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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 autolearn=ham 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 E29E4C433F5 for ; Tue, 21 Sep 2021 13:52:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1C2160F13 for ; Tue, 21 Sep 2021 13:52:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233426AbhIUNyE (ORCPT ); Tue, 21 Sep 2021 09:54:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38867 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233114AbhIUNyD (ORCPT ); Tue, 21 Sep 2021 09:54:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632232353; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=V0zAq0x+oqzBpgunFTqnsA/mjDvVGVJTfSNQG5aaHl4=; b=Y2wbzX+xXlAZPDs9yIQMb77vXlV2yau+gHsQKyP9rMcQ4Qc7eeLFUdcrS0k0r3ZWX8VMq4 zuFuAa4BKdZBKc3kXv4ODhbB9qRk9cLUow6GM4D7/uePRojQxVSGpwaqMwip+cpiijJHMu BYuFNkCis+TCyGlX83xCIFm3KqcgWx4= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-318-nBEW-VHXMCC0ca2CQhtDFQ-1; Tue, 21 Sep 2021 09:52:32 -0400 X-MC-Unique: nBEW-VHXMCC0ca2CQhtDFQ-1 Received: by mail-wr1-f69.google.com with SMTP id s13-20020a5d69cd000000b00159d49442cbso8871141wrw.13 for ; Tue, 21 Sep 2021 06:52:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=V0zAq0x+oqzBpgunFTqnsA/mjDvVGVJTfSNQG5aaHl4=; b=C6lj+lK9lUAJMXnTzTppWXwCJYbBlXcJrOnBEC5kgOv2Cz73cYGA+5VCbonHwGpqyN YhPc4fpB3cKmIzU9qGD1kBcjCaKXfZoONeLta2YDiXXlnh8f4UE0jHutrbK4aYxabukX UnJBb1tKERcvNV6h1cm52J9/R1n9Pv2VBhSbI08HsrbsxibNpM7i59WYoB/rgxwIje45 BGDq1AZJCIGr1KfWH4PAQAG+4OCxW7w10MCgLOS0oUg87BqG7cH99mOrrAVSQjJ6/VeV tIZ/9eH83A93O5Z0ZmbWJ9AWnqqTSayUg2o3RuHm/oeq/gwj50oWpTXV5s0PqYkKy3Ym Pu4Q== X-Gm-Message-State: AOAM530OnDkRvRGl+peZ8FyWhf+l4iQQ3HzxK2DUEILJuzDqBbcgJ8Xz EdiOdrLfqIvdpq2R/6SA4ScX81AO4uIwQsHGS6KvRHZdSXDJaSZni4CG/w1kzv++oYQU/dTVngp 3eAWW5k6zjU6h X-Received: by 2002:a5d:64ab:: with SMTP id m11mr32878895wrp.343.1632232351223; Tue, 21 Sep 2021 06:52:31 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwqNngkbqDMiHzQQklz3eCjHb4+L2IXwXQtwQ4UV/2L86vZDwomrKKd2RNX5DwoTklZM8hAcw== X-Received: by 2002:a5d:64ab:: with SMTP id m11mr32878879wrp.343.1632232351058; Tue, 21 Sep 2021 06:52:31 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id g25sm3701252wrc.88.2021.09.21.06.52.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Sep 2021 06:52:30 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reiji Watanabe Subject: Re: [PATCH v2 02/10] KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT In-Reply-To: <20210921000303.400537-3-seanjc@google.com> References: <20210921000303.400537-1-seanjc@google.com> <20210921000303.400537-3-seanjc@google.com> Date: Tue, 21 Sep 2021 15:52:29 +0200 Message-ID: <878rzq9gte.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > Explicitly zero the guest's CR3 and mark it available+dirty at RESET/INIT. > Per Intel's SDM and AMD's APM, CR3 is zeroed at both RESET and INIT. For > RESET, this is a nop as vcpu is zero-allocated. For INIT, the bug has > likely escaped notice because no firmware/kernel puts its page tables root > at PA=0, let alone relies on INIT to get the desired CR3 for such page > tables. > > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/x86.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e77a5bf2d940..2cb38c67ed43 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10899,6 +10899,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > kvm_set_rflags(vcpu, X86_EFLAGS_FIXED); > kvm_rip_write(vcpu, 0xfff0); > > + vcpu->arch.cr3 = 0; > + kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); kvm_register_mark_dirty() is redundant here as PATCH1 does vcpu->arch.regs_avail = ~0; vcpu->arch.regs_dirty = ~0; just a few lines above. The dependency is, however, implicit and this patch is marked for stable@ (well, PATCH1 has 8 Fixes: tags so I'd expect it to get picked by everyone too, especially by robots) and flipping two bits is cheap. Reviewed-by: Vitaly Kuznetsov > + > /* > * CR0.CD/NW are set on RESET, preserved on INIT. Note, some versions > * of Intel's SDM list CD/NW as being set on INIT, but they contradict -- Vitaly