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Message-ID: <CA+sq2CfYosrbZUEb0hLZS1u6tiz+m4oxEXF3-43ZxyoHq=cAVg@mail.gmail.com>
Date: Wed, 14 Feb 2018 01:05:16 +0530
From: Sunil Kovvuri <sunil.kovvuri@...il.com>
To: Jesper Dangaard Brouer <brouer@...hat.com>
Cc: Linux Netdev List <netdev@...r.kernel.org>,
Sunil Goutham <sgoutham@...ium.com>,
Aleksey Makarov <aleksey.makarov@...ium.com>,
"David S. Miller" <davem@...emloft.net>,
Christina Jacob <cjacob@...iumnetworks.com>,
Daniel Borkmann <borkmann@...earbox.net>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [net PATCH] Revert "net: thunderx: Add support for xdp redirect"
On Tue, Feb 13, 2018 at 10:29 PM, Jesper Dangaard Brouer
<brouer@...hat.com> wrote:
> This reverts commit aa136d0c82fcd6af14535853c30e219e02b2692d.
>
> As I previously[1] pointed out this implementation of XDP_REDIRECT is
> wrong. XDP_REDIRECT is a facility that must work between different
> NIC drivers. Another NIC driver can call ndo_xdp_xmit/nicvf_xdp_xmit,
> but your driver patch assumes payload data (at top of page) will
> contain a queue index and a DMA addr, this is not true and worse will
> likely contain garbage.
>
> Given you have not fixed this in due time (just reached v4.16-rc1),
> the only option I see is a revert.
Sorry that i missed your email ie didn't respond.
This driver is not for a generic PCI endpoint NIC, it's an on-silicon
ethernet device
found only on Cavium's ThunderX or OCTEONTX SOCs which supports upto 16 ports.
XDP_REDIRECT here is mainly aimed at forwarding packets from one port
to another
port of same type.
The only way I could have avoided the payload data is by unmapping and remapping
of DMA buffer which is quite expensive especially when IOMMU is enabled.
So I thought this small optimization should be acceptable.
If you still think that this shouldn't be done this way then go ahead
and revert the patch,
I will try to redo this as and when i find time.
Thanks,
Sunil.
>
> [1] http://lkml.kernel.org/r/20171211130902.482513d3@redhat.com
>
> Cc: Sunil Goutham <sgoutham@...ium.com>
> Cc: Christina Jacob <cjacob@...iumnetworks.com>
> Cc: Aleksey Makarov <aleksey.makarov@...ium.com>
> Fixes: aa136d0c82fc ("net: thunderx: Add support for xdp redirect")
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> ---
> drivers/net/ethernet/cavium/thunder/nicvf_main.c | 110 +++++---------------
> drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 11 +-
> drivers/net/ethernet/cavium/thunder/nicvf_queues.h | 4 -
> 3 files changed, 31 insertions(+), 94 deletions(-)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> index b68cde9f17d2..7d9c5ffbd041 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> @@ -67,11 +67,6 @@ module_param(cpi_alg, int, S_IRUGO);
> MODULE_PARM_DESC(cpi_alg,
> "PFC algorithm (0=none, 1=VLAN, 2=VLAN16, 3=IP Diffserv)");
>
> -struct nicvf_xdp_tx {
> - u64 dma_addr;
> - u8 qidx;
> -};
> -
> static inline u8 nicvf_netdev_qidx(struct nicvf *nic, u8 qidx)
> {
> if (nic->sqs_mode)
> @@ -507,29 +502,14 @@ static int nicvf_init_resources(struct nicvf *nic)
> return 0;
> }
>
> -static void nicvf_unmap_page(struct nicvf *nic, struct page *page, u64 dma_addr)
> -{
> - /* Check if it's a recycled page, if not unmap the DMA mapping.
> - * Recycled page holds an extra reference.
