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Message-ID: <CAHS8izO-7pPk7xyY4JdyaY4hZpd7zerbjhGanRvaTk+OOsvY0A@mail.gmail.com>
Date: Thu, 3 Oct 2024 11:43:02 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Taehee Yoo <ap420073@...il.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
edumazet@...gle.com, netdev@...r.kernel.org, linux-doc@...r.kernel.org,
donald.hunter@...il.com, corbet@....net, michael.chan@...adcom.com,
kory.maincent@...tlin.com, andrew@...n.ch, maxime.chevallier@...tlin.com,
danieller@...dia.com, hengqi@...ux.alibaba.com, ecree.xilinx@...il.com,
przemyslaw.kitszel@...el.com, hkallweit1@...il.com, ahmed.zaki@...el.com,
paul.greenwalt@...el.com, rrameshbabu@...dia.com, idosch@...dia.com,
asml.silence@...il.com, kaiyuanz@...gle.com, willemb@...gle.com,
aleksander.lobakin@...el.com, dw@...idwei.uk, sridhar.samudrala@...el.com,
bcreeley@....com
Subject: Re: [PATCH net-next v3 7/7] bnxt_en: add support for device memory tcp
On Thu, Oct 3, 2024 at 9:07 AM Taehee Yoo <ap420073@...il.com> wrote:
>
> Currently, bnxt_en driver satisfies the requirements of Device memory
> TCP, which is tcp-data-split.
> So, it implements Device memory TCP for bnxt_en driver.
>
> From now on, the aggregation ring handles netmem_ref instead of page
> regardless of the on/off of netmem.
> So, for the aggregation ring, memory will be handled with the netmem
> page_pool API instead of generic page_pool API.
>
> If Devmem is enabled, netmem_ref is used as-is and if Devmem is not
> enabled, netmem_ref will be converted to page and that is used.
>
> Driver recognizes whether the devmem is set or unset based on the
> mp_params.mp_priv is not NULL.
> Only if devmem is set, it passes PP_FLAG_ALLOW_UNREADABLE_NETMEM.
>
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
>
> v3:
> - Patch added
>
> drivers/net/ethernet/broadcom/Kconfig | 1 +
> drivers/net/ethernet/broadcom/bnxt/bnxt.c | 98 +++++++++++++++--------
> drivers/net/ethernet/broadcom/bnxt/bnxt.h | 2 +-
> 3 files changed, 66 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/Kconfig b/drivers/net/ethernet/broadcom/Kconfig
> index 75ca3ddda1f5..f37ff12d4746 100644
> --- a/drivers/net/ethernet/broadcom/Kconfig
> +++ b/drivers/net/ethernet/broadcom/Kconfig
> @@ -211,6 +211,7 @@ config BNXT
> select FW_LOADER
> select LIBCRC32C
> select NET_DEVLINK
> + select NET_DEVMEM
> select PAGE_POOL
> select DIMLIB
> select AUXILIARY_BUS
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 872b15842b11..64e07d247f97 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -55,6 +55,7 @@
> #include <net/page_pool/helpers.h>
> #include <linux/align.h>
> #include <net/netdev_queues.h>
> +#include <net/netdev_rx_queue.h>
>
> #include "bnxt_hsi.h"
> #include "bnxt.h"
> @@ -863,6 +864,22 @@ static void bnxt_tx_int(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
> bnapi->events &= ~BNXT_TX_CMP_EVENT;
> }
>
> +static netmem_ref __bnxt_alloc_rx_netmem(struct bnxt *bp, dma_addr_t *mapping,
> + struct bnxt_rx_ring_info *rxr,
> + unsigned int *offset,
> + gfp_t gfp)
> +{
> + netmem_ref netmem;
> +
> + netmem = page_pool_alloc_netmem(rxr->page_pool, GFP_ATOMIC);
> + if (!netmem)
> + return 0;
> + *offset = 0;
> +
> + *mapping = page_pool_get_dma_addr_netmem(netmem) + *offset;
> + return netmem;
> +}
> +
> static struct page *__bnxt_alloc_rx_page(struct bnxt *bp, dma_addr_t *mapping,
> struct bnxt_rx_ring_info *rxr,
> unsigned int *offset,
> @@ -972,21 +989,21 @@ static inline u16 bnxt_find_next_agg_idx(struct bnxt_rx_ring_info *rxr, u16 idx)
> return next;
> }
>
> -static inline int bnxt_alloc_rx_page(struct bnxt *bp,
> - struct bnxt_rx_ring_info *rxr,
> - u16 prod, gfp_t gfp)
> +static inline int bnxt_alloc_rx_netmem(struct bnxt *bp,
> + struct bnxt_rx_ring_info *rxr,
> + u16 prod, gfp_t gfp)
> {
> struct rx_bd *rxbd =
> &rxr->rx_agg_desc_ring[RX_AGG_RING(bp, prod)][RX_IDX(prod)];
> struct bnxt_sw_rx_agg_bd *rx_agg_buf;
> - struct page *page;
> + netmem_ref netmem;
> dma_addr_t mapping;
> u16 sw_prod = rxr->rx_sw_agg_prod;
> unsigned int offset = 0;
>
> - page = __bnxt_alloc_rx_page(bp, &mapping, rxr, &offset, gfp);
> + netmem = __bnxt_alloc_rx_netmem(bp, &mapping, rxr, &offset, gfp);
Does __bnxt_alloc_rx_page become dead code after this change? Or is it
still used for something?
>
> - if (!page)
> + if (!netmem)
> return -ENOMEM;
>
> if (unlikely(test_bit(sw_prod, rxr->rx_agg_bmap)))
> @@ -996,7 +1013,7 @@ static inline int bnxt_alloc_rx_page(struct bnxt *bp,
> rx_agg_buf = &rxr->rx_agg_ring[sw_prod];
> rxr->rx_sw_agg_prod = RING_RX_AGG(bp, NEXT_RX_AGG(sw_prod));
>
> - rx_agg_buf->page = page;
> + rx_agg_buf->netmem = netmem;
> rx_agg_buf->offset = offset;
> rx_agg_buf->mapping = mapping;
> rxbd->rx_bd_haddr = cpu_to_le64(mapping);
> @@ -1044,7 +1061,7 @@ static void bnxt_reuse_rx_agg_bufs(struct bnxt_cp_ring_info *cpr, u16 idx,
> struct rx_agg_cmp *agg;
> struct bnxt_sw_rx_agg_bd *cons_rx_buf, *prod_rx_buf;
> struct rx_bd *prod_bd;
> - struct page *page;
> + netmem_ref netmem;
>
> if (p5_tpa)
> agg = bnxt_get_tpa_agg_p5(bp, rxr, idx, start + i);
> @@ -1061,11 +1078,11 @@ static void bnxt_reuse_rx_agg_bufs(struct bnxt_cp_ring_info *cpr, u16 idx,
> cons_rx_buf = &rxr->rx_agg_ring[cons];
>
> /* It is possible for sw_prod to be equal to cons, so
> - * set cons_rx_buf->page to NULL first.
> + * set cons_rx_buf->netmem to 0 first.
> */
> - page = cons_rx_buf->page;
> - cons_rx_buf->page = NULL;
> - prod_rx_buf->page = page;
> + netmem = cons_rx_buf->netmem;
> + cons_rx_buf->netmem = 0;
> + prod_rx_buf->netmem = netmem;
> prod_rx_buf->offset = cons_rx_buf->offset;
>
> prod_rx_buf->mapping = cons_rx_buf->mapping;
> @@ -1192,6 +1209,7 @@ static struct sk_buff *bnxt_rx_skb(struct bnxt *bp,
>
> static u32 __bnxt_rx_agg_pages(struct bnxt *bp,
> struct bnxt_cp_ring_info *cpr,
> + struct sk_buff *skb,
> struct skb_shared_info *shinfo,
> u16 idx, u32 agg_bufs, bool tpa,
> struct xdp_buff *xdp)
> @@ -1211,7 +1229,7 @@ static u32 __bnxt_rx_agg_pages(struct bnxt *bp,
> u16 cons, frag_len;
> struct rx_agg_cmp *agg;
> struct bnxt_sw_rx_agg_bd *cons_rx_buf;
> - struct page *page;
> + netmem_ref netmem;
> dma_addr_t mapping;
>
> if (p5_tpa)
> @@ -1223,9 +1241,15 @@ static u32 __bnxt_rx_agg_pages(struct bnxt *bp,
> RX_AGG_CMP_LEN) >> RX_AGG_CMP_LEN_SHIFT;
>
> cons_rx_buf = &rxr->rx_agg_ring[cons];
> - skb_frag_fill_page_desc(frag, cons_rx_buf->page,
> - cons_rx_buf->offset, frag_len);
> - shinfo->nr_frags = i + 1;
> + if (skb) {
> + skb_add_rx_frag_netmem(skb, i, cons_rx_buf->netmem,
> + cons_rx_buf->offset, frag_len,
> + BNXT_RX_PAGE_SIZE);
> + } else {
> + skb_frag_fill_page_desc(frag, netmem_to_page(cons_rx_buf->netmem),
> + cons_rx_buf->offset, frag_len);
Our intention with the whole netmem design is that drivers should
never have to call netmem_to_page(). I.e. the driver should use netmem
unaware of whether it's page or non-page underneath, to minimize
complexity driver needs to handle.
