Re: [PATCH 2/3] perf: require exclude_guest to use PEBS - kernel side enforcement

[David Ahern <dsahern@gmail.com>]

On 9/12/12 8:38 PM, Namhyung Kim wrote:
> Hi David,
>
> On Wed, 12 Sep 2012 09:16:29 -0600, David Ahern wrote:
>> From: Peter Zijlstra <peterz@infradead.org>
>>
>> Per Peter:
>>    "Intel PEBS in VT-x context uses the DS address as a guest linear address,
>>    even though its programmed by the host as a host linear address. This
>>    either results in guest memory corruption and or the hardware faulting and
>>    'crashing' the virtual machine.  Therefore we have to disable PEBS on VT-x
>>    enter and re-enable on VT-x exit, enforcing a strict exclude_guest.
>>
>> This patch enforces exclude_guest kernel side.
>>
> [snip]
>> @@ -380,6 +383,9 @@ int x86_pmu_hw_config(struct perf_event *event)
>>   	if (event->attr.precise_ip) {
>>   		int precise = 0;
>>
>> +		if (!event->attr.exclude_guest)
>> +				return -EOPNOTSUPP;
>
> I see a whitespace problem here. :)

grr.... an extra freaking tab.