------- Comment From [email protected] 2017-11-30 08:18 EDT-------
Hello!

I'm also trying to reproduce the problem on QEMU/KVM side but I haven't
hit it so far.

My setup:

[1]
host: 8247-42L
kernel: 4.13.0-16-generic
guest: vanilla ubuntu-16.04.3-server-ppc64el.iso

[2]
host: 8335-GCA
kernel: 4.13.0-17-generic
guest: vanilla ubuntu-16.04.3-server-ppc64el.iso

I tried several command line combinations, both KVM PR/HV modules and
everything works flawlessly.

After reading the logs (#comment 10) the following line called my
attention:

interrupt: 901 at plpar_hcall_norets+0x1c/0x28

Searching the code, I found pieces like:

for_each_online_cpu(cpu)
plpar_hcall_norets(...);

So I'm thinking that *maybe* if one of your hw threads died and KVM
alloc'ed that core it could trigger the issue. If that's the case, set
the processor affinity may let the error consistent.

In my case, all cores and threads looks good:

$ sudo ppc64_cpu --smt=8
$ sudo ppc64_cpu --info
Core   0:    0*    1*    2*    3*    4*    5*    6*    7*
Core   1:    8*    9*   10*   11*   12*   13*   14*   15*
Core   2:   16*   17*   18*   19*   20*   21*   22*   23*
Core   3:   24*   25*   26*   27*   28*   29*   30*   31*
Core   4:   32*   33*   34*   35*   36*   37*   38*   39*
Core   5:   40*   41*   42*   43*   44*   45*   46*   47*
Core   6:   48*   49*   50*   51*   52*   53*   54*   55*
Core   7:   56*   57*   58*   59*   60*   61*   62*   63*
Core   8:   64*   65*   66*   67*   68*   69*   70*   71*
Core   9:   72*   73*   74*   75*   76*   77*   78*   79*
Core  10:   80*   81*   82*   83*   84*   85*   86*   87*
Core  11:   88*   89*   90*   91*   92*   93*   94*   95*
Core  12:   96*   97*   98*   99*  100*  101*  102*  103*
Core  13:  104*  105*  106*  107*  108*  109*  110*  111*
Core  14:  112*  113*  114*  115*  116*  117*  118*  119*
Core  15:  120*  121*  122*  123*  124*  125*  126*  127*
Core  16:  128*  129*  130*  131*  132*  133*  134*  135*
Core  17:  136*  137*  138*  139*  140*  141*  142*  143*
Core  18:  144*  145*  146*  147*  148*  149*  150*  151*
Core  19:  152*  153*  154*  155*  156*  157*  158*  159*
Core  20:  160*  161*  162*  163*  164*  165*  166*  167*
Core  21:  168*  169*  170*  171*  172*  173*  174*  175*
Core  22:  176*  177*  178*  179*  180*  181*  182*  183*
Core  23:  184*  185*  186*  187*  188*  189*  190*  191*

Could you guys turn your core threads as well and give me the output?

Thank you

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https://bugs.launchpad.net/bugs/1733864

Title:
  kernel 4.10.0-40 is hanging with a CPU soft lock

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