What triggers a "*** Guest State ***" register dump from the linux kernel?

Prefix: There is no kernel crash.

Something, rarely, is triggering Guest State, Host State, Control State register and other debug variable dump to kernel log.

The system in question is running many many virtual machines via qemu/kvm. The kernel messages are less often than any running vm is starting or ending.

What triggers this?

[3818340.021513] *** Guest State ***
[3818340.021543] CR0: actual=0x0000000000000030, shadow=0x0000000000000010, gh_mask=fffffffffffffff7
[3818340.021581] CR4: actual=0x0000000000002040, shadow=0x0000000000000000, gh_mask=ffffffffffffe871
[3818340.021619] CR3 = 0x00000000001aa000
[3818340.021653] RSP = 0x000000000000f6e8  RIP = 0x0000000000008000
[3818340.021680] RFLAGS=0x00000002         DR7 = 0x0000000000000400
[3818340.021707] Sysenter RSP=0000000000000000 CS:RIP=0000:0000000000000000
[3818340.021736] CS:   sel=0xa000, attr=0x08093, limit=0xffffffff, base=0x00000000000a0000
[3818340.021770] DS:   sel=0x0000, attr=0x08093, limit=0xffffffff, base=0x0000000000000000
[3818340.021804] SS:   sel=0x0000, attr=0x00093, limit=0xffffffff, base=0x0000000000000000
[3818340.021837] ES:   sel=0x0000, attr=0x08093, limit=0xffffffff, base=0x0000000000000000
[3818340.021871] FS:   sel=0x0000, attr=0x08093, limit=0xffffffff, base=0x0000000000000000
[3818340.021905] GS:   sel=0x0000, attr=0x08093, limit=0xffffffff, base=0x0000000000000000
[3818340.021939] GDTR:                           limit=0x0000007f, base=0x00000000001a7000
[3818340.021973] LDTR: sel=0x0000, attr=0x10000, limit=0x000fffff, base=0x0000000000000000
[3818340.022007] IDTR:                           limit=0x00000000, base=0x0000000000000000
[3818340.022042] TR:   sel=0x0040, attr=0x0008b, limit=0x00000077, base=0x0000000000025f50
[3818340.022076] EFER =     0x0000000000000000  PAT = 0x0007040600070406
[3818340.022104] DebugCtl = 0x0000000000000000  DebugExceptions = 0x0000000000000000
[3818340.022137] Interruptibility = 00000008  ActivityState = 00000000
[3818340.022164] InterruptStatus = 0000
[3818340.022181] *** Host State ***
[3818340.022197] RIP = 0xffffffffc070d095  RSP = 0xffff8fe22c50bc88
[3818340.022223] CS=0010 SS=0018 DS=0000 ES=0000 FS=0000 GS=0000 TR=0040
[3818340.022251] FSBase=00007efe6d591700 GSBase=ffff8c17ff600000 TRBase=fffffe0000003000
[3818340.022291] GDTBase=fffffe0000001000 IDTBase=fffffe0000000000
[3818340.022317] CR0=0000000080050033 CR3=0000000b1ddae002 CR4=00000000001626f0
[3818340.022347] Sysenter RSP=fffffe0000003000 CS:RIP=0010:ffffffff98801540
[3818340.022376] EFER = 0x0000000000000d01  PAT = 0x0407050600070106
[3818340.022402] *** Control State ***
[3818340.022436] PinBased=000000bf CPUBased=b5a06dfa SecondaryExec=00000fe3
[3818340.022466] EntryControls=0000d1ff ExitControls=002fefff
[3818340.022490] ExceptionBitmap=00060042 PFECmask=00000000 PFECmatch=00000000
[3818340.022521] VMEntry: intr_info=00000000 errcode=00000000 ilen=00000002
[3818340.022550] VMExit: intr_info=00000000 errcode=00000000 ilen=00000002
[3818340.022579]         reason=80000021 qualification=0000000000000000
[3818340.022605] IDTVectoring: info=00000000 errcode=00000000
[3818340.022629] TSC Offset = 0xff11e9bd0803c1cc
[3818340.022649] TPR Threshold = 0x00
[3818340.022666] PostedIntrVec = 0xf2
[3818340.022683] EPT pointer = 0x0000002ee42c701e
[3818340.022703] PLE Gap=00000080 Window=00001000
[3818340.022722] Virtual processor ID = 0x0005