(&netdev_genl_nb); > return err; > -- > 2.41.0.640.ga95def55d0-goog
