On Mon, Jul 18, 2016 at 11:26:50AM -0400, Paolo Bonzini wrote:
>
> > kvm is pretty noisy when you have guests poking at MSRs that the kernel
> > doesn't implement. The conveniently named 'ignore_msrs' option initially
> > seemed
> > like it was what I was looking for, but it changes the printk instead
> > of eliding it.
> >
> > Untested patch below converts ignore_msrs to a bitmask and adds an option to
> > be
> > completely silent. The idea being if after testing, things still work and you
> > don't care about those messages, you can deploy in production with the
> > silence option.
> >
> > Would something like this be acceptable ?
>
> Indeed, ignore_msrs does a completely different thing. It suppresses
> general protection faults in the guest. It is related to behavior that
> KVM injects in the guests, not to the things that KVM spews in the host.
>
> What about just downgrading the printf to KERN_DEBUG? You could simply
> change from vcpu_unimpl to vcpu_debug, but it's probably a good idea to
> keep the ratelimiting; there's a kvm_pr_unimpl, so maybe add a new
> kvm_pr_debug and vcpu_pr_debug.
Hm, we've certainly got a lot of options in terms of print primitives these days.
We could just do this...
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1c9c973a7dd9..a80b9a0a5f8c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -423,7 +423,7 @@ struct kvm {
#define kvm_debug(fmt, ...) \
pr_debug("kvm [%i]: " fmt, task_pid_nr(current), ## __VA_ARGS__)
#define kvm_pr_unimpl(fmt, ...) \
- pr_err_ratelimited("kvm [%i]: " fmt, \
+ pr_debug_ratelimited("kvm [%i]: " fmt, \
task_tgid_nr(current), ## __VA_ARGS__)
/* The guest did something we don't support. */
Which I think would have the desired effect, and also gets us dynamic debug
support for free.
Thoughts ?
Dave
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