From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27CBEC4332D for ; Tue, 16 Feb 2021 16:53:05 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D111664DCF for ; Tue, 16 Feb 2021 16:53:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D111664DCF Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=62UCO5ea6ADx0mpLoC6LQH65KF8XapeprE3qWSzfKZc=; b=FfdgbpWEJ0AjSfR8WgjxNfmyU pF2EdTWmYkx886AXXm/8BUxE+FYjbV2DI13sCuXNOzFAj3WAi0aUTnpaiilGSObvXzGMiT//RfQyB btULLNC0jZr7RGWxnS7gCKTINeOu3ZcMOpI9m1UOXkQ+JO9iHZRD3ni+X5z8vhR0/xIkbX7gZrL5B BDr4Y0K2b/IUP9QVtQLSnK3HvtNZgFfsJ8lDjLv8cp1SXwFSE2prXJS/g0HHTKlc76zkNF0q/hCTL ydzsg6Yi8Ke5lyATAClAslnZ5gNOle6pKDp50hW5rztcmCwsYSCAr7OcJ5c0LpU1ORVCA2C3y2ZKK jwAVdD9Sw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lC3Zf-0005hC-DI; Tue, 16 Feb 2021 16:51:43 +0000 Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lC3Za-0005fZ-Lf; Tue, 16 Feb 2021 16:51:41 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1613494295; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fv1cqvwsI0OzZQzjo9Fzqiw9J9sAKYM15trtTiADU8I=; b=m+7A3yBnlzXwcSFUtKDR2Y9JcLQQ7GBKZLbjSDY4uRJe8Oprcc1t3A0Yb4nCpmSjJzTq71 m2lvwh4POgKc94rijkZTo8EsctDQ8udo5YFmIVVBqcDZmQE+zdGsrWJMYIvr1Q40Hpav5m AI5AIoiWGkF74EgEjx/NO759Sl7hNIs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 93467AE05; Tue, 16 Feb 2021 16:51:35 +0000 (UTC) Date: Tue, 16 Feb 2021 17:51:34 +0100 From: Michal Hocko To: James Bottomley Subject: Re: [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: References: <20210214091954.GM242749@kernel.org> <052DACE9-986B-424C-AF8E-D6A4277DE635@redhat.com> <244f86cba227fa49ca30cd595c4e5538fe2f7c2b.camel@linux.ibm.com> <12c3890b233c8ec8e3967352001a7b72a8e0bfd0.camel@linux.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <12c3890b233c8ec8e3967352001a7b72a8e0bfd0.camel@linux.ibm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210216_115138_975982_ED6B76DB X-CRM114-Status: GOOD ( 22.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , David Hildenbrand , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "H. Peter Anvin" , Christopher Lameter , Shuah Khan , Thomas Gleixner , Elena Reshetova , linux-arch@vger.kernel.org, Tycho Andersen , linux-nvdimm@lists.01.org, Will Deacon , x86@kernel.org, Matthew Wilcox , Mike Rapoport , Ingo Molnar , Michael Kerrisk , Palmer Dabbelt , Arnd Bergmann , Hagen Paul Pfeifer , Borislav Petkov , Alexander Viro , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-fsdevel@vger.kernel.org, Shakeel Butt , Andrew Morton , Rick Edgecombe , Roman Gushchin , Mike Rapoport Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue 16-02-21 08:25:39, James Bottomley wrote: > On Mon, 2021-02-15 at 20:20 +0100, Michal Hocko wrote: > [...] > > > > What kind of flags are we talking about and why would that be a > > > > problem with memfd_create interface? Could you be more specific > > > > please? > > > > > > You mean what were the ioctl flags in the patch series linked > > > above? They were SECRETMEM_EXCLUSIVE and SECRETMEM_UNCACHED in > > > patch 3/5. > > > > OK I see. How many potential modes are we talking about? A few or > > potentially many? > > Well I initially thought there were two (uncached or not) until you > came up with the migratable or non-migratable, which affects the > security properties. But now there's also potential for hardware > backing, like mktme, described by flags as well. I do not remember details about mktme but from what I still recall it had keys associated with direct maps. Is the key management something that fits into flags management? > I suppose you could > also use RDT to restrict which cache the data goes into: say L1 but not > L2 on to lessen the impact of fully uncached (although the big thrust > of uncached was to blunt hyperthread side channels). So there is > potential for quite a large expansion even though I'd be willing to bet > that a lot of the modes people have thought about turn out not to be > very effective in the field. Are those very HW specific features really viable through a generic syscall? Don't get me wrong but I find it much more likely somebody will want a hugetlb (pretty HW independent) without a direct map than a very close to the HW caching mode soon. But thanks for the clarification anyway. -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel