From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43998) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFIZD-0006Um-Bt for qemu-devel@nongnu.org; Wed, 15 Jul 2015 05:01:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZFIZ7-0007vH-H8 for qemu-devel@nongnu.org; Wed, 15 Jul 2015 05:01:27 -0400 Received: from [59.151.112.132] (port=25156 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFIZ6-0007oo-DC for qemu-devel@nongnu.org; Wed, 15 Jul 2015 05:01:21 -0400 Message-ID: <55A6222D.1040908@cn.fujitsu.com> Date: Wed, 15 Jul 2015 17:04:45 +0800 From: Wen Congyang MIME-Version: 1.0 References: <55A617E9.9080503@cn.fujitsu.com> <55A61CE1.2040200@redhat.com> In-Reply-To: <55A61CE1.2040200@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 for-2.4] virtio-net: remove virtio queues if the guest doesn't support multiqueue List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang , qemu-devl , "Michael S. Tsirkin" Cc: Fam Zheng , Stefan Hajnoczi On 07/15/2015 04:42 PM, Jason Wang wrote: > > > On 07/15/2015 04:20 PM, Wen Congyang wrote: >> commit da51a335 adds all queues in .realize(). But if the >> guest doesn't support multiqueue, we forget to remove them. And >> we cannot handle the ctrl vq corretly. The guest will hang. >> >> Signed-off-by: Wen Congyang >> --- >> hw/net/virtio-net.c | 93 ++++++++++++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 78 insertions(+), 15 deletions(-) >> >> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >> index e3c2db3..48c7705 100644 >> --- a/hw/net/virtio-net.c >> +++ b/hw/net/virtio-net.c >> @@ -1306,9 +1306,86 @@ static void virtio_net_tx_bh(void *opaque) >> } >> } >> >> +static void virtio_net_add_queue(VirtIONet *n, int index) >> +{ >> + VirtIODevice *vdev = VIRTIO_DEVICE(n); >> + >> + n->vqs[index].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx); >> + if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) { >> + n->vqs[index].tx_vq = >> + virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer); >> + n->vqs[index].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, >> + virtio_net_tx_timer, >> + &n->vqs[index]); >> + } else { >> + n->vqs[index].tx_vq = >> + virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh); >> + n->vqs[index].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[index]); >> + } >> + >> + n->vqs[index].tx_waiting = 0; >> + n->vqs[index].n = n; >> +} >> + >> +static void virtio_net_del_queue(VirtIONet *n, int index) >> +{ >> + VirtIODevice *vdev = VIRTIO_DEVICE(n); >> + VirtIONetQueue *q = &n->vqs[index]; >> + NetClientState *nc = qemu_get_subqueue(n->nic, index); >> + >> + qemu_purge_queued_packets(nc); >> + >> + virtio_del_queue(vdev, index * 2); >> + if (q->tx_timer) { >> + timer_del(q->tx_timer); >> + timer_free(q->tx_timer); >> + } else { >> + qemu_bh_delete(q->tx_bh); >> + } >> + virtio_del_queue(vdev, index * 2 + 1); >> +} > > Ok, then in unrealize() you may just want to delete bhs/timers up to > curr_queues. Otherwise it may cause a use after free? One question: If the max_queues in qemu is 3, and the guest set queues to 2. which vq is ctrl vq? vq[4] or vq[6]? Thanks Wen Congyang > >> + >> +static void virtio_net_change_num_queues(VirtIONet *n, int new_max_queues) >> +{ >> + VirtIODevice *vdev = VIRTIO_DEVICE(n); >> + int old_num_queues = virtio_get_num_queues(vdev); >> + int new_num_queues = new_max_queues * 2 + 1; >> + int i; >> + >> + assert(old_num_queues >= 3); >> + assert(old_num_queues % 2 == 1); >> + >> + if (old_num_queues == new_num_queues) { >> + return; >> + } >> + >> + /* >> + * We always need to remove and add ctrl vq if >> + * old_num_queues != new_num_queues. Remove ctrl_vq first, >> + * and then we only enter one of the following too loops. >> + */ >> + virtio_del_queue(vdev, old_num_queues - 1); >> + >> + for (i = new_num_queues - 1; i < old_num_queues - 1; i += 2) { >> + /* new_num_queues < old_num_queues */ >> + virtio_net_del_queue(n, i / 2); >> + } >> + >> + for (i = old_num_queues - 1; i < new_num_queues - 1; i += 2) { >> + /* new_num_queues > old_num_queues */ >> + virtio_net_add_queue(n, i / 2); >> + } >> + >> + /* add ctrl_vq last */ >> + n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl); >> +} >> + >> static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue) >> { >> + int max = multiqueue ? n->max_queues : 1; >> + >> n->multiqueue = multiqueue; >> + virtio_net_change_num_queues(n, max); >> >> virtio_net_set_queues(n); >> } >> @@ -1583,21 +1660,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp) >> } >> >> for (i = 0; i < n->max_queues; i++) { >> - n->vqs[i].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx); >> - if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) { >> - n->vqs[i].tx_vq = >> - virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer); >> - n->vqs[i].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, >> - virtio_net_tx_timer, >> - &n->vqs[i]); >> - } else { >> - n->vqs[i].tx_vq = >> - virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh); >> - n->vqs[i].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[i]); >> - } >> - >> - n->vqs[i].tx_waiting = 0; >> - n->vqs[i].n = n; >> + virtio_net_add_queue(n, i); >> } >> >> n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl); > > . >