Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory Encryption

Tom Lendacky
2017-05-04T14:14:07Z

On 4/27/2017 2:25 AM, Dave Young wrote:
> On 04/21/17 at 02:55pm, Dave Hansen wrote:
>> On 04/18/2017 02:22 PM, Tom Lendacky wrote:
>>> Add sysfs support for SME so that user-space utilities (kdump, etc.) can
>>> determine if SME is active.
>>>
>>> A new directory will be created:
>>> /sys/kernel/mm/sme/
>>>
>>> And two entries within the new directory:
>>> /sys/kernel/mm/sme/active
>>> /sys/kernel/mm/sme/encryption_mask
>>
>> Why do they care, and what will they be doing with this information?
>
> Since kdump will copy old memory but need this to know if the old memory
> was encrypted or not. With this sysfs file we can know the previous SME
> status and pass to kdump kernel as like a kernel param.
>
> Tom, have you got chance to try if it works or not?

Sorry, I haven't had a chance to test this yet.

Thanks,
Tom

>
> Thanks
> Dave
>