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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED 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 3E272C2BCA1 for ; Fri, 7 Jun 2019 15:23:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A7652089E for ; Fri, 7 Jun 2019 15:23:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="ItLnYD6x" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729786AbfFGPXf (ORCPT ); Fri, 7 Jun 2019 11:23:35 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:46362 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728287AbfFGPXe (ORCPT ); Fri, 7 Jun 2019 11:23:34 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x57FIgZJ065043; Fri, 7 Jun 2019 15:23:02 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=p/h/K8U+S9UnTSMqywSHyFTN/pAmAlatfrvFdGLk/l8=; b=ItLnYD6xsbm6K2ULW5f4F0sC4QrVHQxpoaLSaYag1a9WcwBzDVrv1WJpIB4Ecym8/DBd 9Mt36Mnnsk1P/W7GgpPWdHzOWkZ+vmOpE6xPwAeI9kv6WLa5WqdaX/mzHfFHILcXnThl xAX494GEg/Ycoxzmdhw0nNWmnMzieaZcLQ0SGpNI0keHbImQbsnYCzoXWikb1mvtlvRQ dlmX+AIrMNnE51RAxOiEvP1jngbzE5rQnx97jIQCVxJRD9mL1FvDxZ1+wBPY1QloLVDk 4nLPX5TZKHA2hWzYq24oeHCq1ioZExxgO9sJ2hn67F6iVBt+LPE0k0XdaVDEWm7snLIf cQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 2sugstxwmr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 07 Jun 2019 15:23:02 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x57FM0vF160167; Fri, 7 Jun 2019 15:23:02 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 2swngk2tcu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 07 Jun 2019 15:23:01 +0000 Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x57FN0mk005625; Fri, 7 Jun 2019 15:23:00 GMT Received: from [10.175.171.136] (/10.175.171.136) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 07 Jun 2019 08:23:00 -0700 Subject: Re: [RFC PATCH 00/16] xenhost support To: Juergen Gross Cc: Ankur Arora , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, pbonzini@redhat.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, sstabellini@kernel.org References: <20190509172540.12398-1-ankur.a.arora@oracle.com> <5649cfd1-24df-2196-2888-b00fc3ace7ad@suse.com> From: Joao Martins Message-ID: Date: Fri, 7 Jun 2019 16:22:56 +0100 MIME-Version: 1.0 In-Reply-To: <5649cfd1-24df-2196-2888-b00fc3ace7ad@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9280 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906070107 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9280 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906070107 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/7/19 3:51 PM, Juergen Gross wrote: > On 09.05.19 19:25, Ankur Arora wrote: >> Hi all, >> >> This is an RFC for xenhost support, outlined here by Juergen here: >> https://lkml.org/lkml/2019/4/8/67. > > First: thanks for all the effort you've put into this series! > >> The high level idea is to provide an abstraction of the Xen >> communication interface, as a xenhost_t. >> >> xenhost_t expose ops for communication between the guest and Xen >> (hypercall, cpuid, shared_info/vcpu_info, evtchn, grant-table and on top >> of those, xenbus, ballooning), and these can differ based on the kind >> of underlying Xen: regular, local, and nested. > > I'm not sure we need to abstract away hypercalls and cpuid. I believe in > case of nested Xen all contacts to the L0 hypervisor should be done via > the L1 hypervisor. So we might need to issue some kind of passthrough > hypercall when e.g. granting a page to L0 dom0, but this should be > handled via the grant abstraction (events should be similar). > Just to be clear: By "kind of passthrough hypercall" you mean (e.g. for every access/modify of grant table frames) you would proxy hypercall to L0 Xen via L1 Xen? > So IMO we should drop patches 2-5. > >> (Since this abstraction is largely about guest -- xenhost communication, >> no ops are needed for timer, clock, sched, memory (MMU, P2M), VCPU mgmt. >> etc.) >> >> Xenhost use-cases: >> >> Regular-Xen: the standard Xen interface presented to a guest, >> specifically for comunication between Lx-guest and Lx-Xen. >> >> Local-Xen: a Xen like interface which runs in the same address space as >> the guest (dom0). This, can act as the default xenhost. >> >> The major ways it differs from a regular Xen interface is in presenting >> a different hypercall interface (call instead of a syscall/vmcall), and >> in an inability to do grant-mappings: since local-Xen exists in the same >> address space as Xen, there's no way for it to cheaply change the >> physical page that a GFN maps to (assuming no P2M tables.) >> >> Nested-Xen: this channel is to Xen, one level removed: from L1-guest to >> L0-Xen. The use case is that we want L0-dom0-backends to talk to >> L1-dom0-frontend drivers which can then present PV devices which can >> in-turn be used by the L1-dom0-backend drivers as raw underlying devices. >> The interfaces themselves, broadly remain similar. >> >> Note: L0-Xen, L1-Xen represent Xen running at that nesting level >> and L0-guest, L1-guest represent guests that are children of Xen >> at that nesting level. Lx, represents any level. >> >> Patches 1-7, >> "x86/xen: add xenhost_t interface" >> "x86/xen: cpuid support in xenhost_t" >> "x86/xen: make hypercall_page generic" >> "x86/xen: hypercall support for xenhost_t" >> "x86/xen: add feature support in xenhost_t" >> "x86/xen: add shared_info support to xenhost_t" >> "x86/xen: make vcpu_info part of xenhost_t" >> abstract out interfaces that setup hypercalls/cpuid/shared_info/vcpu_info etc. >> >> Patch 8, "x86/xen: irq/upcall handling with multiple xenhosts" >> sets up the upcall and pv_irq ops based on vcpu_info. >> >> Patch 9, "xen/evtchn: support evtchn in xenhost_t" adds xenhost based >> evtchn support for evtchn_2l. >> >> Patches 10 and 16, "xen/balloon: support ballooning in xenhost_t" and >> "xen/grant-table: host_addr fixup in mapping on xenhost_r0" >> implement support from GNTTABOP_map_grant_ref for xenhosts of type >> xenhost_r0 (xenhost local.) >> >> Patch 12, "xen/xenbus: support xenbus frontend/backend with xenhost_t" >> makes xenbus so that both its frontend and backend can be bootstrapped >> separately via separate xenhosts. >> >> Remaining patches, 11, 13, 14, 15: >> "xen/grant-table: make grant-table xenhost aware" >> "drivers/xen: gnttab, evtchn, xenbus API changes" >> "xen/blk: gnttab, evtchn, xenbus API changes" >> "xen/net: gnttab, evtchn, xenbus API changes" >> are mostly mechanical changes for APIs that now take xenhost_t * >> as parameter. >> >> The code itself is RFC quality, and is mostly meant to get feedback before >> proceeding further. Also note that the FIFO logic and some Xen drivers >> (input, pciback, scsi etc) are mostly unchanged, so will not build. >> >> >> Please take a look. > > > Juergen >