Re: [PATCH 6/7] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature

Tim Chen
2018-01-04T19:02:35Z

On 01/04/2018 10:34 AM, Andrea Arcangeli wrote:
> On Thu, Jan 04, 2018 at 09:56:47AM -0800, Tim Chen wrote:
>> There are 2 ways to control IBRS
>>
>> 1. At boot time
>> noibrs kernel boot parameter will disable IBRS usage
>>
>> Otherwise if the above parameters are not specified, the system
>> will enable ibrs and ibpb usage if the cpu supports it.
>>
>> 2. At run time
>> echo 0 > /sys/kernel/debug/ibrs_enabled will turn off IBRS
>> echo 1 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in kernel
>> echo 2 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in both userspace and kernel
>
> debug/x86/?
>
> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
>
> Thanks,
> Andrea
>

Yes, will correct.

Thanks.