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Message-Id: <200801152147.15588.rusty@rustcorp.com.au>
Date: Tue, 15 Jan 2008 21:47:15 +1100
From: Rusty Russell <rusty@...tcorp.com.au>
To: netdev@...r.kernel.org
Cc: virtualization@...ts.linux-foundation.org,
Max Krasnyansky <maxk@...lcomm.com>
Subject: [PATCH 3/3] tun/tap GSO/partial csum support
This implements partial checksum and GSO support for tun/tap.
We use the virtio_net_hdr: it is an ABI already and designed to
encapsulate such metadata as GSO and partial checksums.
lguest performance (160MB sendfile, worst/best/avg, 20 runs):
Before: 5.06/3.39/3.82
After: 4.69/0.84/2.84
Note that the way tun works, you have to use the TUNSETIFF ioctl to set
this if you want to detect older kernels which don't have support.
Questions:
1) Should we rename/move virtio_net_hdr to something more generic?
2) Is this the right way to build a paged skb from user pages?
3) Do we need more checking for invalid GSO fields?
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
drivers/net/tun.c | 213 +++++++++++++++++++++++++++++++++++++++++------
include/linux/if_tun.h | 2
3 files changed, 189 insertions(+), 28 deletions(-)
diff -r 1057851c060f drivers/net/tun.c
--- a/drivers/net/tun.c Tue Jan 15 16:59:58 2008 +1100
+++ b/drivers/net/tun.c Tue Jan 15 20:47:41 2008 +1100
@@ -62,6 +62,7 @@
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/crc32.h>
+#include <linux/virtio_net.h>
#include <net/net_namespace.h>
#include <asm/system.h>
@@ -238,35 +239,195 @@ static unsigned int tun_chr_poll(struct
return mask;
}
+static struct sk_buff *copy_user_skb(size_t align, struct iovec *iv, size_t len)
+{
+ struct sk_buff *skb;
+
+ if (!(skb = alloc_skb(len + align, GFP_KERNEL)))
+ return ERR_PTR(-ENOMEM);
+
+ if (align)
+ skb_reserve(skb, align);
+
+ if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
+ kfree_skb(skb);
+ return ERR_PTR(-EFAULT);
+ }
+ return skb;
+}
+
+/* This will fail if they give us a crazy iovec, but that's their own fault. */
+static int get_user_skb_frags(const struct iovec *iv, size_t count,
+ struct skb_frag_struct *f)
+{
+ unsigned int i, j, num_pg = 0;
+ int err;
+ struct page *pages[MAX_SKB_FRAGS];
+
+ down_read(¤t->mm->mmap_sem);
+ for (i = 0; i < count; i++) {
+ int n, npages;
+ unsigned long base, len;
+ base = (unsigned long)iv[i].iov_base;
+ len = (unsigned long)iv[i].iov_len;
+
+ if (len == 0)
+ continue;
+
+ /* How many pages will this take? */
+ npages = 1 + (base + len - 1)/PAGE_SIZE - base/PAGE_SIZE;
+ if (unlikely(num_pg + npages > MAX_SKB_FRAGS)) {
+ err = -ENOSPC;
+ goto fail;
+ }
+ n = get_user_pages(current, current->mm, base, npages,
+ 0, 0, pages, NULL);
+ if (unlikely(n < 0)) {
+ err = n;
+ goto fail;
+ }
+
+ /* Transfer pages to the frag array */
+ for (j = 0; j < n; j++) {
+ f[num_pg].page = pages[j];
+ if (j == 0) {
+ f[num_pg].page_offset = offset_in_page(base);
+ f[num_pg].size = min(len, PAGE_SIZE -
+ f[num_pg].page_offset);
+ } else {
+ f[num_pg].page_offset = 0;
+ f[num_pg].size = min(len, PAGE_SIZE);
+ }
+ len -= f[num_pg].size;
+ base += f[num_pg].size;
+ num_pg++;
+ }
+
+ if (unlikely(n != npages)) {
+ err = -EFAULT;
