Re: [PATCH net-next v2 1/2] net/smc: support SMC-R V2 for rdma devices with max_recv_sge equals to 1

Wenjia Zhang
2024-12-06T19:12:38Z

On 02.12.24 13:52, Guangguan Wang wrote:
> For SMC-R V2, llc msg can be larger than SMC_WR_BUF_SIZE, thus every
> recv wr has 2 sges, the first sge with length SMC_WR_BUF_SIZE is for
> V1/V2 compatible llc/cdc msg, and the second sge with length
> SMC_WR_BUF_V2_SIZE-SMC_WR_TX_SIZE is for V2 specific llc msg, like
> SMC_LLC_DELETE_RKEY and SMC_LLC_ADD_LINK for SMC-R V2. The memory
> buffer in the second sge is shared by all recv wr in one link and
> all link in one lgr for saving memory usage purpose.
>
> But not all RDMA devices with max_recv_sge greater than 1. Thus SMC-R
> V2 can not support on such RDMA devices and SMC_CLC_DECL_INTERR fallback
> happens because of the failure of create qp.
>
> This patch introduce the support for SMC-R V2 on RDMA devices with
> max_recv_sge equals to 1. Every recv wr has only one sge with individual
> buffer whose size is SMC_WR_BUF_V2_SIZE once the RDMA device's max_recv_sge
> equals to 1. It may use more memory, but it is better than
> SMC_CLC_DECL_INTERR fallback.
>
find good!
> Co-developed-by: Wen Gu <guwen@linux.alibaba.com>
> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
> ---
> net/smc/smc_core.c | 5 +++++
> net/smc/smc_core.h | 11 ++++++++++-
> net/smc/smc_ib.c | 3 +--
> net/smc/smc_llc.c | 21 +++++++++++++++------
> net/smc/smc_wr.c | 42 +++++++++++++++++++++---------------------
> 5 files changed, 52 insertions(+), 30 deletions(-)
>
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
> index 500952c2e67b..ede4d5f3111b 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -795,9 +795,14 @@ int smcr_link_init(struct smc_link_group *lgr, struct smc_link *lnk,
> if (lgr->smc_version == SMC_V2) {
> lnk->smcibdev = ini->smcrv2.ib_dev_v2;
> lnk->ibport = ini->smcrv2.ib_port_v2;
> + lnk->wr_rx_sge_cnt = lnk->smcibdev->ibdev->attrs.max_recv_sge < 2 ? 1 : 2;
> + lnk->wr_rx_buflen = smc_link_shared_v2_rxbuf(lnk) ?
> + SMC_WR_BUF_SIZE : SMC_WR_BUF_V2_SIZE;
> } else {
> lnk->smcibdev = ini->ib_dev;
> lnk->ibport = ini->ib_port;
> + lnk->wr_rx_sge_cnt = 1;
> + lnk->wr_rx_buflen = SMC_WR_BUF_SIZE;
> }
> get_device(&lnk->smcibdev->ibdev->dev);
> atomic_inc(&lnk->smcibdev->lnk_cnt);
> diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
> index 69b54ecd6503..48a1b1dcb576 100644
> --- a/net/smc/smc_core.h
> +++ b/net/smc/smc_core.h
> @@ -122,10 +122,14 @@ struct smc_link {
> } ____cacheline_aligned_in_smp;
> struct completion tx_ref_comp;
>
> - struct smc_wr_buf *wr_rx_bufs; /* WR recv payload buffers */
> + u8 *wr_rx_bufs; /* WR recv payload buffers */
> struct ib_recv_wr *wr_rx_ibs; /* WR recv meta data */
> struct ib_sge *wr_rx_sges; /* WR recv scatter meta data */
> /* above three vectors have wr_rx_cnt elements and use the same index */
> + int wr_rx_sge_cnt; /* rx sge, V1 is 1, V2 is either 2 or 1 */
> + int wr_rx_buflen; /* buffer len for the first sge, len for the
> + * second sge is lgr shared if rx sge is 2.
