[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PULL v2 31/82] vhost: Change the sequence of device start
From: |
Christian A. Ehrhardt |
Subject: |
Re: [PULL v2 31/82] vhost: Change the sequence of device start |
Date: |
Mon, 7 Nov 2022 18:31:00 +0100 |
On Mon, Nov 07, 2022 at 08:30:32AM -0500, Michael S. Tsirkin wrote:
> On Sun, Nov 06, 2022 at 07:00:33PM +0100, Christian A. Ehrhardt wrote:
> >
> > Hi,
> >
> > On Sat, Nov 05, 2022 at 12:43:05PM -0400, Michael S. Tsirkin wrote:
> > > On Sat, Nov 05, 2022 at 05:35:57PM +0100, Bernhard Beschow wrote:
> > > >
> > > >
> > > > On Wed, Nov 2, 2022 at 5:24 PM Michael S. Tsirkin <mst@redhat.com>
> > > > wrote:
> > > >
> > > > From: Yajun Wu <yajunw@nvidia.com>
> > > >
> > > > This patch is part of adding vhost-user vhost_dev_start support. The
> > > > motivation is to improve backend configuration speed and reduce live
> > > > migration VM downtime.
> > > >
> > > > Moving the device start routines after finishing all the necessary
> > > > device
> > > > and VQ configuration, further aligning to the virtio specification
> > > > for
> > > > "device initialization sequence".
> > > >
> > > > Following patch will add vhost-user vhost_dev_start support.
> > > >
> > > > Signed-off-by: Yajun Wu <yajunw@nvidia.com>
> > > > Acked-by: Parav Pandit <parav@nvidia.com>
> > > >
> > > > Message-Id: <20221017064452.1226514-2-yajunw@nvidia.com>
> > > > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > ---
> > > > hw/block/vhost-user-blk.c | 18 +++++++++++-------
> > > > hw/net/vhost_net.c | 12 ++++++------
> > > > 2 files changed, 17 insertions(+), 13 deletions(-)
> > > >
> > > >
> > > > A git bisect tells me that this is the first bad commit for failing
> > > > qos-tests
> > > > which only fail when parallel jobs are enabled, e.g. `make check-qtest
> > > > -j8`:
> >
> > Parallel test run is not required provided that the test machine is
> > sufficiently busy (load > number of CPU threads). In this case a single
> > invocation of the qos test will fail reliably with this change.
> >
> > However, the change is not really the root cause of the failures.
> >
> > > > Summary of Failures:
> > > >
> > > > 76/541 qemu:qtest+qtest-aarch64 / qtest-aarch64/qos-test
> > > >
> > > > ERROR 18.68s killed by signal 6 SIGABRT
> > > > 77/541 qemu:qtest+qtest-arm / qtest-arm/qos-test
> > > >
> > > > ERROR 17.60s killed by signal 6 SIGABRT
> > > > 93/541 qemu:qtest+qtest-i386 / qtest-i386/qos-test
> > > >
> > > > ERROR 18.98s killed by signal 6 SIGABRT
> > > > 108/541 qemu:qtest+qtest-ppc64 / qtest-ppc64/qos-test
> > > >
> > > > ERROR 16.40s killed by signal 6 SIGABRT
> > > > 112/541 qemu:qtest+qtest-i386 / qtest-i386/bios-tables-test
> > > >
> > > > ERROR 145.94s killed by signal 6 SIGABRT
> > > > 130/541 qemu:qtest+qtest-x86_64 / qtest-x86_64/qos-test
> > > >
> > > > ERROR 17.32s killed by signal 6 SIGABRT
> > > > 243/541 qemu:qtest+qtest-x86_64 / qtest-x86_64/bios-tables-test
> > > >
> > > > ERROR 127.70s killed by signal 6 SIGABRT
> > > >
> > > > Ok: 500
> > > > Expected Fail: 0
> > > > Fail: 7
> > > > Unexpected Pass: 0
> > > > Skipped: 34
> > > > Timeout: 0
> > > >
> > > > Can anyone else reproduce this?
> > >
> > > Could you pls try latest for_upstream in my tree?
> > > That should have this fixed.
> >
> > Your new pull request simply drops this change and this does fix
> > make check-qtest. However, this looks accidental to me and the real
> > bug is there in plain origin/master, too.
> >
> > What happens is this backtrace a recursive call to vu_gpio_stop
> > via the backtrace below. It is caused by a delayed of the TCP
> > connection (the delayed part only triggers with heavy load on the
> > machine).
> >
> > You can get the failure back (probably in upstream) if the test is
> > forced to us "use-started=off" which can be set on the command line.
