[fedora-virt] Another weird KVM glitch

[Avi Kivity]

On 12/20/2009 05:10 PM, Tom Horsley wrote:
> I've been looking at a few days worth of testbed results,
> and rarely (but more than once) a fantastically weird failure
> happens:
>
> Some random process (bash, gcc, etc) will die with a
> Trace/Breakpoint trap reported as the reason for the abort.
>
> I am running tests of debugging on most of the virtual
> machines, but I'm not debugging these apps, I'm debugging
> other stuff on other virtual machines.
>
> It is almost like the emulation code is looking at stale
> register values when reporting a breakpoint or address
> trap and directing it to the wrong process. So far, I've
> never seen this on my Xeon based host, only on my Opteron
> based host.
>
> There are 8 CPUs on this thing. I wonder if there is
> a missing lock somewhere in some infrequently executed
> code path.
>    

kvm tries very hard to avoid switching cpu registers when it is 
expensive to do so; it's possible it tries too hard sometimes.

Can you give a reliable scenario for triggering this?

What host kernel are you running?


-- 
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