Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On 6/3/25 09:56, Jason Wang wrote:
On Thu, May 29, 2025 at 8:28 PM Bui Quang Minh wrote:
On 5/29/25 12:59, Jason Wang wrote:
On Wed, May 28, 2025 at 12:19 AM Bui Quang Minh
wrote:
Currently, in zerocopy mode with mergeable receive buffer, virtio-net
does not support multi buffer but a single buffer only. This commit adds
support for multi mergeable receive buffer in the zerocopy XDP path by
utilizing XDP buffer with frags.
Signed-off-by: Bui Quang Minh
---
drivers/net/virtio_net.c | 123 +--
1 file changed, 66 insertions(+), 57 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..a9558650f205 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
#define VIRTIO_XDP_TX BIT(0)
#define VIRTIO_XDP_REDIR BIT(1)
+#define VIRTNET_MAX_ZC_SEGS8
+
/* 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-
@@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct net_device *dev,
}
}
-static int xsk_append_merge_buffer(struct virtnet_info *vi,
- struct receive_queue *rq,
- struct sk_buff *head_skb,
- u32 num_buf,
- struct virtio_net_hdr_mrg_rxbuf *hdr,
- struct virtnet_rq_stats *stats)
+static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
+ struct receive_queue *rq,
+ u32 num_buf,
+ struct xdp_buff *xdp,
+ struct virtnet_rq_stats *stats)
{
- struct sk_buff *curr_skb;
- struct xdp_buff *xdp;
- u32 len, truesize;
- struct page *page;
+ unsigned int len;
void *buf;
- curr_skb = head_skb;
+ if (num_buf < 2)
+ return 0;
+
+ while (num_buf > 1) {
+ struct xdp_buff *new_xdp;
- while (--num_buf) {
buf = virtqueue_get_buf(rq->vq, &len);
- if (unlikely(!buf)) {
- pr_debug("%s: rx error: %d buffers out of %d missing\n",
-vi->dev->name, num_buf,
-virtio16_to_cpu(vi->vdev,
-hdr->num_buffers));
+ if (!unlikely(buf)) {
+ pr_debug("%s: rx error: %d buffers missing\n",
+vi->dev->name, num_buf);
DEV_STATS_INC(vi->dev, rx_length_errors);
- return -EINVAL;
- }
-
- u64_stats_add(&stats->bytes, len);
-
- xdp = buf_to_xdp(vi, rq, buf, len);
- if (!xdp)
- goto err;
-
- buf = napi_alloc_frag(len);
- if (!buf) {
- xsk_buff_free(xdp);
- goto err;
+ return -1;
}
- memcpy(buf, xdp->data - vi->hdr_len, len);
-
- xsk_buff_free(xdp);
+ new_xdp = buf_to_xdp(vi, rq, buf, len);
+ if (!new_xdp)
+ goto drop_bufs;
- page = virt_to_page(buf);
+ /* In virtnet_add_recvbuf_xsk(), we ask the host to fill from
+* xdp->data - vi->hdr_len with both virtio_net_hdr and data.
+* However, only the first packet has the virtio_net_hdr, the
+* following ones do not. So we need to adjust the following
Typo here.
I'm sorry, could you clarify which word contains the typo?
+* packets' data pointer to the correct place.
+*/
I wonder what happens if we don't use this trick? I meant we don't
reuse the header room for the virtio-net header. This seems to be fine
for a mergeable buffer and can help to reduce the trick.
I don't think using the header room for virtio-net header creates this
case handling. In my opinion, it comes from the slightly difference in
the recvbuf between single buffer and multi-buffer. When we have n
single-buffer packets, each buffer will have its own virtio-net header.
But when we have 1 multi-buffer packet (which spans across n buffers),
only the first buffer has virtio-net header, the following buffers do not.
There 2 important pointers here. The pointer we announce to the vhost
side to fill the data, let's call it announced_addr, and xdp_buff->data
which is expected to point the the start of Ethernet frame. Currently,
announced_addr = xdp_buff->data - hdr_len
The host side will write the
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
Tested this patch with virtio-net regression tests, everything works fine.
