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Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active |
Date: |
Mon, 14 Nov 2016 10:09:32 -0700 |
On Mon, 14 Nov 2016 14:41:42 +0100
Paolo Bonzini <address@hidden> wrote:
> On 11/11/2016 22:03, Alex Williamson wrote:
> > On Fri, 11 Nov 2016 21:24:33 +0100
> > Paolo Bonzini <address@hidden> wrote:
> >> If you can post a backtrace of all threads at the time of the hang, from
> >> origin/master (so without vhost, and not at ad07cd6) that could help.
> >
> > Yes, it occurs with all of the vfio devices removed using VNC/Cirrus.
>
> I cannot reproduce it anyway. :(
>
> As you said on IRC it's a pretty standard "event loop doing nothing"
> backtrace, so it seems that an eventfd write was lost.
>
> Since I was lucky with the vhost patch, perhaps this can help:
>
> diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
> index f2ea29d..22d6cd5 100644
> --- a/hw/scsi/virtio-scsi-dataplane.c
> +++ b/hw/scsi/virtio-scsi-dataplane.c
> @@ -202,13 +202,15 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
>
> aio_context_acquire(s->ctx);
> virtio_scsi_clear_aio(s);
> - aio_context_release(s->ctx);
> -
> - blk_drain_all(); /* ensure there are no in-flight requests */
>
> for (i = 0; i < vs->conf.num_queues + 2; i++) {
> + VirtQueue *vq = virtio_get_queue(vdev, i);
> virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
> +
> virtio_queue_host_notifier_aio_read(virtio_queue_get_guest_notifier(vq));
> }
> + aio_context_release(s->ctx);
> +
> + blk_drain_all(); /* ensure there are no in-flight requests */
>
> /* Clean up guest notifier (irq) */
> k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 89b0b80..9c894d7 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2018,7 +2018,7 @@ EventNotifier
> *virtio_queue_get_guest_notifier(VirtQueue *vq)
> return &vq->guest_notifier;
> }
>
> -static void virtio_queue_host_notifier_aio_read(EventNotifier *n)
> +void virtio_queue_host_notifier_aio_read(EventNotifier *n)
> {
> VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
> if (event_notifier_test_and_clear(n)) {
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 35ede30..d3dfc69 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -274,6 +274,7 @@ int virtio_device_grab_ioeventfd(VirtIODevice *vdev);
> void virtio_device_release_ioeventfd(VirtIODevice *vdev);
> bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev);
> EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
> +void virtio_queue_host_notifier_aio_read(EventNotifier *n);
> void virtio_queue_host_notifier_read(EventNotifier *n);
> void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext
> *ctx,
> void (*fn)(VirtIODevice *,
>
Hmm, fixed yet not fixed. I get a nice shutdown and it even eliminates
a cpu spike shown in virt-manager at the end of shutdown that was
typical previously, but then I noticed dmesg showing me segfaults, so I
hooked up gdb and:
Thread 3 "CPU 0/KVM" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fb4f73ba700 (LWP 2713)]
0x00005593dacc2800 in virtio_queue_notify_aio_vq (vq=0x5593dd4a7378) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:1242
1242 trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
(gdb) bt
#0 0x00005593dacc2800 in virtio_queue_notify_aio_vq (vq=0x5593dd4a7378) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:1242
#1 0x00005593dacc4a4e in virtio_queue_host_notifier_aio_read
(n=0x5593dd4a73d8) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:2025
#2 0x00005593daca4997 in virtio_scsi_dataplane_stop (vdev=0x5593dc0cc0f0) at
/net/gimli/home/alwillia/Work/qemu.git/hw/scsi/virtio-scsi-dataplane.c:209
#3 0x00005593daf6a4b7 in virtio_bus_stop_ioeventfd (bus=0x5593dc0cc078) at
hw/virtio/virtio-bus.c:219
#4 0x00005593daf64279 in virtio_pci_stop_ioeventfd (proxy=0x5593dc0c3ce0) at
hw/virtio/virtio-pci.c:344
#5 0x00005593daf643d5 in virtio_ioport_write (opaque=0x5593dc0c3ce0, addr=18,
val=0) at hw/virtio/virtio-pci.c:380
#6 0x00005593daf6484d in virtio_pci_config_write (opaque=0x5593dc0c3ce0,
addr=18, val=0, size=1) at hw/virtio/virtio-pci.c:508
#7 0x00005593dac592fd in memory_region_write_accessor (mr=0x5593dc0c45d0,
addr=18, value=0x7fb4f73b74b8, size=1, shift=0, mask=255, attrs=...)
