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Date: Fri, 4 May 2018 14:49:46 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: Björn Töpel <bjorn.topel@...il.com>,
magnus.karlsson@...el.com, alexander.h.duyck@...el.com,
alexander.duyck@...il.com, john.fastabend@...il.com, ast@...com,
brouer@...hat.com, willemdebruijn.kernel@...il.com, mst@...hat.com,
netdev@...r.kernel.org
Cc: michael.lundkvist@...csson.com, jesse.brandeburg@...el.com,
anjali.singhai@...el.com, qi.z.zhang@...el.com
Subject: Re: [PATCH bpf-next v3 03/15] xsk: add umem fill queue support and
mmap
On 05/02/2018 01:01 PM, Björn Töpel wrote:
> From: Magnus Karlsson <magnus.karlsson@...el.com>
>
> Here, we add another setsockopt for registered user memory (umem)
> called XDP_UMEM_FILL_QUEUE. Using this socket option, the process can
> ask the kernel to allocate a queue (ring buffer) and also mmap it
> (XDP_UMEM_PGOFF_FILL_QUEUE) into the process.
>
> The queue is used to explicitly pass ownership of umem frames from the
> user process to the kernel. These frames will in a later patch be
> filled in with Rx packet data by the kernel.
>
> v2: Fixed potential crash in xsk_mmap.
>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
> ---
> include/uapi/linux/if_xdp.h | 15 +++++++++++
> net/xdp/Makefile | 2 +-
> net/xdp/xdp_umem.c | 5 ++++
> net/xdp/xdp_umem.h | 2 ++
> net/xdp/xsk.c | 65 ++++++++++++++++++++++++++++++++++++++++++++-
> net/xdp/xsk_queue.c | 58 ++++++++++++++++++++++++++++++++++++++++
> net/xdp/xsk_queue.h | 38 ++++++++++++++++++++++++++
> 7 files changed, 183 insertions(+), 2 deletions(-)
> create mode 100644 net/xdp/xsk_queue.c
> create mode 100644 net/xdp/xsk_queue.h
>
> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> index 41252135a0fe..975661e1baca 100644
> --- a/include/uapi/linux/if_xdp.h
> +++ b/include/uapi/linux/if_xdp.h
> @@ -23,6 +23,7 @@
>
> /* XDP socket options */
> #define XDP_UMEM_REG 3
> +#define XDP_UMEM_FILL_RING 4
>
> struct xdp_umem_reg {
> __u64 addr; /* Start of packet data area */
> @@ -31,4 +32,18 @@ struct xdp_umem_reg {
> __u32 frame_headroom; /* Frame head room */
> };
>
> +/* Pgoff for mmaping the rings */
> +#define XDP_UMEM_PGOFF_FILL_RING 0x100000000
> +
> +struct xdp_ring {
> + __u32 producer __attribute__((aligned(64)));
> + __u32 consumer __attribute__((aligned(64)));
> +};
> +
> +/* Used for the fill and completion queues for buffers */
> +struct xdp_umem_ring {
> + struct xdp_ring ptrs;
> + __u32 desc[0] __attribute__((aligned(64)));
> +};
> +
> #endif /* _LINUX_IF_XDP_H */
> diff --git a/net/xdp/Makefile b/net/xdp/Makefile
> index a5d736640a0f..074fb2b2d51c 100644
> --- a/net/xdp/Makefile
> +++ b/net/xdp/Makefile
> @@ -1,2 +1,2 @@
> -obj-$(CONFIG_XDP_SOCKETS) += xsk.o xdp_umem.o
> +obj-$(CONFIG_XDP_SOCKETS) += xsk.o xdp_umem.o xsk_queue.o
>
> diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
> index ec8b3552be44..e1f627d0cc1c 100644
> --- a/net/xdp/xdp_umem.c
> +++ b/net/xdp/xdp_umem.c
> @@ -65,6 +65,11 @@ static void xdp_umem_release(struct xdp_umem *umem)
> struct task_struct *task;
> struct mm_struct *mm;
>
> + if (umem->fq) {
> + xskq_destroy(umem->fq);
> + umem->fq = NULL;
