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

On 4/27/2017 2:25 AM, Dave Young wrote:

On 04/21/17 at 02:55pm, Dave Hansen wrote:

quoted

On 04/18/2017 02:22 PM, Tom Lendacky wrote:

quoted

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