at /net/gimli/home/alwillia/Work/qemu.git/memory.c:526
#8 0x00005593dac59515 in access_with_adjusted_size (addr=18,
value=0x7fb4f73b74b8, size=1, access_size_min=1, access_size_max=4, access=
0x5593dac59213 <memory_region_write_accessor>, mr=0x5593dc0c45d0,
attrs=...) at /net/gimli/home/alwillia/Work/qemu.git/memory.c:592
#9 0x00005593dac5bc55 in memory_region_dispatch_write (mr=0x5593dc0c45d0,
addr=18, data=0, size=1, attrs=...) at
/net/gimli/home/alwillia/Work/qemu.git/memory.c:1323
#10 0x00005593dac07583 in address_space_write_continue (as=0x5593db727de0
<address_space_io>, addr=49298, attrs=..., buf=0x7fb520354000 "", len=1,
addr1=18, l=1, mr=0x5593dc0c45d0)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2621
#11 0x00005593dac076cb in address_space_write (as=0x5593db727de0
<address_space_io>, addr=49298, attrs=..., buf=0x7fb520354000 "", len=1)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2666
#12 0x00005593dac07a57 in address_space_rw (as=0x5593db727de0
<address_space_io>, addr=49298, attrs=..., buf=0x7fb520354000 "", len=1,
is_write=true)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2768
#13 0x00005593dac558d7 in kvm_handle_io (port=49298, attrs=...,
data=0x7fb520354000, direction=1, size=1, count=1) at
/net/gimli/home/alwillia/Work/qemu.git/kvm-all.c:1800
#14 0x00005593dac55ddd in kvm_cpu_exec (cpu=0x5593dc0a6490) at
/net/gimli/home/alwillia/Work/qemu.git/kvm-all.c:1958
#15 0x00005593dac3cc58 in qemu_kvm_cpu_thread_fn (arg=0x5593dc0a6490) at
/net/gimli/home/alwillia/Work/qemu.git/cpus.c:998
#16 0x00007fb5054715ca in start_thread (arg=0x7fb4f73ba700) at
pthread_create.c:333
#17 0x00007fb5051ab0ed in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:109
> And if it doesn't work here is some printf debugging. It's pretty verbose but
> the interesting part starts pretty much where you issue the virsh shutdown or
> system_powerdown command:
>
> diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
> index f2ea29d..ec0f750 100644
> --- a/hw/scsi/virtio-scsi-dataplane.c
> +++ b/hw/scsi/virtio-scsi-dataplane.c
> @@ -108,11 +108,13 @@ static void virtio_scsi_clear_aio(VirtIOSCSI *s)
> VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
> int i;
>
> + printf("before clear\n");
> virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
> virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
> for (i = 0; i < vs->conf.num_queues; i++) {
> virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx,
> NULL);
> }
> + printf("after clear\n");
> }
>
> /* Context: QEMU global mutex held */
> @@ -202,15 +204,20 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
>
> aio_context_acquire(s->ctx);
> virtio_scsi_clear_aio(s);
> - aio_context_release(s->ctx);
> -
> - blk_drain_all(); /* ensure there are no in-flight requests */
>
> for (i = 0; i < vs->conf.num_queues + 2; i++) {
> + VirtQueue *vq = virtio_get_queue(vdev, i);
> virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
> +
> virtio_queue_host_notifier_aio_read(virtio_queue_get_guest_notifier(vq));
> }
> + aio_context_release(s->ctx);
> +
> + printf("before drain\n");
> + blk_drain_all(); /* ensure there are no in-flight requests */
> + printf("after drain\n");
>
> /* Clean up guest notifier (irq) */
> + printf("end of virtio_scsi_dataplane_stop\n");
> k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
> s->dataplane_stopping = false;
> s->dataplane_started = false;
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 3e5ae6a..e8b83d4 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -75,6 +75,7 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
> }
>
> if (req->sreq) {
> + printf("finish %x\n", req->sreq->tag);
> req->sreq->hba_private = NULL;
> scsi_req_unref(req->sreq);
> }
> @@ -549,6 +549,7 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI
> *s, VirtIOSCSIReq *req)
> return -ENOENT;
> }
> virtio_scsi_ctx_check(s, d);
> + printf("prepare %lx %x\n", req->req.cmd.tag, req->req.cmd.cdb[0]);
> req->sreq = scsi_req_new(d, req->req.cmd.tag,
> virtio_scsi_get_lun(req->req.cmd.lun),
> req->req.cmd.cdb, req);
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 62001b4..c75dec3 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -336,11 +336,13 @@ static int virtio_pci_ioeventfd_assign(DeviceState *d,
> EventNotifier *notifier,
>
> static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
> {
> + printf("start ioeventfd %s\n",
> object_class_get_name(object_get_class(OBJECT(proxy))));
> virtio_bus_start_ioeventfd(&proxy->bus);
> }
>
> static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
> {
> + printf("stop ioeventfd %s\n",
> object_class_get_name(object_get_class(OBJECT(proxy))));
> virtio_bus_stop_ioeventfd(&proxy->bus);
> }
>
> @@ -376,6 +378,7 @@ static void virtio_ioport_write(void *opaque, uint32_t
> addr, uint32_t val)
> }
> break;
> case VIRTIO_PCI_STATUS:
> + printf("set status %s %x\n",
