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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 084C9C433ED for ; Mon, 12 Apr 2021 11:03:41 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B95F76100B for ; Mon, 12 Apr 2021 11:03:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B95F76100B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.108990.208013 (Exim 4.92) (envelope-from ) id 1lVuLf-0002J1-U2; Mon, 12 Apr 2021 11:03:19 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 108990.208013; Mon, 12 Apr 2021 11:03:19 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lVuLf-0002Iu-Qn; Mon, 12 Apr 2021 11:03:19 +0000 Received: by outflank-mailman (input) for mailman id 108990; Mon, 12 Apr 2021 11:03:19 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lVuLf-0002Ip-3E for xen-devel@lists.xenproject.org; Mon, 12 Apr 2021 11:03:19 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id f375b326-ce99-48b1-87e4-8578bf560c5f; Mon, 12 Apr 2021 11:03:17 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id ACD69AE20; Mon, 12 Apr 2021 11:03:16 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f375b326-ce99-48b1-87e4-8578bf560c5f X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1618225396; h=from:from:reply-to: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=SggUo5vEkMMchFi34/C1qyVNuuNBzopDvY6Ert2iC9s=; b=Fcn6dD9P6QQLrfbeg2hWV/mjhH7epteNGb3ffZenKKC/OcwwSD3i7CiHLI3E4joRtpXKCa rK759chmpFJC+fLmX5TXxE5ki2M4XA2Dr9kR+6sM94ljaf6GSbmC5UWNrpYlP38JYapnsD LJlkmQCKC1/4ksI/icLiI+BlipSC3aE= Subject: Re: [PATCH v3 2/4] xen/arm: Handle cases when hardware_domain is NULL To: Luca Fancellu Cc: bertrand.marquis@arm.com, wei.chen@arm.com, Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Ian Jackson , Wei Liu , Rahul Singh , xen-devel@lists.xenproject.org References: <20210412105243.23354-1-luca.fancellu@arm.com> <20210412105243.23354-3-luca.fancellu@arm.com> From: Jan Beulich Message-ID: Date: Mon, 12 Apr 2021 13:03:17 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210412105243.23354-3-luca.fancellu@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 12.04.2021 12:52, Luca Fancellu wrote: > --- a/xen/include/xen/sched.h > +++ b/xen/include/xen/sched.h > @@ -1022,6 +1022,9 @@ static always_inline bool is_hardware_domain(const struct domain *d) > if ( IS_ENABLED(CONFIG_PV_SHIM_EXCLUSIVE) ) > return false; > > + if ( !d ) > + return false; > + > return evaluate_nospec(d == hardware_domain); > } On v2 I did say on the respective code that was here (and my suggestion of this alternative adjustment): "Can you point out code paths where d may actually be NULL, and where [...] would not behave as intended (i.e. where bad speculation would result)?" Since you've taken the suggestion as-is, and since the commit message says nothing in either direction here, did you actually verify that there's no abuse of speculation possible with this extra return path? And did you find any caller at all which may pass NULL into here? Jan