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Message-ID: <c4c62a4563d6669ca3c5d5efee0e54bc8742f27d.camel@gmail.com>
Date: Fri, 16 Dec 2022 09:14:23 -0800
From: Alexander H Duyck <alexander.duyck@...il.com>
To: William Tu <u9012063@...il.com>, netdev@...r.kernel.org
Cc: tuc@...are.com, gyang@...are.com, doshir@...are.com
Subject: Re: [PATCH v6] vmxnet3: Add XDP support.
On Fri, 2022-12-16 at 06:41 -0800, William Tu wrote:
> The patch adds native-mode XDP support: XDP DROP, PASS, TX, and REDIRECT.
>
> Background:
> The vmxnet3 rx consists of three rings: ring0, ring1, and dataring.
> For r0 and r1, buffers at r0 are allocated using alloc_skb APIs and dma
> mapped to the ring's descriptor. If LRO is enabled and packet size larger
> than 3K, VMXNET3_MAX_SKB_BUF_SIZE, then r1 is used to mapped the rest of
> the buffer larger than VMXNET3_MAX_SKB_BUF_SIZE. Each buffer in r1 is
> allocated using alloc_page. So for LRO packets, the payload will be in one
> buffer from r0 and multiple from r1, for non-LRO packets, only one
> descriptor in r0 is used for packet size less than 3k.
>
> When receiving a packet, the first descriptor will have the sop (start of
> packet) bit set, and the last descriptor will have the eop (end of packet)
> bit set. Non-LRO packets will have only one descriptor with both sop and
> eop set.
>
> Other than r0 and r1, vmxnet3 dataring is specifically designed for
> handling packets with small size, usually 128 bytes, defined in
> VMXNET3_DEF_RXDATA_DESC_SIZE, by simply copying the packet from the backend
> driver in ESXi to the ring's memory region at front-end vmxnet3 driver, in
> order to avoid memory mapping/unmapping overhead. In summary, packet size:
> A. < 128B: use dataring
> B. 128B - 3K: use ring0 (VMXNET3_RX_BUF_SKB)
> C. > 3K: use ring0 and ring1 (VMXNET3_RX_BUF_SKB + VMXNET3_RX_BUF_PAGE)
> As a result, the patch adds XDP support for packets using dataring
> and r0 (case A and B), not the large packet size when LRO is enabled.
>
> XDP Implementation:
> When user loads and XDP prog, vmxnet3 driver checks configurations, such
> as mtu, lro, and re-allocate the rx buffer size for reserving the extra
> headroom, XDP_PACKET_HEADROOM, for XDP frame. The XDP prog will then be
> associated with every rx queue of the device. Note that when using dataring
> for small packet size, vmxnet3 (front-end driver) doesn't control the
> buffer allocation, as a result the XDP frame's headroom is zero.
>
> The receive side of XDP is implemented for case A and B, by invoking the
> bpf program at vmxnet3_rq_rx_complete and handle its returned action.
> The new vmxnet3_run_xdp function handles the difference of using dataring
> or ring0, and decides the next journey of the packet afterward.
>
> For TX, vmxnet3 has split header design. Outgoing packets are parsed
> first and protocol headers (L2/L3/L4) are copied to the backend. The
> rest of the payload are dma mapped. Since XDP_TX does not parse the
> packet protocol, the entire XDP frame is using dma mapped for the
> transmission. Because the actual TX is deferred until txThreshold, it's
> possible that an rx buffer is being overwritten by incoming burst of rx
> packets, before tx buffer being transmitted. As a result, we allocate new
> skb and introduce a copy.
>
> Performance:
> Tested using two VMs inside one ESXi machine, using single core on each
> vmxnet3 device, sender using DPDK testpmd tx-mode attached to vmxnet3
> device, sending 64B or 512B packet.
>
> VM1 txgen:
> $ dpdk-testpmd -l 0-3 -n 1 -- -i --nb-cores=3 \
> --forward-mode=txonly --eth-peer=0,<mac addr of vm2>
> option: add "--txonly-multi-flow"
> option: use --txpkts=512 or 64 byte
>
> VM2 running XDP:
> $ ./samples/bpf/xdp_rxq_info -d ens160 -a <options> --skb-mode
> $ ./samples/bpf/xdp_rxq_info -d ens160 -a <options>
> options: XDP_DROP, XDP_PASS, XDP_TX
>
> To test REDIRECT to cpu 0, use
> $ ./samples/bpf/xdp_redirect_cpu -d ens160 -c 0 -e drop
>
> Single core performance comparison with skb-mode.
> 64B: skb-mode -> native-mode (with this patch)
> XDP_DROP: 932Kpps -> 2.0Mpps
> XDP_PASS: 284Kpps -> 314Kpps
> XDP_TX: 591Kpps -> 1.8Mpps
> REDIRECT: 453Kpps -> 501Kpps
>
> 512B: skb-mode -> native-mode (with this patch)
> XDP_DROP: 890Kpps -> 1.3Mpps
> XDP_PASS: 284Kpps -> 314Kpps
> XDP_TX: 555Kpps -> 1.2Mpps
> REDIRECT: 670Kpps -> 430Kpps
>
I hadn't noticed it before. Based on this it looks like native mode is
performing worse then skb-mode for redirect w/ 512B packets? Have you
looked into why that might be?
My main concern would be that you are optimizing for recyling in the Tx
and Redirect paths, when you might be better off just releasing the
buffers and batch allocating new pages in your Rx path.
> Limitations:
> a. LRO will be disabled when users load XDP program
> b. MTU will be checked and limit to
> VMXNET3_MAX_SKB_BUF_SIZE(3K) - XDP_PACKET_HEADROOM(256) -
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info))
>
> Signed-off-by: William Tu <u9012063@...il.com>
> ---
> v5 -> v6:
> work on feedbacks from Alexander Duyck
> - remove unused skb parameter at vmxnet3_xdp_xmit
> - add trace point for XDP_ABORTED
> - avoid TX packet buffer being overwritten by allocatin
> new skb and memcpy (TX performance drop from 2.3 to 1.8Mpps)
> - update some of the performance number and a demo video
> https://youtu.be/I3nx5wQDTXw
> - pass VMware internal regression test using non-ENS: vmxnet3v2,
> vmxnet3v3, vmxnet3v4, so remove RFC tag.
>
> v4 -> v5:
> - move XDP code to separate file: vmxnet3_xdp.{c, h},
> suggested by Guolin
> - expose vmxnet3_rq_create_all and vmxnet3_adjust_rx_ring_size
> - more test using samples/bpf/{xdp1, xdp2, xdp_adjust_tail}
> - add debug print
> - rebase on commit 65e6af6cebe
>
> v3 -> v4:
> - code refactoring and improved commit message
> - make dataring and non-dataring case clear
> - in XDP_PASS, handle xdp.data and xdp.data_end change after
> bpf program executed
> - now still working on internal testing
> - v4 applied on net-next commit 65e6af6cebef
>
> v2 -> v3:
> - code refactoring: move the XDP processing to the front
> of the vmxnet3_rq_rx_complete, and minimize the places
> of changes to existing code.
> - Performance improvement over BUF_SKB (512B) due to skipping
> skb allocation when DROP and TX.
>
> v1 -> v2:
> - Avoid skb allocation for small packet size (when dataring is used)
> - Use rcu_read_lock unlock instead of READ_ONCE
> - Peroformance improvement over v1
> - Merge xdp drop, tx, pass, and redirect into 1 patch
>
> I tested the patch using below script:
> while [ true ]; do
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_DROP --skb-mode
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_DROP
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_PASS --skb-mode
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_PASS
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_TX --skb-mode
> timeout 20 ./samples/bpf/xdp_rxq_info -d ens160 -a XDP_TX
> timeout 20 ./samples/bpf/xdp_redirect_cpu -d ens160 -c 0 -e drop
> timeout 20 ./samples/bpf/xdp_redirect_cpu -d ens160 -c 0 -e pass
> done
> ---
> drivers/net/vmxnet3/Makefile | 2 +-
> drivers/net/vmxnet3/vmxnet3_drv.c | 48 ++-
> drivers/net/vmxnet3/vmxnet3_ethtool.c | 14 +
> drivers/net/vmxnet3/vmxnet3_int.h | 20 ++
> drivers/net/vmxnet3/vmxnet3_xdp.c | 458 ++++++++++++++++++++++++++
> drivers/net/vmxnet3/vmxnet3_xdp.h | 39 +++
> 6 files changed, 573 insertions(+), 8 deletions(-)
> create mode 100644 drivers/net/vmxnet3/vmxnet3_xdp.c
> create mode 100644 drivers/net/vmxnet3/vmxnet3_xdp.h
>
> diff --git a/drivers/net/vmxnet3/Makefile b/drivers/net/vmxnet3/Makefile
> index a666a88ac1ff..f82870c10205 100644
> --- a/drivers/net/vmxnet3/Makefile
> +++ b/drivers/net/vmxnet3/Makefile
> @@ -32,4 +32,4 @@
>
> obj-$(CONFIG_VMXNET3) += vmxnet3.o
>
> -vmxnet3-objs := vmxnet3_drv.o vmxnet3_ethtool.o
> +vmxnet3-objs := vmxnet3_drv.o vmxnet3_ethtool.o vmxnet3_xdp.o
> diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
> index d3e7b27eb933..b55fec2ac2bf 100644
> --- a/drivers/net/vmxnet3/vmxnet3_drv.c
> +++ b/drivers/net/vmxnet3/vmxnet3_drv.c
> @@ -28,6 +28,7 @@
> #include <net/ip6_checksum.h>
>
> #include "vmxnet3_int.h"
> +#include "vmxnet3_xdp.h"
>
> char vmxnet3_driver_name[] = "vmxnet3";
> #define VMXNET3_DRIVER_DESC "VMware vmxnet3 virtual NIC driver"
> @@ -351,7 +352,6 @@ vmxnet3_unmap_pkt(u32 eop_idx, struct vmxnet3_tx_queue *tq,
> BUG_ON(VMXNET3_TXDESC_GET_EOP(&(tq->tx_ring.base[eop_idx].txd)) != 1);
>
> skb = tq->buf_info[eop_idx].skb;
> - BUG_ON(skb == NULL);
> tq->buf_info[eop_idx].skb = NULL;
>
> VMXNET3_INC_RING_IDX_ONLY(eop_idx, tq->tx_ring.size);
> @@ -592,6 +592,9 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
> rbi->skb = __netdev_alloc_skb_ip_align(adapter->netdev,
> rbi->len,
> GFP_KERNEL);
> + if (adapter->xdp_enabled)
> + skb_reserve(rbi->skb, XDP_PACKET_HEADROOM);
> +
> if (unlikely(rbi->skb == NULL)) {
> rq->stats.rx_buf_alloc_failure++;
> break;
> @@ -1404,6 +1407,8 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
> struct Vmxnet3_RxDesc rxCmdDesc;
> struct Vmxnet3_RxCompDesc rxComp;
> #endif
> + bool need_flush = 0;
> +
> vmxnet3_getRxComp(rcd, &rq->comp_ring.base[rq->comp_ring.next2proc].rcd,
> &rxComp);
> while (rcd->gen == rq->comp_ring.gen) {
> @@ -1444,6 +1449,19 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
> goto rcd_done;
> }
>
> + if (unlikely(rcd->sop && rcd->eop && adapter->xdp_enabled)) {
> + int act = vmxnet3_process_xdp(adapter, rq, rcd, rbi,
> + rxd, &need_flush);
> + ctx->skb = NULL;
> + switch (act) {
> + case VMXNET3_XDP_TAKEN:
> + goto rcd_done;
> + case VMXNET3_XDP_CONTINUE:
> + default:
> + break;
> + }
> + }
> +
> if (rcd->sop) { /* first buf of the pkt */
> bool rxDataRingUsed;
> u16 len;
> @@ -1483,6 +1501,10 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
> goto rcd_done;
> }
>
> + if (adapter->xdp_enabled && !rxDataRingUsed)
> + skb_reserve(new_skb,
> + XDP_PACKET_HEADROOM);
> +
> if (rxDataRingUsed) {
> size_t sz;
>
> @@ -1730,6 +1752,8 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
> vmxnet3_getRxComp(rcd,
> &rq->comp_ring.base[rq->comp_ring.next2proc].rcd, &rxComp);
> }
> + if (need_flush)
> + xdp_do_flush_map();
>
> return num_pkts;
> }
> @@ -1776,6 +1800,7 @@ vmxnet3_rq_cleanup(struct vmxnet3_rx_queue *rq,
>
> rq->comp_ring.gen = VMXNET3_INIT_GEN;
> rq->comp_ring.next2proc = 0;
> + rq->xdp_bpf_prog = NULL;
> }
>
>
> @@ -1788,7 +1813,6 @@ vmxnet3_rq_cleanup_all(struct vmxnet3_adapter *adapter)
> vmxnet3_rq_cleanup(&adapter->rx_queue[i], adapter);
> }
>
> -
> static void vmxnet3_rq_destroy(struct vmxnet3_rx_queue *rq,
> struct vmxnet3_adapter *adapter)
> {
> @@ -1832,6 +1856,8 @@ static void vmxnet3_rq_destroy(struct vmxnet3_rx_queue *rq,
> kfree(rq->buf_info[0]);
> rq->buf_info[0] = NULL;
> rq->buf_info[1] = NULL;
> +
> + vmxnet3_unregister_xdp_rxq(rq);
> }
>
> static void
> @@ -1893,6 +1919,10 @@ vmxnet3_rq_init(struct vmxnet3_rx_queue *rq,
> }
> vmxnet3_rq_alloc_rx_buf(rq, 1, rq->rx_ring[1].size - 1, adapter);
>
> + /* always register, even if no XDP prog used */
> + if (vmxnet3_register_xdp_rxq(rq, adapter))
> + return -EINVAL;
> +
> /* reset the comp ring */
> rq->comp_ring.next2proc = 0;
> memset(rq->comp_ring.base, 0, rq->comp_ring.size *
> @@ -1989,7 +2019,7 @@ vmxnet3_rq_create(struct vmxnet3_rx_queue *rq, struct vmxnet3_adapter *adapter)
> }
>
>
> -static int
> +int
> vmxnet3_rq_create_all(struct vmxnet3_adapter *adapter)
> {
> int i, err = 0;
> @@ -2585,7 +2615,8 @@ vmxnet3_setup_driver_shared(struct vmxnet3_adapter *adapter)
> if (adapter->netdev->features & NETIF_F_RXCSUM)
> devRead->misc.uptFeatures |= UPT1_F_RXCSUM;
>
> - if (adapter->netdev->features & NETIF_F_LRO) {
> + if (adapter->netdev->features & NETIF_F_LRO &&
> + !adapter->xdp_enabled) {
> devRead->misc.uptFeatures |= UPT1_F_LRO;
> devRead->misc.maxNumRxSG = cpu_to_le16(1 + MAX_SKB_FRAGS);
> }
> @@ -3026,7 +3057,7 @@ vmxnet3_free_pci_resources(struct vmxnet3_adapter *adapter)
> }
>
>
> -static void
> +void
> vmxnet3_adjust_rx_ring_size(struct vmxnet3_adapter *adapter)
> {
> size_t sz, i, ring0_size, ring1_size, comp_size;
> @@ -3035,7 +3066,8 @@ vmxnet3_adjust_rx_ring_size(struct vmxnet3_adapter *adapter)
> if (adapter->netdev->mtu <= VMXNET3_MAX_SKB_BUF_SIZE -
> VMXNET3_MAX_ETH_HDR_SIZE) {
> adapter->skb_buf_size = adapter->netdev->mtu +
> - VMXNET3_MAX_ETH_HDR_SIZE;
> + VMXNET3_MAX_ETH_HDR_SIZE +
> + vmxnet3_xdp_headroom(adapter);
> if (adapter->skb_buf_size < VMXNET3_MIN_T0_BUF_SIZE)
> adapter->skb_buf_size = VMXNET3_MIN_T0_BUF_SIZE;
>
> @@ -3563,7 +3595,6 @@ vmxnet3_reset_work(struct work_struct *data)
> clear_bit(VMXNET3_STATE_BIT_RESETTING, &adapter->state);
> }
>
> -
> static int
> vmxnet3_probe_device(struct pci_dev *pdev,
> const struct pci_device_id *id)
> @@ -3585,6 +3616,8 @@ vmxnet3_probe_device(struct pci_dev *pdev,
> #ifdef CONFIG_NET_POLL_CONTROLLER
> .ndo_poll_controller = vmxnet3_netpoll,
> #endif
> + .ndo_bpf = vmxnet3_xdp,
> + .ndo_xdp_xmit = vmxnet3_xdp_xmit,
> };
> int err;
> u32 ver;
> @@ -3900,6 +3933,7 @@ vmxnet3_probe_device(struct pci_dev *pdev,
> goto err_register;
> }
>
> + adapter->xdp_enabled = false;
> vmxnet3_check_link(adapter, false);
> return 0;
>
> diff --git a/drivers/net/vmxnet3/vmxnet3_ethtool.c b/drivers/net/vmxnet3/vmxnet3_ethtool.c
> index 18cf7c723201..6f542236b26e 100644
> --- a/drivers/net/vmxnet3/vmxnet3_ethtool.c
> +++ b/drivers/net/vmxnet3/vmxnet3_ethtool.c
> @@ -76,6 +76,10 @@ vmxnet3_tq_driver_stats[] = {
> copy_skb_header) },
> { " giant hdr", offsetof(struct vmxnet3_tq_driver_stats,
> oversized_hdr) },
> + { " xdp xmit", offsetof(struct vmxnet3_tq_driver_stats,
> + xdp_xmit) },
> + { " xdp xmit err", offsetof(struct vmxnet3_tq_driver_stats,
> + xdp_xmit_err) },
> };
>
> /* per rq stats maintained by the device */
> @@ -106,6 +110,16 @@ vmxnet3_rq_driver_stats[] = {
> drop_fcs) },
> { " rx buf alloc fail", offsetof(struct vmxnet3_rq_driver_stats,
> rx_buf_alloc_failure) },
> + { " xdp packets", offsetof(struct vmxnet3_rq_driver_stats,
> + xdp_packets) },
> + { " xdp tx", offsetof(struct vmxnet3_rq_driver_stats,
> + xdp_tx) },
> + { " xdp redirects", offsetof(struct vmxnet3_rq_driver_stats,
> + xdp_redirects) },
> + { " xdp drops", offsetof(struct vmxnet3_rq_driver_stats,
> + xdp_drops) },
> + { " xdp aborted", offsetof(struct vmxnet3_rq_driver_stats,
> + xdp_aborted) },
> };
>
> /* global stats maintained by the driver */
> diff --git a/drivers/net/vmxnet3/vmxnet3_int.h b/drivers/net/vmxnet3/vmxnet3_int.h
> index 3367db23aa13..5cf4033930d8 100644
> --- a/drivers/net/vmxnet3/vmxnet3_int.h
> +++ b/drivers/net/vmxnet3/vmxnet3_int.h
> @@ -56,6 +56,8 @@
> #include <linux/if_arp.h>
> #include <linux/inetdevice.h>
> #include <linux/log2.h>
> +#include <linux/bpf.h>
> +#include <linux/skbuff.h>
>
> #include "vmxnet3_defs.h"
>
> @@ -217,6 +219,9 @@ struct vmxnet3_tq_driver_stats {
> u64 linearized; /* # of pkts linearized */
> u64 copy_skb_header; /* # of times we have to copy skb header */
> u64 oversized_hdr;
> +
> + u64 xdp_xmit;
> + u64 xdp_xmit_err;
> };
>
> struct vmxnet3_tx_ctx {
> @@ -285,6 +290,12 @@ struct vmxnet3_rq_driver_stats {
> u64 drop_err;
> u64 drop_fcs;
> u64 rx_buf_alloc_failure;
> +
> + u64 xdp_packets; /* Total packets processed by XDP. */
> + u64 xdp_tx;
> + u64 xdp_redirects;
> + u64 xdp_drops;
> + u64 xdp_aborted;
> };
>
> struct vmxnet3_rx_data_ring {
> @@ -307,6 +318,8 @@ struct vmxnet3_rx_queue {
> struct vmxnet3_rx_buf_info *buf_info[2];
> struct Vmxnet3_RxQueueCtrl *shared;
> struct vmxnet3_rq_driver_stats stats;
> + struct bpf_prog __rcu *xdp_bpf_prog;
> + struct xdp_rxq_info xdp_rxq;
> } __attribute__((__aligned__(SMP_CACHE_BYTES)));
>
> #define VMXNET3_DEVICE_MAX_TX_QUEUES 32
> @@ -415,6 +428,7 @@ struct vmxnet3_adapter {
> u16 tx_prod_offset;
> u16 rx_prod_offset;
> u16 rx_prod2_offset;
> + bool xdp_enabled;
> };
>
> #define VMXNET3_WRITE_BAR0_REG(adapter, reg, val) \
> @@ -490,6 +504,12 @@ vmxnet3_tq_destroy_all(struct vmxnet3_adapter *adapter);
> void
> vmxnet3_rq_destroy_all(struct vmxnet3_adapter *adapter);
>
> +int
> +vmxnet3_rq_create_all(struct vmxnet3_adapter *adapter);
> +
> +void
> +vmxnet3_adjust_rx_ring_size(struct vmxnet3_adapter *adapter);
> +
> netdev_features_t
> vmxnet3_fix_features(struct net_device *netdev, netdev_features_t features);
>
> diff --git a/drivers/net/vmxnet3/vmxnet3_xdp.c b/drivers/net/vmxnet3/vmxnet3_xdp.c
> new file mode 100644
> index 000000000000..afb2d43b5464
> --- /dev/null
> +++ b/drivers/net/vmxnet3/vmxnet3_xdp.c
> @@ -0,0 +1,458 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Linux driver for VMware's vmxnet3 ethernet NIC.
