diff options
| author | Paul Durrant <pdurrant@amazon.com> | 2019-12-23 09:59:23 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-12-26 15:16:26 -0800 |
| commit | 9476654bd5e8ad42abe8ee9f9e90069ff8e60c17 (patch) | |
| tree | d063572a1f27c26bb642e0fb30a5afe50ba5afb4 /drivers/net/xen-netback/interface.c | |
| parent | 8d347992989465fc7135ef1a84ca4c710a705c1a (diff) | |
xen-netback: support dynamic unbind/bind
By re-attaching RX, TX, and CTL rings during connect() rather than
assuming they are freshly allocated (i.e. assuming the counters are zero),
and avoiding forcing state to Closed in netback_remove() it is possible
for vif instances to be unbound and re-bound from and to (respectively) a
running guest.
Dynamic unbind/bind is a highly useful feature for a backend module as it
allows it to be unloaded and re-loaded (i.e. updated) without requiring
domUs to be halted.
This has been tested by running iperf as a server in the test VM and
then running a client against it in a continuous loop, whilst also
running:
while true;
do echo vif-$DOMID-$VIF >unbind;
echo down;
rmmod xen-netback;
echo unloaded;
modprobe xen-netback;
cd $(pwd);
brctl addif xenbr0 vif$DOMID.$VIF;
ip link set vif$DOMID.$VIF up;
echo up;
sleep 5;
done
in dom0 from /sys/bus/xen-backend/drivers/vif to continuously unbind,
unload, re-load, re-bind and re-plumb the backend.
Clearly a performance drop was seen but no TCP connection resets were
observed during this test and moreover a parallel SSH connection into the
guest remained perfectly usable throughout.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/xen-netback/interface.c')
| -rw-r--r-- | drivers/net/xen-netback/interface.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index f15ba3de6195..0c8a02a1ead7 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -585,6 +585,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref, struct net_device *dev = vif->dev; void *addr; struct xen_netif_ctrl_sring *shared; + RING_IDX rsp_prod, req_prod; int err; err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif), @@ -593,7 +594,14 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref, goto err; shared = (struct xen_netif_ctrl_sring *)addr; - BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE); + rsp_prod = READ_ONCE(shared->rsp_prod); + req_prod = READ_ONCE(shared->req_prod); + + BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE); + + err = -EIO; + if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl)) + goto err_unmap; err = bind_interdomain_evtchn_to_irq(vif->domid, evtchn); if (err < 0) |