This netmem_to_page() call can be removed by using
skb_frag_fill_netmem_desc() instead of the page variant. But, more
improtantly, why did the code change here? The code before calls
skb_frag_fill_page_desc, but the new code sometimes will
skb_frag_fill_netmem_desc() and sometimes will skb_add_rx_frag_netmem.
I'm not sure why that logic changed.
> + shinfo->nr_frags = i + 1;
> + }
> __clear_bit(cons, rxr->rx_agg_bmap);
>
> /* It is possible for bnxt_alloc_rx_page() to allocate
> @@ -1233,15 +1257,15 @@ static u32 __bnxt_rx_agg_pages(struct bnxt *bp,
> * need to clear the cons entry now.
> */
> mapping = cons_rx_buf->mapping;
> - page = cons_rx_buf->page;
> - cons_rx_buf->page = NULL;
> + netmem = cons_rx_buf->netmem;
> + cons_rx_buf->netmem = 0;
>
> - if (xdp && page_is_pfmemalloc(page))
> + if (xdp && page_is_pfmemalloc(netmem_to_page(netmem)))
Similarly, add netmem_is_pfmemalloc to netmem.h, instead of doing a
netmem_to_page() call here I think.
> xdp_buff_set_frag_pfmemalloc(xdp);
>
> - if (bnxt_alloc_rx_page(bp, rxr, prod, GFP_ATOMIC) != 0) {
> + if (bnxt_alloc_rx_netmem(bp, rxr, prod, GFP_ATOMIC) != 0) {
> --shinfo->nr_frags;
> - cons_rx_buf->page = page;
> + cons_rx_buf->netmem = netmem;
>
> /* Update prod since possibly some pages have been
> * allocated already.
> @@ -1269,7 +1293,7 @@ static struct sk_buff *bnxt_rx_agg_pages_skb(struct bnxt *bp,
> struct skb_shared_info *shinfo = skb_shinfo(skb);
> u32 total_frag_len = 0;
>
> - total_frag_len = __bnxt_rx_agg_pages(bp, cpr, shinfo, idx,
> + total_frag_len = __bnxt_rx_agg_pages(bp, cpr, skb, shinfo, idx,
> agg_bufs, tpa, NULL);
> if (!total_frag_len) {
> skb_mark_for_recycle(skb);
> @@ -1277,9 +1301,6 @@ static struct sk_buff *bnxt_rx_agg_pages_skb(struct bnxt *bp,
> return NULL;
> }
>
> - skb->data_len += total_frag_len;
> - skb->len += total_frag_len;
> - skb->truesize += BNXT_RX_PAGE_SIZE * agg_bufs;
> return skb;
> }
>
> @@ -1294,7 +1315,7 @@ static u32 bnxt_rx_agg_pages_xdp(struct bnxt *bp,
> if (!xdp_buff_has_frags(xdp))
> shinfo->nr_frags = 0;
>
> - total_frag_len = __bnxt_rx_agg_pages(bp, cpr, shinfo,
> + total_frag_len = __bnxt_rx_agg_pages(bp, cpr, NULL, shinfo,
> idx, agg_bufs, tpa, xdp);
> if (total_frag_len) {
> xdp_buff_set_frags_flag(xdp);
> @@ -3342,15 +3363,15 @@ static void bnxt_free_one_rx_agg_ring(struct bnxt *bp, struct bnxt_rx_ring_info
>
> for (i = 0; i < max_idx; i++) {
> struct bnxt_sw_rx_agg_bd *rx_agg_buf = &rxr->rx_agg_ring[i];
> - struct page *page = rx_agg_buf->page;
> + netmem_ref netmem = rx_agg_buf->netmem;
>
> - if (!page)
> + if (!netmem)
> continue;
>
> - rx_agg_buf->page = NULL;
> + rx_agg_buf->netmem = 0;
> __clear_bit(i, rxr->rx_agg_bmap);
>
> - page_pool_recycle_direct(rxr->page_pool, page);
> + page_pool_put_full_netmem(rxr->page_pool, netmem, true);
> }
> }
>
> @@ -3608,9 +3629,11 @@ static void bnxt_free_rx_rings(struct bnxt *bp)
