Re: [PATCH] KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message

[Steven Rostedt]

On Wed, 9 Jun 2021 09:12:40 -0700
Sean Christopherson <seanjc@xxxxxxxxxx> wrote:

> > I can observe tons of other kvm tracepoints warning like this after
> > commit 9a6944fee68e25 (tracing: Add a verifier to check string
> > pointers for trace events), just echo 1 >
> > /sys/kernel/tracing/events/kvm/enable and boot a linux guest.  
> 
> Can you provide your .config?  With all of events/kvm and events/kvmmmu enabled
> I don't get any warnings running a Linux guest, a nested Linux guest, and
> kvm-unit-tests.
> 
> Do you see the behavior with other tracepoints?  E.g. enabling all events on my
> systems yields warnings for a USB module, but everything else is clean.

Right, I tested this with running KVM guests when it was added. I was
actually surprised with Sean's report saying it was a kvm trace event,
until I noticed that the problem event is only triggered on error paths.

-- Steve