> - */
> - if (page_ref_count(page) == 1) {
> - dma_addr &= PAGE_MASK;
> - dma_unmap_page_attrs(&nic->pdev->dev, dma_addr,
> - RCV_FRAG_LEN + XDP_HEADROOM,
> - DMA_FROM_DEVICE,
> - DMA_ATTR_SKIP_CPU_SYNC);
> - }
> -}
> -
> static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> struct cqe_rx_t *cqe_rx, struct snd_queue *sq,
> struct rcv_queue *rq, struct sk_buff **skb)
> {
> struct xdp_buff xdp;
> struct page *page;
> - struct nicvf_xdp_tx *xdp_tx = NULL;
> u32 action;
> - u16 len, err, offset = 0;
> + u16 len, offset = 0;
> u64 dma_addr, cpu_addr;
> void *orig_data;
>
> @@ -543,7 +523,7 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> cpu_addr = (u64)phys_to_virt(cpu_addr);
> page = virt_to_page((void *)cpu_addr);
>
> - xdp.data_hard_start = page_address(page) + RCV_BUF_HEADROOM;
> + xdp.data_hard_start = page_address(page);
> xdp.data = (void *)cpu_addr;
> xdp_set_data_meta_invalid(&xdp);
> xdp.data_end = xdp.data + len;
> @@ -563,7 +543,18 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
>
> switch (action) {
> case XDP_PASS:
> - nicvf_unmap_page(nic, page, dma_addr);
> + /* Check if it's a recycled page, if not
> + * unmap the DMA mapping.
> + *
> + * Recycled page holds an extra reference.
> + */
> + if (page_ref_count(page) == 1) {
> + dma_addr &= PAGE_MASK;
> + dma_unmap_page_attrs(&nic->pdev->dev, dma_addr,
> + RCV_FRAG_LEN + XDP_PACKET_HEADROOM,
> + DMA_FROM_DEVICE,
> + DMA_ATTR_SKIP_CPU_SYNC);
> + }
>
> /* Build SKB and pass on packet to network stack */
> *skb = build_skb(xdp.data,
> @@ -576,20 +567,6 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> case XDP_TX:
> nicvf_xdp_sq_append_pkt(nic, sq, (u64)xdp.data, dma_addr, len);
> return true;
> - case XDP_REDIRECT:
> - /* Save DMA address for use while transmitting */
> - xdp_tx = (struct nicvf_xdp_tx *)page_address(page);
> - xdp_tx->dma_addr = dma_addr;
> - xdp_tx->qidx = nicvf_netdev_qidx(nic, cqe_rx->rq_idx);
> -
> - err = xdp_do_redirect(nic->pnicvf->netdev, &xdp, prog);
> - if (!err)
> - return true;
> -
> - /* Free the page on error */
> - nicvf_unmap_page(nic, page, dma_addr);
> - put_page(page);
> - break;
> default:
> bpf_warn_invalid_xdp_action(action);
> /* fall through */
> @@ -597,7 +574,18 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> trace_xdp_exception(nic->netdev, prog, action);
> /* fall through */
> case XDP_DROP:
> - nicvf_unmap_page(nic, page, dma_addr);
> + /* Check if it's a recycled page, if not
> + * unmap the DMA mapping.
> + *
> + * Recycled page holds an extra reference.
> + */
> + if (page_ref_count(page) == 1) {
> + dma_addr &= PAGE_MASK;
> + dma_unmap_page_attrs(&nic->pdev->dev, dma_addr,
> + RCV_FRAG_LEN + XDP_PACKET_HEADROOM,
> + DMA_FROM_DEVICE,
> + DMA_ATTR_SKIP_CPU_SYNC);
> + }
> put_page(page);
> return true;
> }
> @@ -1864,50 +1852,6 @@ static int nicvf_xdp(struct net_device *netdev, struct netdev_bpf *xdp)
> }
> }
>
> -static int nicvf_xdp_xmit(struct net_device *netdev, struct xdp_buff *xdp)
> -{
> - struct nicvf *nic = netdev_priv(netdev);
> - struct nicvf *snic = nic;
> - struct nicvf_xdp_tx *xdp_tx;
> - struct snd_queue *sq;
> - struct page *page;
> - int err, qidx;
> -
> - if (!netif_running(netdev) || !nic->xdp_prog)
> - return -EINVAL;
> -
> - page = virt_to_page(xdp->data);
> - xdp_tx = (struct nicvf_xdp_tx *)page_address(page);