Tested-by: Lei Yang
On Tue, Jun 3, 2025 at 10:57 AM Jason Wang wrote:
>
> On Thu, May 29, 2025 at 8:28 PM Bui Quang Minh
> wrote:
> >
> > On 5/29/25 12:59, Jason Wang wrote:
> > > On Wed, May 28, 2025 at 12:19 AM Bui Quang Minh
> > > wrote:
> > >> Currently, in zerocopy mode with mergeable receive buffer, virtio-net
> > >> does not support multi buffer but a single buffer only. This commit adds
> > >> support for multi mergeable receive buffer in the zerocopy XDP path by
> > >> utilizing XDP buffer with frags.
> > >>
> > >> Signed-off-by: Bui Quang Minh
> > >> ---
> > >> drivers/net/virtio_net.c | 123 +--
> > >> 1 file changed, 66 insertions(+), 57 deletions(-)
> > >>
> > >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > >> index e53ba600605a..a9558650f205 100644
> > >> --- a/drivers/net/virtio_net.c
> > >> +++ b/drivers/net/virtio_net.c
> > >> @@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
> > >> #define VIRTIO_XDP_TX BIT(0)
> > >> #define VIRTIO_XDP_REDIR BIT(1)
> > >>
> > >> +#define VIRTNET_MAX_ZC_SEGS8
> > >> +
> > >> /* 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-
> > >> @@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct
> > >> net_device *dev,
> > >> }
> > >> }
> > >>
> > >> -static int xsk_append_merge_buffer(struct virtnet_info *vi,
> > >> - struct receive_queue *rq,
> > >> - struct sk_buff *head_skb,
> > >> - u32 num_buf,
> > >> - struct virtio_net_hdr_mrg_rxbuf *hdr,
> > >> - struct virtnet_rq_stats *stats)
> > >> +static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
> > >> + struct receive_queue *rq,
> > >> + u32 num_buf,
> > >> + struct xdp_buff *xdp,
> > >> + struct virtnet_rq_stats *stats)
> > >> {
> > >> - struct sk_buff *curr_skb;
> > >> - struct xdp_buff *xdp;
> > >> - u32 len, truesize;
> > >> - struct page *page;
> > >> + unsigned int len;
> > >> void *buf;
> > >>
> > >> - curr_skb = head_skb;
> > >> + if (num_buf < 2)
> > >> + return 0;
> > >> +
> > >> + while (num_buf > 1) {
> > >> + struct xdp_buff *new_xdp;
> > >>
> > >> - while (--num_buf) {
> > >> buf = virtqueue_get_buf(rq->vq, &len);
> > >> - if (unlikely(!buf)) {
> > >> - pr_debug("%s: rx error: %d buffers out of %d
> > >> missing\n",
> > >> -vi->dev->name, num_buf,
> > >> -virtio16_to_cpu(vi->vdev,
> > >> -hdr->num_buffers));
> > >> + if (!unlikely(buf)) {
> > >> + pr_debug("%s: rx error: %d buffers missing\n",
> > >> +vi->dev->name, num_buf);
> > >> DEV_STATS_INC(vi->dev, rx_length_errors);
> > >> - return -EINVAL;
> > >> - }
> > >> -
> > >> - u64_stats_add(&stats->bytes, len);
> > >> -
> > >> - xdp = buf_to_xdp(vi, rq, buf, len);
> > >> - if (!xdp)
> > >> - goto err;
> > >> -
> > >> - buf = napi_alloc_frag(len);
> > >> - if (!buf) {
> > >> - xsk_buff_free(xdp);
> > >> - goto err;
> > >> + return -1;
> > >> }
> > >>
> > >> - memcpy(buf, xdp->data - vi->hdr_len, len);
> > >> -
> > >> - xsk_buff_free(xdp);
> > >> + new_xdp = buf_to_xdp(vi, rq, buf, len);
> > >> + if (!new_xdp)
> > >> + goto drop_bufs;
> > >>
> > >> - page = virt_to_page(buf);
> > >> + /* In virtnet_add_recvbuf_xsk(), we ask the host to fill
> > >> from
> > >> +* xdp->data - vi->hdr_len with both virtio_net_hdr and
> > >> data.
> > >> +* However, only the first packet has the
> > >> virtio_net_hdr, the
> > >> +* following ones do not. So we need to adjust the
> > >> following
> > > Typo here.
> >
> > I'm sorry, could you clarify which word contains the typo?
