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Date: Fri, 7 Dec 2018 14:54:30 +0300
From: "Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME)
Message-ID: <20181207115430.xrj64q4j7hqdmbsw@kshutemo-mobl1>
References: <cover.1543903910.git.alison.schofield@intel.com>
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To: "Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>
Cc: "kirill.shutemov@linux.intel.com" <kirill.shutemov@linux.intel.com>, "peterz@infradead.org" <peterz@infradead.org>, "jmorris@namei.org" <jmorris@namei.org>, "Huang, Kai" <kai.huang@intel.com>, "keyrings@vger.kernel.org" <keyrings@vger.kernel.org>, "tglx@linutronix.de" <tglx@linutronix.de>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "dhowells@redhat.com" <dhowells@redhat.com>, "linux-security-module@vger.kernel.org" <linux-security-module@vger.kernel.org>, "Williams, Dan J" <dan.j.williams@intel.com>, "x86@kernel.org" <x86@kernel.org>, "hpa@zytor.com" <hpa@zytor.com>, "mingo@redhat.com" <mingo@redhat.com>, "luto@kernel.org" <luto@kernel.org>, "bp@alien8.de" <bp@alien8.de>, "Hansen, Dave" <dave.hansen@intel.com>, "Schofield, Alison" <alison.schofield@intel.com>, "Nakajima, Jun" <jun.nakajima@intel.com>

On Thu, Dec 06, 2018 at 09:23:20PM +0000, Sakkinen, Jarkko wrote:
> On Thu, 2018-12-06 at 14:22 +0300, Kirill A. Shutemov wrote:
> > When you say "disable encryption to a page" does the encryption get
> > > actually disabled or does the CPU just decrypt it transparently i.e.
> > > what happens physically?
> > 
> > Yes, it gets disabled. Physically. It overrides TME encryption.
> 
> OK, thanks for confirmation. BTW, how much is the penalty to keep it
> always enabled? Is it something that would not make sense for some
> other reasons?

We don't have any numbers to share at this point.

-- 
 Kirill A. Shutemov