From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39520) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF84T-0002Th-OH for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:44:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XF83z-0005nX-8H for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:44:29 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:42043) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF83z-0005nN-1q for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:43:59 -0400 Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Aug 2014 14:43:58 -0600 From: Michael Roth Date: Wed, 6 Aug 2014 15:39:37 -0500 Message-Id: <1407357598-21541-88-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PATCH 087/108] virtio-net: byteswap virtio-net header List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org From: Cédric Le Goater TCP connectivity fails when the guest has a different endianness. The packets are silently dropped on the host by the tap backend when they are read from user space because the endianness of the virtio-net header is in the wrong order. These lines may appear in the guest console: [ 454.709327] skbuff: bad partial csum: csum=8704/4096 len=74 [ 455.702554] skbuff: bad partial csum: csum=8704/4096 len=74 The issue that got first spotted with a ppc64le PowerKVM guest, but it also exists for the less common case of a x86_64 guest run by a big-endian ppc64 TCG hypervisor. Signed-off-by: Cédric Le Goater [ Ported from PowerKVM, Greg Kurz ] Signed-off-by: Greg Kurz Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit 032a74a1c0fcdd5fd1c69e56126b4c857ee36611) Signed-off-by: Michael Roth --- hw/net/virtio-net.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 940a7cf..2ac6ce5 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -863,6 +863,14 @@ static int virtio_net_has_buffers(VirtIONetQueue *q, int bufsize) return 1; } +static void virtio_net_hdr_swap(struct virtio_net_hdr *hdr) +{ + tswap16s(&hdr->hdr_len); + tswap16s(&hdr->gso_size); + tswap16s(&hdr->csum_start); + tswap16s(&hdr->csum_offset); +} + /* dhclient uses AF_PACKET but doesn't pass auxdata to the kernel so * it never finds out that the packets don't have valid checksums. This * causes dhclient to get upset. Fedora's carried a patch for ages to @@ -898,6 +906,7 @@ static void receive_header(VirtIONet *n, const struct iovec *iov, int iov_cnt, void *wbuf = (void *)buf; work_around_broken_dhclient(wbuf, wbuf + n->host_hdr_len, size - n->host_hdr_len); + virtio_net_hdr_swap(wbuf); iov_from_buf(iov, iov_cnt, 0, buf, sizeof(struct virtio_net_hdr)); } else { struct virtio_net_hdr hdr = { @@ -1106,6 +1115,14 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) exit(1); } + if (n->has_vnet_hdr) { + if (out_sg[0].iov_len < n->guest_hdr_len) { + error_report("virtio-net header incorrect"); + exit(1); + } + virtio_net_hdr_swap((void *) out_sg[0].iov_base); + } + /* * If host wants to see the guest header as is, we can * pass it on unchanged. Otherwise, copy just the parts -- 1.9.1