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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 7C0A9C3A59B for ; Sat, 31 Aug 2019 02:41:07 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 457652342E for ; Sat, 31 Aug 2019 02:41:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="LMorm/Kg"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="gvmwFq3p" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 457652342E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zMWHm0WQxkZVZ+oebwXYqz2/0UTp7UT4AEU83FSQ3Ks=; b=LMorm/Kg2gcuth U4zyLUxdsntyR284cYGmaapm2BiUhUO1bk1nVLkXIXQmkJjVoc2OjnNsEbimNWBEEjXj407TOd9yz 7kgU0f6ssTzTq16QRDGkMaIWs1bU7nW3jS5yl96tV+LVsZHjBmiqwVO4y6sJrcD24U5vLk87m6ZAc kwscbE0IreUhY+suBPH6VHfa/OWCJNWWFYo3DlCZMMZIvVE2DSmUKNOooHYIIlDbSRttKTKE9fUS0 Cckc/5OM+oRbbBnzIYVXuUMjzc5+F6eWorp9mLmTzvYoNSCJuhVEUYtHCtnEovxq0sxPkIn+y7wm0 S52eTK2AEx9q7VHZ7U/g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i3tJv-0006hQ-TK; Sat, 31 Aug 2019 02:40:55 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i3tJr-0006gg-OV for linux-arm-kernel@lists.infradead.org; Sat, 31 Aug 2019 02:40:53 +0000 Received: from localhost (c-67-164-102-47.hsd1.ca.comcast.net [67.164.102.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0870A2342E; Sat, 31 Aug 2019 02:40:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567219250; bh=JMKsqnwwgnBGpJ8VeH9x8cWpA1gtiIBeSZVZl27H2DQ=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=gvmwFq3pY5ccH5CCkB4Ugbg/tMcPSx94oSmxQjeR09qKdawAweVRy+ftYilt0NgBa usG1q3SgGfitAHlFFq20MSlmtok8sJZq49uKbGwenqoZdqTJJdUl/hesQArj/MGDX0 DKmKFaMvUjziQw1oQYuf5m++yBZbQ7qW8Hm8+CYQ= Date: Fri, 30 Aug 2019 19:40:42 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: Christoph Hellwig Subject: Re: [PATCH V2] arm: xen: mm: use __GPF_DMA32 for arm64 In-Reply-To: <20190830085807.GA15771@infradead.org> Message-ID: References: <1567175255-1798-1-git-send-email-peng.fan@nxp.com> <20190830085807.GA15771@infradead.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190830_194051_822444_D9CB7C91 X-CRM114-Status: GOOD ( 11.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jgross@suse.com, Peng Fan , "sstabellini@kernel.org" , Catalin Marinas , "linux@armlinux.org.uk" , Julien Grall , dl-linux-imx , "xen-devel@lists.xenproject.org" , boris.ostrovsky@oracle.com, nd , "will@kernel.org" , "linux-arm-kernel@lists.infradead.org" , Robin Murphy Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org + Juergen, Boris On Fri, 30 Aug 2019, Christoph Hellwig wrote: > Can we take a step back and figure out what we want to do here? > > AFAICS this function allocates memory for the swiotlb-xen buffer, > and that means it must be <= 32-bit addressable to satisfy the DMA API > guarantees. That means we generally want to use GFP_DMA32 everywhere > that exists, but on systems with odd zones we might want to dip into > GFP_DMA. This also means swiotlb-xen doesn't actually do the right > thing on x86 at the moment. So shouldn't we just have one common > routine in swiotlb-xen.c that checks if we have CONFIG_ZONE_DMA32 > set, then try GFP_DMA32, and if not check if CONFIG_ZONE_DMA is set > and then try that, else default to GFP_KERNEL? Yes, for ARM/ARM64 it makes a lot of sense given that dom0 is 1:1 mapped (pseudo-physical == physical). I'll let Juergen and Boris comment on the x86 side of things, but on x86 PV Dom0 is not 1:1 mapped so GFP_DMA32 is probably not meaningful. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel