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Message-Id: <20240924013204.13763-8-xuanzhuo@linux.alibaba.com>
Date: Tue, 24 Sep 2024 09:31:59 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: netdev@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
virtualization@...ts.linux.dev,
bpf@...r.kernel.org
Subject: [RFC net-next v1 07/12] virtio_net: refactor the xmit type
Because the af-xdp will introduce a new xmit type, so I refactor the
xmit type mechanism first.
In general, pointers are aligned to 4 or 8 bytes. If it is aligned to 4
bytes, then only two bits are free for a pointer. But there are 4 types
here, so we can't use bits to distinguish them. And 2 bits is enough for
4 types:
00 for skb
01 for SKB_ORPHAN
10 for XDP
11 for af-xdp tx
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
drivers/net/virtio_net.c | 90 +++++++++++++++++++++++-----------------
1 file changed, 51 insertions(+), 39 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 630e5b21ad69..41a5ea9b788d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -45,9 +45,6 @@ module_param(napi_tx, bool, 0644);
#define VIRTIO_XDP_TX BIT(0)
#define VIRTIO_XDP_REDIR BIT(1)
-#define VIRTIO_XDP_FLAG BIT(0)
-#define VIRTIO_ORPHAN_FLAG BIT(1)
-
/* RX packet size EWMA. The average packet size is used to determine the packet
* buffer size when refilling RX rings. As the entire RX ring may be refilled
* at once, the weight is chosen so that the EWMA will be insensitive to short-
@@ -512,34 +509,35 @@ static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
struct page *page, void *buf,
int len, int truesize);
-static bool is_xdp_frame(void *ptr)
-{
- return (unsigned long)ptr & VIRTIO_XDP_FLAG;
-}
+enum virtnet_xmit_type {
+ VIRTNET_XMIT_TYPE_SKB,
+ VIRTNET_XMIT_TYPE_SKB_ORPHAN,
+ VIRTNET_XMIT_TYPE_XDP,
+};
-static void *xdp_to_ptr(struct xdp_frame *ptr)
-{
- return (void *)((unsigned long)ptr | VIRTIO_XDP_FLAG);
-}
+/* We use the last two bits of the pointer to distinguish the xmit type. */
+#define VIRTNET_XMIT_TYPE_MASK (BIT(0) | BIT(1))
-static struct xdp_frame *ptr_to_xdp(void *ptr)
+static enum virtnet_xmit_type virtnet_xmit_ptr_strip(void **ptr)
{
- return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
-}
+ unsigned long p = (unsigned long)*ptr;
-static bool is_orphan_skb(void *ptr)
-{
- return (unsigned long)ptr & VIRTIO_ORPHAN_FLAG;
+ *ptr = (void *)(p & ~VIRTNET_XMIT_TYPE_MASK);
+
+ return p & VIRTNET_XMIT_TYPE_MASK;
}
-static void *skb_to_ptr(struct sk_buff *skb, bool orphan)
+static void *virtnet_xmit_ptr_mix(void *ptr, enum virtnet_xmit_type type)
{
- return (void *)((unsigned long)skb | (orphan ? VIRTIO_ORPHAN_FLAG : 0));
+ return (void *)((unsigned long)ptr | type);
}
-static struct sk_buff *ptr_to_skb(void *ptr)
+static int virtnet_add_outbuf(struct send_queue *sq, int num, void *data,
+ enum virtnet_xmit_type type)
{
- return (struct sk_buff *)((unsigned long)ptr & ~VIRTIO_ORPHAN_FLAG);
+ return virtqueue_add_outbuf(sq->vq, sq->sg, num,
+ virtnet_xmit_ptr_mix(data, type),
+ GFP_ATOMIC);
}
static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
@@ -552,29 +550,37 @@ static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
static void __free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
bool in_napi, struct virtnet_sq_free_stats *stats)
{
+ struct xdp_frame *frame;
+ struct sk_buff *skb;
unsigned int len;
void *ptr;
while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
- if (!is_xdp_frame(ptr)) {
- struct sk_buff *skb = ptr_to_skb(ptr);
+ switch (virtnet_xmit_ptr_strip(&ptr)) {
+ case VIRTNET_XMIT_TYPE_SKB:
+ skb = ptr;
pr_debug("Sent skb %p\n", skb);
+ stats->napi_packets++;
+ stats->napi_bytes += skb->len;
+ napi_consume_skb(skb, in_napi);
+ break;
- if (is_orphan_skb(ptr)) {
- stats->packets++;
- stats->bytes += skb->len;
- } else {
- stats->napi_packets++;
- stats->napi_bytes += skb->len;
- }
+ case VIRTNET_XMIT_TYPE_SKB_ORPHAN:
+ skb = ptr;
+
+ stats->packets++;
+ stats->bytes += skb->len;
napi_consume_skb(skb, in_napi);
- } else {
- struct xdp_frame *frame = ptr_to_xdp(ptr);
+ break;
+
+ case VIRTNET_XMIT_TYPE_XDP:
+ frame = ptr;
stats->packets++;
stats->bytes += xdp_get_frame_len(frame);
xdp_return_frame(frame);
+ break;
}
}
netdev_tx_completed_queue(txq, stats->napi_packets, stats->napi_bytes);
@@ -1431,8 +1437,7 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
skb_frag_size(frag), skb_frag_off(frag));
}
- err = virtqueue_add_outbuf(sq->vq, sq->sg, nr_frags + 1,
- xdp_to_ptr(xdpf), GFP_ATOMIC);
+ err = virtnet_add_outbuf(sq, nr_frags + 1, xdpf, VIRTNET_XMIT_TYPE_XDP);
if (unlikely(err))
return -ENOSPC; /* Caller handle free/refcnt */
@@ -3040,8 +3045,9 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb, bool orphan)
return num_sg;
num_sg++;
}
- return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg,
- skb_to_ptr(skb, orphan), GFP_ATOMIC);
+
+ return virtnet_add_outbuf(sq, num_sg, skb,
+ orphan ? VIRTNET_XMIT_TYPE_SKB_ORPHAN : VIRTNET_XMIT_TYPE_SKB);
}
static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -5918,10 +5924,16 @@ static void free_receive_page_frags(struct virtnet_info *vi)
static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
{
- if (!is_xdp_frame(buf))
+ switch (virtnet_xmit_ptr_strip(&buf)) {
+ case VIRTNET_XMIT_TYPE_SKB:
+ case VIRTNET_XMIT_TYPE_SKB_ORPHAN:
dev_kfree_skb(buf);
- else
- xdp_return_frame(ptr_to_xdp(buf));
+ break;
+
+ case VIRTNET_XMIT_TYPE_XDP:
+ xdp_return_frame(buf);
+ break;
+ }
}
static void free_unused_bufs(struct virtnet_info *vi)
--
2.32.0.3.g01195cf9f
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