>
> static int bnxt_alloc_rx_page_pool(struct bnxt *bp,
> struct bnxt_rx_ring_info *rxr,
> + int queue_idx,
> int numa_node)
> {
> struct page_pool_params pp = { 0 };
> + struct netdev_rx_queue *rxq;
>
> pp.pool_size = bp->rx_agg_ring_size;
> if (BNXT_RX_PAGE_MODE(bp))
> @@ -3621,8 +3644,15 @@ static int bnxt_alloc_rx_page_pool(struct bnxt *bp,
> pp.dev = &bp->pdev->dev;
> pp.dma_dir = bp->rx_dir;
> pp.max_len = PAGE_SIZE;
> - pp.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
> + pp.order = 0;
> +
> + rxq = __netif_get_rx_queue(bp->dev, queue_idx);
> + if (rxq->mp_params.mp_priv)
> + pp.flags = PP_FLAG_DMA_MAP | PP_FLAG_ALLOW_UNREADABLE_NETMEM;
This is not the intended use of PP_FLAG_ALLOW_UNREADABLE_NETMEM.
The driver should set PP_FLAG_ALLOW_UNREADABLE_NETMEM when it's able
to handle unreadable netmem, it should not worry about whether
rxq->mp_params.mp_priv is set or not.
You should set PP_FLAG_ALLOW_UNREADABLE_NETMEM when HDS is enabled.
Let core figure out if mp_params.mp_priv is enabled. All the driver
needs to report is whether it's configured to be able to handle
unreadable netmem (which practically means HDS is enabled).
> + else
> + pp.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
>
> + pp.queue_idx = queue_idx;
> rxr->page_pool = page_pool_create(&pp);
> if (IS_ERR(rxr->page_pool)) {
> int err = PTR_ERR(rxr->page_pool);
> @@ -3655,7 +3685,7 @@ static int bnxt_alloc_rx_rings(struct bnxt *bp)
> cpu_node = cpu_to_node(cpu);
> netdev_dbg(bp->dev, "Allocating page pool for rx_ring[%d] on numa_node: %d\n",
> i, cpu_node);
> - rc = bnxt_alloc_rx_page_pool(bp, rxr, cpu_node);
> + rc = bnxt_alloc_rx_page_pool(bp, rxr, i, cpu_node);
> if (rc)
> return rc;
>
> @@ -4154,7 +4184,7 @@ static void bnxt_alloc_one_rx_ring_page(struct bnxt *bp,
>
> prod = rxr->rx_agg_prod;
> for (i = 0; i < bp->rx_agg_ring_size; i++) {
> - if (bnxt_alloc_rx_page(bp, rxr, prod, GFP_KERNEL)) {
> + if (bnxt_alloc_rx_netmem(bp, rxr, prod, GFP_KERNEL)) {
> netdev_warn(bp->dev, "init'ed rx ring %d with %d/%d pages only\n",
> ring_nr, i, bp->rx_ring_size);
> break;
> @@ -15063,7 +15093,7 @@ static int bnxt_queue_mem_alloc(struct net_device *dev, void *qmem, int idx)
> clone->rx_sw_agg_prod = 0;
> clone->rx_next_cons = 0;
>
> - rc = bnxt_alloc_rx_page_pool(bp, clone, rxr->page_pool->p.nid);
> + rc = bnxt_alloc_rx_page_pool(bp, clone, idx, rxr->page_pool->p.nid);
> if (rc)
> return rc;
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> index 48f390519c35..3cf57a3c7664 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
> @@ -895,7 +895,7 @@ struct bnxt_sw_rx_bd {
> };
>
> struct bnxt_sw_rx_agg_bd {
> - struct page *page;
> + netmem_ref netmem;
> unsigned int offset;
> dma_addr_t mapping;
> };
> --
> 2.34.1
>
--
Thanks,
Mina
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