From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48271) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFHYG-000146-2l for qemu-devel@nongnu.org; Wed, 15 Jul 2015 03:56:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZFHY7-0002dZ-4o for qemu-devel@nongnu.org; Wed, 15 Jul 2015 03:56:24 -0400 From: Jason Wang Date: Wed, 15 Jul 2015 15:56:07 +0800 Message-Id: <1436946967-26349-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PATCH V2] virtio-net: unbreak any layout List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mst@redhat.com, qemu-devel@nongnu.org Cc: pbonzini@redhat.com, Jason Wang , clg@fr.ibm.com, qemu-stable@nongnu.org Commit 032a74a1c0fcdd5fd1c69e56126b4c857ee36611 ("virtio-net: byteswap virtio-net header") breaks any layout by requiring out_sg[0].iov_len >= n->guest_hdr_len. Fixing this by copying header to temporary buffer if swap is needed, and then use this buffer as part of out_sg. Fixes 032a74a1c0fcdd5fd1c69e56126b4c857ee36611 ("virtio-net: byteswap virtio-net header") Cc: qemu-stable@nongnu.org Cc: clg@fr.ibm.com Signed-off-by: Jason Wang --- Changes from V1: - avoid header copying if there's no need to do header swap - don't write the header back --- hw/net/virtio-net.c | 17 ++++++++++++++--- include/hw/virtio/virtio-access.h | 9 +++++++++ 2 files changed, 23 insertions(+), 3 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index e3c2db3..12322bd 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1142,7 +1142,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) ssize_t ret, len; unsigned int out_num = elem.out_num; struct iovec *out_sg = &elem.out_sg[0]; - struct iovec sg[VIRTQUEUE_MAX_SIZE]; + struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE]; + struct virtio_net_hdr hdr; if (out_num < 1) { error_report("virtio-net header not in first element"); @@ -1150,11 +1151,21 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) } if (n->has_vnet_hdr) { - if (out_sg[0].iov_len < n->guest_hdr_len) { + if (iov_size(out_sg, out_num) < n->guest_hdr_len) { error_report("virtio-net header incorrect"); exit(1); } - virtio_net_hdr_swap(vdev, (void *) out_sg[0].iov_base); + if (virtio_needs_swap(vdev)) { + iov_to_buf(out_sg, out_num, 0, &hdr, sizeof(hdr)); + virtio_net_hdr_swap(vdev, (void *) &hdr); + sg2[0].iov_base = &hdr; + sg2[0].iov_len = sizeof(hdr); + out_num = iov_copy(&sg2[1], ARRAY_SIZE(sg2) - 1, + out_sg, out_num, + sizeof(hdr), -1); + out_num += 1; + out_sg = sg2; + } } /* diff --git a/include/hw/virtio/virtio-access.h b/include/hw/virtio/virtio-access.h index cee5dd7..1ec1dfd 100644 --- a/include/hw/virtio/virtio-access.h +++ b/include/hw/virtio/virtio-access.h @@ -143,6 +143,15 @@ static inline uint64_t virtio_ldq_p(VirtIODevice *vdev, const void *ptr) } } +static inline bool virtio_needs_swap(VirtIODevice *vdev) +{ +#ifdef HOST_WORDS_BIGENDIAN + return virtio_access_is_big_endian(vdev) ? false : true; +#else + return virtio_access_is_big_endian(vdev) ? true : false; +#endif +} + static inline uint16_t virtio_tswap16(VirtIODevice *vdev, uint16_t s) { #ifdef HOST_WORDS_BIGENDIAN -- 2.1.4