linux-kernel - Re: [PATCH v8 0/8] x86: Show in sysfs if a memory node is able to do encryption

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Date:   Wed, 18 May 2022 11:28:49 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Richard Hughes <hughsient@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Martin Fernandez <martin.fernandez@...ypsium.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org, Linux MM <linux-mm@...ck.org>,
        "H. Peter Anvin" <hpa@...or.com>, daniel.gutson@...ypsium.com,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>, X86 ML <x86@...nel.org>,
        "Schofield, Alison" <alison.schofield@...el.com>,
        alex.bazhaniuk@...ypsium.com, Greg KH <gregkh@...uxfoundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        Ben Widawsky <ben.widawsky@...el.com>,
        "Huang, Kai" <kai.huang@...el.com>
Subject: Re: [PATCH v8 0/8] x86: Show in sysfs if a memory node is able to do encryption

On Wed, May 18, 2022 at 12:53 AM Borislav Petkov <bp@...en8.de> wrote:
>
> On Mon, May 16, 2022 at 09:39:06AM +0100, Richard Hughes wrote:
> > This is still something consumers need; at the moment users have no
> > idea if data is *actually* being encrypted.
>
> As it was already pointed out - that's in /proc/cpuinfo.

For TME you still need to compare it against the EFI memory map as
there are exclusion ranges for things like persistent memory. Given
that persistent memory can be forced into volatile "System RAM"
operation by various command line options and driver overrides, you
need to at least trim the assumptions of what is encrypted to the
default "conventional memory" conveyed by platform firmware / BIOS.