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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 C0165C4727D for ; Tue, 22 Sep 2020 08:03:20 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 5293223A34 for ; Tue, 22 Sep 2020 08:03:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="MwsBxKGF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5293223A34 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kKdGO-0003Ia-60; Tue, 22 Sep 2020 08:03:00 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kKdGM-0003IV-Ug for xen-devel@lists.xenproject.org; Tue, 22 Sep 2020 08:02:58 +0000 X-Inumbo-ID: 75e20209-d04b-4e6a-87c4-3535bdbe7ffb Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 75e20209-d04b-4e6a-87c4-3535bdbe7ffb; Tue, 22 Sep 2020 08:02:57 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1600761776; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yPuFcaOXJac6Lv4zU78OIESuHNZa4SP2/5oHjbjv6GY=; b=MwsBxKGFYn6GYr4PXqXkMll1wLEln31OLLXVnEQZQmWsR4UA6rrjOjjKJ0Mj1YzCyGvcUN dOra5OLsSg6gpcKc1VXgi/2p60zUGCWXJJ2cnp5W9bV56Vkil0DEIFrOyiUYQZD4albq20 f0kXgU/lcxq6GEM6tlomSqNlYgUeZh8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 1944AAF98; Tue, 22 Sep 2020 08:03:33 +0000 (UTC) Subject: Re: [PATCH v4 4/4] xen/mm: Provide dummy M2P-related helpers when !CONFIG_HAVE_M2P To: Julien Grall Cc: xen-devel@lists.xenproject.org, Julien Grall , Stefano Stabellini , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Ian Jackson , Wei Liu References: <20200921180214.4842-1-julien@xen.org> <20200921180214.4842-5-julien@xen.org> From: Jan Beulich Message-ID: <26387b5d-97f7-3c6a-ad40-94b144a3b0ae@suse.com> Date: Tue, 22 Sep 2020 10:02:56 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200921180214.4842-5-julien@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 21.09.2020 20:02, Julien Grall wrote: > --- a/xen/include/xen/mm.h > +++ b/xen/include/xen/mm.h > @@ -685,4 +685,17 @@ static inline void put_page_alloc_ref(struct page_info *page) > } > } > > +/* > + * Dummy implementation of M2P-related helpers for common code when > + * the architecture doesn't have an M2P. > + */ > +#ifndef CONFIG_HAS_M2P > + > +#define INVALID_M2P_ENTRY (~0UL) > +#define SHARED_M2P(_e) false > + > +static inline void set_gpfn_from_mfn(unsigned long mfn, unsigned long pfn) {} While I think this would better BUG() or at least ASSERT_UNREACHABLE(), I realize its use in page_alloc.c prevents this. However, if this was a macro, I think the need for having INVALID_P2M_ENTRY would vanish, as long as the stub macro didn't evaluate its 2nd argument. I'm feeling somewhat uneasy with the SHARED_M2P() definition: This would seem to better be tied to CONFIG_MEM_SHARING rather than M2P existence. Jan