> + * Copyright (C) 2008-2023, VMware, Inc. All Rights Reserved.
> + * Maintained by: pv-drivers@...are.com
> + *
> + */
> +
> +#include "vmxnet3_int.h"
> +#include "vmxnet3_xdp.h"
> +
> +static void
> +vmxnet3_xdp_exchange_program(struct vmxnet3_adapter *adapter,
> + struct bpf_prog *prog)
> +{
> + struct vmxnet3_rx_queue *rq;
> + int i;
> +
> + for (i = 0; i < adapter->num_rx_queues; i++) {
> + rq = &adapter->rx_queue[i];
> + rcu_assign_pointer(rq->xdp_bpf_prog, prog);
> + }
> + if (prog)
> + adapter->xdp_enabled = true;
> + else
> + adapter->xdp_enabled = false;
> +}
> +
> +static int
> +vmxnet3_xdp_set(struct net_device *netdev, struct netdev_bpf *bpf,
> + struct netlink_ext_ack *extack)
> +{
> + struct vmxnet3_adapter *adapter = netdev_priv(netdev);
> + struct bpf_prog *new_bpf_prog = bpf->prog;
> + struct bpf_prog *old_bpf_prog;
> + bool need_update;
> + bool running;
> + int err = 0;
> +
> + if (new_bpf_prog && netdev->mtu > VMXNET3_XDP_MAX_MTU) {
> + NL_SET_ERR_MSG_MOD(extack, "MTU too large for XDP");
> + return -EOPNOTSUPP;
> + }
> +
> + old_bpf_prog = READ_ONCE(adapter->rx_queue[0].xdp_bpf_prog);
> + if (!new_bpf_prog && !old_bpf_prog) {
> + adapter->xdp_enabled = false;
> + return 0;
> + }
> + running = netif_running(netdev);
> + need_update = !!old_bpf_prog != !!new_bpf_prog;
> +
> + if (running && need_update)
> + vmxnet3_quiesce_dev(adapter);
> +
> + vmxnet3_xdp_exchange_program(adapter, new_bpf_prog);
> + if (old_bpf_prog)
> + bpf_prog_put(old_bpf_prog);
> +
> + if (running && need_update) {
> + vmxnet3_reset_dev(adapter);
> + vmxnet3_rq_destroy_all(adapter);
> + vmxnet3_adjust_rx_ring_size(adapter);
> + err = vmxnet3_rq_create_all(adapter);
> + if (err) {
> + NL_SET_ERR_MSG_MOD(extack,
> + "failed to re-create rx queues for XDP.");
> + err = -EOPNOTSUPP;
> + goto out;
> + }
> + err = vmxnet3_activate_dev(adapter);
> + if (err) {
> + NL_SET_ERR_MSG_MOD(extack,
> + "failed to activate device for XDP.");
> + err = -EOPNOTSUPP;
> + goto out;
> + }
> + clear_bit(VMXNET3_STATE_BIT_RESETTING, &adapter->state);
> + }
> +out:
> + return err;
> +}
> +
> +/* This is the main xdp call used by kernel to set/unset eBPF program. */
> +int
> +vmxnet3_xdp(struct net_device *netdev, struct netdev_bpf *bpf)
> +{
> + switch (bpf->command) {
> + case XDP_SETUP_PROG:
> + netdev_dbg(netdev, "XDP: set program to ");
> + return vmxnet3_xdp_set(netdev, bpf, bpf->extack);
> + default:
> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> +int
> +vmxnet3_xdp_headroom(struct vmxnet3_adapter *adapter)
> +{
> + if (adapter->xdp_enabled)
> + return VMXNET3_XDP_ROOM;
> + else
> + return 0;
> +}
> +
> +void
> +vmxnet3_unregister_xdp_rxq(struct vmxnet3_rx_queue *rq)
> +{
> + xdp_rxq_info_unreg_mem_model(&rq->xdp_rxq);
> + xdp_rxq_info_unreg(&rq->xdp_rxq);
> +}
> +
> +int
> +vmxnet3_register_xdp_rxq(struct vmxnet3_rx_queue *rq,
> + struct vmxnet3_adapter *adapter)
> +{
> + int err;
> +
> + err = xdp_rxq_info_reg(&rq->xdp_rxq, adapter->netdev, rq->qid, 0);
> + if (err < 0)
> + return err;
> +
> + err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq, MEM_TYPE_PAGE_SHARED,
> + NULL);
> + if (err < 0) {
> + xdp_rxq_info_unreg(&rq->xdp_rxq);
> + return err;
> + }
> + return 0;
> +}
> +
> +static int
> +vmxnet3_xdp_xmit_frame(struct vmxnet3_adapter *adapter,
> + struct xdp_frame *xdpf,
> + struct vmxnet3_tx_queue *tq)
> +{
> + struct vmxnet3_tx_buf_info *tbi = NULL;
> + union Vmxnet3_GenericDesc *gdesc;
> + struct vmxnet3_tx_ctx ctx;
> + int tx_num_deferred;
> + struct sk_buff *skb;
> + u32 buf_size;
> + int ret = 0;
> + u32 dw2;
> +
> + if (vmxnet3_cmd_ring_desc_avail(&tq->tx_ring) == 0) {
> + tq->stats.tx_ring_full++;
> + ret = -ENOMEM;
> + goto exit;
> + }
> +
> + skb = __netdev_alloc_skb(adapter->netdev, xdpf->len, GFP_KERNEL);
> + if (unlikely(!skb))
> + goto exit;
> +
Any reason for this not to return an error. Seems like this might be
better off being the ENOMEM w/ the no descriptor case being something
like ENOSPC.
