[RFC PATCH] KVM: Only print vcpu_unimpl when DEBUG is set

[RFC PATCH] KVM: Only print vcpu_unimpl when DEBUG is set

[Markus Trippelsdorf]

Every time I start qemu-kvm on my system the following line is added to
the syslog:

 vcpu0 unhandled rdmsr: 0xc0010001

AFAICS all calls to vcpu_unimpl only contain debugging info with little
or no value for the end user.

Wouldn't something like the following patch make sense?

Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b70b48b..6bd816f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -321,7 +321,7 @@ 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. */

-- 
Markus

Re: [RFC PATCH] KVM: Only print vcpu_unimpl when DEBUG is set

[Marcelo Tosatti]

On Thu, Jul 26, 2012 at 02:22:48PM +0200, Markus Trippelsdorf wrote:
> Every time I start qemu-kvm on my system the following line is added to
> the syslog:
> 
>  vcpu0 unhandled rdmsr: 0xc0010001
> 
> AFAICS all calls to vcpu_unimpl only contain debugging info with little
> or no value for the end user.
> 
> Wouldn't something like the following patch make sense?
> 
> Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>

It could be useful for debugging (but then lots of other things could).

Anyone has a use for this?

> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index b70b48b..6bd816f 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -321,7 +321,7 @@ 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. */
> 
> -- 
> Markus
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [RFC PATCH] KVM: Only print vcpu_unimpl when DEBUG is set

[Avi Kivity]

On 08/01/2012 06:19 AM, Marcelo Tosatti wrote:
> On Thu, Jul 26, 2012 at 02:22:48PM +0200, Markus Trippelsdorf wrote:
>> Every time I start qemu-kvm on my system the following line is added to
>> the syslog:
>> 
>>  vcpu0 unhandled rdmsr: 0xc0010001
>> 
>> AFAICS all calls to vcpu_unimpl only contain debugging info with little
>> or no value for the end user.
>> 
>> Wouldn't something like the following patch make sense?
>> 
>> Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
> 
> It could be useful for debugging (but then lots of other things could).
> 
> Anyone has a use for this?

The current scenario is:

<guest breaks>
Maintainer asks for dmesg
If something shows up, it's something to consider

Following this patch, the scenario will be

<guest breaks>
Maintainer: please enable dynamic debug for kvm and reproduce
If something shows up, it's something to consider

I guess with dynamic debug it's acceptable, we just need to make sure
that it doesn't spew tons of other stuff.

-- 
error compiling committee.c: too many arguments to function