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=-12.9 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL 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 37BF8C55ABD for ; Sat, 14 Nov 2020 00:26:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 024682225D for ; Sat, 14 Nov 2020 00:26:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bHZo0ee3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726249AbgKNA0P (ORCPT ); Fri, 13 Nov 2020 19:26:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725866AbgKNA0M (ORCPT ); Fri, 13 Nov 2020 19:26:12 -0500 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5210CC0613D1 for ; Fri, 13 Nov 2020 16:26:12 -0800 (PST) Received: by mail-pl1-x644.google.com with SMTP id s2so5331375plr.9 for ; Fri, 13 Nov 2020 16:26:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=Eyi3ibuvYWMCo7i6ODa9MSLY3tsErf7jEpym/+H+ah4=; b=bHZo0ee3XBP9p4M+ZN66+nahhWFE7yUfvbiG5bA6o1mruvmC3Yww3mynB3xOxEvtZM dXMICkYjdvO2ADU7o7Cgg6Ittbb0fNtX2JmKSb9Zews8kBA2YRq3+H3PMffKmJy8R98Z b9I43agtiQZjKyzPjHkpenN1Mc2Bf3LvlxVMk54MoRm5RnQYy/oAKsvpqbfWjMimZRib Ua2BZf3WMCDbmFyGy8BFT6X24fM1a7+f9f/v5F50CZGeyanXn+znzPjnizEY1N9Hh1sn cgBzOe2WIZiAC7+98J0+loMccJvGk4jxhzYg9JAw8HD0lURkU29EyqHZBaF2uf+/1P4O SlNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=Eyi3ibuvYWMCo7i6ODa9MSLY3tsErf7jEpym/+H+ah4=; b=CKwKNxYouRlTtFlTGYH4QsxvbKiJldKt/KHKwt0e/gHyYd3V4DcxD1N5VJm6llvof9 Kcp1TWGutoSU76ogDW+oWYf7/V1mH9xHKfpNvo3bS2LZ809GuTvEhgscjak0I9009t8E 2egXB157Dp0109wR33xm9dgSp1pOYM8ar7oZAdm88ZwSb9mjz5RTJdporYxvLmU97TiJ 2q+RBkX3SAeOZqckSDi6P+cim1aYEB3HF5mRU3aM/8SvGmcR0wvn3Do31bMBdzbxDf/7 v8XrxRr0rdRunqmIASJiTsLe7+p4gtLsPidOU7N+50HxClgr6OTzRVck3V+HgfhucLd9 9e8A== X-Gm-Message-State: AOAM532Eea3c5G//PyXLetCeZSksBhYaDGk+R1ciEPqccbxGs60H6OnJ ++V5u3cG2SQxC9KjpbwrdSk2bA== X-Google-Smtp-Source: ABdhPJywVAaDqs9IyJIDm5Sl7H77CxDksVRaFSoKiKT8KoxP5BJQn/Gqp6ooi5bqKBGdE2M/Av1EOw== X-Received: by 2002:a17:902:8341:b029:d8:d123:2297 with SMTP id z1-20020a1709028341b02900d8d1232297mr3991532pln.65.1605313571693; Fri, 13 Nov 2020 16:26:11 -0800 (PST) Received: from [2620:15c:17:3:4a0f:cfff:fe51:6667] ([2620:15c:17:3:4a0f:cfff:fe51:6667]) by smtp.gmail.com with ESMTPSA id n9sm4436027pjk.1.2020.11.13.16.26.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2020 16:26:10 -0800 (PST) Date: Fri, 13 Nov 2020 16:26:09 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Sean Christopherson , Janosch Frank , Christian Borntraeger cc: Vipin Sharma , "Lendacky, Thomas" , pbonzini@redhat.com, tj@kernel.org, lizefan@huawei.com, joro@8bytes.org, corbet@lwn.net, "Singh, Brijesh" , "Grimm, Jon" , "Van Tassell, Eric" , gingell@google.com, kvm@vger.kernel.org, x86@kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC Patch 0/2] KVM: SVM: Cgroup support for SVM SEV ASIDs In-Reply-To: <20201103020623.GJ21563@linux.intel.com> Message-ID: References: <20200922004024.3699923-1-vipinsh@google.com> <20200922014836.GA26507@linux.intel.com> <20200922211404.GA4141897@google.com> <20200924192116.GC9649@linux.intel.com> <20200925222220.GA977797@google.com> <20201002204810.GA3179405@google.com> <20201103020623.GJ21563@linux.intel.com> User-Agent: Alpine 2.23 (DEB 453 2020-06-18) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2 Nov 2020, Sean Christopherson wrote: > On Fri, Oct 02, 2020 at 01:48:10PM -0700, Vipin Sharma wrote: > > On Fri, Sep 25, 2020 at 03:22:20PM -0700, Vipin Sharma wrote: > > > I agree with you that the abstract name is better than the concrete > > > name, I also feel that we must provide HW extensions. Here is one > > > approach: > > > > > > Cgroup name: cpu_encryption, encryption_slots, or memcrypt (open to > > > suggestions) > > > > > > Control files: slots.{max, current, events} > > I don't particularly like the "slots" name, mostly because it could be confused > with KVM's memslots. Maybe encryption_ids.ids.{max, current, events}? I don't > love those names either, but "encryption" and "IDs" are the two obvious > commonalities betwee TDX's encryption key IDs and SEV's encryption address > space IDs. > Looping Janosch and Christian back into the thread. I interpret this suggestion as encryption.{sev,sev_es,keyids}.{max,current,events} for AMD and Intel offerings, which was my thought on this as well. Certainly the kernel could provide a single interface for all of these and key value pairs depending on the underlying encryption technology but it seems to only introduce additional complexity in the kernel in string parsing that can otherwise be avoided. I think we all agree that a single interface for all encryption keys or one-value-per-file could be done in the kernel and handled by any userspace agent that is configuring these values. I think Vipin is adding a root level file that describes how many keys we have available on the platform for each technology. So I think this comes down to, for example, a single encryption.max file vs encryption.{sev,sev_es,keyid}.max. SEV and SEV-ES ASIDs are provisioned separately so we treat them as their own resource here. So which is easier? $ cat encryption.sev.max 10 $ echo -n 15 > encryption.sev.max or $ cat encryption.max sev 10 sev_es 10 keyid 0 $ echo -n "sev 10" > encryption.max I would argue the former is simplest (always preferring one-value-per-file) and avoids any string parsing or resource controller lookups that need to match on that string in the kernel. The set of encryption.{sev,sev_es,keyid} files that exist would depend on CONFIG_CGROUP_ENCRYPTION and whether CONFIG_AMD_MEM_ENCRYPT or CONFIG_INTEL_TDX is configured. Both can be configured so we have all three files, but the root file will obviously indicate 0 keys available for one of them (can't run on AMD and Intel at the same time :). So I'm inclined to suggest that the one-value-per-file format is the ideal way to go unless there are objections to it.