Re: [QEMU PATCH v4 1/3] virtio-net: remove layout assumptions for ctrl vq

Amos Kong
2013-01-22T14:38:57Z

On Mon, Jan 21, 2013 at 05:03:30PM +0100, Stefan Hajnoczi wrote:
> On Sat, Jan 19, 2013 at 09:54:26AM +0800, akong@redhat.com wrote:
> > From: "Michael S. Tsirkin" <mst@redhat.com>
> >
> > Virtio-net code makes assumption about virtqueue descriptor layout
> > (e.g. sg[0] is the header, sg[1] is the data buffer).
> >
> > This patch makes code not rely on the layout of descriptors.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Amos Kong <akong@redhat.com>
> > ---
> > hw/virtio-net.c | 128 ++++++++++++++++++++++++++++++++------------------------
> > 1 file changed, 74 insertions(+), 54 deletions(-)
> >
> > diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> > index 3bb01b1..113e194 100644
> > --- a/hw/virtio-net.c
> > +++ b/hw/virtio-net.c
> > @@ -315,44 +315,44 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
> > }
> >
> > static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
> > - VirtQueueElement *elem)
> > + struct iovec *iov, unsigned int iov_cnt)
> > {
> > uint8_t on;
> > + size_t s;
> >
> > - if (elem->out_num != 2 || elem->out_sg[1].iov_len != sizeof(on)) {
> > - error_report("virtio-net ctrl invalid rx mode command");
> > - exit(1);
> > + s = iov_to_buf(iov, iov_cnt, 0, &on, sizeof(on));
> > + if (s != sizeof(on)) {
> > + return VIRTIO_NET_ERR;
> > }
> >
> > - on = ldub_p(elem->out_sg[1].iov_base);
> > -
> > - if (cmd == VIRTIO_NET_CTRL_RX_MODE_PROMISC)
> > + if (cmd == VIRTIO_NET_CTRL_RX_MODE_PROMISC) {
> > n->promisc = on;
> > - else if (cmd == VIRTIO_NET_CTRL_RX_MODE_ALLMULTI)
> > + } else if (cmd == VIRTIO_NET_CTRL_RX_MODE_ALLMULTI) {
> > n->allmulti = on;
> > - else if (cmd == VIRTIO_NET_CTRL_RX_MODE_ALLUNI)
> > + } else if (cmd == VIRTIO_NET_CTRL_RX_MODE_ALLUNI) {
> > n->alluni = on;
> > - else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOMULTI)
> > + } else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOMULTI) {
> > n->nomulti = on;
> > - else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOUNI)
> > + } else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOUNI) {
> > n->nouni = on;
> > - else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOBCAST)
> > + } else if (cmd == VIRTIO_NET_CTRL_RX_MODE_NOBCAST) {
> > n->nobcast = on;
> > - else
> > + } else {
> > return VIRTIO_NET_ERR;
> > + }
> >
> > return VIRTIO_NET_OK;
> > }
> >
> > static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
> > - VirtQueueElement *elem)
> > + struct iovec *iov, unsigned int iov_cnt)
> > {
> > struct virtio_net_ctrl_mac mac_data;
> > + size_t s;
> >
> > - if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET || elem->out_num != 3 ||
> > - elem->out_sg[1].iov_len < sizeof(mac_data) ||
> > - elem->out_sg[2].iov_len < sizeof(mac_data))
> > + if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET) {
> > return VIRTIO_NET_ERR;
> > + }
> >
> > n->mac_table.in_use = 0;
> > n->mac_table.first_multi = 0;
> > @@ -360,54 +360,71 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
> > n->mac_table.multi_overflow = 0;
> > memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
> >
> > - mac_data.entries = ldl_p(elem->out_sg[1].iov_base);
> > + s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
> > + sizeof(mac_data.entries));

Hi Stefan, can we adjust the endianness after each iov_to_buf() copy?

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 72d7857..0088d6c 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -321,6 +321,7 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
size_t s;

s = iov_to_buf(iov, iov_cnt, 0, &on, sizeof(on));
+ on = ldub_p(&on);
if (s != sizeof(on)) {
return VIRTIO_NET_ERR;
}
@@ -362,7 +363,7 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,

s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
sizeof(mac_data.entries));
-
+ mac_data.entries = ldl_p(&mac_data.entries);
if (s != sizeof(mac_data.entries)) {
return VIRTIO_NET_ERR;
}
@@ -389,7 +390,7 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,

s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
sizeof(mac_data.entries));
-
+ mac_data.entries = ldl_p(&mac_data.entries);
if (s != sizeof(mac_data.entries)) {
return VIRTIO_NET_ERR;
}
@@ -421,6 +422,7 @@ static int virtio_net_handle_vlan_table(VirtIONet *n, uint8_t cmd,
size_t s;

s = iov_to_buf(iov, iov_cnt, 0, &vid, sizeof(vid));
+ vid = lduw_p(&vid);
if (s != sizeof(vid)) {
return VIRTIO_NET_ERR;
}
@@ -458,6 +460,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
iov = elem.out_sg;
iov_cnt = elem.out_num;
s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
+ ctrl.class = ldub_p(&ctrl.class);
+ ctrl.cmd = ldub_p(&ctrl.class + sizeof(ctrl.class));
iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
if (s != sizeof(ctrl)) {
status = VIRTIO_NET_ERR;