Re: [Qemu-devel] host stalls when qemu-system-aarch64 with kvm and pflash

[Radha Mohan]

On Thu, Mar 30, 2017 at 9:47 AM, Laszlo Ersek <address@hidden> wrote:
> On 03/29/17 20:56, Christoffer Dall wrote:
>> On Tue, Mar 28, 2017 at 01:24:15PM -0700, Radha Mohan wrote:
>>> On Tue, Mar 28, 2017 at 1:16 PM, Christoffer Dall <address@hidden> wrote:
>>>> Hi Radha,
>>>>
>>>> On Tue, Mar 28, 2017 at 12:58:24PM -0700, Radha Mohan wrote:
>>>>> Hi,
>>>>> I am seeing an issue with qemu-system-aarch64 when using pflash
>>>>> (booting kernel via UEFI bios).
>>>>>
>>>>> Host kernel: 4.11.0-rc3-next-20170323
>>>>> Qemu version: v2.9.0-rc1
>>>>>
>>>>> Command used:
>>>>> ./aarch64-softmmu/qemu-system-aarch64 -cpu host -enable-kvm -M
>>>>> virt,gic_version=3 -nographic -smp 1 -m 2048 -drive
>>>>> if=none,id=hd0,file=/root/zesty-server-cloudimg-arm64.img,id=0 -device
>>>>> virtio-blk-device,drive=hd0 -pflash /root/flash0.img -pflash
>>>>> /root/flash1.img
>>>>>
>>>>>
>>>>> As soon as the guest kernel boots the host starts to stall and prints
>>>>> the below messages. And the system never recovers. I can neither
>>>>> poweroff the guest nor the host. So I have resort to external power
>>>>> reset of the host.
>>>>>
>>>>> ==================
>>>>> [  116.199077] NMI watchdog: BUG: soft lockup - CPU#25 stuck for 23s!
>>>>> [kworker/25:1:454]
>>>>> [  116.206901] Modules linked in: binfmt_misc nls_iso8859_1 aes_ce_blk
>>>>> shpchp crypto_simd gpio_keys cryptd aes_ce_cipher ghash_ce sha2_ce
>>>>> sha1_ce uio_pdrv_genirq uio autofs4 btrfs raid10 rai
>>>>> d456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor
>>>>> raid6_pq libcrc32c raid1 raid0 multipath linear ast i2c_algo_bit ttm
>>>>> drm_kms_helper syscopyarea sysfillrect sysimgblt fb_s
>>>>> ys_fops drm nicvf ahci nicpf libahci thunder_bgx thunder_xcv
>>>>> mdio_thunder mdio_cavium
>>>>>
>>>>> [  116.206995] CPU: 25 PID: 454 Comm: kworker/25:1 Not tainted
>>>>> 4.11.0-rc3-next-20170323 #1
>>>>> [  116.206997] Hardware name: www.cavium.com crb-1s/crb-1s, BIOS 0.3 Feb 
>>>>> 23 2017
>>>>> [  116.207010] Workqueue: events netstamp_clear
>>>>> [  116.207015] task: ffff801f906b5400 task.stack: ffff801f901a4000
>>>>> [  116.207020] PC is at smp_call_function_many+0x284/0x2e8
>>>>> [  116.207023] LR is at smp_call_function_many+0x244/0x2e8
>>>>> [  116.207026] pc : [<ffff000008156ecc>] lr : [<ffff000008156e8c>]
>>>>> pstate: 80000145
>>>>> [  116.207028] sp : ffff801f901a7be0
>>>>> [  116.207030] x29: ffff801f901a7be0 x28: ffff000009139000
>>>>> [  116.207036] x27: ffff000009139434 x26: 0000000000000080
>>>>> [  116.207041] x25: 0000000000000000 x24: ffff0000081565d0
>>>>> [  116.207047] x23: 0000000000000001 x22: ffff000008e11e00
>>>>> [  116.207052] x21: ffff801f6d5cff00 x20: ffff801f6d5cff08
>>>>> [  116.207057] x19: ffff000009138e38 x18: 0000000000000a03
>>>>> [  116.207063] x17: 0000ffffb77c9028 x16: ffff0000082e81d8
>>>>> [  116.207068] x15: 00003d0d6dd44d08 x14: 0036312196549b4a
>>>>> [  116.207073] x13: 0000000058dabe4c x12: 0000000000000018
>>>>> [  116.207079] x11: 00000000366e2f04 x10: 00000000000009f0
>>>>> [  116.207084] x9 : ffff801f901a7d30 x8 : 0000000000000002
>>>>> [  116.207089] x7 : 0000000000000000 x6 : 0000000000000000
>>>>> [  116.207095] x5 : ffffffff00000000 x4 : 0000000000000020
>>>>> [  116.207100] x3 : 0000000000000020 x2 : 0000000000000000
>>>>> [  116.207105] x1 : ffff801f6d682578 x0 : 0000000000000003
>>>>>
>>>>> [  150.443116] INFO: rcu_sched self-detected stall on CPU
>>>>> [  150.448261]  25-...: (14997 ticks this GP)
>>>>> idle=47a/140000000000001/0 softirq=349/349 fqs=7495
>>>>> [  150.451115] INFO: rcu_sched detected stalls on CPUs/tasks:
>>>>> [  150.451123]  25-...: (14997 ticks this GP)
>>>>> idle=47a/140000000000001/0 softirq=349/349 fqs=7495
