From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52359) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g077G-0007Yy-VJ for qemu-devel@nongnu.org; Wed, 12 Sep 2018 11:31:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g077D-0006QK-O1 for qemu-devel@nongnu.org; Wed, 12 Sep 2018 11:31:42 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:36726 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1g077D-0006Pu-Gj for qemu-devel@nongnu.org; Wed, 12 Sep 2018 11:31:39 -0400 Date: Wed, 12 Sep 2018 11:31:37 -0400 From: "Michael S. Tsirkin" Message-ID: <20180912112516-mutt-send-email-mst@kernel.org> References: <905c68e0-531a-d915-4033-474bda42a643@gliwa.com> <20180912082250-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] virtio-net sporadic error with QNX 7.0 guest: virtio-net ctrl missing headers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Claudio Cc: Jason Wang , qemu-devel@nongnu.org, paolo bonzini On Wed, Sep 12, 2018 at 05:16:38PM +0200, Claudio wrote: > Thank you both for your responses, > > and ciao Paolo, > > On 09/12/2018 02:37 PM, Michael S. Tsirkin wrote: > > On Wed, Sep 12, 2018 at 10:01:34AM +0200, Claudio wrote: > >> Hello Michael, Jason and all, > >> > >> I am currently using latest mainline QEMU on x86_64 to run a QNX 7 guest. > >> > >> QNX 7 is not free software anymore unfortunately, with the > >> the last open source versions in the 6.x range. > >> > >> I am using the official virtio-net guest driver from QNX 7. > >> > >> During initialization I sporadically get this error message: > >> > >> $ qemu-system-x86_64 -machine pc,accel=kvm,kernel_irqchip=on -smp 2 -m 2048 -display none -nodefconfig -nodefaults -chardev stdio,mux=on,id=char0 -serial chardev:char0 -monitor none -mon chardev=char0,mode=readline -netdev user,id=user0,hostfwd=udp::9004-:9004 -device virtio-net,netdev=user0 qnx.img > >> > >> virtio-net ctrl missing headers > > > > This means a control buffer is sent either without the input element > > or without an output element, or with a single byte output element. > > > >> and following that my host->guest UDP port forwarding does not work, that is, > >> the qemu process shows up as listening on the interface, but no packets appear in the guest. > >> > >> This error during initialization does not appear every time I launch QEMU. > >> It appears to be more or less random. > >> > >> Whenever the error does not appear, the interface works as expected, and port forwarding works. > >> > >> Latest commit is > >> > >> 19b599f7664b ("Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2018-08-27-v2'") > >> > >> Thanks a lot for any advice! > >> > >> Ciao, > >> > >> Claudio > > > > If it's easy to reproduce, you can try printing out all commands. > > E.g.: > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > index f154756e85..34251273a9 100644 > > --- a/hw/net/virtio-net.c > > +++ b/hw/net/virtio-net.c > > @@ -987,6 +987,10 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) > > if (!elem) { > > break; > > } > > + fprintf(stderr, "%s: in %d/%d, out %d/%d\n", > > + elem->in_num, iov_size(elem->in_sg, elem->in_num), > > + elem->out_num, iov_size(elem->out_sg, elem->out_num)); > > + > > if (iov_size(elem->in_sg, elem->in_num) < sizeof(status) || > > iov_size(elem->out_sg, elem->out_num) < sizeof(ctrl)) { > > virtio_error(vdev, "virtio-net ctrl missing headers"); > > @@ -1014,6 +1018,9 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) > > } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) { > > status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt); > > } > > + fprintf(stderr, "%s: class 0x%x cmd 0x%x cnt %d status 0x%x\n", > > + ctrl.class, ctrl.cmd, iov_cnt, status); > > + > > > > s = iov_from_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status)); > > assert(s == sizeof(status)); > > > > > > You can also try replacing virtio_error with fprintf - that will > > avoid wedging the device on an error and let you proceed > > with debugging. > > > > I managed to automate the detection of the error, and it does appear to be a regression from my point of view. > > I did a git bisect, and you can see the result and log as follows: > > >From 4a3f03ba8dbf53fce36d0c1dd5d0cc0f340fe5f3 Mon Sep 17 00:00:00 2001 > From: Paolo Bonzini > Date: Wed, 11 Jan 2017 09:38:15 +0100 > Subject: [PATCH] virtio-net: enable ioeventfd even if vhost=off > > virtio-net-pci does not enable ioeventfd for historical reasons (and > nobody ever checked whether it should be revisited). Note that other > backends do enable ioeventfd for virtio-net. > > However, it has a major effect on performance. On Windows, throughput is > _multiplied_ by 2 or 3 on TCP_STREAM (on small packets it is "only" a 30% > improvement) and a little less so on TCP_MAERTS albeit still very much > statistically significant. Latency also has a single digit improvement. > > This is not visible when using vhost, which forces ioeventfd=on, but it > is substantial without vhost. In addition, also on Windows and with the > RHEL 7.3 kernel, APICv seems to slow down virtio-net performance a bit, > but the penalty with this patch goes from -25% to -7%. > > Signed-off-by: Paolo Bonzini > Reviewed-by: Michael S. Tsirkin > Signed-off-by: Michael S. Tsirkin > --- > hw/virtio/virtio-pci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index 854b8f2..8baaf2b 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -2278,7 +2278,7 @@ static const TypeInfo virtio_serial_pci_info = { > > static Property virtio_net_properties[] = { > DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, > - VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false), > + VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true), > DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3), > DEFINE_PROP_END_OF_LIST(), > }; > -- > 2.7.4 > > > > git bisect start > # good: [ec57db1630f9cdcd13c8c55acbc8daf5237aabf1] virtio-net: unbreak the minix guest > git bisect good ec57db1630f9cdcd13c8c55acbc8daf5237aabf1 > # good: [ec57db1630f9cdcd13c8c55acbc8daf5237aabf1] virtio-net: unbreak the minix guest > git bisect good ec57db1630f9cdcd13c8c55acbc8daf5237aabf1 > # good: [ec57db1630f9cdcd13c8c55acbc8daf5237aabf1] virtio-net: unbreak the minix guest > git bisect good ec57db1630f9cdcd13c8c55acbc8daf5237aabf1 > # bad: [19b599f7664b2ebfd0f405fb79c14dd241557452] Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2018-08-27-v2' into staging > git bisect bad 19b599f7664b2ebfd0f405fb79c14dd241557452 > # good: [c0f3f6754a120abc3451ebf7a7c703fbaf7b29e7] block: m25p80: 4byte address mode > git bisect good c0f3f6754a120abc3451ebf7a7c703fbaf7b29e7 > # bad: [67b9c5d4f37ea373ebf9aad251883886e34bf2e1] Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging > git bisect bad 67b9c5d4f37ea373ebf9aad251883886e34bf2e1 > # good: [6bbcb76301a72dc80c8d29af13d40bb9a759c9c6] MAINTAINERS: Remove obsolete stable branches > git bisect good 6bbcb76301a72dc80c8d29af13d40bb9a759c9c6 > # bad: [ff79d5e939c38677a575e3493eb9b4d36eb21865] Merge remote-tracking branch 'remotes/xtensa/tags/20170306-xtensa' into staging > git bisect bad ff79d5e939c38677a575e3493eb9b4d36eb21865 > # bad: [a0def594286d9110a6035e02eef558cf3cf5d847] Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging > git bisect bad a0def594286d9110a6035e02eef558cf3cf5d847 > # good: [b6c08970bc989bfddcf830684ea7a96b7a4d62a7] Merge remote-tracking branch 'remotes/bkoppelmann/tags/pull-tricore-2017-01-11-2' into staging > git bisect good b6c08970bc989bfddcf830684ea7a96b7a4d62a7 > # good: [c5fc89b36c0a167548ae7af40dc085707a7756d2] hw/intc/arm_gicv3: Implement gicv3_cpuif_virt_update() > git bisect good c5fc89b36c0a167548ae7af40dc085707a7756d2 > # bad: [009fad7f4ccbbf3ea115e9196edde88c0a17c1c2] migration: Change name of live migration thread > git bisect bad 009fad7f4ccbbf3ea115e9196edde88c0a17c1c2 > # bad: [ebe9383caefd56d519e965a5d87bca29f0aeffe3] target-hppa: Implement floating-point insns > git bisect bad ebe9383caefd56d519e965a5d87bca29f0aeffe3 > # bad: [db655a9653af05aaa90f41e55433d41e398d4b75] Merge remote-tracking branch 'remotes/jasowang/tags/net-pull-request' into staging > git bisect bad db655a9653af05aaa90f41e55433d41e398d4b75 > # bad: [2943b53f682f54548e7ddcf2ebb6c6d12d8dc821] virtio: force VIRTIO_F_IOMMU_PLATFORM > git bisect bad 2943b53f682f54548e7ddcf2ebb6c6d12d8dc821 > # bad: [a5b3ebfd23bc70fa68461dff1d7145ff65e07150] fw-cfg: bump "x-file-slots" to 0x20 for 2.9+ machine types > git bisect bad a5b3ebfd23bc70fa68461dff1d7145ff65e07150 > # bad: [c471ad0e9bd46ca5f5c9c796e727230e043a091d] vhost_net: device IOTLB support > git bisect bad c471ad0e9bd46ca5f5c9c796e727230e043a091d > # bad: [332fa82d0963409fa14997a02639289afa226596] Revert "virtio: turn vq->notification into a nested counter" > git bisect bad 332fa82d0963409fa14997a02639289afa226596 > # bad: [4a3f03ba8dbf53fce36d0c1dd5d0cc0f340fe5f3] virtio-net: enable ioeventfd even if vhost=off > git bisect bad 4a3f03ba8dbf53fce36d0c1dd5d0cc0f340fe5f3 > # first bad commit: [4a3f03ba8dbf53fce36d0c1dd5d0cc0f340fe5f3] virtio-net: enable ioeventfd even if vhost=off > > > I reverted the commit on master, and this solves the problem for me. > > Ciao, > > Claudio Well this seems to tell us this is some kind of race. Does it change anything if we just retry? diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index f154756e85..8d4e0cce61 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -987,12 +987,22 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) if (!elem) { break; } + fprintf(stderr, "%s: in %d/%d, out %d/%d\n", + elem->in_num, iov_size(elem->in_sg, elem->in_num), + elem->out_num, iov_size(elem->out_sg, elem->out_num)); + if (iov_size(elem->in_sg, elem->in_num) < sizeof(status) || iov_size(elem->out_sg, elem->out_num) < sizeof(ctrl)) { + virtqueue_unpop(vq, elem, 0); + g_free(elem); + continue; +#if 0 + virtio_error(vdev, "virtio-net ctrl missing headers"); virtqueue_detach_element(vq, elem, 0); g_free(elem); break; +#endif } iov_cnt = elem->out_num; @@ -1014,6 +1024,9 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) { status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt); } + fprintf(stderr, "%s: class 0x%x cmd 0x%x cnt %d status 0x%x\n", + ctrl.class, ctrl.cmd, iov_cnt, status); + s = iov_from_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status)); assert(s == sizeof(status));