From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Subject: Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory
	Encryption
Date: Thu, 18 May 2017 19:01:53 +0200
Message-ID: <20170518170153.eqiyat5s6q3yeejl@pd.tnic>
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To: Tom Lendacky <thomas.lendacky-5C7GfCeVMHo@public.gmane.org>
Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Brijesh Singh <brijesh.singh-5C7GfCeVMHo@public.gmane.org>, Toshimitsu Kani <toshi.kani-ZPxbGqLxI0U@public.gmane.org>, Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Alexander Potapenko <glider-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Larry Woodman <lwoodman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kasan-dev-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Andrey Ryabinin <aryabinin-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>, Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Rik van Riel <riel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>, Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Dmitry Vyukov <dvyukov-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, "Michael S. Tsirkin" <mst@r>
List-Id: linux-efi@vger.kernel.org

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.