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 A56CEC433EF for ; Wed, 9 Feb 2022 22:55:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236567AbiBIWzQ (ORCPT ); Wed, 9 Feb 2022 17:55:16 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:33578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236561AbiBIWzB (ORCPT ); Wed, 9 Feb 2022 17:55:01 -0500 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DDC4E04FF0C for ; Wed, 9 Feb 2022 14:55:04 -0800 (PST) Received: by mail-pj1-x1033.google.com with SMTP id h14-20020a17090a130e00b001b88991a305so6670699pja.3 for ; Wed, 09 Feb 2022 14:55:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=5OgBvBtD/pqZyY1Wyl2wDigiqIzipvE7VvYdDX53RaU=; b=lr8JBDfah6TBBfm+fcfoKKyOkr4qRbOpNZKNSz0jmz/yX6P+3I80Gf127D2r/XjQUA 3Ks3cAXBSu53tT9w1ibvn5Il5wp07oxQoNqoZM1zcxtyyxZQIfHHyMuH9Wu320T/VBSm k21jxvs3Wk0sFwnWQ/apaH2I3G85S6jN0k4LlkwrlkW2AKh84OQTIFYY2tRdMAOHMMV/ dfkRftgcaKD3gXqcUskLTUJDhSvmru45c+ZrJg5RDsasia1xMO8axDk51mSdiBvv5IkB 8wNBRxeXfiFuT4lbyXRgU8v4Qw+Z4RiFePK00zyExo7XeCKjmjW2zkmocLU63lo4OBBP x8lQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=5OgBvBtD/pqZyY1Wyl2wDigiqIzipvE7VvYdDX53RaU=; b=OgdwMz89HXplpfWbYIZEgfx9zLBHc70nEAsRbjlyFkPunf7YjSmNLJBfGkwZEG4wts TbDZUtTZUsIy4SlYkX3sDP+gVQlZswGb3xMm7Y8K/VbQWOlBjYXAaPuMJszbmtB21IES 2WdyLKUJ5YRucbPcPFq6wX3ce3ZtLJO2I5DHZmAelnbbynd79AhSB3dd4QPazjcrnHht Qd170BuE6HBVK6/OH1H1SchNOuKFPNphE6Pb6wN8+miF0P6DGi51ffZ7oFhQt4POyX1h MEP4NapV5KS4yV3+QTeFbFieu24IPkgcbUi0FskOMXSkCIROd00Rx8wPHFZut4r1OKH1 HnHA== X-Gm-Message-State: AOAM530zo45KtHoAl7d2wTPJ/SpOCTD+gUT2hKW1zHGG5IqNCKR4ZqQ9 zKQOGK5lM5Y1XnXksV4nPz/IZA== X-Google-Smtp-Source: ABdhPJx3fRoFf3m1YrhBm9bwMf/KNqL/k72G8kAET9jEP4tr4GMXepaIFbIEk883VTIOOZ9EPhHXZg== X-Received: by 2002:a17:90b:4f8f:: with SMTP id qe15mr5110563pjb.94.1644447303388; Wed, 09 Feb 2022 14:55:03 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id nl7sm7362138pjb.5.2022.02.09.14.55.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Feb 2022 14:55:02 -0800 (PST) Date: Wed, 9 Feb 2022 22:54:59 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, dmatlack@google.com, vkuznets@redhat.com Subject: Re: [PATCH 03/23] KVM: MMU: remove valid from extended role Message-ID: References: <20220204115718.14934-1-pbonzini@redhat.com> <20220204115718.14934-4-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220204115718.14934-4-pbonzini@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Feb 04, 2022, Paolo Bonzini wrote: > The level field of the MMU role can act as a marker for validity > instead: it is guaranteed to be nonzero so a zero value means the role > is invalid and the MMU properties will be computed again. Nope, it's not guaranteed to be non-zero: static int role_regs_to_root_level(struct kvm_mmu_role_regs *regs) { if (!____is_cr0_pg(regs)) return 0; <============================================= else if (____is_efer_lma(regs)) return ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL; else if (____is_cr4_pae(regs)) return PT32E_ROOT_LEVEL; else return PT32_ROOT_LEVEL; } static union kvm_mmu_role kvm_calc_nested_mmu_role(struct kvm_vcpu *vcpu, struct kvm_mmu_role_regs *regs) { union kvm_mmu_role role; role = kvm_calc_shadow_root_page_role_common(vcpu, regs, false); /* * Nested MMUs are used only for walking L2's gva->gpa, they never have * shadow pages of their own and so "direct" has no meaning. Set it * to "true" to try to detect bogus usage of the nested MMU. */ role.base.direct = true; role.base.level = role_regs_to_root_level(regs); return role; } static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); union kvm_mmu_role new_role = kvm_calc_nested_mmu_role(vcpu, ®s); struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; if (new_role.as_u64 == g_context->mmu_role.as_u64) <== theoretically can get a false positive return;