> >
> > >
> > >> +* packets' data pointer to the correct place.
> > >> +*/
> > > I wonder what happens if we don't use this trick?
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On Thu, May 29, 2025 at 8:28 PM Bui Quang Minh wrote:
>
> On 5/29/25 12:59, Jason Wang wrote:
> > On Wed, May 28, 2025 at 12:19 AM Bui Quang Minh
> > wrote:
> >> Currently, in zerocopy mode with mergeable receive buffer, virtio-net
> >> does not support multi buffer but a single buffer only. This commit adds
> >> support for multi mergeable receive buffer in the zerocopy XDP path by
> >> utilizing XDP buffer with frags.
> >>
> >> Signed-off-by: Bui Quang Minh
> >> ---
> >> drivers/net/virtio_net.c | 123 +--
> >> 1 file changed, 66 insertions(+), 57 deletions(-)
> >>
> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> >> index e53ba600605a..a9558650f205 100644
> >> --- a/drivers/net/virtio_net.c
> >> +++ b/drivers/net/virtio_net.c
> >> @@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
> >> #define VIRTIO_XDP_TX BIT(0)
> >> #define VIRTIO_XDP_REDIR BIT(1)
> >>
> >> +#define VIRTNET_MAX_ZC_SEGS8
> >> +
> >> /* 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-
> >> @@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct net_device
> >> *dev,
> >> }
> >> }
> >>
> >> -static int xsk_append_merge_buffer(struct virtnet_info *vi,
> >> - struct receive_queue *rq,
> >> - struct sk_buff *head_skb,
> >> - u32 num_buf,
> >> - struct virtio_net_hdr_mrg_rxbuf *hdr,
> >> - struct virtnet_rq_stats *stats)
> >> +static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
> >> + struct receive_queue *rq,
> >> + u32 num_buf,
> >> + struct xdp_buff *xdp,
> >> + struct virtnet_rq_stats *stats)
> >> {
> >> - struct sk_buff *curr_skb;
> >> - struct xdp_buff *xdp;
> >> - u32 len, truesize;
> >> - struct page *page;
> >> + unsigned int len;
> >> void *buf;
> >>
> >> - curr_skb = head_skb;
> >> + if (num_buf < 2)
> >> + return 0;
> >> +
> >> + while (num_buf > 1) {
> >> + struct xdp_buff *new_xdp;
> >>
> >> - while (--num_buf) {
> >> buf = virtqueue_get_buf(rq->vq, &len);
> >> - if (unlikely(!buf)) {
> >> - pr_debug("%s: rx error: %d buffers out of %d
> >> missing\n",
> >> -vi->dev->name, num_buf,
> >> -virtio16_to_cpu(vi->vdev,
> >> -hdr->num_buffers));
> >> + if (!unlikely(buf)) {
> >> + pr_debug("%s: rx error: %d buffers missing\n",
> >> +vi->dev->name, num_buf);
> >> DEV_STATS_INC(vi->dev, rx_length_errors);
> >> - return -EINVAL;
> >> - }
> >> -
> >> - u64_stats_add(&stats->bytes, len);
> >> -
> >> - xdp = buf_to_xdp(vi, rq, buf, len);
> >> - if (!xdp)
> >> - goto err;
> >> -
> >> - buf = napi_alloc_frag(len);
> >> - if (!buf) {
> >> - xsk_buff_free(xdp);
> >> - goto err;
> >> + return -1;
> >> }
> >>
> >> - memcpy(buf, xdp->data - vi->hdr_len, len);
> >> -
> >> - xsk_buff_free(xdp);
> >> + new_xdp = buf_to_xdp(vi, rq, buf, len);
> >> + if (!new_xdp)
> >> + goto drop_bufs;
> >>
> >> - page = virt_to_page(buf);
> >> + /* In virtnet_add_recvbuf_xsk(), we ask the host to fill
> >> from
> >> +* xdp->data - vi->hdr_len with both virtio_net_hdr and
> >> data.
> >> +* However, only the first packet has the virtio_net_hdr,
> >> the
> >> +* following ones do not. So we need to adjust the
> >> following
> > Typo here.
>
> I'm sorry, could you clarify which word contains the typo?
>
> >
> >> +* packets' data pointer to the correct place.
