From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58927) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1duYIZ-0000b7-DS for qemu-devel@nongnu.org; Wed, 20 Sep 2017 02:15:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1duYIV-0008PR-Ag for qemu-devel@nongnu.org; Wed, 20 Sep 2017 02:15:51 -0400 Received: from proxmox.maurer-it.com ([212.186.127.180]:20823) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1duYIV-00088F-2l for qemu-devel@nongnu.org; Wed, 20 Sep 2017 02:15:47 -0400 From: Wolfgang Bumiller Date: Wed, 20 Sep 2017 08:09:33 +0200 Message-Id: <20170920060933.11593-1-w.bumiller@proxmox.com> Subject: [Qemu-devel] [PATCH] virtio: fix descriptor counting in virtqueue_pop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Michael S . Tsirkin" , Paolo Bonzini While changing the s/g list allocation, commit 3b3b0628 also changed the descriptor counting to count iovec entries as split by cpu_physical_memory_map(). Previously only the actual descriptor entries were counted and the split into the iovec happened afterwards in virtqueue_map(). Count the entries again instead to avoid erroneous "Looped descriptor" errors. Reported-by: Hans Middelhoek Link: https://forum.proxmox.com/threads/vm-crash-with-memory-hotplug.35904/ Fixes: 3b3b0628217e ("virtio: slim down allocation of VirtQueueElements") Signed-off-by: Wolfgang Bumiller --- hw/virtio/virtio.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 890b4d7eb7..33bb770177 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -834,7 +834,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) int64_t len; VirtIODevice *vdev = vq->vdev; VirtQueueElement *elem = NULL; - unsigned out_num, in_num; + unsigned out_num, in_num, elem_entries; hwaddr addr[VIRTQUEUE_MAX_SIZE]; struct iovec iov[VIRTQUEUE_MAX_SIZE]; VRingDesc desc; @@ -852,7 +852,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) smp_rmb(); /* When we start there are none of either input nor output. */ - out_num = in_num = 0; + out_num = in_num = elem_entries = 0; max = vq->vring.num; @@ -922,7 +922,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) } /* If we've got too many, that implies a descriptor loop. */ - if ((in_num + out_num) > max) { + if (++elem_entries > max) { virtio_error(vdev, "Looped descriptor"); goto err_undo_map; } -- 2.11.0