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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 36932C433E0 for ; Mon, 25 Jan 2021 11:10:08 +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 C934120848 for ; Mon, 25 Jan 2021 11:10:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C934120848 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.74021.133044 (Exim 4.92) (envelope-from ) id 1l3zko-0003ag-R3; Mon, 25 Jan 2021 11:09:54 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 74021.133044; Mon, 25 Jan 2021 11:09:54 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l3zko-0003aZ-Nf; Mon, 25 Jan 2021 11:09:54 +0000 Received: by outflank-mailman (input) for mailman id 74021; Mon, 25 Jan 2021 11:09:53 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l3zkn-0003aU-8x for xen-devel@lists.xenproject.org; Mon, 25 Jan 2021 11:09:53 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 70082ea4-afad-42c3-8ebc-a18680745a82; Mon, 25 Jan 2021 11:09:52 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 89744B8F5; Mon, 25 Jan 2021 11:09:51 +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: 70082ea4-afad-42c3-8ebc-a18680745a82 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=1611572991; 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=ROjV2mQJTeGT53+ouaUlkPLW9IdZOeuI2Ik/UaFukPA=; b=aea5q/XQBeLP/CJShC9dhievNSRiOuHbDFKBlEr4OwUMJ5SXTvMEovf3gK0dKk6Fm6Cpig j+xbT3/0MPXLms/bweklY4V4ErfxQFSSpfZAPDBL4LDV81FRJ/zyIbdn4xvvUeUgjKjQgC 5KiLrKVq+so+bifouYxPEBeInODFdMI= Subject: Re: [PATCH 15/17] x86/shadow: drop SH_type_l2h_pae_shadow To: Tim Deegan Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , George Dunlap References: <4f1975a9-bdd9-f556-9db5-eb6c428f258f@suse.com> From: Jan Beulich Message-ID: <052d05be-2bd8-cf7e-6cdf-1ea3b37719fe@suse.com> Date: Mon, 25 Jan 2021 12:09:51 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 22.01.2021 21:02, Tim Deegan wrote: > At 17:31 +0100 on 22 Jan (1611336662), Jan Beulich wrote: >> On 22.01.2021 14:11, Tim Deegan wrote: >>> At 16:10 +0100 on 14 Jan (1610640627), Jan Beulich wrote: >>>> hash_{domain,vcpu}_foreach() have a use each of literal 15. It's not >>>> clear to me what the proper replacement constant would be, as it >>>> doesn't look as if SH_type_monitor_table was meant. >>> >>> Good spot. I think the '<= 15' should be replaced with '< SH_type_unused'. >>> It originally matched the callback arrays all being coded as >>> "static hash_callback_t callbacks[16]". >> >> So are you saying this was off by one then prior to this patch >> (when SH_type_unused was still 17), albeit in apparently a >> benign way? > > Yes - this assertion is just to catch overruns of the callback table, > and so it was OK for its limit to be too low. The new types that were > added since then are never put in the hash table, so don't trigger > this assertion. > >> And the comments in sh_remove_write_access(), >> sh_remove_all_mappings(), sh_remove_shadows(), and >> sh_reset_l3_up_pointers() are then wrong as well, and would >> instead better be like in shadow_audit_tables()? > > Yes, it looks like those comments are also out of date where they > mention 'unused'. For this, which likely will end up being part of ... >> Because of this having been benign (due to none of the callback >> tables specifying non-NULL entries there), wouldn't it make >> sense to dimension the tables by SH_type_max_shadow + 1 only? >> Or would you consider this too risky? > > Yes, I think that would be fine, also changing '<= 15' to > '<= SH_type_max_shadow'. Maybe add a matching > ASSERT(t <= SH_type_max_shadow) in shadow_hash_insert as well? ... this, I'll send a patch for 4.16 going beyond the more immediate one sent, which I'll ask Ian to consider for 4.15 (assuming of course you consider it okay in the first place). Jan