> - qidx = xdp_tx->qidx;
> -
> - if (xdp_tx->qidx >= nic->xdp_tx_queues)
> - return -EINVAL;
> -
> - /* Get secondary Qset's info */
> - if (xdp_tx->qidx >= MAX_SND_QUEUES_PER_QS) {
> - qidx = xdp_tx->qidx / MAX_SND_QUEUES_PER_QS;
> - snic = (struct nicvf *)nic->snicvf[qidx - 1];
> - if (!snic)
> - return -EINVAL;
> - qidx = xdp_tx->qidx % MAX_SND_QUEUES_PER_QS;
> - }
> -
> - sq = &snic->qs->sq[qidx];
> - err = nicvf_xdp_sq_append_pkt(snic, sq, (u64)xdp->data,
> - xdp_tx->dma_addr,
> - xdp->data_end - xdp->data);
> - if (err)
> - return -ENOMEM;
> -
> - nicvf_xdp_sq_doorbell(snic, sq, qidx);
> - return 0;
> -}
> -
> -static void nicvf_xdp_flush(struct net_device *dev)
> -{
> - return;
> -}
> -
> static int nicvf_config_hwtstamp(struct net_device *netdev, struct ifreq *ifr)
> {
> struct hwtstamp_config config;
> @@ -1986,8 +1930,6 @@ static const struct net_device_ops nicvf_netdev_ops = {
> .ndo_fix_features = nicvf_fix_features,
> .ndo_set_features = nicvf_set_features,
> .ndo_bpf = nicvf_xdp,
> - .ndo_xdp_xmit = nicvf_xdp_xmit,
> - .ndo_xdp_flush = nicvf_xdp_flush,
> .ndo_do_ioctl = nicvf_ioctl,
> };
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> index 3eae9ff9b53a..d42704d07484 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> @@ -204,7 +204,7 @@ static inline int nicvf_alloc_rcv_buffer(struct nicvf *nic, struct rbdr *rbdr,
>
> /* Reserve space for header modifications by BPF program */
> if (rbdr->is_xdp)
> - buf_len += XDP_HEADROOM;
> + buf_len += XDP_PACKET_HEADROOM;
>
> /* Check if it's recycled */
> if (pgcache)
> @@ -224,9 +224,8 @@ static inline int nicvf_alloc_rcv_buffer(struct nicvf *nic, struct rbdr *rbdr,
> nic->rb_page = NULL;
> return -ENOMEM;
> }
> -
> if (pgcache)
> - pgcache->dma_addr = *rbuf + XDP_HEADROOM;
> + pgcache->dma_addr = *rbuf + XDP_PACKET_HEADROOM;
> nic->rb_page_offset += buf_len;
> }
>
> @@ -1244,7 +1243,7 @@ int nicvf_xdp_sq_append_pkt(struct nicvf *nic, struct snd_queue *sq,
> int qentry;
>
> if (subdesc_cnt > sq->xdp_free_cnt)
> - return -1;
> + return 0;
>
> qentry = nicvf_get_sq_desc(sq, subdesc_cnt);
>
> @@ -1255,7 +1254,7 @@ int nicvf_xdp_sq_append_pkt(struct nicvf *nic, struct snd_queue *sq,
>
> sq->xdp_desc_cnt += subdesc_cnt;
>
> - return 0;
> + return 1;
> }
>
> /* Calculate no of SQ subdescriptors needed to transmit all
> @@ -1656,7 +1655,7 @@ static void nicvf_unmap_rcv_buffer(struct nicvf *nic, u64 dma_addr,
> if (page_ref_count(page) != 1)
> return;
>
> - len += XDP_HEADROOM;
> + len += XDP_PACKET_HEADROOM;
> /* Receive buffers in XDP mode are mapped from page start */
> dma_addr &= PAGE_MASK;
> }
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> index ce1eed7a6d63..5e9a03cf1b4d 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> @@ -11,7 +11,6 @@
>
> #include <linux/netdevice.h>
> #include <linux/iommu.h>
> -#include <linux/bpf.h>
> #include <net/xdp.h>
> #include "q_struct.h"
>
> @@ -94,9 +93,6 @@
> #define RCV_FRAG_LEN (SKB_DATA_ALIGN(DMA_BUFFER_LEN + NET_SKB_PAD) + \
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
>
> -#define RCV_BUF_HEADROOM 128 /* To store dma address for XDP redirect */
> -#define XDP_HEADROOM (XDP_PACKET_HEADROOM + RCV_BUF_HEADROOM)
> -
> #define MAX_CQES_FOR_TX ((SND_QUEUE_LEN / MIN_SQ_DESC_PER_PKT_XMIT) * \
> MAX_CQE_PER_PKT_XMIT)
>
>
>
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