> >> +*/
> > I wonder what happens if we don't use this trick? I meant we don't
> > reuse the header room for the virtio-net header. This seems to be fine
> > for a mergeable buffer and can help to reduce the trick.
>
> I don't think using the header room for virtio-net header creates this
> case handling. In my opinion, it comes from the slightly difference in
> the recvbuf between single buffer and multi-buffer. When we have n
> single-bu
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On 5/29/25 12:59, Jason Wang wrote:
On Wed, May 28, 2025 at 12:19 AM Bui Quang Minh
wrote:
Currently, in zerocopy mode with mergeable receive buffer, virtio-net
does not support multi buffer but a single buffer only. This commit adds
support for multi mergeable receive buffer in the zerocopy XDP path by
utilizing XDP buffer with frags.
Signed-off-by: Bui Quang Minh
---
drivers/net/virtio_net.c | 123 +--
1 file changed, 66 insertions(+), 57 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..a9558650f205 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
#define VIRTIO_XDP_TX BIT(0)
#define VIRTIO_XDP_REDIR BIT(1)
+#define VIRTNET_MAX_ZC_SEGS8
+
/* 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-
@@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct net_device *dev,
}
}
-static int xsk_append_merge_buffer(struct virtnet_info *vi,
- struct receive_queue *rq,
- struct sk_buff *head_skb,
- u32 num_buf,
- struct virtio_net_hdr_mrg_rxbuf *hdr,
- struct virtnet_rq_stats *stats)
+static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
+ struct receive_queue *rq,
+ u32 num_buf,
+ struct xdp_buff *xdp,
+ struct virtnet_rq_stats *stats)
{
- struct sk_buff *curr_skb;
- struct xdp_buff *xdp;
- u32 len, truesize;
- struct page *page;
+ unsigned int len;
void *buf;
- curr_skb = head_skb;
+ if (num_buf < 2)
+ return 0;
+
+ while (num_buf > 1) {
+ struct xdp_buff *new_xdp;
- while (--num_buf) {
buf = virtqueue_get_buf(rq->vq, &len);
- if (unlikely(!buf)) {
- pr_debug("%s: rx error: %d buffers out of %d missing\n",
-vi->dev->name, num_buf,
-virtio16_to_cpu(vi->vdev,
-hdr->num_buffers));
+ if (!unlikely(buf)) {
+ pr_debug("%s: rx error: %d buffers missing\n",
+vi->dev->name, num_buf);
DEV_STATS_INC(vi->dev, rx_length_errors);
- return -EINVAL;
- }
-
- u64_stats_add(&stats->bytes, len);
-
- xdp = buf_to_xdp(vi, rq, buf, len);
- if (!xdp)
- goto err;
-
- buf = napi_alloc_frag(len);
- if (!buf) {
- xsk_buff_free(xdp);
- goto err;
+ return -1;
}
- memcpy(buf, xdp->data - vi->hdr_len, len);
-
- xsk_buff_free(xdp);
+ new_xdp = buf_to_xdp(vi, rq, buf, len);
+ if (!new_xdp)
+ goto drop_bufs;
- page = virt_to_page(buf);
+ /* In virtnet_add_recvbuf_xsk(), we ask the host to fill from
+* xdp->data - vi->hdr_len with both virtio_net_hdr and data.
+* However, only the first packet has the virtio_net_hdr, the
+* following ones do not. So we need to adjust the following
Typo here.
I'm sorry, could you clarify which word contains the typo?
+* packets' data pointer to the correct place.
+*/
I wonder what happens if we don't use this trick? I meant we don't
reuse the header room for the virtio-net header. This seems to be fine
for a mergeable buffer and can help to reduce the trick.
I don't think using the header room for virtio-net header creates this
case handling. In my opinion, it comes from the slightly difference in
the recvbuf between single buffer and multi-buffer. When we have n
single-buffer packets, each buffer will have its own virtio-net header.
But when we have 1 multi-buffer packet (which spans across n buffers),
only the first buffer has virtio-net header, the following buffers do not.
