linux-kernel - Re: [Xen-devel] [PATCH] xen: Make VPMU init message look less scary

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Date:	Mon, 1 Aug 2016 17:48:52 +0200
From:	Juergen Gross <jgross@...e.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
	boris.ostrovsky@...cle.com, david.vrabel@...rix.com
Subject: Re: [Xen-devel] [PATCH] xen: Make VPMU init message look less scary

On 01/08/16 16:11, Konrad Rzeszutek Wilk wrote:
> On Mon, Aug 01, 2016 at 01:41:20PM +0200, Juergen Gross wrote:
>> The default for the Xen hypervisor is to not enable VPMU in order to
>> avoid security issues. In this case the Linux kernel will issue the
>> message "Could not initialize VPMU for cpu 0, error -95" which looks
>> more like an error than a normal state.
>>
>> Change the message to something less scary in case the hypervisor
>> returns EOPNOTSUPP when trying to activate VPMU.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>>  arch/x86/xen/pmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
>> index 32bdc2c..e9d66fa 100644
>> --- a/arch/x86/xen/pmu.c
>> +++ b/arch/x86/xen/pmu.c
>> @@ -547,8 +547,11 @@ void xen_pmu_init(int cpu)
>>  	return;
>>  
>>  fail:
>> -	pr_info_once("Could not initialize VPMU for cpu %d, error %d\n",
>> -		cpu, err);
>> +	if (err == -EOPNOTSUPP)
>> +		pr_info_once("VPMU usage disabled due to Xen settings\n");
> 
> How about 'VPMU disabled by hypevisor.'

Hmm, why not. Boris, are you okay with this message, too?


Juergen