So I installed my first KVM guest image (a prerelease of Ubuntu 9.10
that I had lying around) this morning (through virt-manager, as it
happens). Everything worked fine, the install was searingly fast
compared to the UML virtual machines I'm used to.
I got back to it this evening, restarted the VM, and found that it had
suddenly slowed right down again, with one CPU being saturated with work
even when nothing was happening. Looking at the syslog shows (what would
be but for ratelimit) incredible numbers of these messages being logged:
Nov 27 21:44:00 spindle info: [444857.792205] device vnet0 entered promiscuous mode
Nov 27 21:44:00 spindle info: [444857.794347] linux-net: port 2(vnet0) entering learning state
Nov 27 21:44:03 spindle warning: [444860.856640] __ratelimit: 928705 callbacks suppressed
Nov 27 21:44:03 spindle err: [444860.856729] emulation failed (pagetable) rip 7f3845f36a7b 66 0f 7f 07