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=-13.3 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_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 26735C07E9C for ; Wed, 14 Jul 2021 18:14:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DE9A613CC for ; Wed, 14 Jul 2021 18:14:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230091AbhGNSRr (ORCPT ); Wed, 14 Jul 2021 14:17:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230264AbhGNSRq (ORCPT ); Wed, 14 Jul 2021 14:17:46 -0400 Received: from mail-qk1-x734.google.com (mail-qk1-x734.google.com [IPv6:2607:f8b0:4864:20::734]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E3E4C061760 for ; Wed, 14 Jul 2021 11:14:54 -0700 (PDT) Received: by mail-qk1-x734.google.com with SMTP id r125so2531459qkf.1 for ; Wed, 14 Jul 2021 11:14:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3WKLZGhjXG90Fatu5wm7XoigXrQeEPeI0ZySxgtrf1E=; b=K34aiEbq6IThsKWJBJDDGsckcOYXonTslRsCf6xEi7ghhFV+UbwNIfzQP6Tq5ldAxz x/gfvgeDt8i9UmUFByP8JylSs7uppp+LheXconENxXR/wPDkP+0iUfG5YhfwPEmQU1fy 4tTjvgWpmY3o7IvTFaQR7Z34VuSgQbU+YmK0iN4AE41bZtFsm7nGfsIz6oRpkXpW6axf 6b+9SsmHKDPDXxNXQY2L0ih10uAe1HpuGUVydXvTdbXoxG4rjZrIfD2Nskrohj6TdZDI j2Q+YXsv7xUpGHDh1ZKrJ93dEG0SbTKyIkbyJdcn2EcTIo/QYOSql+60mVB0ixujp++K tFqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3WKLZGhjXG90Fatu5wm7XoigXrQeEPeI0ZySxgtrf1E=; b=Cxusd5oh9O3gYb50NmvTYdXevcUdq1yCjh2aT3HgbVoE4skVacq9bXF/Y9S76YIRTJ /ujr2LGG09DlrFkTMxTWd7cGguWXFBVd7uG+wZr38/lfKFNGuFb6knb2/5jtOiu4XqNV e1z2VKezXaLxjqD8QPSN6eMgU1gGcGMfSLNCaDPs2xvBSKCuVQHUNLV7xWQq7QJosAJN iMrdgrIhhyNZjvo8mQY1H6eocQFrrRkt8rgA28CLjD3zXiV7i1sNosvVhBvZsuHH0ZJO YbH1y+lTVkz+pieCve1IpRi7JbaLV06icpXI5lvyT3VNisk8xEcVsIRVSX9QvFzod3FJ 4E0g== X-Gm-Message-State: AOAM532+RsU9SzJixTA6NyyUwUWC296DhjeuFpVaGFSfiPncZ/wUxzBw ovghdRazMn1tD6VDBYRn8Xqr4+mXhVBy6qB1duABFA== X-Google-Smtp-Source: ABdhPJxM1wp8nSe3bkx8dg/pQpdxw78kl5esOD57NTfXsDoAxivKWcg01aZjKeev4L+fz4X+d7136TERrs+FRe6NY50= X-Received: by 2002:a05:620a:a90:: with SMTP id v16mr11085310qkg.150.1626286493309; Wed, 14 Jul 2021 11:14:53 -0700 (PDT) MIME-Version: 1.0 References: <20210707183616.5620-1-brijesh.singh@amd.com> <20210707183616.5620-16-brijesh.singh@amd.com> <98ac737d-83a8-6ee8-feac-554bab673191@amd.com> In-Reply-To: <98ac737d-83a8-6ee8-feac-554bab673191@amd.com> From: Marc Orr Date: Wed, 14 Jul 2021 11:14:41 -0700 Message-ID: Subject: Re: [PATCH Part2 RFC v4 15/40] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled To: Brijesh Singh Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm list , linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , tony.luck@intel.com, npmccallum@redhat.com, brijesh.ksingh@gmail.com, Alper Gun Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > > Should this return a non-zero value -- maybe `-ENODEV`? Otherwise, the > > `snp_alloc_firmware_page()` API will return a page that the caller > > believes is suitable to use with FW. My concern is that someone > > decides to use this API to stash a page very early on during kernel > > boot and that page becomes a time bomb. > > But that means the caller now need to know that SNP is enabled before > calling the APIs. The idea behind the API was that caller does not need > to know whether the firmware is in the INIT state. If the firmware has > initialized the SNP, then it will transparently set the immutable bit in > the RMP table. For SNP, isn't that already the case? There are three scenarios: #1: The PSP driver is loaded and `snp_inited` is `true`: These returns are never hit. #2: The PSP driver is not loaded. The first return, `!psp || !psp->sev_data` fires. As written, it returns `0`, indicating success. However, we never called RMPUPDATE on the page. Thus, later, when the PSP driver is loaded, the page that was previously returned as usable with FW is in fact not usable with FW. Unless SNP is disabled (e.g., SEV, SEV-ES only). In which case I guess the page is OK. #3 The PSP driver is loaded but the SNP_INIT command has not been issued. Looking at this again, I guess `return 0` is OK. Because if we got this far, then `sev_pci_init()` has been called, and the SNP_INIT command has been issued if we're supporting SNP VMs. So in summary, I think we should change the first return to return an error and leave the 2nd return as is. > > If we initialize `rc` to `-ENODEV` (or something similar), then every > > return in this function can be `return rc`. > > > >> + > >> + /* If SEV-SNP is initialized then add the page in RMP table. */ > >> + sev = psp->sev_data; > >> + if (!sev->snp_inited) > >> + return 0; > > > > Ditto. Should this turn a non-zero value? > > > >> + > >> + while (pfn < pfn_end) { > >> + if (need_reclaim) > >> + if (snp_reclaim_page(pfn_to_page(pfn), locked)) > >> + return -EFAULT; > >> + > >> + rc = rmpupdate(pfn_to_page(pfn), val); > >> + if (rc) > >> + return rc; > >> + > >> + pfn++; > >> + } > >> + > >> + return 0; > >> +}