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=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 3C704C28CF6 for ; Fri, 3 Aug 2018 07:06:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6C1C2172A for ; Fri, 3 Aug 2018 07:06:43 +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="V7mgYnod" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6C1C2172A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728787AbeHCJBf (ORCPT ); Fri, 3 Aug 2018 05:01:35 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:55096 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727498AbeHCJBe (ORCPT ); Fri, 3 Aug 2018 05:01:34 -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=DSazAx+/m05vrq2/RcGe6D1zl7+O39Y0CcGFHj6u9fk=; b=V7mgYnod2ytNUUPK6Gahqd+SC Lf9QMEwIoUc3pwDnCY8R8s8luXeWHl3Un/f1jKd/woBVuTF1SUr8gbfIpUAa/wAUG+HGwX9VHqrkt y6tWvduoe8HV1eDpGUuPoF32CI6l+9xBN0B+pIq/qdaYGl/cyUCDkOZgxhPhZ9XeS6nR66Rjgam1w cfHtKcLlmPPjRkAUtdscwUehZfoysBJ2awNOg12Aln0aWBfVoFmcs3v4fzS39KopRvWGBx/xniECd yotVkzfGojuWWfdBzaW/IBgFq6VfwVLOwvpuXLJBmSMIjXOz6zDbuiN/2ZX/pK4gxKVFVNDIUv0hd oLC5WGNMQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1flUAY-00025R-AE; Fri, 03 Aug 2018 07:06:38 +0000 Date: Fri, 3 Aug 2018 00:06:38 -0700 From: Christoph Hellwig To: "Michael S. Tsirkin" Cc: Benjamin Herrenschmidt , Christoph Hellwig , Will Deacon , Anshuman Khandual , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, jasowang@redhat.com, mpe@ellerman.id.au, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, robin.murphy@arm.com, jean-philippe.brucker@arm.com, marc.zyngier@arm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Message-ID: <20180803070638.GB1344@infradead.org> References: <20180727095804.GA25592@arm.com> <20180730093414.GD26245@infradead.org> <20180730125100-mutt-send-email-mst@kernel.org> <20180730111802.GA9830@infradead.org> <20180730155633-mutt-send-email-mst@kernel.org> <20180731173052.GA17153@infradead.org> <3d6e81511571260de1c8047aaffa8ac4df093d2e.camel@kernel.crashing.org> <20180802003823-mutt-send-email-mst@kernel.org> <7779442d7889ee943b3e4ff6c63ec90b4a58b79d.camel@kernel.crashing.org> <20180802235233-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180802235233-mutt-send-email-mst@kernel.org> 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 Thu, Aug 02, 2018 at 11:53:08PM +0300, Michael S. Tsirkin wrote: > > We don't need cache flushing tricks. > > You don't but do real devices on same platform need them? IBMs power plaforms are always cache coherent. There are some powerpc platforms have not cache coherent DMA, but I guess this scheme isn't intended for them.