Also at some point you may want to look at supporting handling page
fragments or XDP frames as allocating an skb for an XDP transmit can be
expensive.
> + memcpy(skb->data, xdpf->data, xdpf->len);
> + dw2 = (tq->tx_ring.gen ^ 0x1) << VMXNET3_TXD_GEN_SHIFT;
> + dw2 |= xdpf->len;
> + ctx.sop_txd = tq->tx_ring.base + tq->tx_ring.next2fill;
> + gdesc = ctx.sop_txd;
> +
> + buf_size = xdpf->len;
> + tbi = tq->buf_info + tq->tx_ring.next2fill;
> + tbi->map_type = VMXNET3_MAP_SINGLE;
> + tbi->dma_addr = dma_map_single(&adapter->pdev->dev,
> + skb->data, buf_size,
> + DMA_TO_DEVICE);
> + if (dma_mapping_error(&adapter->pdev->dev, tbi->dma_addr)) {
> + ret = -EFAULT;
> + goto exit;
> + }
Don't you need to free the skb here?
> + tbi->len = buf_size;
> +
> + gdesc = tq->tx_ring.base + tq->tx_ring.next2fill;
> + WARN_ON_ONCE(gdesc->txd.gen == tq->tx_ring.gen);
> +
> + gdesc->txd.addr = cpu_to_le64(tbi->dma_addr);
> + gdesc->dword[2] = cpu_to_le32(dw2);
> +
> + /* Setup the EOP desc */
> + gdesc->dword[3] = cpu_to_le32(VMXNET3_TXD_CQ | VMXNET3_TXD_EOP);
> +
> + gdesc->txd.om = 0;
> + gdesc->txd.msscof = 0;
> + gdesc->txd.hlen = 0;
> + gdesc->txd.ti = 0;
> +
> + tx_num_deferred = le32_to_cpu(tq->shared->txNumDeferred);
> + tq->shared->txNumDeferred += 1;
> + tx_num_deferred++;
> +
> + vmxnet3_cmd_ring_adv_next2fill(&tq->tx_ring);
> +
> + /* set the last buf_info for the pkt */
> + tbi->skb = skb;
> + tbi->sop_idx = ctx.sop_txd - tq->tx_ring.base;
> +
> + dma_wmb();
> + gdesc->dword[2] = cpu_to_le32(le32_to_cpu(gdesc->dword[2]) ^
> + VMXNET3_TXD_GEN);
> + if (tx_num_deferred >= le32_to_cpu(tq->shared->txThreshold)) {
> + tq->shared->txNumDeferred = 0;
> + VMXNET3_WRITE_BAR0_REG(adapter,
> + VMXNET3_REG_TXPROD + tq->qid * 8,
> + tq->tx_ring.next2fill);
> + }
> +exit:
> + return ret;
> +}
> +
> +static int
> +vmxnet3_xdp_xmit_back(struct vmxnet3_adapter *adapter,
> + struct xdp_frame *xdpf)
> +{
> + struct vmxnet3_tx_queue *tq;
> + struct netdev_queue *nq;
> + int err = 0, cpu;
> + int tq_number;
> +
> + tq_number = adapter->num_tx_queues;
> + cpu = smp_processor_id();
> + tq = &adapter->tx_queue[cpu % tq_number];
> + if (tq->stopped)
> + return -ENETDOWN;
> +
> + nq = netdev_get_tx_queue(adapter->netdev, tq->qid);
> +
> + __netif_tx_lock(nq, cpu);
> + err = vmxnet3_xdp_xmit_frame(adapter, xdpf, tq);
> + if (err)
> + goto exit;
> +
> +exit:
What is the point of the label/goto? I don't see another spot that
references it.
