Commit d542800d authored by Brijesh Singh's avatar Brijesh Singh Committed by Jason Wang
Browse files

tap: set vhostfd passed from qemu cli to non-blocking 



A guest boot hangs while probing the network interface when
iommu_platform=on is used.

The following qemu cli hangs without this patch:

# $QEMU \
  -netdev tap,fd=3,id=hostnet0,vhost=on,vhostfd=4 3<>/dev/tap67 4<>/dev/host-net \
  -device virtio-net-pci,netdev=hostnet0,id=net0,iommu_platform=on,disable-legacy=on \
  ...

Commit: c471ad0e (vhost_net: device IOTLB support) took care of
setting vhostfd to non-blocking when QEMU opens /dev/host-net but if
the fd is passed from qemu cli then we need to ensure that fd is set
to non-blocking.

Fixes: c471ad0e ("vhost_net: device IOTLB support")
Cc: qemu-stable@nongnu.org
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
parent 409c241f

net/tap.c

+2 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include "qemu-common.h"

#include "qemu/cutils.h"

#include "qemu/error-report.h"

#include "qemu/sockets.h"



#include "net/tap.h"
@@ -693,6 +694,7 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer, 
                }

                return;

            }

            qemu_set_nonblock(vhostfd);

        } else {

            vhostfd = open("/dev/vhost-net", O_RDWR);

            if (vhostfd < 0) {