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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A7B4EC3A5A9 for ; Mon, 4 May 2020 17:00:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 801FC206D9 for ; Mon, 4 May 2020 17:00:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TiA80Azv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729776AbgEDRAJ (ORCPT ); Mon, 4 May 2020 13:00:09 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:33746 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729540AbgEDRAJ (ORCPT ); Mon, 4 May 2020 13:00:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588611608; 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=T5ofgZ5+dv6kvzg6y8qAYvtHj1yOL06CYyaplh6HCPI=; b=TiA80AzvapkTObw96l/+0IhRii5ES9/H39kQC3eE0ZtXHpiZ5dfipv9n6MW9NL7u7Ex7BR 0On8TinStg7uush96npPAR+pHpodB97KLluaVVNnsLUiyykxAdfobZbTIubOUoNXuTLOgx l0X5FjlpsZXVdZW2EaZAtbDY7JXOJK8= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-50-HtgPs4HDPrGwG-CSPAREyA-1; Mon, 04 May 2020 12:59:56 -0400 X-MC-Unique: HtgPs4HDPrGwG-CSPAREyA-1 Received: by mail-wr1-f71.google.com with SMTP id q13so11682wrn.14 for ; Mon, 04 May 2020 09:59:56 -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=T5ofgZ5+dv6kvzg6y8qAYvtHj1yOL06CYyaplh6HCPI=; b=JfpOvHHj6fbuG7bVCGnHGAlEwxRf6vZ+fC7zFeYnu21LFerY8MiDVdOF42d88FzfZ5 HH8OljYNbq6kcK4L2wOtfzDLN+YLTzEbaQJNKbU6Sbq4frkY/oWSBdWmS5v0zARD6qOG VSdaW2k51KlFaSIUWMqS4p6Bqm7gjB7saJrt+2zQ7o3nNYG5YrVEuNLSuuTAy572yZGE lHnFy8wmQYXjkbIOynpa1b7udwz9Hx6NfGTbN7C53FR5oMB/Nz/Y92BH1uX+2WM3hVc2 KteLvTIgeFk6FnqZS9zEo4rqEkaoFtjXmNggZtOPTrXEz96Sby/t7QB76UrEZ/C6RLuS Ty2A== X-Gm-Message-State: AGi0PuacId9rSAIVEMrmFp97A0vQzfRUGSyJ32I0BQGFpUL0yirRAVOa YHzPeIiUHEs9kAYsJ9IO62zPcS1L+owO+bGnsuQyjOzicc7o/EeYfuDFpci2iJuOcKDm8wV435v WNymQWpyt1Y8I X-Received: by 2002:adf:9447:: with SMTP id 65mr8663890wrq.331.1588611595430; Mon, 04 May 2020 09:59:55 -0700 (PDT) X-Google-Smtp-Source: APiQypJ+KIAi0eC0xc/MKvOmRj5G3YFr3fTwZrqCcx5ZM71qDGqxJYRhwafgE0Ns5QUMpNxOJyP2VA== X-Received: by 2002:adf:9447:: with SMTP id 65mr8663867wrq.331.1588611595221; Mon, 04 May 2020 09:59:55 -0700 (PDT) Received: from [192.168.178.58] ([151.20.132.175]) by smtp.gmail.com with ESMTPSA id y9sm23390wmm.26.2020.05.04.09.59.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 May 2020 09:59:54 -0700 (PDT) Subject: Re: [PATCH] KVM: X86: Sanity check on gfn before removal To: Peter Xu , kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov References: <20200416155910.267514-1-peterx@redhat.com> From: Paolo Bonzini Message-ID: <62c1d747-aca3-fc9e-f4a5-8a147012ded5@redhat.com> Date: Mon, 4 May 2020 18:59:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200416155910.267514-1-peterx@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 16/04/20 17:59, Peter Xu wrote: > The index returned by kvm_async_pf_gfn_slot() will be removed when an > async pf gfn is going to be removed. However kvm_async_pf_gfn_slot() > is not reliable in that it can return the last key it loops over even > if the gfn is not found in the async gfn array. It should never > happen, but it's still better to sanity check against that to make > sure no unexpected gfn will be removed. > > Signed-off-by: Peter Xu > --- > arch/x86/kvm/x86.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fc74dafa72ff..f1c6e604dd12 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10308,6 +10308,10 @@ static void kvm_del_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn) > u32 i, j, k; > > i = j = kvm_async_pf_gfn_slot(vcpu, gfn); > + > + if (WARN_ON_ONCE(vcpu->arch.apf.gfns[i] != gfn)) > + return; > + > while (true) { > vcpu->arch.apf.gfns[i] = ~0; > do { > Queued, thanks. Paolo