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=-26.3 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, USER_AGENT_GIT,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 38B8CC433E0 for ; Fri, 5 Mar 2021 01:11:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18ED564F67 for ; Fri, 5 Mar 2021 01:11:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231132AbhCEBLz (ORCPT ); Thu, 4 Mar 2021 20:11:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230453AbhCEBLs (ORCPT ); Thu, 4 Mar 2021 20:11:48 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F18A6C0613D9 for ; Thu, 4 Mar 2021 17:11:46 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id u17so680084ybi.10 for ; Thu, 04 Mar 2021 17:11:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=1d75g85xgtYE6EG7cfU2REgYRmx185ZHiOuo3S9KNAA=; b=txRUg8YkvyfqIJ0/XuPt5R/AlheVjwdXFDUJapIwiRlZfuO1aTxi7EME12Kt4vEcGi hHumJL9TnwIbyLcyuFKqpeLtXJL5WWf+5pc1CcI0IH/lziTzBSDxuj0p+3hjvVJO4dqI eTvVqADPE/JcQamgBZ9NfUe8/C7ww/mTuimP96Lavhvgo6rhz+YUEdM+taue2t+xlZbG ZRN9PPVOZdlckrxevuXpR2bLlPnBad9AwoWUF4JObK+/+sIJTF52TcULbf4W03kwTaQS Nf/fgJQyepDxAY1KjPj2QutFZr37DCSyif1Ff9w1pqTMiChnONWfsJ7BVjjja/6yEtRC Z+Ww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=1d75g85xgtYE6EG7cfU2REgYRmx185ZHiOuo3S9KNAA=; b=m8+YZQdjIxPOfjtgbZeVCBorVqA929BWXmV9+v8axN36VYCyfh39OqszxT40YrElUT Rxdm5FNZwUJvA36gmerccJ0gdj+y8PsPiGTGcXEAUdVSqVSnaK46UTOKPCx23m87m5NQ IS9A+NyQhO20Dd0llbH7ZN7h3DPPF3QuZIL5rbdGW+zwFLqQh2cyQxEECWNypavukJrQ rf6DgGoC/PPvBba4d9TEqa/ACFzayIGAzVooqKY3jjIAfRSf7fTR2AwEkBS5vM2FI5n2 0NC08Z/mZLbtjXKRZGovl1+bKooYNMjW7XdmNjaX00h1/vlcE3Ni5sEc5drqzorzVtiV QQtg== X-Gm-Message-State: AOAM530X/2HjLnpd3fjuZnrFErNmlecDjoE+sExibf3OLyZzBKdSYSTe Ekn9LncD4VwqdP+q46cpvqGy3XqXweQ= X-Google-Smtp-Source: ABdhPJyML4KoyC8fISaQe2/KDV43JeBYfE/oli0AyNxL8l43JmeZozRuqeue98etV5vlZnI0RdCiqZp3a0k= Sender: "seanjc via sendgmr" X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:9857:be95:97a2:e91c]) (user=seanjc job=sendgmr) by 2002:a25:3417:: with SMTP id b23mr10520532yba.257.1614906706188; Thu, 04 Mar 2021 17:11:46 -0800 (PST) Reply-To: Sean Christopherson Date: Thu, 4 Mar 2021 17:11:01 -0800 In-Reply-To: <20210305011101.3597423-1-seanjc@google.com> Message-Id: <20210305011101.3597423-18-seanjc@google.com> Mime-Version: 1.0 References: <20210305011101.3597423-1-seanjc@google.com> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [PATCH v2 17/17] KVM: x86/mmu: WARN on NULL pae_root or lm_root, or bad shadow root level From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Brijesh Singh , Tom Lendacky Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org WARN if KVM is about to dereference a NULL pae_root or lm_root when loading an MMU, and convert the BUG() on a bad shadow_root_level into a WARN (now that errors are handled cleanly). With nested NPT, botching the level and sending KVM down the wrong path is all too easy, and the on-demand allocation of pae_root and lm_root means bugs crash the host. Obviously, KVM could unconditionally allocate the roots, but that's arguably a worse failure mode as it would potentially corrupt the guest instead of crashing it. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index bceff7d815c3..eb9dd8144fa5 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3253,6 +3253,9 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level, true); mmu->root_hpa = root; } else if (shadow_root_level == PT32E_ROOT_LEVEL) { + if (WARN_ON_ONCE(!mmu->pae_root)) + return -EIO; + for (i = 0; i < 4; ++i) { WARN_ON_ONCE(mmu->pae_root[i]); @@ -3262,8 +3265,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) shadow_me_mask; } mmu->root_hpa = __pa(mmu->pae_root); - } else - BUG(); + } else { + WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); + return -EIO; + } /* root_pgd is ignored for direct MMUs. */ mmu->root_pgd = 0; @@ -3307,6 +3312,9 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) goto set_root_pgd; } + if (WARN_ON_ONCE(!mmu->pae_root)) + return -EIO; + /* * We shadow a 32 bit page table. This may be a legacy 2-level * or a PAE 3-level page table. In either case we need to be aware that @@ -3316,6 +3324,9 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) { pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; + if (WARN_ON_ONCE(!mmu->lm_root)) + return -EIO; + mmu->lm_root[0] = __pa(mmu->pae_root) | pm_mask; } -- 2.30.1.766.gb4fecdf3b7-goog