| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <c6bb16cc-fdda-3c4e-41f6-9155911aa2c8@grimberg.me>
Date: Thu, 8 Oct 2020 15:19:34 -0700
From: Sagi Grimberg <sagi@...mberg.me>
To: Boris Pismenny <borisp@...lanox.com>, kuba@...nel.org,
davem@...emloft.net, saeedm@...dia.com, hch@....de, axboe@...com,
kbusch@...nel.org, viro@...iv.linux.org.uk, edumazet@...gle.com
Cc: Yoray Zack <yorayz@...lanox.com>,
Ben Ben-Ishay <benishay@...lanox.com>,
boris.pismenny@...il.com, linux-nvme@...ts.infradead.org,
netdev@...r.kernel.org, Or Gerlitz <ogerlitz@...lanox.com>
Subject: Re: [PATCH net-next RFC v1 05/10] nvme-tcp: Add DDP offload control
path
On 9/30/20 9:20 AM, Boris Pismenny wrote:
> This commit introduces direct data placement offload to NVME
> TCP. There is a context per queue, which is established after the
> handshake
> using the tcp_ddp_sk_add/del NDOs.
>
> Additionally, a resynchronization routine is used to assist
> hardware recovery from TCP OOO, and continue the offload.
> Resynchronization operates as follows:
> 1. TCP OOO causes the NIC HW to stop the offload
> 2. NIC HW identifies a PDU header at some TCP sequence number,
> and asks NVMe-TCP to confirm it.
> This request is delivered from the NIC driver to NVMe-TCP by first
> finding the socket for the packet that triggered the request, and
> then fiding the nvme_tcp_queue that is used by this routine.
> Finally, the request is recorded in the nvme_tcp_queue.
> 3. When NVMe-TCP observes the requested TCP sequence, it will compare
> it with the PDU header TCP sequence, and report the result to the
> NIC driver (tcp_ddp_resync), which will update the HW,
> and resume offload when all is successful.
>
> Furthermore, we let the offloading driver advertise what is the max hw
> sectors/segments via tcp_ddp_limits.
>
> A follow-up patch introduces the data-path changes required for this
> offload.
>
> Signed-off-by: Boris Pismenny <borisp@...lanox.com>
> Signed-off-by: Ben Ben-Ishay <benishay@...lanox.com>
> Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
> Signed-off-by: Yoray Zack <yorayz@...lanox.com>
> ---
> drivers/nvme/host/tcp.c | 188 +++++++++++++++++++++++++++++++++++++++
> include/linux/nvme-tcp.h | 2 +
> 2 files changed, 190 insertions(+)
>
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 8f4f29f18b8c..06711ac095f2 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -62,6 +62,7 @@ enum nvme_tcp_queue_flags {
> NVME_TCP_Q_ALLOCATED = 0,
> NVME_TCP_Q_LIVE = 1,
> NVME_TCP_Q_POLLING = 2,
> + NVME_TCP_Q_OFFLOADS = 3,
> };
>
> enum nvme_tcp_recv_state {
> @@ -110,6 +111,8 @@ struct nvme_tcp_queue {
> void (*state_change)(struct sock *);
> void (*data_ready)(struct sock *);
> void (*write_space)(struct sock *);
> +
> + atomic64_t resync_req;
> };
>
> struct nvme_tcp_ctrl {
> @@ -129,6 +132,8 @@ struct nvme_tcp_ctrl {
> struct delayed_work connect_work;
> struct nvme_tcp_request async_req;
> u32 io_queues[HCTX_MAX_TYPES];
> +
> + struct net_device *offloading_netdev;
> };
>
> static LIST_HEAD(nvme_tcp_ctrl_list);
> @@ -223,6 +228,159 @@ static inline size_t nvme_tcp_pdu_last_send(struct nvme_tcp_request *req,
> return nvme_tcp_pdu_data_left(req) <= len;
> }
>
> +#ifdef CONFIG_TCP_DDP
> +
> +bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags);
> +const struct tcp_ddp_ulp_ops nvme_tcp_ddp_ulp_ops __read_mostly = {
> + .resync_request = nvme_tcp_resync_request,
> +};
> +
> +static
> +int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue,
> + struct nvme_tcp_config *config)
> +{
> + struct net_device *netdev = get_netdev_for_sock(queue->sock->sk, true);
> + struct tcp_ddp_config *ddp_config = (struct tcp_ddp_config *)config;
> + int ret;
> +
> + if (unlikely(!netdev)) {
Let's remove unlikely from non datapath routines, its slightly
confusing.
