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Subject: Re: [PATCH] Ability to read the MKTME status from userspace (patch
 v2)
To:     Andy Lutomirski <luto@amacapital.net>
Cc:     Borislav Petkov <bp@alien8.de>,
        Daniel Gutson <daniel@eclypsium.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>, Tony Luck <tony.luck@intel.com>,
        Rahul Tanwar <rahul.tanwar@linux.intel.com>,
        Xiaoyao Li <xiaoyao.li@intel.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Richard Hughes <hughsient@gmail.com>
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Message-ID: <b3ea365a-816c-b712-29c6-9f49df1bd41f@intel.com>
Date:   Thu, 25 Jun 2020 14:43:42 -0700
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On 6/25/20 2:39 PM, Andy Lutomirski wrote:
> What about MKTME platforms that (using hypothetical future kernel
> support) have encryption enabled for a node but have disabled it for
> specific pages using madvise()?  Or that have any other nontrivial
> policy like that?

I think it's fine if the magic new bit means "normal allocations get
hardware encryption".  If we have a way for users to opt out of that,
that's fine with me because the default is to provide it and a user must
have gone through _some_ hoop to undo the protection.

BTW, although the MKTME hardware and architecture support disabling
encryption, we don't have any plans to expose that to applications.