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[192.55.52.151]) by mx.google.com with ESMTPS id a69si3320006pla.178.2019.05.13.07.27.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 May 2019 07:27:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.151 as permitted sender) client-ip=192.55.52.151; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.151 as permitted sender) smtp.mailfrom=kirill.shutemov@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 May 2019 07:27:43 -0700 X-ExtLoop1: 1 Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga005.fm.intel.com with ESMTP; 13 May 2019 07:27:40 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 489FE2B1; Mon, 13 May 2019 17:27:39 +0300 (EEST) Date: Mon, 13 May 2019 17:27:39 +0300 From: "Kirill A. Shutemov" To: Dave Hansen Cc: Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , David Howells , Kees Cook , Kai Huang , Jacob Pan , Alison Schofield , linux-mm@kvack.org, kvm@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH, RFC 03/62] mm/ksm: Do not merge pages with different KeyIDs Message-ID: <20190513142739.7v3cnrnnnsdldcuc@black.fi.intel.com> References:<20190508144422.13171-1-kirill.shutemov@linux.intel.com> <20190508144422.13171-4-kirill.shutemov@linux.intel.com> <1697adad-6ae2-ea85-bab5-0144929ed2d9@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To:<1697adad-6ae2-ea85-bab5-0144929ed2d9@intel.com> User-Agent: NeoMutt/20170714-126-deb55f (1.8.3) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 10, 2019 at 06:07:11PM +0000, Dave Hansen wrote: > On 5/8/19 7:43 AM, Kirill A. Shutemov wrote: > > KeyID indicates what key to use to encrypt and decrypt page's content. > > Depending on the implementation a cipher text may be tied to physical > > address of the page. It means that pages with an identical plain text > > would appear different if KSM would look at a cipher text. It effectively > > disables KSM for encrypted pages. > > > > In addition, some implementations may not allow to read cipher text at all. > > > > KSM compares plain text instead (transparently to KSM code). > > > > But we still need to make sure that pages with identical plain text will > > not be merged together if they are encrypted with different keys. > > > > To make it work kernel only allows merging pages with the same KeyID. > > The approach guarantees that the merged page can be read by all users. > > I can't really parse this description. Can I suggest replacement text? Sure. -- Kirill A. Shutemov