> + pr_info_ratelimited("%s: netdev not found\n", __func__);
dev_info_ratelimited with queue->ctrl->ctrl.device ?
Also, lets remove __func__. This usually is not very helpful.
> + return -EINVAL;
> + }
> +
> + if (!(netdev->features & NETIF_F_HW_TCP_DDP)) {
> + dev_put(netdev);
> + return -EINVAL;
EINVAL or ENODEV?
> + }
> +
> + ret = netdev->tcp_ddp_ops->tcp_ddp_sk_add(netdev,
> + queue->sock->sk,
> + ddp_config);
> + if (!ret)
> + inet_csk(queue->sock->sk)->icsk_ulp_ddp_ops = &nvme_tcp_ddp_ulp_ops;
> + else
> + dev_put(netdev);
> + return ret;
> +}
> +
> +static
> +void nvme_tcp_unoffload_socket(struct nvme_tcp_queue *queue)
> +{
> + struct net_device *netdev = queue->ctrl->offloading_netdev;
> +
> + if (unlikely(!netdev)) {
> + pr_info_ratelimited("%s: netdev not found\n", __func__);
Same here.
> + return;
> + }
> +
> + netdev->tcp_ddp_ops->tcp_ddp_sk_del(netdev, queue->sock->sk);
> +
> + inet_csk(queue->sock->sk)->icsk_ulp_ddp_ops = NULL;
Just a general question, why is this needed?
> + dev_put(netdev); /* put the queue_init get_netdev_for_sock() */
> +}
> +
> +static
> +int nvme_tcp_offload_limits(struct nvme_tcp_queue *queue,
> + struct tcp_ddp_limits *limits)
> +{
> + struct net_device *netdev = get_netdev_for_sock(queue->sock->sk, true);
> + int ret = 0;
> +
> + if (unlikely(!netdev)) {
> + pr_info_ratelimited("%s: netdev not found\n", __func__);
> + return -EINVAL;
Same here
> + }
> +
> + if (netdev->features & NETIF_F_HW_TCP_DDP &&
> + netdev->tcp_ddp_ops &&
> + netdev->tcp_ddp_ops->tcp_ddp_limits)
> + ret = netdev->tcp_ddp_ops->tcp_ddp_limits(netdev, limits);
> + else
> + ret = -EOPNOTSUPP;
> +
> + if (!ret) {
> + queue->ctrl->offloading_netdev = netdev;
> + pr_info("%s netdev %s offload limits: max_ddp_sgl_len %d\n",
> + __func__, netdev->name, limits->max_ddp_sgl_len);
dev_info, and given that it per-queue, please make it dev_dbg.
> + queue->ctrl->ctrl.max_segments = limits->max_ddp_sgl_len;
> + queue->ctrl->ctrl.max_hw_sectors =
> + limits->max_ddp_sgl_len << (ilog2(SZ_4K) - 9);
> + } else {
> + queue->ctrl->offloading_netdev = NULL;
Maybe nullify in the controller setup intead?
> + }
> +
> + dev_put(netdev);
> +
> + return ret;
> +}
> +
> +static
> +void nvme_tcp_resync_response(struct nvme_tcp_queue *queue,
> + unsigned int pdu_seq)
> +{
> + struct net_device *netdev = queue->ctrl->offloading_netdev;
> + u64 resync_val;
> + u32 resync_seq;
> +
> + if (unlikely(!netdev)) {
> + pr_info_ratelimited("%s: netdev not found\n", __func__);
> + return;
What happens now, fallback to SW? Maybe dev_warn then..
will the SW keep seeing these responses after one failed?
> + }
> +
> + resync_val = atomic64_read(&queue->resync_req);
> + if ((resync_val & TCP_DDP_RESYNC_REQ) == 0)
> + return;
> +
> + resync_seq = resync_val >> 32;
> + if (before(pdu_seq, resync_seq))
> + return;
I think it will be better to pass the skb to this func and keep the
pdu_seq contained locally.
> +
> + if (atomic64_cmpxchg(&queue->resync_req, resync_val, (resync_val - 1)))
> + netdev->tcp_ddp_ops->tcp_ddp_resync(netdev, queue->sock->sk, pdu_seq);
A small comment on this manipulation may help the reader.
