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Date:   Tue, 03 Jan 2023 08:23:55 -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,
        gerhard@...leder-embedded.com
Subject: Re: [PATCH v8] vmxnet3: Add XDP support.

On Mon, 2023-01-02 at 18:22 -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
> XDP_DROP: 915Kpps -> 2.0Mpps
> XDP_PASS: 280Kpps -> 374Kpps
> XDP_TX:   591Kpps -> 1.7Mpps
> REDIRECT-drop: 703Kpps -> 1.9Mpps
> 
> 512B:      skb-mode -> native-mode
> XDP_DROP: 890Kpps -> 1.3Mpps
> XDP_PASS: 275Kpps -> 376Kpps
> XDP_TX:   564Kpps -> 1.2Mpps
> REDIRECT-drop: 682Kpps -> 1.2Mpps
> 
> 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>
> ---
> v7 -> v8:
> - work on feedbacks from Gerhard Engleder and Alexander
> - change memory model to use page pool API, introduce xdp_frame
>   to the rx ring, rewrite some of the XDP processing code
> - attach bpf xdp prog to adapter, not per rx queue
> - I reference some of the XDP implementation from
>   drivers/net/ethernet/mediatek and
>   drivers/net/ethernet/stmicro/stmmac/
> - drop support for rxdataring for this version
> - redo performance evaluation and demo here
>   https://youtu.be/T7_0yrCXCe0
> - check using /sys/kernel/debug/kmemleak
> - should I consider break into smaller and multiple patches?
> v6 -> v7:
> work on feedbacks from Alexander Duyck on XDP_TX and XDP_REDIRECT
> - fix memleak of xdp frame when doing ndo_xdp_xmit (vmxnet3_xdp_xmit)
> - at vmxnet3_xdp_xmit_frame, fix return value, -NOSPC and ENOMEM,
>   and free skb when dma map fails
> - add xdp_buff_clean_frags_flag since we don't support frag
> - update experiements of XDP_TX and XDP_REDIRECT
> - for XDP_REDIRECT, I assume calling xdp_do_redirect will take
> the buffer and free it, so I need to allocate a new buffer to
> refill the rx ring. However, I hit some OOM when testing using
> ./samples/bpf/xdp_redirect_cpu -d ens160 -c 0 -e <drop or pass>
> - I couldn't find the reason so mark this patch as RFC
> 
> 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/Kconfig                   |   1 +
>  drivers/net/vmxnet3/Makefile          |   2 +-
>  drivers/net/vmxnet3/vmxnet3_drv.c     | 156 +++++++++-
>  drivers/net/vmxnet3/vmxnet3_ethtool.c |  14 +
>  drivers/net/vmxnet3/vmxnet3_int.h     |  29 +-
>  drivers/net/vmxnet3/vmxnet3_xdp.c     | 415 ++++++++++++++++++++++++++
>  drivers/net/vmxnet3/vmxnet3_xdp.h     |  39 +++
>  7 files changed, 639 insertions(+), 17 deletions(-)
>  create mode 100644 drivers/net/vmxnet3/vmxnet3_xdp.c
>  create mode 100644 drivers/net/vmxnet3/vmxnet3_xdp.h
> 
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 9e63b8c43f3e..a4419d661bdd 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -571,6 +571,7 @@ config VMXNET3
>  	tristate "VMware VMXNET3 ethernet driver"
>  	depends on PCI && INET
>  	depends on PAGE_SIZE_LESS_THAN_64KB
> +	select PAGE_POOL
>  	help
>  	  This driver supports VMware's vmxnet3 virtual ethernet NIC.
>  	  To compile this driver as a module, choose M here: the
> 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..5ce5603542e7 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"
> @@ -332,9 +333,12 @@ vmxnet3_unmap_tx_buf(struct vmxnet3_tx_buf_info *tbi,
>  	else if (tbi->map_type == VMXNET3_MAP_PAGE)
>  		dma_unmap_page(&pdev->dev, tbi->dma_addr, tbi->len,
>  			       DMA_TO_DEVICE);
> +	else if (tbi->map_type == VMXNET3_MAP_PP_PAGE && tbi->xdpf)
> +		xdp_return_frame(tbi->xdpf);
> +	else if (tbi->map_type == VMXNET3_MAP_XDP_NDO && tbi->xdpf)
> +		xdp_return_frame(tbi->xdpf);
>  	else
>  		BUG_ON(tbi->map_type != VMXNET3_MAP_NONE);
> -
>  	tbi->map_type = VMXNET3_MAP_NONE; /* to help debugging */
>  }
>  

