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=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_PASS,USER_AGENT_MUTT 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 9DE24C10F11 for ; Wed, 24 Apr 2019 14:58:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C9192089F for ; Wed, 24 Apr 2019 14:58:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="p5YV03+v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733117AbfDXO60 (ORCPT ); Wed, 24 Apr 2019 10:58:26 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:55696 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733098AbfDXO6W (ORCPT ); Wed, 24 Apr 2019 10:58:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=1mouZczOeO2A7CdGV7/0QYREGnlTGGd5nVQgKU+H42o=; b=p5YV03+vE+syj+TAByVW/aniU RZYQk9+H/T4WDdbmtLIgHJSQwHfvddmj58rmxH3243LCcDb43RapjFTZZyehzd2BPZyuzhBQgjceh kawuyDSmYFqC01BfHMzV366RiS4MnHby8QhzTPhUDZL5PzjkgN8nEMmwfz0X/V2l6huBX+056QLuS WmjAq3sEUIOw4oDRQDhURe0N+1McX9GiokAECSK2NVu41/jXK8curzbr04PO3GgsSAo0kzhYEK4qd ge2IbIKaKqXeKcs8RU8kvC7xcWqxEXoSuhOic7yX9yZxRaOKuwS2x+X5ZLsZps4lfaAKqhDlAc3xJ CFICgANVw==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJJLn-0004P1-Gm; Wed, 24 Apr 2019 14:58:19 +0000 Date: Wed, 24 Apr 2019 07:58:19 -0700 From: Christoph Hellwig To: Tom Murphy , Joerg Roedel Cc: Christoph Hellwig , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Tom Murphy Subject: Re: [PATCH] iommu/amd: flush not present cache in iommu_map_page Message-ID: <20190424145819.GA16141@infradead.org> References: <20190424141900.8883-1-tmurphy@arista.com> <20190424143246.GA24079@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 24, 2019 at 03:47:39PM +0100, Tom Murphy wrote: > >And I'd really like to understand the unlikely - amd_iommu_np_cache > >is set based on a hardware capability, so it seems rather odd to mark > >it unlikely. Dynamic branch prediction really should do the right thing > >here usually. > > Here is the commit which added it without any explanation: > https://github.com/torvalds/linux/commit/270cab2426cdc6307725e4f1f46ecf8ab8e69193 > > should we remove it seen as there's no explanation given ? I'd be tempted to do that. But lets just ask Joerg if he has any opinion..