> + __netif_tx_unlock(nq);
> + return err;
> +}
> +
> +int
> +vmxnet3_xdp_xmit(struct net_device *dev,
> + int n, struct xdp_frame **frames, u32 flags)
> +{
> + struct vmxnet3_adapter *adapter;
> + struct vmxnet3_tx_queue *tq;
> + struct netdev_queue *nq;
> + int i, err, cpu;
> + int nxmit = 0;
> + int tq_number;
> +
> + adapter = netdev_priv(dev);
> +
> + if (unlikely(test_bit(VMXNET3_STATE_BIT_QUIESCED, &adapter->state)))
> + return -ENETDOWN;
> + if (unlikely(test_bit(VMXNET3_STATE_BIT_RESETTING, &adapter->state)))
> + return -EINVAL;
> +
> + tq_number = adapter->num_tx_queues;
> + cpu = smp_processor_id();
> + tq = &adapter->tx_queue[cpu % tq_number];
> + if (tq->stopped)
> + return -ENETDOWN;
> +
> + nq = netdev_get_tx_queue(adapter->netdev, tq->qid);
> +
> + __netif_tx_lock(nq, cpu);
> + for (i = 0; i < n; i++) {
> + err = vmxnet3_xdp_xmit_frame(adapter, frames[i], tq);
> + if (err) {
> + tq->stats.xdp_xmit_err++;
> + break;
> + }
> + nxmit++;
> + }
> +
> + tq->stats.xdp_xmit += nxmit;
> + __netif_tx_unlock(nq);
> +
Are you doing anything to free the frames after you transmit them? If I
am not mistaken you are just copying them over into skbs aren't you, so
what is freeing the frames after that?
> + return nxmit;
> +}
> +
> +static int
> +__vmxnet3_run_xdp(struct vmxnet3_rx_queue *rq, void *data, int data_len,
> + int headroom, int frame_sz, bool *need_xdp_flush,
> + struct sk_buff *skb)
> +{
> + struct xdp_frame *xdpf;
> + void *buf_hard_start;
> + struct xdp_buff xdp;
> + struct page *page;
> + void *orig_data;
> + int err, delta;
> + int delta_len;
> + u32 act;
> +
> + buf_hard_start = data;
> + xdp_init_buff(&xdp, frame_sz, &rq->xdp_rxq);
> + xdp_prepare_buff(&xdp, buf_hard_start, headroom, data_len, true);
> + orig_data = xdp.data;
> +
> + act = bpf_prog_run_xdp(rq->xdp_bpf_prog, &xdp);
> + rq->stats.xdp_packets++;
> +
> + switch (act) {
> + case XDP_DROP:
> + rq->stats.xdp_drops++;
> + break;
> + case XDP_PASS:
> + /* bpf prog might change len and data position.
> + * dataring does not use skb so not support this.
> + */
> + delta = xdp.data - orig_data;
> + delta_len = (xdp.data_end - xdp.data) - data_len;
> + if (skb) {
> + skb_reserve(skb, delta);
> + skb_put(skb, delta_len);
> + }
> + break;
> + case XDP_TX:
> + xdpf = xdp_convert_buff_to_frame(&xdp);
> + if (!xdpf ||
> + vmxnet3_xdp_xmit_back(rq->adapter, xdpf)) {
> + rq->stats.xdp_drops++;
> + } else {
> + rq->stats.xdp_tx++;
> + }
> + break;
> + case XDP_ABORTED:
> + trace_xdp_exception(rq->adapter->netdev, rq->xdp_bpf_prog,
> + act);
> + rq->stats.xdp_aborted++;
> + break;
> + case XDP_REDIRECT:
> + page = alloc_page(GFP_ATOMIC);
> + if (!page) {
> + rq->stats.rx_buf_alloc_failure++;
> + return XDP_DROP;
> + }
So I think I see the problem I had questions about here. If I am not
mistaken you are copying the buffer to this page, and then copying this
page to an skb right? I think you might be better off just writing off
the Tx/Redirect pages and letting them go through their respective
paths and just allocating new pages instead assuming these pages were
consumed.
> + xdp_init_buff(&xdp, PAGE_SIZE, &rq->xdp_rxq);
> + xdp_prepare_buff(&xdp, page_address(page),
> + XDP_PACKET_HEADROOM,
> + data_len, true);
> + memcpy(xdp.data, data, data_len);
> + err = xdp_do_redirect(rq->adapter->netdev, &xdp,
> + rq->xdp_bpf_prog);
> + if (!err) {
> + rq->stats.xdp_redirects++;
> + } else {
> + __free_page(page);
> + rq->stats.xdp_drops++;
> + }
> + *need_xdp_flush = true;
> + break;
> + default:
> + bpf_warn_invalid_xdp_action(rq->adapter->netdev,
> + rq->xdp_bpf_prog, act);
> + break;
> + }
> + return act;
> +}
> +
> +static int
> +vmxnet3_run_xdp(struct vmxnet3_rx_queue *rq, struct vmxnet3_rx_buf_info *rbi,
> + struct Vmxnet3_RxCompDesc *rcd, bool *need_flush,
> + bool rxDataRingUsed)
> +{
> + struct vmxnet3_adapter *adapter;
> + struct ethhdr *ehdr;
> + int act = XDP_PASS;
> + void *data;
> + int sz;
> +
