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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 14C1BC433EF for ; Wed, 8 Sep 2021 07:16:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFB8D61163 for ; Wed, 8 Sep 2021 07:16:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349058AbhIHHR2 (ORCPT ); Wed, 8 Sep 2021 03:17:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348916AbhIHHRU (ORCPT ); Wed, 8 Sep 2021 03:17:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55B0AC06175F for ; Wed, 8 Sep 2021 00:16:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=MnjsixqmosBihT6Q0qVYXXqBZ2K/JeOxHPpv883b1xQ=; b=XbM8Xg3PjSFGTYmv3zW07WfyaY yWEdMq1eEqx0RRQqf2r7e6pYKpvEx0oG4KVrQaoCagb/MmI7o0acywnXwpXSPJTo/1MkSPkPOEFJy mKVPyz7XoUQE44YQmLjxnlC/1P/RLwrxrspgdaqdkFsWsJpB2cRQfFSd4r+Bz7k7bOYyGJ9XCEdOU VV701Kva713ECwwrgTRZcHhYdgohcpF+ORONW/M/BNUXYF7JoqGFO0tJVrTc+1JqjXQEOCwt3RRqO IbwKTqnS0QnoY/SeWesV1xBSinYJz2jyaANLtuvExQupl4FPr9q6HdJd1s3vCXjHopyF3JjAZ7vVe 7+fwQCwQ==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mNrml-008b2V-QY; Wed, 08 Sep 2021 07:14:58 +0000 Date: Wed, 8 Sep 2021 08:14:19 +0100 From: Christoph Hellwig To: Jan Beulich Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini , lkml , "xen-devel@lists.xenproject.org" , the arch/x86 maintainers , Thomas Gleixner , Ingo Molnar , Borislav Petkov Subject: Re: [PATCH 12/12] swiotlb-xen: this is PV-only on x86 Message-ID: References: <588b3e6d-2682-160c-468e-44ca4867a570@suse.com> <004feaef-f3bb-e4bb-fb10-f205a9f69f28@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <004feaef-f3bb-e4bb-fb10-f205a9f69f28@suse.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 07, 2021 at 02:13:21PM +0200, Jan Beulich wrote: > The code is unreachable for HVM or PVH, and it also makes little sense > in auto-translated environments. On Arm, with > xen_{create,destroy}_contiguous_region() both being stubs, I have a hard > time seeing what good the Xen specific variant does - the generic one > ought to be fine for all purposes there. Still Arm code explicitly > references symbols here, so the code will continue to be included there. Can the Xen/arm folks look into that? Getting ARM out of using swiotlb-xen would be a huge step forward cleaning up some DMA APIs. > > Instead of making PCI_XEN's "select" conditional, simply drop it - > SWIOTLB_XEN will be available unconditionally in the PV case anyway, and > is - as explained above - dead code in non-PV environments. > > This in turn allows dropping the stubs for > xen_{create,destroy}_contiguous_region(), the former of which was broken > anyway - it failed to set the DMA handle output. Looks good: Reviewed-by: Christoph Hellwig