>>>>> [  150.451124]  (detected by 13, t=15002 jiffies, g=805, c=804, q=8384)
>>>>> [  150.451136] Task dump for CPU 25:
>>>>> [  150.451138] kworker/25:1    R  running task        0   454      2 
>>>>> 0x00000002
>>>>> [  150.451155] Workqueue: events netstamp_clear
>>>>> [  150.451158] Call trace:
>>>>> [  150.451164] [<ffff000008086188>] __switch_to+0x90/0xa8
>>>>> [  150.451172] [<ffff0000081f6240>] static_key_slow_inc+0x128/0x138
>>>>> [  150.451175] [<ffff0000081f6284>] static_key_enable+0x34/0x60
>>>>> [  150.451178] [<ffff000008843268>] netstamp_clear+0x68/0x80
>>>>> [  150.451181] [<ffff0000080e49a0>] process_one_work+0x158/0x478
>>>>> [  150.451183] [<ffff0000080e4d10>] worker_thread+0x50/0x4a8
>>>>> [  150.451187] [<ffff0000080ebd78>] kthread+0x108/0x138
>>>>> [  150.451190] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
>>>>> [  150.477451]   (t=15008 jiffies g=805 c=804 q=8384)
>>>>> [  150.482242] Task dump for CPU 25:
>>>>> [  150.482245] kworker/25:1    R  running task        0   454      2 
>>>>> 0x00000002
>>>>> [  150.482259] Workqueue: events netstamp_clear
>>>>> [  150.482264] Call trace:
>>>>> [  150.482271] [<ffff00000808a530>] dump_backtrace+0x0/0x2b0
>>>>> [  150.482277] [<ffff00000808a804>] show_stack+0x24/0x30
>>>>> [  150.482281] [<ffff0000080fb750>] sched_show_task+0x128/0x178
>>>>> [  150.482285] [<ffff0000080fd298>] dump_cpu_task+0x48/0x58
>>>>> [  150.482288] [<ffff0000081f81e4>] rcu_dump_cpu_stacks+0xa0/0xe8
>>>>> [  150.482297] [<ffff00000813983c>] rcu_check_callbacks+0x774/0x938
>>>>> [  150.482305] [<ffff00000813fcb4>] update_process_times+0x34/0x60
>>>>> [  150.482314] [<ffff000008151b80>] tick_sched_handle.isra.7+0x38/0x70
>>>>> [  150.482319] [<ffff000008151c04>] tick_sched_timer+0x4c/0x98
>>>>> [  150.482324] [<ffff000008140510>] __hrtimer_run_queues+0xd8/0x2b8
>>>>> [  150.482328] [<ffff000008141180>] hrtimer_interrupt+0xa8/0x228
>>>>> [  150.482334] [<ffff0000087f2a2c>] arch_timer_handler_phys+0x3c/0x50
>>>>> [  150.482341] [<ffff00000812c194>] handle_percpu_devid_irq+0x8c/0x230
>>>>> [  150.482344] [<ffff000008126174>] generic_handle_irq+0x34/0x50
>>>>> [  150.482347] [<ffff000008126898>] __handle_domain_irq+0x68/0xc0
>>>>> [  150.482351] [<ffff0000080817e4>] gic_handle_irq+0xc4/0x170
>>>>> [  150.482356] Exception stack(0xffff801f901a7ab0 to 0xffff801f901a7be0)
>>>>> [  150.482360] 7aa0:
>>>>> 0000000000000003 ffff801f6d682578
>>>>> [  150.482364] 7ac0: 0000000000000000 0000000000000020
>>>>> 0000000000000020 ffffffff00000000
>>>>> [  150.482367] 7ae0: 0000000000000000 0000000000000000
>>>>> 0000000000000002 ffff801f901a7d30
>>>>> [  150.482371] 7b00: 00000000000009f0 00000000366e2f04
>>>>> 0000000000000018 0000000058dabe4c
>>>>> [  150.482375] 7b20: 0036312196549b4a 00003d0d6dd44d08
>>>>> ffff0000082e81d8 0000ffffb77c9028
>>>>> [  150.482378] 7b40: 0000000000000a03 ffff000009138e38
>>>>> ffff801f6d5cff08 ffff801f6d5cff00
>>>>> [  150.482382] 7b60: ffff000008e11e00 0000000000000001
>>>>> ffff0000081565d0 0000000000000000
>>>>> [  150.482386] 7b80: 0000000000000080 ffff000009139434
>>>>> ffff000009139000 ffff801f901a7be0
>>>>> [  150.482390] 7ba0: ffff000008156e8c ffff801f901a7be0
>>>>> ffff000008156ecc 0000000080000145
>>>>> [  150.482394] 7bc0: ffff801f901a7be0 ffff000008156e68
>>>>> ffffffffffffffff ffff000008156e8c
>>>>> [  150.482397] [<ffff000008082ff4>] el1_irq+0xb4/0x140
>>>>> [  150.482401] [<ffff000008156ecc>] smp_call_function_many+0x284/0x2e8
>>>>> [  150.482405] [<ffff000008157020>] kick_all_cpus_sync+0x30/0x38
>>>>> [  150.482409] [<ffff00000897c6cc>] aarch64_insn_patch_text+0xec/0xf8
>>>>> [  150.482415] [<ffff000008095978>] arch_jump_label_transform+0x60/0x98
>>>>> [  150.482420] [<ffff0000081f593c>] __jump_label_update+0x8c/0xa8
>>>>> [  150.482423] [<ffff0000081f6088>] jump_label_update+0x58/0xe8