It looks like you forgot to unmap the buffer in the XDP_NDO case.

See my comment below, it might be worth while to use a bitmap for
map_type instead of just an enum.

> @@ -351,7 +355,6 @@ 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);
> @@ -587,7 +590,17 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
>  		gd = ring->base + ring->next2fill;
>  		rbi->comp_state = VMXNET3_RXD_COMP_PENDING;
>  
> -		if (rbi->buf_type == VMXNET3_RX_BUF_SKB) {
> +		if (rbi->buf_type == VMXNET3_RX_BUF_XDP) {
> +			void *data = vmxnet3_pp_get_buff(rq->page_pool,
> +							 &rbi->dma_addr,
> +							 GFP_KERNEL);
> +			if (!data) {
> +				rq->stats.rx_buf_alloc_failure++;
> +				break;
> +			}
> +			rbi->pp_page = virt_to_head_page(data);
> +			val = VMXNET3_RXD_BTYPE_HEAD << VMXNET3_RXD_BTYPE_SHIFT;
> +		} else if (rbi->buf_type == VMXNET3_RX_BUF_SKB) {
>  			if (rbi->skb == NULL) {
>  				rbi->skb = __netdev_alloc_skb_ip_align(adapter->netdev,
>  								       rbi->len,
> @@ -1253,6 +1266,46 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
>  	return NETDEV_TX_OK;
>  }
>  
> +static int
> +vmxnet3_create_pp(struct vmxnet3_adapter *adapter,
> +		  struct vmxnet3_rx_queue *rq, int size)
> +{
> +	struct page_pool_params pp_params = {
> +		.order = 0,
> +		.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
> +		.pool_size = size,
> +		.nid = NUMA_NO_NODE,
> +		.dev = &adapter->pdev->dev,
> +		.offset = XDP_PACKET_HEADROOM,
> +		.max_len = VMXNET3_XDP_MAX_MTU,
> +		.dma_dir = DMA_BIDIRECTIONAL,
> +	};
> +	struct page_pool *pp;
> +	int err;
> +

You mentioned a memcpy up above for XDP_TX in the patch description and
you are using DMA_BIDIRECTIONAL here. Looking at the code it looks like
you are transmitting the original frame now so you probably need to
update the patch description.

> +	pp = page_pool_create(&pp_params);
> +	if (IS_ERR(pp))
> +		return PTR_ERR(pp);
> +
> +	err = xdp_rxq_info_reg(&rq->xdp_rxq, adapter->netdev, rq->qid,
> +			       rq->napi.napi_id);
> +	if (err < 0)
> +		goto err_free_pp;
> +
> +	err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq, MEM_TYPE_PAGE_POOL, pp);
> +	if (err)
> +		goto err_unregister_rxq;
> +
> +	rq->page_pool = pp;
> +	return 0;
> +
> +err_unregister_rxq:
> +	xdp_rxq_info_unreg(&rq->xdp_rxq);
> +err_free_pp:
> +	page_pool_destroy(pp);
> +
> +	return err;
> +}
>  
>  static netdev_tx_t
>  vmxnet3_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
> @@ -1265,6 +1318,27 @@ vmxnet3_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
>  			       adapter, netdev);
>  }
>  
> +void *
> +vmxnet3_pp_get_buff(struct page_pool *pp, dma_addr_t *dma_addr,
> +		    gfp_t gfp_mask)
> +{
> +	struct page *page;
> +
> +	page = page_pool_alloc_pages(pp, gfp_mask | __GFP_NOWARN);
> +	if (!page)
> +		return NULL;
> +
> +	*dma_addr = page_pool_get_dma_addr(page) + XDP_PACKET_HEADROOM;
> +	return page_address(page);
> +}
> +
> +static void
> +vmxnet3_pp_put_buff(struct vmxnet3_rx_queue *rq, struct page *page)
> +{
> +	if (rq->page_pool)
> +		page_pool_put_full_page(rq->page_pool, page,
> +					rq->napi.napi_id);
> +}
>  
>  static void
>  vmxnet3_rx_csum(struct vmxnet3_adapter *adapter,
> @@ -1404,6 +1478,8 @@ 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 +1520,31 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
>  			goto rcd_done;
>  		}
>  
> +		if (rcd->sop && rcd->eop && adapter->xdp_enabled) {
> +			struct sk_buff *skb_xdp_pass;
> +			int act;
> +
> +			if (rbi->buf_type != VMXNET3_RX_BUF_XDP)
> +				goto rcd_done;
> +
> +			if (VMXNET3_RX_DATA_RING(adapter, rcd->rqID)) {
> +				netdev_warn(adapter->netdev,
> +					    "Rx data ring not support XDP\n");
> +				break;
> +			}
> +
> +			act = vmxnet3_process_xdp(adapter, rq, rcd, rbi, rxd,
> +						  &skb_xdp_pass);
> +			if (act == XDP_PASS) {
> +				ctx->skb = skb_xdp_pass;
> +				goto sop_done;
> +			}
> +			ctx->skb = NULL;
> +			if (act == XDP_REDIRECT)
> +				need_flush = true;
> +			goto rcd_done;
> +		}
> +
>  		if (rcd->sop) { /* first buf of the pkt */
>  			bool rxDataRingUsed;
>  			u16 len;
> @@ -1485,9 +1586,7 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
>  
>  			if (rxDataRingUsed) {
>  				size_t sz;
> -
>  				BUG_ON(rcd->len > rq->data_ring.desc_size);
> -
>  				ctx->skb = new_skb;
>  				sz = rcd->rxdIdx * rq->data_ring.desc_size;
>  				memcpy(new_skb->data,

You should keep the space between the variable declaration and the
BUG_ON.

> @@ -1621,7 +1720,7 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
>  			}
>  		}
>  
> -
> +sop_done:
>  		skb = ctx->skb;
>  		if (rcd->eop) {
>  			u32 mtu = adapter->netdev->mtu;
> @@ -1730,6 +1829,8 @@ 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;
>  }
> @@ -1753,8 +1854,14 @@ vmxnet3_rq_cleanup(struct vmxnet3_rx_queue *rq,
>  #endif
>  			vmxnet3_getRxDesc(rxd,
>  				&rq->rx_ring[ring_idx].base[i].rxd, &rxDesc);
> -
>  			if (rxd->btype == VMXNET3_RXD_BTYPE_HEAD &&
> +			    rq->buf_info[ring_idx][i].pp_page &&
> +			    rq->buf_info[ring_idx][i].buf_type ==
> +							VMXNET3_RX_BUF_XDP) {
> +				vmxnet3_pp_put_buff(rq,
> +						    rq->buf_info[ring_idx][i].pp_page);
> +				rq->buf_info[ring_idx][i].pp_page = NULL;
> +			} else if (rxd->btype == VMXNET3_RXD_BTYPE_HEAD &&
>  					rq->buf_info[ring_idx][i].skb) {
>  				dma_unmap_single(&adapter->pdev->dev, rxd->addr,
>  						 rxd->len, DMA_FROM_DEVICE);
> @@ -1786,9 +1893,9 @@ vmxnet3_rq_cleanup_all(struct vmxnet3_adapter *adapter)
>  
>  	for (i = 0; i < adapter->num_rx_queues; i++)
>  		vmxnet3_rq_cleanup(&adapter->rx_queue[i], adapter);
> +	adapter->xdp_bpf_prog = NULL;
>  }
>  
> -
>  static void vmxnet3_rq_destroy(struct vmxnet3_rx_queue *rq,
>  			       struct vmxnet3_adapter *adapter)
>  {
> @@ -1815,6 +1922,13 @@ static void vmxnet3_rq_destroy(struct vmxnet3_rx_queue *rq,
>  		}
>  	}
>  
> +	if (rq->page_pool) {
> +		if (xdp_rxq_info_is_reg(&rq->xdp_rxq))
> +			xdp_rxq_info_unreg(&rq->xdp_rxq);
> +		page_pool_destroy(rq->page_pool);
> +		rq->page_pool = NULL;
> +	}
> +
>  	if (rq->data_ring.base) {
>  		dma_free_coherent(&adapter->pdev->dev,
>  				  rq->rx_ring[0].size * rq->data_ring.desc_size,
> @@ -1858,14 +1972,15 @@ static int
>  vmxnet3_rq_init(struct vmxnet3_rx_queue *rq,
>  		struct vmxnet3_adapter  *adapter)
>  {
> -	int i;
> +	int i, err = 0;
>  
>  	/* initialize buf_info */
>  	for (i = 0; i < rq->rx_ring[0].size; i++) {
>  
>  		/* 1st buf for a pkt is skbuff */
>  		if (i % adapter->rx_buf_per_pkt == 0) {
> -			rq->buf_info[0][i].buf_type = VMXNET3_RX_BUF_SKB;
> +			rq->buf_info[0][i].buf_type = adapter->xdp_enabled ?
> +				VMXNET3_RX_BUF_XDP : VMXNET3_RX_BUF_SKB;
>  			rq->buf_info[0][i].len = adapter->skb_buf_size;
>  		} else { /* subsequent bufs for a pkt is frag */
>  			rq->buf_info[0][i].buf_type = VMXNET3_RX_BUF_PAGE;
> @@ -1886,11 +2001,18 @@ vmxnet3_rq_init(struct vmxnet3_rx_queue *rq,
>  		rq->rx_ring[i].gen = VMXNET3_INIT_GEN;
>  		rq->rx_ring[i].isOutOfOrder = 0;
>  	}
> +
> +	err = vmxnet3_create_pp(adapter, rq,
> +				rq->rx_ring[0].size + rq->rx_ring[1].size);
> +	if (err)
> +		return err;
> +
>  	if (vmxnet3_rq_alloc_rx_buf(rq, 0, rq->rx_ring[0].size - 1,
>  				    adapter) == 0) {
>  		/* at least has 1 rx buffer for the 1st ring */
>  		return -ENOMEM;
>  	}
> +
>  	vmxnet3_rq_alloc_rx_buf(rq, 1, rq->rx_ring[1].size - 1, adapter);
>  
>  	/* reset the comp ring */
> @@ -1989,7 +2111,7 @@ 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 +2707,8 @@ 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 +3149,7 @@ 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 +3158,8 @@ 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 +3687,6 @@ 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 +3708,8 @@ 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 +4025,7 @@ 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..4c41ceecf785 100644
> --- a/drivers/net/vmxnet3/vmxnet3_int.h
> +++ b/drivers/net/vmxnet3/vmxnet3_int.h
> @@ -56,6 +56,9 @@
>  #include <linux/if_arp.h>
>  #include <linux/inetdevice.h>
>  #include <linux/log2.h>
> +#include <linux/bpf.h>
> +#include <linux/skbuff.h>
> +#include <net/page_pool.h>
>  
>  #include "vmxnet3_defs.h"
>  
> @@ -193,6 +196,8 @@ enum vmxnet3_buf_map_type {
>  	VMXNET3_MAP_NONE,
>  	VMXNET3_MAP_SINGLE,
>  	VMXNET3_MAP_PAGE,
> +	VMXNET3_MAP_PP_PAGE, /* Page pool */
> +	VMXNET3_MAP_XDP_NDO,
>  };
>  

One thing you might look at doing here would be to consider making this
a bitfield rather than just using integer types. You could then do
something to the effect of:
Bit	Value
0	MAP_SINGLE
1	MAP_PAGE
2	XDP

Then you won't need as many if statements as you can quickly identify
if you are dealing with an sk_buff or an xdp_frame and the unmapping
could be streamlined as it becomes more of a decision tree rather than
having to hammer through each value sequentially.

>  struct vmxnet3_tx_buf_info {
> @@ -201,6 +206,7 @@ struct vmxnet3_tx_buf_info {
>  	u16      sop_idx;
>  	dma_addr_t  dma_addr;
>  	struct sk_buff *skb;
> +	struct xdp_frame *xdpf;
>  };
>  

To save yourself space you might want to make this an anonymous union
with skb, assuming you are triggering on MAP_TYPE and not just the
pointers themselves.

>  struct vmxnet3_tq_driver_stats {
> @@ -217,6 +223,9 @@ 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 {
> @@ -258,7 +267,8 @@ struct vmxnet3_tx_queue {
>  enum vmxnet3_rx_buf_type {
>  	VMXNET3_RX_BUF_NONE = 0,
>  	VMXNET3_RX_BUF_SKB = 1,
> -	VMXNET3_RX_BUF_PAGE = 2
> +	VMXNET3_RX_BUF_PAGE = 2,
> +	VMXNET3_RX_BUF_XDP = 3
>  };
>  
>  #define VMXNET3_RXD_COMP_PENDING        0
> @@ -271,6 +281,7 @@ struct vmxnet3_rx_buf_info {
>  	union {
>  		struct sk_buff *skb;
>  		struct page    *page;
> +		struct page    *pp_page;
>  	};
>  	dma_addr_t dma_addr;
>  };
> @@ -285,6 +296,12 @@ 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 +324,8 @@ struct vmxnet3_rx_queue {
>  	struct vmxnet3_rx_buf_info     *buf_info[2];
>  	struct Vmxnet3_RxQueueCtrl            *shared;
>  	struct vmxnet3_rq_driver_stats  stats;
> +	struct xdp_rxq_info xdp_rxq;
> +	struct page_pool *page_pool;
>  } __attribute__((__aligned__(SMP_CACHE_BYTES)));
>  
>  #define VMXNET3_DEVICE_MAX_TX_QUEUES 32
> @@ -415,6 +434,8 @@ struct vmxnet3_adapter {
>  	u16    tx_prod_offset;
>  	u16    rx_prod_offset;
>  	u16    rx_prod2_offset;
> +	bool   xdp_enabled;
> +	struct bpf_prog __rcu *xdp_bpf_prog;
>  };
>  
>  #define VMXNET3_WRITE_BAR0_REG(adapter, reg, val)  \
> @@ -490,6 +511,12 @@ 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..d38394ffd98a
> --- /dev/null
> +++ b/drivers/net/vmxnet3/vmxnet3_xdp.c
> @@ -0,0 +1,415 @@
> +// 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)
> +{
> +	rcu_assign_pointer(adapter->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].adapter->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, bool dma_map)
> +{
> +	struct vmxnet3_tx_buf_info *tbi = NULL;
> +	union Vmxnet3_GenericDesc *gdesc;
> +	struct vmxnet3_tx_ctx ctx;
> +	int tx_num_deferred;
> +	struct page *page;
> +	u32 buf_size;
> +	int ret = 0;
> +	u32 dw2;
> +
> +	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;
> +
> +	if (vmxnet3_cmd_ring_desc_avail(&tq->tx_ring) == 0) {
> +		tq->stats.tx_ring_full++;
> +		ret = -ENOSPC;
> +		goto exit;
> +	}
> +
> +	if (dma_map) { /* ndo_xdp_xmit */
> +		tbi->map_type = VMXNET3_MAP_XDP_NDO;
> +		tbi->dma_addr = dma_map_single(&adapter->pdev->dev,
> +				       xdpf->data, buf_size,
> +				       DMA_TO_DEVICE);
> +		if (dma_mapping_error(&adapter->pdev->dev, tbi->dma_addr)) {
> +			ret = -EFAULT;
> +			goto exit;
> +		}
> +		tbi->xdpf = xdpf;
> +	} else { /* XDP buffer from page pool */
> +		tbi->map_type = VMXNET3_MAP_PP_PAGE;
> +		page = virt_to_head_page(xdpf->data);
> +		tbi->dma_addr = page_pool_get_dma_addr(page) +
> +				XDP_PACKET_HEADROOM;
> +		dma_sync_single_for_device(&adapter->pdev->dev,
> +					   tbi->dma_addr, buf_size,
> +					   DMA_BIDIRECTIONAL);
> +		tbi->skb = NULL;
> +		tbi->xdpf = xdpf;
> +	}
> +	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->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, false);
> +	__netif_tx_unlock(nq);
> +	return err;
> +}
> +
> +/* ndo_xdp_xmit */
> +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 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 possible you may want to avoid the modulus operation as it costs a
signficant number of cycles. You may be better off either doing it
conditionally if you normally expect tq_number > cpu or using
reciprocal_scale like we do in skb_tx_hash if you expect it to occur
more often.

> +	if (tq->stopped)
> +		return -ENETDOWN;
> +
> +	nq = netdev_get_tx_queue(adapter->netdev, tq->qid);
> +
> +	for (i = 0; i < n; i++) {
> +		err = vmxnet3_xdp_xmit_frame(adapter, frames[i], tq, true);
> +		if (err) {
> +			tq->stats.xdp_xmit_err++;
> +			break;
> +		}
> +	}
> +	tq->stats.xdp_xmit += i;
> +
> +	return i;
> +}
> +
> +static int
> +vmxnet3_run_xdp(struct vmxnet3_rx_queue *rq, struct xdp_buff *xdp)
> +{
> +	struct xdp_frame *xdpf;
> +	int err;
> +	u32 act;
> +
> +	act = bpf_prog_run_xdp(rq->adapter->xdp_bpf_prog, xdp);
> +	rq->stats.xdp_packets++;
> +
> +	switch (act) {
> +	case XDP_PASS:
> +		goto out;
> +	case XDP_REDIRECT:
> +		err = xdp_do_redirect(rq->adapter->netdev, xdp,
> +				      rq->adapter->xdp_bpf_prog);
> +		if (!err)
> +			rq->stats.xdp_redirects++;
> +		else
> +			rq->stats.xdp_drops++;
> +		goto out;
> +	case XDP_TX:
> +		xdpf = xdp_convert_buff_to_frame(xdp);
> +		if (!xdpf || vmxnet3_xdp_xmit_back(rq->adapter, xdpf)) {
> +			rq->stats.xdp_drops++;
> +			goto out_recycle;
> +		}
> +		rq->stats.xdp_tx++;
> +		goto out;
> +	default:
> +		bpf_warn_invalid_xdp_action(rq->adapter->netdev,
> +					    rq->adapter->xdp_bpf_prog, act);
> +		fallthrough;
> +	case XDP_ABORTED:
> +		trace_xdp_exception(rq->adapter->netdev,
> +				    rq->adapter->xdp_bpf_prog, act);
> +		rq->stats.xdp_aborted++;
> +		break;
> +	case XDP_DROP:
> +		rq->stats.xdp_drops++;
> +		break;
> +	}
> +
> +out_recycle:
> +	page_pool_recycle_direct(rq->page_pool,
> +				 virt_to_head_page(xdp->data_hard_start));
> +out:
> +	return act;
> +}
> +
> +static struct sk_buff *
> +vmxnet3_build_skb(struct vmxnet3_rx_queue *rq, struct page *page)
> +{
> +	struct sk_buff *skb;
> +
> +	if (!page)
> +		return NULL;
> +
> +	skb = build_skb(page_address(page), PAGE_SIZE);
> +	if (unlikely(!skb)) {
> +		page_pool_put_full_page(rq->page_pool, page, true);
> +		rq->stats.rx_buf_alloc_failure++;
> +		return NULL;
> +	}
> +	return skb;
> +}
> +
> +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,
> +		    struct sk_buff **skb_xdp_pass)
> +{
> +	struct bpf_prog *xdp_prog;
> +	dma_addr_t new_dma_addr;
> +	struct sk_buff *skb;
> +	struct xdp_buff xdp;
> +	struct page *page;
> +	void *new_data;
> +	int act;
> +
> +	act = XDP_DROP;
> +	if (unlikely(rcd->len == 0))
> +		goto refill;
> +
> +	page = rbi->pp_page;
> +	if (!page)
> +		goto refill;

