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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDDC6C19F2A for ; Thu, 4 Aug 2022 17:42:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239203AbiHDRmS (ORCPT ); Thu, 4 Aug 2022 13:42:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236546AbiHDRmR (ORCPT ); Thu, 4 Aug 2022 13:42:17 -0400 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B3BB2316D for ; Thu, 4 Aug 2022 10:42:16 -0700 (PDT) Received: by mail-pj1-x102f.google.com with SMTP id x2-20020a17090ab00200b001f4da5cdc9cso6000854pjq.0 for ; Thu, 04 Aug 2022 10:42:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=I+2klbPtMg8JDmNlmkLOfkLK7UdOD2bPaKewB5S493I=; b=JWRc8lpzmI1XPDrZdYpOkOaHGJM9cuJ6S36qN6rCIkka1D+pCnjBmWL2QpgE58pchQ Y8hetXvTbbN4FGz9bTRUf5auA47ghrM+ozLswJ5TfKY7AoeM1GvCh8KepCnQJXvTlGeL c91qNyGukSxvdUOhw0mStLikLlq5FvEcWa12peKE/HYibXsvRKJkjKLn5fuKHI8e14TJ tJX4azNySy7c3fVDb1DtoDw1GCvA703nGeQMJ+74ydgW6ujkD/Zg2ho+694ShFqYEw4F 1lHb1H7JbUkptA0PWqduIT+12ebhOD4kZWJ6JIZ1GPyD9FD8Mx0K6fzBX28aYJa6jikG p+ow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=I+2klbPtMg8JDmNlmkLOfkLK7UdOD2bPaKewB5S493I=; b=eeocyYeO6rG7SitzAFSAj8yOneJsVrSL8zzVPPrfToSM3YBefxMtZkt7iXSykJmMvm 2cQRnfCSOK8RqpW/KkktO6DB7OEhOXrgq9YFLuGe4QKty2Lws8Cui5+N53RRi5jiO7Z0 RBZfpSMy+SRO8gkQa6ka3RJXYZ8q+OTEzPViko55ZcFSl3s5lmdFpleZYxySBI9Y7+zd eFCfwsomcOgD+OsI4m99kmS68koa44mg9OA66b+wJF7OOJGnCTh7olc7r/cwByg9TYlt fqxV2WnUtCi/F6+Un/LP7IK9AeHuvbn3wIeF17Qn6BHqTrgpYpstTp4bSfArQaCkxeTX 4FJA== X-Gm-Message-State: ACgBeo0Kwg2XTRJDQ/F27vA6dimL2FAgkJORbrEyLsiovG+DADpM56pY q+GvnJGzQxnK8vOFXMyO/masKw== X-Google-Smtp-Source: AA6agR5EqUfD+yYAIdMZCFrx/O7afJKPSNvQUKx2i/l+0HuCml4gPIS9of9x6dhqZTYLQotLOS6qKg== X-Received: by 2002:a17:902:cec8:b0:16f:8081:54bc with SMTP id d8-20020a170902cec800b0016f808154bcmr2833466plg.139.1659634935635; Thu, 04 Aug 2022 10:42:15 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id w79-20020a627b52000000b0052c0a9234e0sm1359044pfc.11.2022.08.04.10.42.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Aug 2022 10:42:15 -0700 (PDT) Date: Thu, 4 Aug 2022 17:42:11 +0000 From: Sean Christopherson To: "Dr. David Alan Gilbert" Cc: Vitaly Kuznetsov , Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Dave Young , Xiaoying Yan , David Woodhouse , stable@vger.kernel.org Subject: Re: [PATCH] KVM: x86: revalidate steal time cache if MSR value changes Message-ID: References: <20220804132832.420648-1-pbonzini@redhat.com> <87v8r8yuvo.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Aug 04, 2022, Dr. David Alan Gilbert wrote: > * Vitaly Kuznetsov (vkuznets@redhat.com) wrote: > > Paolo Bonzini writes: > > > - gfn_t gfn = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; > > > - > > > /* We rely on the fact that it fits in a single page. */ > > > BUILD_BUG_ON((sizeof(*st) - 1) & KVM_STEAL_VALID_BITS); > > > > > > - if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gfn, sizeof(*st)) || > > > + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st)) || > > > > (It would be nice to somehow get at least a warning when 'gfn_t' is used > > instead of 'gpa_t' and vice versa) > > Can't sparse be taught to do that? Hmm, it probably could, but the result would likely be a mess. E.g. anything that shifts the GPA on-demand will require explicit casts to make sparse happy. This particular case is solvable without sparse, e.g. WARN if gpa[11:0]!=0, or even better rework the function to actually take a @gfn and then WARN if the incoming gfn would yield an illegal gpa.