> + adapter = rq->adapter;
> + if (rxDataRingUsed) {
> + sz = rcd->rxdIdx * rq->data_ring.desc_size;
> + data = &rq->data_ring.base[sz];
> + ehdr = data;
> + netdev_dbg(adapter->netdev,
> + "XDP: rxDataRing packet size %d, eth proto 0x%x\n",
> + rcd->len, ntohs(ehdr->h_proto));
> + act = __vmxnet3_run_xdp(rq, data, rcd->len, 0,
> + rq->data_ring.desc_size, need_flush,
> + NULL);
> + } else {
> + dma_unmap_single(&adapter->pdev->dev,
> + rbi->dma_addr,
> + rbi->len,
> + DMA_FROM_DEVICE);
> + ehdr = (struct ethhdr *)rbi->skb->data;
> + netdev_dbg(adapter->netdev,
> + "XDP: packet size %d, eth proto 0x%x\n",
> + rcd->len, ntohs(ehdr->h_proto));
> + act = __vmxnet3_run_xdp(rq,
> + rbi->skb->data - XDP_PACKET_HEADROOM,
> + rcd->len, XDP_PACKET_HEADROOM,
> + rbi->len, need_flush, rbi->skb);
> + }
> + return act;
> +}
> +
> +int
> +vmxnet3_process_xdp(struct vmxnet3_adapter *adapter,
> + struct vmxnet3_rx_queue *rq,
> + struct Vmxnet3_RxCompDesc *rcd,
> + struct vmxnet3_rx_buf_info *rbi,
> + struct Vmxnet3_RxDesc *rxd,
> + bool *need_flush)
> +{
> + struct bpf_prog *xdp_prog;
> + dma_addr_t new_dma_addr;
> + struct sk_buff *new_skb;
> + bool rxDataRingUsed;
> + int ret, act;
> +
> + ret = VMXNET3_XDP_CONTINUE;
> + if (unlikely(rcd->len == 0))
> + return VMXNET3_XDP_TAKEN;
> +
> + rxDataRingUsed = VMXNET3_RX_DATA_RING(adapter, rcd->rqID);
> + rcu_read_lock();
> + xdp_prog = rcu_dereference(rq->xdp_bpf_prog);
> + if (!xdp_prog) {
> + rcu_read_unlock();
> + return VMXNET3_XDP_CONTINUE;
> + }
> + act = vmxnet3_run_xdp(rq, rbi, rcd, need_flush, rxDataRingUsed);
> + rcu_read_unlock();
> +
> + switch (act) {
> + case XDP_PASS:
> + ret = VMXNET3_XDP_CONTINUE;
> + break;
> + case XDP_DROP:
> + case XDP_TX:
> + case XDP_REDIRECT:
> + case XDP_ABORTED:
> + default:
> + /* Reuse and remap the existing buffer. */
> + ret = VMXNET3_XDP_TAKEN;
> + if (rxDataRingUsed)
> + return ret;
> +
> + new_skb = rbi->skb;
> + new_dma_addr =
> + dma_map_single(&adapter->pdev->dev,
> + new_skb->data, rbi->len,
> + DMA_FROM_DEVICE);
> + if (dma_mapping_error(&adapter->pdev->dev,
> + new_dma_addr)) {
> + dev_kfree_skb(new_skb);
> + rq->stats.drop_total++;
> + return ret;
> + }
> + rbi->dma_addr = new_dma_addr;
> + rxd->addr = cpu_to_le64(rbi->dma_addr);
> + rxd->len = rbi->len;
> + }
> + return ret;
> +}
> diff --git a/drivers/net/vmxnet3/vmxnet3_xdp.h b/drivers/net/vmxnet3/vmxnet3_xdp.h
> new file mode 100644
> index 000000000000..6a3c662a4464
> --- /dev/null
> +++ b/drivers/net/vmxnet3/vmxnet3_xdp.h
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * Linux driver for VMware's vmxnet3 ethernet NIC.
> + * Copyright (C) 2008-2023, VMware, Inc. All Rights Reserved.
> + * Maintained by: pv-drivers@...are.com
> + *
> + */
> +
> +#ifndef _VMXNET3_XDP_H
> +#define _VMXNET3_XDP_H
> +
> +#include <linux/filter.h>
> +#include <linux/bpf_trace.h>
> +#include <linux/netlink.h>
> +#include <net/xdp.h>
> +
> +#include "vmxnet3_int.h"
> +
> +#define VMXNET3_XDP_ROOM (SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) + \
> + XDP_PACKET_HEADROOM)
> +#define VMXNET3_XDP_MAX_MTU (VMXNET3_MAX_SKB_BUF_SIZE - VMXNET3_XDP_ROOM)
> +
> +#define VMXNET3_XDP_CONTINUE 0 /* Pass to the stack, ex: XDP_PASS. */
> +#define VMXNET3_XDP_TAKEN 1 /* Skip the stack, ex: XDP_DROP/TX/REDIRECT */
> +
> +int vmxnet3_xdp(struct net_device *netdev, struct netdev_bpf *bpf);
> +void vmxnet3_unregister_xdp_rxq(struct vmxnet3_rx_queue *rq);
> +int vmxnet3_register_xdp_rxq(struct vmxnet3_rx_queue *rq,
> + struct vmxnet3_adapter *adapter);
> +int vmxnet3_xdp_headroom(struct vmxnet3_adapter *adapter);
> +int vmxnet3_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
> + u32 flags);
> +int vmxnet3_process_xdp(struct vmxnet3_adapter *adapter,
> + struct vmxnet3_rx_queue *rq,
> + struct Vmxnet3_RxCompDesc *rcd,
> + struct vmxnet3_rx_buf_info *rbi,
> + struct Vmxnet3_RxDesc *rxd,
> + bool *need_flush);
> +#endif
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