> +}
> +
> +bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags)
> +{
> + struct nvme_tcp_queue *queue = sk->sk_user_data;
> +
> + atomic64_set(&queue->resync_req,
> + (((uint64_t)seq << 32) | flags));
> +
> + return true;
> +}
> +
> +#else
> +
> +static
> +int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue,
> + struct nvme_tcp_config *config)
> +{
> + return -EINVAL;
> +}
> +
> +static
> +void nvme_tcp_unoffload_socket(struct nvme_tcp_queue *queue)
> +{}
> +
> +static
> +int nvme_tcp_offload_limits(struct nvme_tcp_queue *queue,
> + struct tcp_ddp_limits *limits)
> +{
> + return -EINVAL;
> +}
> +
> +static
> +void nvme_tcp_resync_response(struct nvme_tcp_queue *queue,
> + unsigned int pdu_seq)
> +{}
> +
> +bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags)
> +{
> + return false;
> +}
> +
> +#endif
> +
> static void nvme_tcp_init_iter(struct nvme_tcp_request *req,
> unsigned int dir)
> {
> @@ -628,6 +786,11 @@ static int nvme_tcp_recv_pdu(struct nvme_tcp_queue *queue, struct sk_buff *skb,
> size_t rcv_len = min_t(size_t, *len, queue->pdu_remaining);
> int ret;
>
> + u64 pdu_seq = TCP_SKB_CB(skb)->seq + *offset - queue->pdu_offset;
> +
> + if (test_bit(NVME_TCP_Q_OFFLOADS, &queue->flags))
> + nvme_tcp_resync_response(queue, pdu_seq);
Here, just pass in (queue, skb)
> +
> ret = skb_copy_bits(skb, *offset,
> &pdu[queue->pdu_offset], rcv_len);
> if (unlikely(ret))
> @@ -1370,6 +1533,8 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
> {
> struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
> struct nvme_tcp_queue *queue = &ctrl->queues[qid];
> + struct nvme_tcp_config config;
> + struct tcp_ddp_limits limits;
> int ret, rcv_pdu_size;
>
> queue->ctrl = ctrl;
> @@ -1487,6 +1652,26 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
> #endif
> write_unlock_bh(&queue->sock->sk->sk_callback_lock);
>
> + if (nvme_tcp_queue_id(queue) != 0) {
if (!nvme_tcp_admin_queue(queue)) {
> + config.cfg.type = TCP_DDP_NVME;
> + config.pfv = NVME_TCP_PFV_1_0;
> + config.cpda = 0;
> + config.dgst = queue->hdr_digest ?
> + NVME_TCP_HDR_DIGEST_ENABLE : 0;
> + config.dgst |= queue->data_digest ?
> + NVME_TCP_DATA_DIGEST_ENABLE : 0;
> + config.queue_size = queue->queue_size;
> + config.queue_id = nvme_tcp_queue_id(queue);
> + config.io_cpu = queue->io_cpu;
Can the config initialization move to nvme_tcp_offload_socket?
> +
> + ret = nvme_tcp_offload_socket(queue, &config);
> + if (!ret)
> + set_bit(NVME_TCP_Q_OFFLOADS, &queue->flags);
> + } else {
> + ret = nvme_tcp_offload_limits(queue, &limits);
> + }
I'm thinking that instead of this conditional, we want to place
nvme nvme_tcp_alloc_admin_queue in nvme_tcp_alloc_admin_queue, and
also move nvme_tcp_alloc_admin_queue to __nvme_tcp_alloc_io_queues
loop.
> + /* offload is opportunistic - failure is non-critical */
Than make it void...
> +
> return 0;
>
> err_init_connect:
> @@ -1519,6 +1704,9 @@ static void __nvme_tcp_stop_queue(struct nvme_tcp_queue *queue)
> kernel_sock_shutdown(queue->sock, SHUT_RDWR);
> nvme_tcp_restore_sock_calls(queue);
> cancel_work_sync(&queue->io_work);
> +
> + if (test_bit(NVME_TCP_Q_OFFLOADS, &queue->flags))
> + nvme_tcp_unoffload_socket(queue);
Why not in nvme_tcp_free_queue, symmetric to the alloc?
> }
>
> static void nvme_tcp_stop_queue(struct nvme_ctrl *nctrl, int qid)
> diff --git a/include/linux/nvme-tcp.h b/include/linux/nvme-tcp.h
> index 959e0bd9a913..65df64c34ecd 100644
> --- a/include/linux/nvme-tcp.h
> +++ b/include/linux/nvme-tcp.h
> @@ -8,6 +8,8 @@
> #define _LINUX_NVME_TCP_H
>
> #include <linux/nvme.h>
> +#include <net/sock.h>
> +#include <net/tcp_ddp.h>
Why is this needed? I think we want to place this in tcp.c no?
Powered by blists - more mailing lists