> + */
> dma_addr_t wr_rx_dma_addr; /* DMA address of wr_rx_bufs */
> dma_addr_t wr_rx_v2_dma_addr; /* DMA address of v2 rx buf*/
> u64 wr_rx_id; /* seq # of last recv WR */
> @@ -506,6 +510,11 @@ static inline bool smc_link_active(struct smc_link *lnk)
> return lnk->state == SMC_LNK_ACTIVE;
> }
>
> +static inline bool smc_link_shared_v2_rxbuf(struct smc_link *lnk)
> +{
> + return lnk->wr_rx_sge_cnt > 1;
> +}
> +
> static inline void smc_gid_be16_convert(__u8 *buf, u8 *gid_raw)
> {
> sprintf(buf, "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x",
> diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c
> index 9c563cdbea90..53828833a3f7 100644
> --- a/net/smc/smc_ib.c
> +++ b/net/smc/smc_ib.c
> @@ -662,7 +662,6 @@ void smc_ib_destroy_queue_pair(struct smc_link *lnk)
> /* create a queue pair within the protection domain for a link */
> int smc_ib_create_queue_pair(struct smc_link *lnk)
> {
> - int sges_per_buf = (lnk->lgr->smc_version == SMC_V2) ? 2 : 1;
> struct ib_qp_init_attr qp_attr = {
> .event_handler = smc_ib_qp_event_handler,
> .qp_context = lnk,
> @@ -676,7 +675,7 @@ int smc_ib_create_queue_pair(struct smc_link *lnk)
> .max_send_wr = SMC_WR_BUF_CNT * 3,
> .max_recv_wr = SMC_WR_BUF_CNT * 3,
> .max_send_sge = SMC_IB_MAX_SEND_SGE,
> - .max_recv_sge = sges_per_buf,
> + .max_recv_sge = lnk->wr_rx_sge_cnt,
> .max_inline_data = 0,
> },
> .sq_sig_type = IB_SIGNAL_REQ_WR,
> diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
> index 018ce8133b02..f865c58c3aa7 100644
> --- a/net/smc/smc_llc.c
> +++ b/net/smc/smc_llc.c
> @@ -997,13 +997,14 @@ static int smc_llc_cli_conf_link(struct smc_link *link,
> }
>
> static void smc_llc_save_add_link_rkeys(struct smc_link *link,
> - struct smc_link *link_new)
> + struct smc_link *link_new,
> + u8 *llc_msg)
> {
> struct smc_llc_msg_add_link_v2_ext *ext;
> struct smc_link_group *lgr = link->lgr;
> int max, i;
>
> - ext = (struct smc_llc_msg_add_link_v2_ext *)((u8 *)lgr->wr_rx_buf_v2 +
> + ext = (struct smc_llc_msg_add_link_v2_ext *)(llc_msg +
> SMC_WR_TX_SIZE);
> max = min_t(u8, ext->num_rkeys, SMC_LLC_RKEYS_PER_MSG_V2);
> down_write(&lgr->rmbs_lock);
> @@ -1098,7 +1099,9 @@ int smc_llc_cli_add_link(struct smc_link *link, struct smc_llc_qentry *qentry)
> if (rc)
> goto out_clear_lnk;
> if (lgr->smc_version == SMC_V2) {
> - smc_llc_save_add_link_rkeys(link, lnk_new);
> + u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ?
> + (u8 *)lgr->wr_rx_buf_v2 : (u8 *)llc;
> + smc_llc_save_add_link_rkeys(link, lnk_new, llc_msg);
> } else {
> rc = smc_llc_cli_rkey_exchange(link, lnk_new);
> if (rc) {
> @@ -1498,7 +1501,9 @@ int smc_llc_srv_add_link(struct smc_link *link,
> if (rc)
> goto out_err;
> if (lgr->smc_version == SMC_V2) {
> - smc_llc_save_add_link_rkeys(link, link_new);
> + u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ?