> > E.g. like this:
> >
> > diff --git a/tests/qtest/libqos/virtio-gpio.c
> > b/tests/qtest/libqos/virtio-gpio.c
> > index 762aa6695b..17c6b71e8b 100644
> > --- a/tests/qtest/libqos/virtio-gpio.c
> > +++ b/tests/qtest/libqos/virtio-gpio.c
> > @@ -154,14 +154,14 @@ static void virtio_gpio_register_nodes(void)
> > QOSGraphEdgeOptions edge_opts = { };
> >
> > /* vhost-user-gpio-device */
> > - edge_opts.extra_device_opts = "id=gpio0,chardev=chr-vhost-user-test";
> > + edge_opts.extra_device_opts =
> > "id=gpio0,chardev=chr-vhost-user-test,use-started=off";
> > qos_node_create_driver("vhost-user-gpio-device",
> > virtio_gpio_device_create);
> > qos_node_consumes("vhost-user-gpio-device", "virtio-bus", &edge_opts);
> > qos_node_produces("vhost-user-gpio-device", "vhost-user-gpio");
> >
> > /* virtio-gpio-pci */
> > - edge_opts.extra_device_opts =
> > "id=gpio0,addr=04.0,chardev=chr-vhost-user-test";
> > + edge_opts.extra_device_opts =
> > "id=gpio0,addr=04.0,chardev=chr-vhost-user-test,use-started=on";
> > add_qpci_address(&edge_opts, &addr);
> > qos_node_create_driver("vhost-user-gpio-pci", virtio_gpio_pci_create);
> > qos_node_consumes("vhost-user-gpio-pci", "pci-bus", &edge_opts);
> >
> >
> > I haven't verified this but from looking at the code other types of
> > vhost devices seem to have the same problem (e.g. vhost-user-i2c looks
> > suspicious).
> >
> > Ok, here's the backtrace:
> >
> > #0 vu_gpio_stop (vdev=vdev@entry=0x560e0ae449d0) at
> > ../hw/virtio/vhost-user-gpio.c:143
> > #1 0x0000560e0768fb1f in vu_gpio_disconnect (dev=<optimized out>) at
> > ../hw/virtio/vhost-user-gpio.c:260
> > #2 vu_gpio_event (opaque=<optimized out>, event=<optimized out>) at
> > ../hw/virtio/vhost-user-gpio.c:279
> > #3 0x0000560e078057b5 in tcp_chr_disconnect_locked (chr=0x560e0a00f800) at
> > ../chardev/char-socket.c:470
> > #4 0x0000560e078058d3 in tcp_chr_write (chr=0x560e0a00f800, buf=<optimized
> > out>, len=<optimized out>) at ../chardev/char-socket.c:129
> > #5 0x0000560e07808a63 in qemu_chr_write_buffer (s=s@entry=0x560e0a00f800,
> > buf=buf@entry=0x7ffc76812ac0 <error: Cannot access memory at address
> > 0x7ffc76812ac0>, len=20, offset=offset@entry=0x7ffc76812a40,
> > write_all=write_all@entry=true) at ../chardev/char.c:121
> > #6 0x0000560e07808e84 in qemu_chr_write (s=0x560e0a00f800,
> > buf=buf@entry=0x7ffc76812ac0 <error: Cannot access memory at address
> > 0x7ffc76812ac0>, len=len@entry=20, write_all=write_all@entry=true) at
> > ../chardev/char.c:173
> > #7 0x0000560e078010e6 in qemu_chr_fe_write_all
> > (be=be@entry=0x560e0ae44bc0, buf=buf@entry=0x7ffc76812ac0 <error: Cannot
> > access memory at address 0x7ffc76812ac0>, len=len@entry=20) at
> > ../chardev/char-fe.c:53
> > #8 0x0000560e07676d16 in vhost_user_write (msg=msg@entry=0x7ffc76812ac0,
> > fds=fds@entry=0x0, fd_num=fd_num@entry=0, dev=<optimized out>,
> > dev=<optimized out>) at ../hw/virtio/vhost-user.c:490
> > #9 0x0000560e076777c0 in vhost_user_get_vring_base (dev=0x560e0ae44c08,
> > ring=0x7ffc76812d80) at ../hw/virtio/vhost-user.c:1260
> > #10 0x0000560e0767314e in vhost_virtqueue_stop
> > (dev=dev@entry=0x560e0ae44c08, vdev=vdev@entry=0x560e0ae449d0,
> > vq=0x560e0ae7a570, idx=0) at ../hw/virtio/vhost.c:1220
> > #11 0x0000560e07675236 in vhost_dev_stop (hdev=hdev@entry=0x560e0ae44c08,
