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

[Tom Lendacky]

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