There 2 important pointers here. The pointer we announce to the vhost
side to fill the data, let's call it announced_addr, and xdp_buff->data
which is expected to point the the start of Ethernet frame. Currently,
announced_addr = xdp_buff->data - hdr_len
The host side will write the virtio-net header to announced_addr then
the Ethernet frame's data in the first buffer. In cas
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On Wed, May 28, 2025 at 12:19 AM Bui Quang Minh
wrote:
>
> Currently, in zerocopy mode with mergeable receive buffer, virtio-net
> does not support multi buffer but a single buffer only. This commit adds
> support for multi mergeable receive buffer in the zerocopy XDP path by
> utilizing XDP buffer with frags.
>
> Signed-off-by: Bui Quang Minh
> ---
> drivers/net/virtio_net.c | 123 +--
> 1 file changed, 66 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index e53ba600605a..a9558650f205 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
> #define VIRTIO_XDP_TX BIT(0)
> #define VIRTIO_XDP_REDIR BIT(1)
>
> +#define VIRTNET_MAX_ZC_SEGS8
> +
> /* 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-
> @@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct net_device
> *dev,
> }
> }
>
> -static int xsk_append_merge_buffer(struct virtnet_info *vi,
> - struct receive_queue *rq,
> - struct sk_buff *head_skb,
> - u32 num_buf,
> - struct virtio_net_hdr_mrg_rxbuf *hdr,
> - struct virtnet_rq_stats *stats)
> +static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
> + struct receive_queue *rq,
> + u32 num_buf,
> + struct xdp_buff *xdp,
> + struct virtnet_rq_stats *stats)
> {
> - struct sk_buff *curr_skb;
> - struct xdp_buff *xdp;
> - u32 len, truesize;
> - struct page *page;
> + unsigned int len;
> void *buf;
>
> - curr_skb = head_skb;
> + if (num_buf < 2)
> + return 0;
> +
> + while (num_buf > 1) {
> + struct xdp_buff *new_xdp;
>
> - while (--num_buf) {
> buf = virtqueue_get_buf(rq->vq, &len);
> - if (unlikely(!buf)) {
> - pr_debug("%s: rx error: %d buffers out of %d
> missing\n",
> -vi->dev->name, num_buf,
> -virtio16_to_cpu(vi->vdev,
> -hdr->num_buffers));
> + if (!unlikely(buf)) {
> + pr_debug("%s: rx error: %d buffers missing\n",
> +vi->dev->name, num_buf);
> DEV_STATS_INC(vi->dev, rx_length_errors);
> - return -EINVAL;
> - }
> -
> - u64_stats_add(&stats->bytes, len);
> -
> - xdp = buf_to_xdp(vi, rq, buf, len);
> - if (!xdp)
> - goto err;
> -
> - buf = napi_alloc_frag(len);
> - if (!buf) {
> - xsk_buff_free(xdp);
> - goto err;
> + return -1;
> }
>
> - memcpy(buf, xdp->data - vi->hdr_len, len);
> -
> - xsk_buff_free(xdp);
> + new_xdp = buf_to_xdp(vi, rq, buf, len);
> + if (!new_xdp)
> + goto drop_bufs;
>
> - page = virt_to_page(buf);
> + /* In virtnet_add_recvbuf_xsk(), we ask the host to fill from
> +* xdp->data - vi->hdr_len with both virtio_net_hdr and data.
> +* However, only the first packet has the virtio_net_hdr, the
> +* following ones do not. So we need to adjust the following
Typo here.
> +* packets' data pointer to the correct place.
> +*/
I wonder what happens if we don't use this trick? I meant we don't
reuse the header room for the virtio-net header. This seems to be fine
for a mergeable buffer and can help to reduce the trick.
> + new_xdp->data -= vi->hdr_len;
> + new_xdp->data_end = new_xdp->data + len;
>
> - truesize = len;
> + if (!xsk_buff_add_frag(xdp, new_xdp))
> + goto drop_bufs;
>
> - curr_skb = virtnet_skb_append_frag(head_skb, curr_skb, page,
> - buf, len, truesize);
> - if (!curr_skb) {
> - put_page(page);
> - goto err;
> - }
> + num_buf--;
> }
>
> return 0;
>
> -err:
> +drop_bufs:
> xsk_drop_follow_bufs(vi->dev, rq, num_buf, stats);
> - return -EINVAL;
> + return -1;
> }
>
> static struc
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On 5/28/25 23:44, ALOK TIWARI wrote:
On 27-05-2025 21:49, Bui Quang Minh wrote:
Currently, in zerocopy mode with mergeable receive buffer, virtio-net
does not support multi buffer but a single buffer only. This commit adds
support for multi mergeable receive buffer in the zerocopy XDP path by
utilizing XDP buffer with frags.
Signed-off-by: Bui Quang Minh
---
drivers/net/virtio_net.c | 123 +--
1 file changed, 66 insertions(+), 57 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..a9558650f205 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
#define VIRTIO_XDP_TX BIT(0)
#define VIRTIO_XDP_REDIR BIT(1)
+#define VIRTNET_MAX_ZC_SEGS 8
+
/* 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-
@@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct
net_device *dev,
}
}
-static int xsk_append_merge_buffer(struct virtnet_info *vi,
- struct receive_queue *rq,
- struct sk_buff *head_skb,
- u32 num_buf,
- struct virtio_net_hdr_mrg_rxbuf *hdr,
- struct virtnet_rq_stats *stats)
+static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
+ struct receive_queue *rq,
+ u32 num_buf,
+ struct xdp_buff *xdp,
+ struct virtnet_rq_stats *stats)
{
- struct sk_buff *curr_skb;
- struct xdp_buff *xdp;
- u32 len, truesize;
- struct page *page;
+ unsigned int len;
void *buf;
- curr_skb = head_skb;
+ if (num_buf < 2)
+ return 0;
+
+ while (num_buf > 1) {
+ struct xdp_buff *new_xdp;
- while (--num_buf) {
buf = virtqueue_get_buf(rq->vq, &len);
- if (unlikely(!buf)) {
- pr_debug("%s: rx error: %d buffers out of %d missing\n",
- vi->dev->name, num_buf,
- virtio16_to_cpu(vi->vdev,
- hdr->num_buffers));
+ if (!unlikely(buf)) {
if (unlikely(!buf)) { ?
Thanks, I'll fix this in the next version.
+ pr_debug("%s: rx error: %d buffers missing\n",
+ vi->dev->name, num_buf);
DEV_STATS_INC(vi->dev, rx_length_errors);
Thanks,
Alok
Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable
On 27-05-2025 21:49, Bui Quang Minh wrote:
Currently, in zerocopy mode with mergeable receive buffer, virtio-net
does not support multi buffer but a single buffer only. This commit adds
support for multi mergeable receive buffer in the zerocopy XDP path by
utilizing XDP buffer with frags.
Signed-off-by: Bui Quang Minh
---
drivers/net/virtio_net.c | 123 +--
1 file changed, 66 insertions(+), 57 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..a9558650f205 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644);
#define VIRTIO_XDP_TX BIT(0)
#define VIRTIO_XDP_REDIR BIT(1)
+#define VIRTNET_MAX_ZC_SEGS 8
+
/* 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-
@@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct net_device *dev,
}
}
-static int xsk_append_merge_buffer(struct virtnet_info *vi,
- struct receive_queue *rq,
- struct sk_buff *head_skb,
- u32 num_buf,
- struct virtio_net_hdr_mrg_rxbuf *hdr,
- struct virtnet_rq_stats *stats)
+static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi,
+ struct receive_queue *rq,
+ u32 num_buf,
+ struct xdp_buff *xdp,
+ struct virtnet_rq_stats *stats)
{
- struct sk_buff *curr_skb;
- struct xdp_buff *xdp;
- u32 len, truesize;
- struct page *page;
+ unsigned int len;
void *buf;
- curr_skb = head_skb;
+ if (num_buf < 2)
+ return 0;
+
+ while (num_buf > 1) {
+ struct xdp_buff *new_xdp;
- while (--num_buf) {
buf = virtqueue_get_buf(rq->vq, &len);
- if (unlikely(!buf)) {
- pr_debug("%s: rx error: %d buffers out of %d missing\n",
-vi->dev->name, num_buf,
-virtio16_to_cpu(vi->vdev,
-hdr->num_buffers));
+ if (!unlikely(buf)) {
if (unlikely(!buf)) { ?
+ pr_debug("%s: rx error: %d buffers missing\n",
+vi->dev->name, num_buf);
DEV_STATS_INC(vi->dev, rx_length_errors);
Thanks,
Alok
