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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0300CC433F5 for ; Wed, 1 Dec 2021 13:02:37 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.236028.409390 (Exim 4.92) (envelope-from ) id 1msPFO-0005Ne-Ox; Wed, 01 Dec 2021 13:02:06 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 236028.409390; Wed, 01 Dec 2021 13:02:06 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1msPFO-0005NX-Lg; Wed, 01 Dec 2021 13:02:06 +0000 Received: by outflank-mailman (input) for mailman id 236028; Wed, 01 Dec 2021 13:02:05 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1msPFN-0005NR-Jo for xen-devel@lists.xenproject.org; Wed, 01 Dec 2021 13:02:05 +0000 Received: from ppsw-43.csi.cam.ac.uk (ppsw-43.csi.cam.ac.uk [131.111.8.143]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id e1b86530-52a6-11ec-b945-1df2895da90e; Wed, 01 Dec 2021 14:02:04 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:40184) by ppsw-43.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.139]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1msPFL-000ywR-ob (Exim 4.95) (return-path ); Wed, 01 Dec 2021 13:02:03 +0000 Received: from [192.168.1.10] (host-92-12-61-86.as13285.net [92.12.61.86]) (Authenticated sender: amc96) by hades.srcf.societies.cam.ac.uk (Postfix) with ESMTPSA id 14E3F1FDDA; Wed, 1 Dec 2021 13:02:03 +0000 (GMT) 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: e1b86530-52a6-11ec-b945-1df2895da90e X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: Date: Wed, 1 Dec 2021 13:02:02 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Content-Language: en-GB To: Jan Beulich , "xen-devel@lists.xenproject.org" Cc: Paul Durrant , Kevin Tian References: <5d72c629-fabf-3d40-aa19-d177826fdde5@suse.com> <8a8dd03a-5447-bc45-1554-50fb5b6c075c@suse.com> From: Andrew Cooper Subject: Re: [PATCH 3/4] VT-d: replace flush_all_cache() In-Reply-To: <8a8dd03a-5447-bc45-1554-50fb5b6c075c@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01/12/2021 09:41, Jan Beulich wrote: > --- a/xen/drivers/passthrough/vtd/iommu.c > +++ b/xen/drivers/passthrough/vtd/iommu.c > @@ -591,7 +591,8 @@ static int __must_check iommu_flush_all( > bool_t flush_dev_iotlb; > int rc = 0; > > - flush_all_cache(); > + flush_local(FLUSH_CACHE); While I agree that the conversion is an improvement, the logic still looks totally bogus. I can believe that it might have been a stopgap to fix problems before we identified the need for sync_cache() for non-coherent IOMMUs, but there's no need I can spot for any WBINVDs on any of these paths. I'm fairly sure this should just be dropped, and Xen will get faster as a result. ~Andrew