> object_class_get_name(object_get_class(OBJECT(proxy))), val & 0xFF);
> if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> virtio_pci_stop_ioeventfd(proxy);
> }
> @@ -1274,6 +1277,7 @@ static void virtio_pci_common_write(void *opaque,
> hwaddr addr,
> vdev->config_vector = val;
> break;
> case VIRTIO_PCI_COMMON_STATUS:
> + printf("set status %s %x\n",
> object_class_get_name(object_get_class(OBJECT(proxy))), (uint8_t)val);
> if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> virtio_pci_stop_ioeventfd(proxy);
> }
>
This required making virtio_queue_host_notifier_aio_read() non-static
and adding the forward declaration, stolen from the first patch. The
attached log starts at the point where there guest is idle and I issue
a virsh shutdown. This also results in a segfault nearly identical to
above:
Thread 4 "CPU 1/KVM" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f7194901700 (LWP 3804)]
0x000056358070788a in virtio_queue_notify_aio_vq (vq=0x56358310d378) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:1242
1242 trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
(gdb) bt
#0 0x000056358070788a in virtio_queue_notify_aio_vq (vq=0x56358310d378) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:1242
#1 0x0000563580709ad8 in virtio_queue_host_notifier_aio_read
(n=0x56358310d3d8) at
/net/gimli/home/alwillia/Work/qemu.git/hw/virtio/virtio.c:2025
#2 0x00005635806e99fd in virtio_scsi_dataplane_stop (vdev=0x563581d320f0) at
/net/gimli/home/alwillia/Work/qemu.git/hw/scsi/virtio-scsi-dataplane.c:211
#3 0x00005635809af5fe in virtio_bus_stop_ioeventfd (bus=0x563581d32078) at
hw/virtio/virtio-bus.c:219
#4 0x00005635809a9353 in virtio_pci_stop_ioeventfd (proxy=0x563581d29ce0) at
hw/virtio/virtio-pci.c:346
#5 0x00005635809a94e0 in virtio_ioport_write (opaque=0x563581d29ce0, addr=18,
val=0) at hw/virtio/virtio-pci.c:383
#6 0x00005635809a995d in virtio_pci_config_write (opaque=0x563581d29ce0,
addr=18, val=0, size=1) at hw/virtio/virtio-pci.c:511
#7 0x000056358069e2fd in memory_region_write_accessor (mr=0x563581d2a5d0,
addr=18, value=0x7f71948fe4b8, size=1, shift=0, mask=255, attrs=...)
at /net/gimli/home/alwillia/Work/qemu.git/memory.c:526
#8 0x000056358069e515 in access_with_adjusted_size (addr=18,
value=0x7f71948fe4b8, size=1, access_size_min=1, access_size_max=4, access=
0x56358069e213 <memory_region_write_accessor>, mr=0x563581d2a5d0,
attrs=...) at /net/gimli/home/alwillia/Work/qemu.git/memory.c:592
#9 0x00005635806a0c55 in memory_region_dispatch_write (mr=0x563581d2a5d0,
addr=18, data=0, size=1, attrs=...) at
/net/gimli/home/alwillia/Work/qemu.git/memory.c:1323
#10 0x000056358064c583 in address_space_write_continue (as=0x56358116cde0
<address_space_io>, addr=49298, attrs=..., buf=0x7f71be099000 "", len=1,
addr1=18, l=1, mr=0x563581d2a5d0)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2621
#11 0x000056358064c6cb in address_space_write (as=0x56358116cde0
<address_space_io>, addr=49298, attrs=..., buf=0x7f71be099000 "", len=1)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2666
#12 0x000056358064ca57 in address_space_rw (as=0x56358116cde0
<address_space_io>, addr=49298, attrs=..., buf=0x7f71be099000 "", len=1,
is_write=true)
at /net/gimli/home/alwillia/Work/qemu.git/exec.c:2768
#13 0x000056358069a8d7 in kvm_handle_io (port=49298, attrs=...,
data=0x7f71be099000, direction=1, size=1, count=1) at
/net/gimli/home/alwillia/Work/qemu.git/kvm-all.c:1800
#14 0x000056358069addd in kvm_cpu_exec (cpu=0x563581d6d030) at
/net/gimli/home/alwillia/Work/qemu.git/kvm-all.c:1958
#15 0x0000563580681c58 in qemu_kvm_cpu_thread_fn (arg=0x563581d6d030) at
/net/gimli/home/alwillia/Work/qemu.git/cpus.c:998
#16 0x00007f71a31b95ca in start_thread (arg=0x7f7194901700) at
pthread_create.c:333
#17 0x00007f71a2ef30ed in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:109
If you care to match line numbers, my tree is based on
6bbcb76301a72dc80c8d29af13d40bb9a759c9c6, it includes you patch:
virtio: introduce grab/release_ioeventfd to fix vhost
Plus your first fix removing the assert and return 0 case from
virtio_bus_set_host_notifier(). Thanks,
Alex
shutdown.log.bz2
Description: application/bzip
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Alex Williamson, 2016/11/10
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Paolo Bonzini, 2016/11/11
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Alex Williamson, 2016/11/11
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Paolo Bonzini, 2016/11/14
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active,
Alex Williamson <=
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Paolo Bonzini, 2016/11/14
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Alex Williamson, 2016/11/14
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Paolo Bonzini, 2016/11/14
- Re: [Qemu-devel] [PATCH 07/13] virtio-scsi: always use dataplane path if ioeventfd is active, Alex Williamson, 2016/11/14