Update panda_ssltut.md with downgrade info #23
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Add some verbiage on how to downgrade qcow2 images to a version PANDA supports.
moyix
added a commit
that referenced
this pull request
Oct 9, 2014
Update panda_ssltut.md with downgrade info
Closed
moyix
pushed a commit
that referenced
this pull request
Feb 8, 2019
During block job completion, nothing is preventing
block_job_defer_to_main_loop_bh from being called in a nested
aio_poll(), which is a trouble, such as in this code path:
qmp_block_commit
commit_active_start
bdrv_reopen
bdrv_reopen_multiple
bdrv_reopen_prepare
bdrv_flush
aio_poll
aio_bh_poll
aio_bh_call
block_job_defer_to_main_loop_bh
stream_complete
bdrv_reopen
block_job_defer_to_main_loop_bh is the last step of the stream job,
which should have been "paused" by the bdrv_drained_begin/end in
bdrv_reopen_multiple, but it is not done because it's in the form of a
main loop BH.
Similar to why block jobs should be paused between drained_begin and
drained_end, BHs they schedule must be excluded as well. To achieve
this, this patch forces draining the BH in BDRV_POLL_WHILE.
As a side effect this fixes a hang in block_job_detach_aio_context
during system_reset when a block job is ready:
#0 0x0000555555aa79f3 in bdrv_drain_recurse
#1 0x0000555555aa825d in bdrv_drained_begin
#2 0x0000555555aa8449 in bdrv_drain
#3 0x0000555555a9c356 in blk_drain
#4 0x0000555555aa3cfd in mirror_drain
#5 0x0000555555a66e11 in block_job_detach_aio_context
#6 0x0000555555a62f4d in bdrv_detach_aio_context
#7 0x0000555555a63116 in bdrv_set_aio_context
#8 0x0000555555a9d326 in blk_set_aio_context
#9 0x00005555557e38da in virtio_blk_data_plane_stop
#10 0x00005555559f9d5f in virtio_bus_stop_ioeventfd
#11 0x00005555559fa49b in virtio_bus_stop_ioeventfd
#12 0x00005555559f6a18 in virtio_pci_stop_ioeventfd
#13 0x00005555559f6a18 in virtio_pci_reset
#14 0x00005555559139a9 in qdev_reset_one
#15 0x0000555555916738 in qbus_walk_children
#16 0x0000555555913318 in qdev_walk_children
#17 0x0000555555916738 in qbus_walk_children
#18 0x00005555559168ca in qemu_devices_reset
#19 0x000055555581fcbb in pc_machine_reset
#20 0x00005555558a4d96 in qemu_system_reset
#21 0x000055555577157a in main_loop_should_exit
#22 0x000055555577157a in main_loop
#23 0x000055555577157a in main
The rationale is that the loop in block_job_detach_aio_context cannot
make any progress in pausing/completing the job, because bs->in_flight
is 0, so bdrv_drain doesn't process the block_job_defer_to_main_loop
BH. With this patch, it does.
Reported-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170418143044.12187-3-famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Tested-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
AndrewFasano
pushed a commit
that referenced
this pull request
Oct 16, 2023
Both virtio-blk and virtio-scsi use virtio_queue_empty() as the
loop condition in VQ handlers (virtio_blk_handle_vq,
virtio_scsi_handle_cmd_vq). When a device is marked broken in
virtqueue_pop, for example if a vIOMMU address translation failed, we
want to break out of the loop.
This fixes a hanging problem when booting a CentOS 3.10.0-862.el7.x86_64
kernel with ATS enabled:
$ qemu-system-x86_64 \
... \
-device intel-iommu,intremap=on,caching-mode=on,eim=on,device-iotlb=on \
-device virtio-scsi-pci,iommu_platform=on,ats=on,id=scsi0,bus=pci.4,addr=0x0
The dead loop happens immediately when the kernel boots and initializes
the device, where virtio_scsi_data_plane_handle_cmd will not return:
> ...
> #13 0x00005586602b7793 in virtio_scsi_handle_cmd_vq
> #14 0x00005586602b8d66 in virtio_scsi_data_plane_handle_cmd
> #15 0x00005586602ddab7 in virtio_queue_notify_aio_vq
> #16 0x00005586602dfc9f in virtio_queue_host_notifier_aio_poll
> #17 0x00005586607885da in run_poll_handlers_once
> #18 0x000055866078880e in try_poll_mode
> #19 0x00005586607888eb in aio_poll
> #20 0x0000558660784561 in aio_wait_bh_oneshot
> #21 0x00005586602b9582 in virtio_scsi_dataplane_stop
> #22 0x00005586605a7110 in virtio_bus_stop_ioeventfd
> #23 0x00005586605a9426 in virtio_pci_stop_ioeventfd
> #24 0x00005586605ab808 in virtio_pci_common_write
> #25 0x0000558660242396 in memory_region_write_accessor
> #26 0x00005586602425ab in access_with_adjusted_size
> #27 0x0000558660245281 in memory_region_dispatch_write
> #28 0x00005586601e008e in flatview_write_continue
> #29 0x00005586601e01d8 in flatview_write
> #30 0x00005586601e04de in address_space_write
> #31 0x00005586601e052f in address_space_rw
> #32 0x00005586602607f2 in kvm_cpu_exec
> #33 0x0000558660227148 in qemu_kvm_cpu_thread_fn
> #34 0x000055866078bde7 in qemu_thread_start
> #35 0x00007f5784906594 in start_thread
> #36 0x00007f5784639e6f in clone
With this patch, virtio_queue_empty will now return 1 as soon as the
vdev is marked as broken, after a "virtio: zero sized buffers are not
allowed" error.
To be consistent, update virtio_queue_empty_rcu as well.
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20180910145616.8598-2-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Add some verbiage on how to downgrade qcow2 images to a version PANDA supports.