> + }
> +
> if (umem->pgs) {
> xdp_umem_unpin_pages(umem);
>
> diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
> index 4597ae81a221..25634b8a5c6f 100644
> --- a/net/xdp/xdp_umem.h
> +++ b/net/xdp/xdp_umem.h
> @@ -19,9 +19,11 @@
> #include <linux/if_xdp.h>
> #include <linux/workqueue.h>
>
> +#include "xsk_queue.h"
> #include "xdp_umem_props.h"
>
> struct xdp_umem {
> + struct xsk_queue *fq;
> struct page **pgs;
> struct xdp_umem_props props;
> u32 npgs;
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index 84e0e867febb..da67a3c5c1c9 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -32,6 +32,7 @@
> #include <linux/netdevice.h>
> #include <net/xdp_sock.h>
>
> +#include "xsk_queue.h"
> #include "xdp_umem.h"
>
> static struct xdp_sock *xdp_sk(struct sock *sk)
> @@ -39,6 +40,21 @@ static struct xdp_sock *xdp_sk(struct sock *sk)
> return (struct xdp_sock *)sk;
> }
>
> +static int xsk_init_queue(u32 entries, struct xsk_queue **queue)
> +{
> + struct xsk_queue *q;
> +
> + if (entries == 0 || *queue || !is_power_of_2(entries))
> + return -EINVAL;
> +
> + q = xskq_create(entries);
> + if (!q)
> + return -ENOMEM;
> +
> + *queue = q;
> + return 0;
> +}
> +
> static int xsk_release(struct socket *sock)
> {
> struct sock *sk = sock->sk;
> @@ -101,6 +117,23 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
> mutex_unlock(&xs->mutex);
> return 0;
> }
> + case XDP_UMEM_FILL_RING:
> + {
> + struct xsk_queue **q;
> + int entries;
> +
> + if (!xs->umem)
> + return -EINVAL;
(Same here as previously mentioned.)
> + if (copy_from_user(&entries, optval, sizeof(entries)))
> + return -EFAULT;
> +
> + mutex_lock(&xs->mutex);
> + q = &xs->umem->fq;
> + err = xsk_init_queue(entries, q);
> + mutex_unlock(&xs->mutex);
> + return err;
> + }
> default:
> break;
> }
> @@ -108,6 +141,36 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
> return -ENOPROTOOPT;
> }
>
> +static int xsk_mmap(struct file *file, struct socket *sock,
> + struct vm_area_struct *vma)
> +{
> + unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
> + unsigned long size = vma->vm_end - vma->vm_start;
> + struct xdp_sock *xs = xdp_sk(sock->sk);
> + struct xsk_queue *q = NULL;
> + unsigned long pfn;
> + struct page *qpg;
> +
> + if (!xs->umem)
> + return -EINVAL;
> +
> + if (offset == XDP_UMEM_PGOFF_FILL_RING)
> + q = xs->umem->fq;
> + else
> + return -EINVAL;
> +
> + if (!q)
> + return -EINVAL;
Nit: since q is NULL above, could be simplified as:
if (offset == XDP_UMEM_PGOFF_FILL_RING)
q = xs->umem->fq;
if (!q)
return -EINVAL;
> +
> + qpg = virt_to_head_page(q->ring);
> + if (size > (PAGE_SIZE << compound_order(qpg)))
> + return -EINVAL;
> +
> + pfn = virt_to_phys(q->ring) >> PAGE_SHIFT;
> + return remap_pfn_range(vma, vma->vm_start, pfn,
> + size, vma->vm_page_prot);
> +}
> +
> static struct proto xsk_proto = {
> .name = "XDP",
> .owner = THIS_MODULE,
> @@ -131,7 +194,7 @@ static const struct proto_ops xsk_proto_ops = {
> .getsockopt = sock_no_getsockopt,
> .sendmsg = sock_no_sendmsg,
> .recvmsg = sock_no_recvmsg,
> - .mmap = sock_no_mmap,
> + .mmap = xsk_mmap,
> .sendpage = sock_no_sendpage,
> };
>
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