This should be some sort of bug shouldn't it? I would think you
shouldn't be processing a buffer if there isn't a page on it already.
If I am not mistaken at this point the hardware has already set sop/eop
on the RCD so that means there was a page there doesn't it?

> +
> +	dma_sync_single_for_cpu(&adapter->pdev->dev,
> +				page_pool_get_dma_addr(page) +
> +				XDP_PACKET_HEADROOM,
> +				rcd->len,
> +				page_pool_get_dma_dir(rq->page_pool));
> +
> +	xdp_init_buff(&xdp, rbi->len, &rq->xdp_rxq);
> +	xdp_prepare_buff(&xdp, page_address(page), XDP_PACKET_HEADROOM,
> +			 rcd->len, false);
> +	xdp_buff_clear_frags_flag(&xdp);
> +
> +	rcu_read_lock();
> +	xdp_prog = rcu_dereference(rq->adapter->xdp_bpf_prog);
> +	if (!xdp_prog) {
> +		rcu_read_unlock();
> +		act = XDP_PASS;
> +		goto refill;
> +	}
> +	act = vmxnet3_run_xdp(rq, &xdp);
> +	rcu_read_unlock();
> +
> +	if (act == XDP_PASS) {
> +		skb = vmxnet3_build_skb(rq, page);
> +		if (!skb) {
> +			rq->stats.rx_buf_alloc_failure++;
> +			page_pool_recycle_direct(rq->page_pool, page);
> +			goto refill;
> +		}
> +
> +		/* bpf prog might change len and data position. */
> +		skb_reserve(skb, xdp.data - xdp.data_hard_start);
> +		skb_put(skb, xdp.data_end - xdp.data);
> +		skb_mark_for_recycle(skb);
> +		/* Pass this skb to the main rx loop. */
> +		*skb_xdp_pass = skb;
> +	}
> +
> +refill:
> +	new_data = vmxnet3_pp_get_buff(rq->page_pool, &new_dma_addr,
> +				       GFP_KERNEL);
> +	if (!new_data) {
> +		rq->stats.rx_buf_alloc_failure++;
> +		return XDP_DROP;
> +	}
> +	rbi->pp_page = virt_to_head_page(new_data);
> +	rbi->dma_addr = new_dma_addr;
> +	rxd->addr = cpu_to_le64(rbi->dma_addr);
> +	rxd->len = rbi->len;
> +	return act;
> +}
> diff --git a/drivers/net/vmxnet3/vmxnet3_xdp.h b/drivers/net/vmxnet3/vmxnet3_xdp.h
> new file mode 100644
> index 000000000000..cac4c9b82c93
> --- /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/page_pool.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 (PAGE_SIZE - VMXNET3_XDP_ROOM)
> +
> +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,
> +			struct sk_buff **skb_xdp_pass);
> +void *vmxnet3_pp_get_buff(struct page_pool *pp, dma_addr_t *dma_addr,
> +			  gfp_t gfp_mask);
> +#endif

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