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Re: migration: broken snapshot saves appear on s390 when small fields in
From: |
Claudio Fontana |
Subject: |
Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed |
Date: |
Wed, 15 Jul 2020 14:25:44 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 |
On 7/15/20 1:10 PM, Claudio Fontana wrote:
> Hi Thomas,
>
> On 7/14/20 4:35 PM, Thomas Huth wrote:
>> On 14/07/2020 16.29, Claudio Fontana wrote:
>>> Hello,
>>>
>>> I have some tiny progress in narrowing down this issue, possibly a qcow2
>>> issue, still unclear,
>>> but involving Kevin Wolf and Max Reitz.
>>>
>>>
>>> The reproducer again:
>>>
>>>> --------------------------------------------cut-------------------------------------------
>>>> diff --git a/cpus.c b/cpus.c
>>>> index 41d1c5099f..443b88697a 100644
>>>> --- a/cpus.c
>>>> +++ b/cpus.c
>>>> @@ -643,7 +643,7 @@ static void qemu_account_warp_timer(void)
>>>>
>>>> static bool icount_state_needed(void *opaque)
>>>> {
>>>> - return use_icount;
>>>> + return 0;
>>>> }
>>>>
>>>> static bool warp_timer_state_needed(void *opaque)
>>>> --------------------------------------------cut-------------------------------------------
>>>
>>> This issue for now appears on s390 only:
>>>
>>> On s390 hardware, test 267 fails (both kvm and tcg) in the qcow2 backing
>>> file part, with broken migration stream data in the s390-skeys vmsave (old
>>> style).
>> [...]
>>> If someone has a good idea let me know - first attempts to reproduce on x86
>>> failed, but maybe more work could lead to it.
>>
>
> small update: in the GOOD case (enough padding added) a qcow_merge() is
> triggered for the last write of 16202 bytes.
> In the BAD case (not enough padding added) a qcow_merge() is not triggered
> for the last write of 16201 bytes.
I am talking about merge_cow() here, and it is more complicated. Will post a
better explanation later on.
>
> Note: manually flushing with qemu_fflush in s390-skeys vmsave also works
> (maybe got lost in the noise).
- migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/12
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Paolo Bonzini, 2020/07/12
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/13
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/14
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Thomas Huth, 2020/07/14
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/15
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed,
Claudio Fontana <=
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/16
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/20
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Claudio Fontana, 2020/07/21
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Bruce Rogers, 2020/07/27
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Vladimir Sementsov-Ogievskiy, 2020/07/28
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Vladimir Sementsov-Ogievskiy, 2020/07/28
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Bruce Rogers, 2020/07/28
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Max Reitz, 2020/07/28
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Vladimir Sementsov-Ogievskiy, 2020/07/28
- Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed, Paolo Bonzini, 2020/07/28