> > vdev=vdev@entry=0x560e0ae449d0) at ../hw/virtio/vhost.c:1884
> > #12 0x0000560e0768f2fd in vu_gpio_stop (vdev=0x560e0ae449d0) at
> > ../hw/virtio/vhost-user-gpio.c:148
> > #13 0x0000560e0766a6a3 in virtio_set_status (vdev=0x560e0ae449d0,
> > val=<optimized out>) at ../hw/virtio/virtio.c:2442
> > #14 0x0000560e0751a2e0 in vm_state_notify (running=running@entry=false,
> > state=state@entry=RUN_STATE_SHUTDOWN) at ../softmmu/runstate.c:334
> > #15 0x0000560e07514d70 in do_vm_stop (send_stop=false,
> > state=RUN_STATE_SHUTDOWN) at ../softmmu/cpus.c:262
> > #16 vm_shutdown () at ../softmmu/cpus.c:280
> > #17 0x0000560e0751af63 in qemu_cleanup () at ../softmmu/runstate.c:827
> > #18 0x0000560e07350f33 in qemu_default_main () at ../softmmu/main.c:38
> > #19 0x00007f0a5655bd90 in __libc_start_call_main
> > (main=main@entry=0x560e0734c3e0 <main>, argc=argc@entry=25,
> > argv=argv@entry=0x7ffc768130a8) at ../sysdeps/nptl/libc_start_call_main.h:58
> > #20 0x00007f0a5655be40 in __libc_start_main_impl (main=0x560e0734c3e0
> > <main>, argc=25, argv=0x7ffc768130a8, init=<optimized out>, fini=<optimized
> > out>, rtld_fini=<optimized out>, stack_end=0x7ffc76813098) at
> > ../csu/libc-start.c:392
> > #21 0x0000560e07350e55 in _start ()
> >
> >
> > Any Ideas how to fix this properly?
> >
> > regards Christian
>
> so fundamentally, any write into a socket can trigger stop?
> I don't think we realized this.
> Hmm this needs some thought there are likely more issues
> like this.
The code in net/vhost-user.c seems to realize this and uses
aio to schedule the close. I was wondering if chardev should
do this for OPEN/CLOSE events by default (or by request).
However, I couldn't figure out how to ensure that the device
remains alive until the callback is actually called.
regards Christian
- [PULL v2 28/82] hw/cxl/cdat: CXL CDAT Data Object Exchange implementation, (continued)
- [PULL v2 28/82] hw/cxl/cdat: CXL CDAT Data Object Exchange implementation, Michael S. Tsirkin, 2022/11/02
- [PULL v2 29/82] hw/mem/cxl-type3: Add CXL CDAT Data Object Exchange, Michael S. Tsirkin, 2022/11/02
- [PULL v2 30/82] hw/pci-bridge/cxl-upstream: Add a CDAT table access DOE, Michael S. Tsirkin, 2022/11/02
- [PULL v2 26/82] hw/pci: PCIe Data Object Exchange emulation, Michael S. Tsirkin, 2022/11/02
- [PULL v2 32/82] vhost-user: Support vhost_dev_start, Michael S. Tsirkin, 2022/11/02
- [PULL v2 31/82] vhost: Change the sequence of device start, Michael S. Tsirkin, 2022/11/02
[PULL v2 34/82] virtio: re-order vm_running and use_started checks, Michael S. Tsirkin, 2022/11/02
[PULL v2 35/82] virtio: introduce __virtio_queue_reset(), Michael S. Tsirkin, 2022/11/02
[PULL v2 33/82] hw/virtio/virtio-iommu-pci: Enforce the device is plugged on the root bus, Michael S. Tsirkin, 2022/11/02
[PULL v2 37/82] virtio: introduce virtio_queue_enable(), Michael S. Tsirkin, 2022/11/02
[PULL v2 38/82] virtio: core: vq reset feature negotation support, Michael S. Tsirkin, 2022/11/02
[PULL v2 36/82] virtio: introduce virtio_queue_reset(), Michael S. Tsirkin, 2022/11/02
[PULL v2 40/82] virtio-pci: support queue enable, Michael S. Tsirkin, 2022/11/02
[PULL v2 42/82] vhost: expose vhost_virtqueue_stop(), Michael S. Tsirkin, 2022/11/02
[PULL v2 39/82] virtio-pci: support queue reset, Michael S. Tsirkin, 2022/11/02