Re: [Xen-devel] Stopping much Linux testing in Xen Project CI

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.03.2020 18:55, Roger Pau Monné wrote:
> On Thu, Mar 12, 2020 at 04:49:51PM +0000, Ian Jackson wrote:
>> Linux stable branches, and Linux upstream tip, are badly broken and
>> have been for months.  Apparently no-one is able to (or has time to)
>> to investigate and fix.
>>
>>   linux-4.4          218 days         to be suspended
>>   linux-4.9          134 days         to be suspended
>>   linux-4.14         134 days         to be suspended
>>   linux-4.19         134 days         to be suspended
>>   linux-5.4           55 days
>>   linux-arm-xen     up to date
>>   linux-linus        372 days         to be suspended
>>
>> These are times since the last push - ie, how long it has been broken.
>> Evidently no-one is paying any attention to this.[1]  I looked at the
>> reports myself and:
>>
>> Nested HVM is broken on Intel in all of the 4.x branches.
> 
> FWIW, it's the Debian installer kernel the one that crashes AFAICT,
> all the failures are:
> 
> [    0.000000] Linux version 4.9.0-6-amd64 (debian-kernel@xxxxxxxxxxxxxxxx) 
> (gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1) ) #1 SMP Debian 
> 4.9.82-1+deb9u3 (2018-03-02)
> [...]
> [    0.000000] clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, 
> max_idle_ns: 30580167144 ns
> [    0.000000] tsc: Fast TSC calibration failed
> [    0.000000] tsc: Unable to calibrate against PIT
> [    0.000000] tsc: HPET/PMTIMER calibration failed
> [    0.000000] divide error: 0000 [#1] SMP
> [    0.000000] Modules linked in:
> [    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.0-6-amd64 #1 
> Debian 4.9.82-1+deb9u3
> [    0.000000] Hardware name: Xen HVM domU, BIOS 4.14-unstable 03/11/2020
> [    0.000000] task: ffffffffab611500 task.stack: ffffffffab600000
> [    0.000000] RIP: 0010:[<ffffffffaaa59e1f>]  [<ffffffffaaa59e1f>] 
> pvclock_tsc_khz+0xf/0x30

Seeing this and ...

> [    0.000000] RSP: 0000:ffffffffab603f38  EFLAGS: 00010246
> [    0.000000] RAX: 000f424000000000 RBX: ffffffffffffffff RCX: 
> 0000000000000000
> [    0.000000] RDX: 0000000000000000 RSI: 0000000000000246 RDI: 
> ffffffffab939020
> [    0.000000] RBP: ffff93806e8f1540 R08: 000000003a637374 R09: 
> 6f6974617262696c
> [    0.000000] R10: 00000032f3af6dcd R11: 4d502f5445504820 R12: 
> ffffffffab7dc920
> [    0.000000] R13: ffffffffab7e82e0 R14: 00000000000146f0 R15: 
> 000000000000008e
> [    0.000000] FS:  0000000000000000(0000) GS:ffff93806e600000(0000) 
> knlGS:0000000000000000
> [    0.000000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    0.000000] CR2: ffff938065f3a000 CR3: 0000000025c08000 CR4: 
> 00000000000406b0
> [    0.000000] Stack:
> [    0.000000]  ffffffffab74b1b6 ffff93806e8f1540 ffffffffab7dc920 
> ba81e537ba81e512
> [    0.000000]  ffffffffffffffff ffff93806e8f1540 ffffffffab73deb6 
> ffffffffab7e82e0
> [    0.000000]  0000000000000000 0000000000000020 0000ffffffffab73 
> 00000000ffffffff
> [    0.000000] Call Trace:
> [    0.000000]  [<ffffffffab74b1b6>] ? tsc_init+0x39/0x25b

... this and looking at xen_tsc_khz(), isn't it supposed to use
per_cpu(xen_vcpu, 0) instead, in case vCPU info got relocated?
(Code looks to be the same in 4.9 and 5.5. I'd also question
the hard-coded zero in there, but that's a different topic.)

Jan

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