From patchwork Fri Mar 5 15:36:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12118775 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, 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 392E9C433DB for ; Fri, 5 Mar 2021 15:36:46 +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 E8BA46508F for ; Fri, 5 Mar 2021 15:36:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8BA46508F 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.93846.177261 (Exim 4.92) (envelope-from ) id 1lICUx-0005zG-OK; Fri, 05 Mar 2021 15:36:15 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 93846.177261; Fri, 05 Mar 2021 15:36:15 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lICUx-0005z9-LB; Fri, 05 Mar 2021 15:36:15 +0000 Received: by outflank-mailman (input) for mailman id 93846; Fri, 05 Mar 2021 15:36:14 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lICUw-0005z4-Ae for xen-devel@lists.xenproject.org; Fri, 05 Mar 2021 15:36:14 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 2e24bb74-7643-4cc7-a9fb-4ec94f7ea29b; Fri, 05 Mar 2021 15:36:13 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id AF84DAD72; Fri, 5 Mar 2021 15:36:12 +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: 2e24bb74-7643-4cc7-a9fb-4ec94f7ea29b 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=1614958572; 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; bh=LKMg3/gTyoAPIQ6oDN88wxQX2CgJkK/YgqsHUdKYIxY=; b=GglIZltPpQH5hNeIVfT4p8GjoAHovwneZ0k2ypYVMmXlr2azCbs8C0/mFjDceoiG0u5PDG ATageAbctyT4eMUdr1TrELOQ5Q0eiQaXq7UD9Jre7G4Em7DL/t1Ppd3cSJ/AKFTrjOQTc3 bB6EZ1BnARzAGEsADF4iNUeiqKjMLjY= To: "xen-devel@lists.xenproject.org" Cc: Tim Deegan , George Dunlap , Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Ian Jackson From: Jan Beulich Subject: [PATCH 0/2][4.15?] x86/shadow: further refinements to "fast fault path" suppression Message-ID: Date: Fri, 5 Mar 2021 16:36:12 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 Content-Language: en-US Andrew points out that 'x86/shadow: suppress "fast fault path" optimization without reserved bits' assumes firm knowledge of the physical machine's address width. When we run virtualized ourselves, we can't reasonably assume that we do, the more that the property may change as we may get migrated. Since we want to further refine this logic anyway, I thought I'd also include the other change that I've previously mentioned, at least for consideration whether to take for 4.15. This reduces the performance impact (albeit perhaps only for very large or exotic guests) that the earlier patch has. 1: suppress "fast fault path" optimization when running virtualized 2: encode full GFN in magic MMIO entries Jan