From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Date: Thu, 06 Dec 2018 14:59:10 +0000 Subject: Re: [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20181204092550.GT11614@hirez.programming.kicks-ass.net> <20181204094647.tjsvwjgp3zq6yqce@black.fi.intel.com> <063026c66b599ba4ff0b30a5ecc7d2c716e4da5b.camel@intel.com> <20181206112255.4bbumbrf5nnz4t2z@kshutemo-mobl1> In-Reply-To: <20181206112255.4bbumbrf5nnz4t2z@kshutemo-mobl1> To: "Kirill A. Shutemov" , "Sakkinen, Jarkko" Cc: "kirill.shutemov@linux.intel.com" , "peterz@infradead.org" , "jmorris@namei.org" , "Huang, Kai" , "keyrings@vger.kernel.org" , "tglx@linutronix.de" , "linux-mm@kvack.org" , "dhowells@redhat.com" , "linux-security-module@vger.kernel.org" , "Williams, Dan J" , "x86@kernel.org" , "hpa@zytor.com" , "mingo@redhat.com" , "luto@kernel.org" , "bp@alien8.de" , "Schofield, Alison" , "Nakajima, Jun" On 12/6/18 3:22 AM, 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. I know MKTME itself has a runtime overhead and we expect it to have a performance impact in the low single digits. Does TME have that overhead? Presumably MKTME plus no-encryption is not expected to have the overhead. We should probably mention that in the changelogs too.