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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 B065AC432C3 for ; Thu, 14 Jan 2021 17:14:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FECE23B1A for ; Thu, 14 Jan 2021 17:14:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728416AbhANROP (ORCPT ); Thu, 14 Jan 2021 12:14:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728374AbhANROO (ORCPT ); Thu, 14 Jan 2021 12:14:14 -0500 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD8E7C061575 for ; Thu, 14 Jan 2021 09:13:33 -0800 (PST) Received: by mail-pf1-x436.google.com with SMTP id b3so3740944pft.3 for ; Thu, 14 Jan 2021 09:13:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=OKPnLLplhRNmeoV6NY+JrG/2XUXd3Jl9oyOtg+gZeHA=; b=jpipB+9kIff5Tv0vnTnurZDN7yGTOeueru9cS/LH34OKylQIyB8U8q3N03m6SRSeJn vM3LPmrRoBl94FX7ZPC/TMselOSAz+Bnb60lS1YG9B5BuBuhvTpWtJDeRd41BU132lXV JiPJsPZY1mdZ89zZQXDPCUZR1rDzd+uy4R4qFidRwDsx9lK7QxCZA2938Lc1Ta2SYTdJ 3nXilJeBCQqHByOHmI4GUNIy4h/S4LgwitTotXTMf2jHrgLtVoefeT26J5pHbbbm4SF0 MPxvRgllVc7ORWs3SxWuGlO0CI8p/no5Qas3zLe//zNO0Y5FIihbU34bG07ufdXFnLJp vlMw== 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:message-id:references :mime-version:content-disposition:in-reply-to; bh=OKPnLLplhRNmeoV6NY+JrG/2XUXd3Jl9oyOtg+gZeHA=; b=dNYCs/W8EgzBm2sQ+rrH5Scc+1Eljs/8w0sHXDrIkjegR+BZCoFMuK1c3c0ccrR3DV 96QPhrKANaikEnLN2c4wVlNZWsWUdS2nmtjMDK/2dD6KauzwAEA1ju9VifodBdhERljV GTui1X1nX46RAdJ0tudnj2oIrVAMc4LvCIKI0ehdAr0d/rfUp0sWbWAUR+FQ40Y4QoCx 9fH2PdSMe5/bOQ9msogwFVe2R23SojmgC998sSKSTj3iqVfkP5pMALwU8hl6nKLX4BXk //0zAYWvCPiRgqGev3J+mFsZIs9caULmTo2ZnKjEnnNnku9DErIHglnpBDETQ/JoIytr mkvg== X-Gm-Message-State: AOAM533PivjywuLS7M+fuaE4PhJcpD4xrVfDYnHKB76Ar/mwmQBAl0WZ qxMQgze/keCp3CTJSL6W0cbwBA== X-Google-Smtp-Source: ABdhPJwUbPwHAM0ys8f0iS52iICwmmGFVz58imXchuP4PQsYRnq24zsPYrz4sUFvEEtZT8tTHG4geg== X-Received: by 2002:a63:eb0c:: with SMTP id t12mr8488528pgh.7.1610644413234; Thu, 14 Jan 2021 09:13:33 -0800 (PST) Received: from google.com ([2620:15c:f:10:1ea0:b8ff:fe73:50f5]) by smtp.gmail.com with ESMTPSA id 19sm5707564pfn.133.2021.01.14.09.13.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Jan 2021 09:13:32 -0800 (PST) Date: Thu, 14 Jan 2021 09:13:25 -0800 From: Sean Christopherson To: Tom Lendacky Cc: Paolo Bonzini , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , Brijesh Singh Subject: Re: [PATCH v2 01/14] KVM: SVM: Zero out the VMCB array used to track SEV ASID association Message-ID: References: <20210114003708.3798992-1-seanjc@google.com> <20210114003708.3798992-2-seanjc@google.com> <3d41137e-e8e0-8139-3050-eac58ad82a4f@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3d41137e-e8e0-8139-3050-eac58ad82a4f@amd.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jan 14, 2021, Tom Lendacky wrote: > On 1/13/21 6:36 PM, Sean Christopherson wrote: > > Zero out the array of VMCB pointers so that pre_sev_run() won't see > > garbage when querying the array to detect when an SEV ASID is being > > associated with a new VMCB. In practice, reading random values is all > > but guaranteed to be benign as a false negative (which is extremely > > unlikely on its own) can only happen on CPU0 on the first VMRUN and would > > only cause KVM to skip the ASID flush. For anything bad to happen, a > > previous instance of KVM would have to exit without flushing the ASID, > > _and_ KVM would have to not flush the ASID at any time while building the > > new SEV guest. > > > > Cc: Borislav Petkov > > Cc: Tom Lendacky > > Cc: Brijesh Singh > > Fixes: 70cd94e60c73 ("KVM: SVM: VMRUN should use associated ASID when SEV is enabled") > > Signed-off-by: Sean Christopherson > > --- > > arch/x86/kvm/svm/svm.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > index 7ef171790d02..ccf52c5531fb 100644 > > --- a/arch/x86/kvm/svm/svm.c > > +++ b/arch/x86/kvm/svm/svm.c > > @@ -573,7 +573,7 @@ static int svm_cpu_init(int cpu) > > if (svm_sev_enabled()) { > > sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1, > > sizeof(void *), > > - GFP_KERNEL); > > + GFP_KERNEL | __GFP_ZERO); > > Alternatively, this call could just be changed to kcalloc(). Agreed, kcalloc() is a better option. I'll do that in v3.