> + (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc;
> + smc_llc_save_add_link_rkeys(link, link_new, llc_msg);
> } else {
> rc = smc_llc_srv_rkey_exchange(link, link_new);
> if (rc)
> @@ -1807,8 +1812,12 @@ static void smc_llc_rmt_delete_rkey(struct smc_link_group *lgr)
> if (lgr->smc_version == SMC_V2) {
> struct smc_llc_msg_delete_rkey_v2 *llcv2;
>
> - memcpy(lgr->wr_rx_buf_v2, llc, sizeof(*llc));
> - llcv2 = (struct smc_llc_msg_delete_rkey_v2 *)lgr->wr_rx_buf_v2;
> + if (smc_link_shared_v2_rxbuf(link)) {
> + memcpy(lgr->wr_rx_buf_v2, llc, sizeof(*llc));
> + llcv2 = (struct smc_llc_msg_delete_rkey_v2 *)lgr->wr_rx_buf_v2;
> + } else {
> + llcv2 = (struct smc_llc_msg_delete_rkey_v2 *)llc;
> + }
> llcv2->num_inval_rkeys = 0;
>
> max = min_t(u8, llcv2->num_rkeys, SMC_LLC_RKEYS_PER_MSG_V2);
> diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
> index 994c0cd4fddb..b04a21b8c511 100644
> --- a/net/smc/smc_wr.c
> +++ b/net/smc/smc_wr.c
> @@ -439,7 +439,7 @@ static inline void smc_wr_rx_demultiplex(struct ib_wc *wc)
> return; /* short message */
> temp_wr_id = wc->wr_id;
> index = do_div(temp_wr_id, link->wr_rx_cnt);
> - wr_rx = (struct smc_wr_rx_hdr *)&link->wr_rx_bufs[index];
> + wr_rx = (struct smc_wr_rx_hdr *)(link->wr_rx_bufs + index * link->wr_rx_buflen);
> hash_for_each_possible(smc_wr_rx_hash, handler, list, wr_rx->type) {
> if (handler->type == wr_rx->type)
> handler->handler(wc, wr_rx);
> @@ -555,7 +555,6 @@ void smc_wr_remember_qp_attr(struct smc_link *lnk)
>
> static void smc_wr_init_sge(struct smc_link *lnk)
> {
> - int sges_per_buf = (lnk->lgr->smc_version == SMC_V2) ? 2 : 1;
> bool send_inline = (lnk->qp_attr.cap.max_inline_data > SMC_WR_TX_SIZE);
> u32 i;
>
> @@ -608,13 +607,14 @@ static void smc_wr_init_sge(struct smc_link *lnk)
> * the larger spillover buffer, allowing easy data mapping.
> */
> for (i = 0; i < lnk->wr_rx_cnt; i++) {
> - int x = i * sges_per_buf;
> + int x = i * lnk->wr_rx_sge_cnt;
>
> lnk->wr_rx_sges[x].addr =
> - lnk->wr_rx_dma_addr + i * SMC_WR_BUF_SIZE;
> - lnk->wr_rx_sges[x].length = SMC_WR_TX_SIZE;
> + lnk->wr_rx_dma_addr + i * lnk->wr_rx_buflen;
> + lnk->wr_rx_sges[x].length = smc_link_shared_v2_rxbuf(lnk) ?
> + SMC_WR_TX_SIZE : lnk->wr_rx_buflen;
> lnk->wr_rx_sges[x].lkey = lnk->roce_pd->local_dma_lkey;
> - if (lnk->lgr->smc_version == SMC_V2) {
> + if (lnk->lgr->smc_version == SMC_V2 && smc_link_shared_v2_rxbuf(lnk)) {
> lnk->wr_rx_sges[x + 1].addr =
> lnk->wr_rx_v2_dma_addr + SMC_WR_TX_SIZE;
> lnk->wr_rx_sges[x + 1].length =
> @@ -624,7 +624,7 @@ static void smc_wr_init_sge(struct smc_link *lnk)
> }
> lnk->wr_rx_ibs[i].next = NULL;
> lnk->wr_rx_ibs[i].sg_list = &lnk->wr_rx_sges[x];
> - lnk->wr_rx_ibs[i].num_sge = sges_per_buf;
> + lnk->wr_rx_ibs[i].num_sge = lnk->wr_rx_sge_cnt;
> }
> lnk->wr_reg.wr.next = NULL;
> lnk->wr_reg.wr.num_sge = 0;
> @@ -655,7 +655,7 @@ void smc_wr_free_link(struct smc_link *lnk)
>
> if (lnk->wr_rx_dma_addr) {
> ib_dma_unmap_single(ibdev, lnk->wr_rx_dma_addr,
> - SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
> + lnk->wr_rx_buflen * lnk->wr_rx_cnt,
> DMA_FROM_DEVICE);
> lnk->wr_rx_dma_addr = 0;
> }
> @@ -740,13 +740,11 @@ int smc_wr_alloc_lgr_mem(struct smc_link_group *lgr)
>
> int smc_wr_alloc_link_mem(struct smc_link *link)
> {
> - int sges_per_buf = link->lgr->smc_version == SMC_V2 ? 2 : 1;
> -
> /* allocate link related memory */
> link->wr_tx_bufs = kcalloc(SMC_WR_BUF_CNT, SMC_WR_BUF_SIZE, GFP_KERNEL);
> if (!link->wr_tx_bufs)
> goto no_mem;
> - link->wr_rx_bufs = kcalloc(SMC_WR_BUF_CNT * 3, SMC_WR_BUF_SIZE,
> + link->wr_rx_bufs = kcalloc(SMC_WR_BUF_CNT * 3, link->wr_rx_buflen,
> GFP_KERNEL);
> if (!link->wr_rx_bufs)
> goto no_mem_wr_tx_bufs;
> @@ -774,7 +772,7 @@ int smc_wr_alloc_link_mem(struct smc_link *link)
> if (!link->wr_tx_sges)
> goto no_mem_wr_tx_rdma_sges;
> link->wr_rx_sges = kcalloc(SMC_WR_BUF_CNT * 3,
> - sizeof(link->wr_rx_sges[0]) * sges_per_buf,
> + sizeof(link->wr_rx_sges[0]) * link->wr_rx_sge_cnt,
> GFP_KERNEL);
> if (!link->wr_rx_sges)
> goto no_mem_wr_tx_sges;
> @@ -872,7 +870,7 @@ int smc_wr_create_link(struct smc_link *lnk)
> smc_wr_tx_set_wr_id(&lnk->wr_tx_id, 0);
> lnk->wr_rx_id = 0;
> lnk->wr_rx_dma_addr = ib_dma_map_single(
> - ibdev, lnk->wr_rx_bufs, SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
> + ibdev, lnk->wr_rx_bufs, lnk->wr_rx_buflen * lnk->wr_rx_cnt,
> DMA_FROM_DEVICE);
> if (ib_dma_mapping_error(ibdev, lnk->wr_rx_dma_addr)) {
> lnk->wr_rx_dma_addr = 0;
> @@ -880,13 +878,15 @@ int smc_wr_create_link(struct smc_link *lnk)
> goto out;
> }
> if (lnk->lgr->smc_version == SMC_V2) {
> - lnk->wr_rx_v2_dma_addr = ib_dma_map_single(ibdev,
> - lnk->lgr->wr_rx_buf_v2, SMC_WR_BUF_V2_SIZE,
> - DMA_FROM_DEVICE);
> - if (ib_dma_mapping_error(ibdev, lnk->wr_rx_v2_dma_addr)) {
> - lnk->wr_rx_v2_dma_addr = 0;
> - rc = -EIO;
> - goto dma_unmap;
> + if (smc_link_shared_v2_rxbuf(lnk)) {
> + lnk->wr_rx_v2_dma_addr =
> + ib_dma_map_single(ibdev, lnk->lgr->wr_rx_buf_v2,
> + SMC_WR_BUF_V2_SIZE, DMA_FROM_DEVICE);
> + if (ib_dma_mapping_error(ibdev, lnk->wr_rx_v2_dma_addr)) {
> + lnk->wr_rx_v2_dma_addr = 0;
> + rc = -EIO;
> + goto dma_unmap;
> + }
> }
> lnk->wr_tx_v2_dma_addr = ib_dma_map_single(ibdev,
> lnk->lgr->wr_tx_buf_v2, SMC_WR_BUF_V2_SIZE,
> @@ -935,7 +935,7 @@ int smc_wr_create_link(struct smc_link *lnk)
> lnk->wr_tx_v2_dma_addr = 0;
> }
> ib_dma_unmap_single(ibdev, lnk->wr_rx_dma_addr,
> - SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
> + lnk->wr_rx_buflen * lnk->wr_rx_cnt,
> DMA_FROM_DEVICE);
> lnk->wr_rx_dma_addr = 0;
> out:
It looks good for me!

Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>

Thanks,
Wenjia