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=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 5BF78C433E2 for ; Fri, 11 Sep 2020 17:26:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06B0F221E7 for ; Fri, 11 Sep 2020 17:26:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Tmybk7QS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726437AbgIKRZ5 (ORCPT ); Fri, 11 Sep 2020 13:25:57 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:39538 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726287AbgIKRZl (ORCPT ); Fri, 11 Sep 2020 13:25:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599845140; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Rq3sqFL6vTqtj3WUeeDyK7taU7BHDxoUtnP2+8arByI=; b=Tmybk7QSPiiqzSjZZsJIiJfDExgyLmwX90fgkW+kNWlTVaRPhWLRDiiMDIOwXvc5sVs09R Oa5YycB/NfDFVs5jdFuwRCX2jt0MynV4HG2288qb3vAXZhZZZxS8WkxnA+9gZXCV+ewklg uZefuWYHSu5a9vW9eX1ouRDjQJMFErI= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-155-9b49q9DuPI-UffjuoPqj7A-1; Fri, 11 Sep 2020 13:25:36 -0400 X-MC-Unique: 9b49q9DuPI-UffjuoPqj7A-1 Received: by mail-wm1-f72.google.com with SMTP id d22so1617605wmd.6 for ; Fri, 11 Sep 2020 10:25:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Rq3sqFL6vTqtj3WUeeDyK7taU7BHDxoUtnP2+8arByI=; b=ZqNPXLKRbDpnxfbRLlmOPGc23YmOySEDFKXqGa/cp6NEUYCk1wGmnQOjKxxiAJtg4k QH9LyAabXqnYNjwXDX3VThLzHxD1U3oiqruXWluUdJ7yhFAg43xuaxGnmiYUO9pihcog jkpA53OmCf+C+L4HWm1DO3of+YFwOl0B+utuF/Td8yOtEn2e5MyviDxoc1xNYN7GpS8f ri7L8mvyxyfCT8531jAm8LpoleSClWZYAfMhoFP8/UuSCH3ZjEen/mnUx62iGl+H02wN +OBLj+qra9SnYs4xe+N7lYVptv2R4cCHAzOEOcjkiXAYwI4/Qz8gN+TYDUrUt/62gl/F EvFw== X-Gm-Message-State: AOAM532NM0u1bsDVI/y/Quey7CaiGWp9eGxo/BT+08zJXFj9A8ThJBtH SyEMvIqlQNMr1RP8imeovmVXMVciRgyRbwmn+um6XmTCFeZOHIX+PBTYtZfItkUC5BABsEbnlOm mpW+Ro7jvwk5kFSmf8a+TMtw2 X-Received: by 2002:a1c:2e4b:: with SMTP id u72mr3249512wmu.69.1599845134542; Fri, 11 Sep 2020 10:25:34 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzE3otLO4wRNpP+aV23Yy58U5CCa3uZE7eu4+twKiyBsylZXDLRLWm38SWtnPOOlZPoIflB5g== X-Received: by 2002:a1c:2e4b:: with SMTP id u72mr3249501wmu.69.1599845134341; Fri, 11 Sep 2020 10:25:34 -0700 (PDT) Received: from [192.168.10.150] ([93.56.170.5]) by smtp.gmail.com with ESMTPSA id k84sm5399436wmf.6.2020.09.11.10.25.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Sep 2020 10:25:33 -0700 (PDT) Subject: Re: [PATCH] KVM: x86: always allow writing '0' to MSR_KVM_ASYNC_PF_EN To: Vitaly Kuznetsov , kvm@vger.kernel.org Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , "Dr . David Alan Gilbert" , linux-kernel@vger.kernel.org References: <20200911093147.484565-1-vkuznets@redhat.com> From: Paolo Bonzini Message-ID: Date: Fri, 11 Sep 2020 19:25:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200911093147.484565-1-vkuznets@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/09/20 11:31, Vitaly Kuznetsov wrote: > Even without in-kernel LAPIC we should allow writing '0' to > MSR_KVM_ASYNC_PF_EN as we're not enabling the mechanism. In > particular, QEMU with 'kernel-irqchip=off' fails to start > a guest with > > qemu-system-x86_64: error: failed to set MSR 0x4b564d02 to 0x0 > > Fixes: 9d3c447c72fb2 ("KVM: X86: Fix async pf caused null-ptr-deref") > Reported-by: Dr. David Alan Gilbert > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/x86.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index d39d6cf1d473..44a86f7f2397 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2730,9 +2730,6 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > if (data & 0x30) > return 1; > > - if (!lapic_in_kernel(vcpu)) > - return 1; > - > vcpu->arch.apf.msr_en_val = data; > > if (!kvm_pv_async_pf_enabled(vcpu)) { > @@ -2741,6 +2738,9 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > return 0; > } > > + if (!lapic_in_kernel(vcpu)) > + return 1; > + > if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa, > sizeof(u64))) > return 1; > Queued, thanks. Paolo