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

From Borislav Petkov <bp@alien8.de>
Newsgroups linux.kernel
Subject Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory Encryption
Date 2017-05-18 19:10 +0200
Message-ID <tIx62-5FV-7@gated-at.bofh.it> (permalink)
References <txTMB-1zl-13@gated-at.bofh.it> <tyOKS-2xl-9@gated-at.bofh.it>
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On Tue, Apr 18, 2017 at 04:22:12PM -0500, Tom Lendacky wrote:
> Add sysfs support for SME so that user-space utilities (kdump, etc.) can
> determine if SME is active.

But why do user-space tools need to know that?

I mean, when we load the kdump kernel, we do it with the first kernel,
with the kexec_load() syscall, AFAICT. And that code does a lot of
things during that init, like machine_kexec_prepare()->init_pgtable() to
prepare the ident mapping of the second kernel, for example.

What I'm aiming at is that the first kernel knows *exactly* whether SME
is enabled or not and doesn't need to tell the second one through some
sysfs entries - it can do that during loading.

So I don't think we need any userspace things at all...

Or?

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory  Encryption Borislav Petkov <bp@alien8.de> - 2017-05-18 19:10 +0200

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