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=HEADER_FROM_DIFFERENT_DOMAINS, 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 8E528C433E0 for ; Wed, 24 Jun 2020 10:05:42 +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 6976B20702 for ; Wed, 24 Jun 2020 10:05:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6976B20702 Authentication-Results: mail.kernel.org; dmarc=none (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 1jo2HW-0001om-Ee; Wed, 24 Jun 2020 10:05:26 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jo2HV-0001od-0G for xen-devel@lists.xenproject.org; Wed, 24 Jun 2020 10:05:25 +0000 X-Inumbo-ID: 38689444-b602-11ea-8496-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 38689444-b602-11ea-8496-bc764e2007e4; Wed, 24 Jun 2020 10:05:24 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id ADEDDAE2B; Wed, 24 Jun 2020 10:05:22 +0000 (UTC) Subject: Re: [PATCH for-4.14] mm: fix public declaration of struct xen_mem_acquire_resource To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= References: <20200623135246.66170-1-roger.pau@citrix.com> <044c278b-e0df-e389-b21a-66c7307997c4@suse.com> <20200623173150.GV735@Air-de-Roger> From: Jan Beulich Message-ID: <3ea0ff91-8e5c-701c-ee31-4140b247f3c9@suse.com> Date: Wed, 24 Jun 2020 12:05:17 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200623173150.GV735@Air-de-Roger> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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: , Cc: Stefano Stabellini , Julien Grall , Wei Liu , paul@xen.org, Andrew Cooper , Ian Jackson , George Dunlap , xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 23.06.2020 19:32, Roger Pau Monné wrote: > On Tue, Jun 23, 2020 at 05:04:53PM +0200, Jan Beulich wrote: >> On 23.06.2020 15:52, Roger Pau Monne wrote: >>> XENMEM_acquire_resource and it's related structure is currently inside >>> a __XEN__ or __XEN_TOOLS__ guarded section to limit it's scope to the >>> hypervisor or the toolstack only. This is wrong as the hypercall is >>> already being used by the Linux kernel at least, and as such needs to >>> be public. >> >> Actually - how does this work for the Linux kernel, seeing >> >> rc = rcu_lock_remote_domain_by_id(xmar.domid, &d); >> if ( rc ) >> return rc; >> >> rc = xsm_domain_resource_map(XSM_DM_PRIV, d); >> if ( rc ) >> goto out; >> >> in the function? > > It's my understanding (I haven't tried to use that hypercall yet on > FreeBSD, so I cannot say I've tested it), that xmar.domid is the > remote domain, which the functions locks and then uses > xsm_domain_resource_map to check whether the current domain has > permissions to do privileged operations against it. Yes, but that's a tool stack operation, not something the kernel would do all by itself. The kernel would only ever pass DOMID_SELF (or the actual local domain ID), I would think. Jan