+ goto fail;
+ }
+ }
+ up_read(¤t->mm->mmap_sem);
+ return num_pg;
+
+fail:
+ for (i = 0; i < num_pg; i++)
+ put_page(f[i].page);
+ up_read(¤t->mm->mmap_sem);
+ return err;
+}
+
+
+static struct sk_buff *map_user_skb(const struct virtio_net_hdr *gso,
+ size_t align, struct iovec *iv,
+ size_t count, size_t len)
+{
+ struct sk_buff *skb;
+ struct skb_shared_info *sinfo;
+ int err;
+
+ if (gso->gso_hdr_len > len)
+ return ERR_PTR(-EINVAL);
+
+ if (!(skb = alloc_skb(gso->gso_hdr_len + align, GFP_KERNEL)))
+ return ERR_PTR(-ENOMEM);
+
+ if (align)
+ skb_reserve(skb, align);
+
+ sinfo = skb_shinfo(skb);
+ sinfo->gso_size = gso->gso_size;
+ sinfo->gso_type = SKB_GSO_DODGY;
+ switch (gso->gso_type) {
+ case VIRTIO_NET_HDR_GSO_TCPV4_ECN:
+ sinfo->gso_type |= SKB_GSO_TCP_ECN;
+ /* fall through */
+ case VIRTIO_NET_HDR_GSO_TCPV4:
+ sinfo->gso_type |= SKB_GSO_TCPV4;
+ break;
+ case VIRTIO_NET_HDR_GSO_TCPV6:
+ sinfo->gso_type |= SKB_GSO_TCPV6;
+ break;
+ case VIRTIO_NET_HDR_GSO_UDP:
+ sinfo->gso_type |= SKB_GSO_UDP;
+ break;
+ default:
+ err = -EINVAL;
+ goto fail;
+ }
+
+ /* Copy in the header. */
+ if (memcpy_fromiovec(skb_put(skb, gso->gso_hdr_len), iv,
+ gso->gso_hdr_len)) {
+ err = -EFAULT;
+ goto fail;
+ }
+
+ err = get_user_skb_frags(iv, count, sinfo->frags);
+ if (err < 0)
+ goto fail;
+
+ sinfo->nr_frags = err;
+ skb->len += len;
+ skb->data_len += len;
+
+ /* GSO code expects transport header set up */
+ skb_set_transport_header(skb, gso->gso_hdr_len);
+
+ return skb;
+
+fail:
+ kfree_skb(skb);
+ return ERR_PTR(err);
+}
+
+static inline size_t iov_total(const struct iovec *iv, unsigned long count)
+{
+ unsigned long i;
+ size_t len;
+
+ for (i = 0, len = 0; i < count; i++)
+ len += iv[i].iov_len;
+
+ return len;
+}
+
/* Get packet from user space buffer */
-static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t count)
+static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t num)
{
struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
+ struct virtio_net_hdr gso = { 0, VIRTIO_NET_HDR_GSO_NONE };
struct sk_buff *skb;
- size_t len = count, align = 0;
+ size_t tot_len = iov_total(iv, num);
+ size_t len = tot_len, align = 0;
if (!(tun->flags & TUN_NO_PI)) {
- if ((len -= sizeof(pi)) > count)
+ if ((len -= sizeof(pi)) > tot_len)
return -EINVAL;
if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
+ return -EFAULT;
+ }
+ if (tun->flags & TUN_GSO_HDR) {
+ if ((len -= sizeof(gso)) > tot_len)
+ return -EINVAL;
+
+ if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))
return -EFAULT;
}
if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
align = NET_IP_ALIGN;
- if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
+ if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE)
+ skb = map_user_skb(&gso, align, iv, num, len);
+ else
+ skb = copy_user_skb(align, iv, len);
+
+ if (IS_ERR(skb)) {
tun->dev->stats.rx_dropped++;
- return -ENOMEM;
- }
-
- if (align)
- skb_reserve(skb, align);
- if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
- tun->dev->stats.rx_dropped++;
- kfree_skb(skb);
- return -EFAULT;
+ return PTR_ERR(skb);
}
switch (tun->flags & TUN_TYPE_MASK) {
@@ -280,7 +441,13 @@ static __inline__ ssize_t tun_get_user(s
break;
};
- if (tun->flags & TUN_NOCHECKSUM)
+ if (gso.flags & (1 << VIRTIO_NET_F_NO_CSUM)) {
+ if (!skb_partial_csum_set(skb,gso.csum_start,gso.csum_offset)) {
+ tun->dev->stats.rx_dropped++;
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+ } else if (tun->flags & TUN_NOCHECKSUM)
skb->ip_summed = CHECKSUM_UNNECESSARY;
netif_rx_ni(skb);
@@ -289,18 +456,7 @@ static __inline__ ssize_t tun_get_user(s
tun->dev->stats.rx_packets++;
tun->dev->stats.rx_bytes += len;
- return count;
-}
-
-static inline size_t iov_total(const struct iovec *iv, unsigned long count)
-{
- unsigned long i;
- size_t len;
-
- for (i = 0, len = 0; i < count; i++)
- len += iv[i].iov_len;
-
- return len;
+ return tot_len;
}
static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
@@ -313,7 +469,7 @@ static ssize_t tun_chr_aio_write(struct
DBG(KERN_INFO "%s: tun_chr_write %ld\n", tun->dev->name, count);
- return tun_get_user(tun, (struct iovec *) iv, iov_total(iv, count));
+ return tun_get_user(tun, (struct iovec *) iv, count);
}
/* Put packet to the user space buffer */
@@ -336,6 +492,42 @@ static __inline__ ssize_t tun_put_user(s
if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
return -EFAULT;
total += sizeof(pi);
+ }
+ if (tun->flags & TUN_GSO_HDR) {
+ struct virtio_net_hdr gso;
+ struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+ if (skb_is_gso(skb)) {
+ gso.gso_hdr_len = skb_transport_header(skb) - skb->data;
+ gso.gso_size = sinfo->gso_size;
+ if (sinfo->gso_type & SKB_GSO_TCP_ECN)
+ gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
+ else if (sinfo->gso_type & SKB_GSO_TCPV4)
+ gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+ else if (sinfo->gso_type & SKB_GSO_TCPV6)
+ gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+ else if (sinfo->gso_type & SKB_GSO_UDP)
+ gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
+ else
+ BUG();
+ } else
+ gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+ gso.csum_start = skb->csum_start - skb_headroom(skb);
+ gso.csum_offset = skb->csum_offset;
+ } else {
+ gso.flags = 0;
+ gso.csum_offset = gso.csum_start = 0;
+ }
+
+ if ((len -= sizeof(gso)) < 0)
+ return -EINVAL;
+
+ if (memcpy_toiovec(iv, (void *)&gso, sizeof(gso)))
+ return -EFAULT;
+ total += sizeof(gso);
}
len = min_t(int, skb->len, len);
@@ -543,6 +735,9 @@ static int tun_set_iff(struct file *file
if (ifr->ifr_flags & IFF_ONE_QUEUE)
tun->flags |= TUN_ONE_QUEUE;
+
+ if (ifr->ifr_flags & IFF_GSO_HDR)
+ tun->flags |= TUN_GSO_HDR;
file->private_data = tun;
tun->attached = 1;
diff -r 1057851c060f include/linux/if_tun.h
--- a/include/linux/if_tun.h Tue Jan 15 16:59:58 2008 +1100
+++ b/include/linux/if_tun.h Tue Jan 15 20:47:41 2008 +1100
@@ -70,6 +70,7 @@ struct tun_struct {
#define TUN_NO_PI 0x0040
#define TUN_ONE_QUEUE 0x0080
#define TUN_PERSIST 0x0100
+#define TUN_GSO_HDR 0x0200
/* Ioctl defines */
#define TUNSETNOCSUM _IOW('T', 200, int)
@@ -85,6 +86,7 @@ struct tun_struct {
#define IFF_TAP 0x0002
#define IFF_NO_PI 0x1000
#define IFF_ONE_QUEUE 0x2000
+#define IFF_GSO_HDR 0x4000
struct tun_pi {
unsigned short flags;
--
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