>>>>> [  150.482429] [<ffff0000081f6240>] static_key_slow_inc+0x128/0x138
>>>>> [  150.482434] [<ffff0000081f6284>] static_key_enable+0x34/0x60
>>>>> [  150.482438] [<ffff000008843268>] netstamp_clear+0x68/0x80
>>>>> [  150.482441] [<ffff0000080e49a0>] process_one_work+0x158/0x478
>>>>> [  150.482444] [<ffff0000080e4d10>] worker_thread+0x50/0x4a8
>>>>> [  150.482448] [<ffff0000080ebd78>] kthread+0x108/0x138
>>>>> [  150.482451] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
>>>>>
>>>>> ====================================
>>>>>
>>>>> I am observing that this usually happens when the guest tries to
>>>>> bringup or use the default virtio-net interface.
>>>>> And I am unable to reproduce this when directly booting the guest
>>>>> kernel without UEFI BIOS.
>>>>> So anyone observed similar issue ?
>>>>>
>>>>
>>>> I haven't seen this myself.
>>>>
>>>> Have you tried with other versions of QEMU and the host kernel by any
>>>> chance using the same setup?
>>>
>>> The earlier qemu version (atleast 2.5 which is default on ubuntu
>>> 16.04) have different issue. The same thing happens when I use
>>> vhost=on but without vhost and with virtio-net didn't see the issue.
>>> The Armband folks have also reported the vhost issue here
>>> https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1673564
>>
>> So I just ran your setup using the flash emulation on the ThunderX in
>> packet.net and my host is happily continuing to run hackbench.
>>
>>>
>>> So I am beginning to think the issue could be related to the flash
>>> emulation but wanted to check on ml if anyone else is seeing it. But
>>> if it is flash emulation how can it hose the host like this ?
>>
>> Why do you think it's related to the flash emulation?
>>
>> From what you're telling me it sounds much more like a vhost regression.
>>
>> Can you try with v4.10 of the kernel with vhost=on ?
>
> Does this QEMU pull req help by any chance?

I will try all the suggestions above and get back. It would take few
days as I have few priority things to clear off my plate.

>
>   [Qemu-devel] [PULL 0/2] vhost, pc: fixes
>   http://lists.nongnu.org/archive/html/qemu-devel/2017-03/msg06103.html
>
> It says "Region caching is still causing issues around reset". (Region
> caching was a recent, very intrusive, virtio change in QEMU that sort of
> blew up everything and developers have been dealing with the fallout
> ever since. <-- my personal account anyway)
>
> In another (separate, downstream) discussion, I explained that the
> VirtioNetDxe driver in OVMF and ArmVirtQemu does a virtio reset on the
> virtio network device in an ExitBootServices() callback; that is, when
> the kernel's UEFI stub takes control of the system. Resetting the virtio
> device is supposed to cause the host to de-configure the device and to
> forget all about it. If that doesn't occur correctly, the guest kernel
> can definitely end up in a crappy state (the host might still consider
> memory areas belong to the virtio device that were originally allocated
> by the firmware, but are now overwritten by the guest kernel).
>
> In addition, I found some relevant-looking, recent vhost commits in the
> kernel:
>
> 275bf960ac69 vhost: better detection of available buffers
> 0ed005ce02fa vhost_net: tx batching
> 635b8c8ecdd2 tap: Renaming tap related APIs, data structures, macros
> 9a393b5d5988 tap: tap as an independent module
> e3b56cdd4351 vhost: try avoiding avail index access when getting
>              descriptor
> f88949138058 vhost: introduce O(1) vq metadata cache
>
> I think the symptoms could be a strange interplay between recent QEMU
> and kernel changes that are tickled by the firmware's virtio-net driver
> the wrong way.
>
> Thanks
> Laszlo
>
>>
>> Thanks,
>> -Christoffer
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