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Fri, 14 Jun 2019 07:20:34 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5E7JejA190190; Fri, 14 Jun 2019 07:20:34 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 2t024vy053-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 14 Jun 2019 07:20:33 +0000 Received: from abhmp0022.oracle.com (abhmp0022.oracle.com [141.146.116.28]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x5E7KVaU023497; Fri, 14 Jun 2019 07:20:31 GMT Received: from [10.159.225.204] (/10.159.225.204) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 14 Jun 2019 00:20:30 -0700 Subject: Re: [Xen-devel] [RFC PATCH 04/16] x86/xen: hypercall support for xenhost_t To: Andrew Cooper , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: jgross@suse.com, sstabellini@kernel.org, konrad.wilk@oracle.com, pbonzini@redhat.com, boris.ostrovsky@oracle.com, joao.m.martins@oracle.com References: <20190509172540.12398-1-ankur.a.arora@oracle.com> <20190509172540.12398-5-ankur.a.arora@oracle.com> <11f8b620-11ac-7075-019a-30d6bad7583c@citrix.com> From: Ankur Arora Message-ID: Date: Fri, 14 Jun 2019 00:20:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <11f8b620-11ac-7075-019a-30d6bad7583c@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9287 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-1906140057 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9287 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-1906140058 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-06-12 2:15 p.m., Andrew Cooper wrote: > On 09/05/2019 18:25, Ankur Arora wrote: >> Allow for different hypercall implementations for different xenhost types. >> Nested xenhost, which has two underlying xenhosts, can use both >> simultaneously. >> >> The hypercall macros (HYPERVISOR_*) implicitly use the default xenhost.x >> A new macro (hypervisor_*) takes xenhost_t * as a parameter and does the >> right thing. >> >> TODO: >> - Multicalls for now assume the default xenhost >> - xen_hypercall_* symbols are only generated for the default xenhost. >> >> Signed-off-by: Ankur Arora > > Again, what is the hypervisor nesting and/or guest layout here? Two hypervisors, L0 and L1, and the guest is a child of the L1 hypervisor but could have PV devices attached to both L0 and L1 hypervisors. > > I can't think of any case where a single piece of software can > legitimately have two hypercall pages, because if it has one working > one, it is by definition a guest, and therefore not privileged enough to > use the outer one. Depending on which hypercall page is used, the hypercall would (eventually) land in the corresponding hypervisor. Juergen elsewhere pointed out proxying hypercalls is a better approach, so I'm not really considering this any more but, given this layout, and assuming that the hypercall pages could be encoded differently would it still not work? Ankur > > ~Andrew > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xenproject.org > https://lists.xenproject.org/mailman/listinfo/xen-devel >