From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:45335 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727333AbfKOK2E (ORCPT ); Fri, 15 Nov 2019 05:28:04 -0500 Subject: Re: [RFC 31/37] KVM: s390: protvirt: Add diag 308 subcode 8 - 10 handling References: <20191024114059.102802-1-frankja@linux.ibm.com> <20191024114059.102802-32-frankja@linux.ibm.com> From: Thomas Huth Message-ID: Date: Fri, 15 Nov 2019 11:27:51 +0100 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-s390-owner@vger.kernel.org List-ID: To: Janosch Frank , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, david@redhat.com, borntraeger@de.ibm.com, imbrenda@linux.ibm.com, mihajlov@linux.ibm.com, mimu@linux.ibm.com, cohuck@redhat.com, gor@linux.ibm.com On 15/11/2019 11.20, Janosch Frank wrote: > On 11/15/19 11:04 AM, Thomas Huth wrote: >> On 24/10/2019 13.40, Janosch Frank wrote: >>> If the host initialized the Ultravisor, we can set stfle bit 161 >>> (protected virtual IPL enhancements facility), which indicates, that >>> the IPL subcodes 8, 9 and are valid. These subcodes are used by a >>> normal guest to set/retrieve a IPIB of type 5 and transition into >>> protected mode. >>> >>> Once in protected mode, the VM will loose the facility bit, as each >> >> So should the bit be cleared in the host code again? ... I don't see >> this happening in this patch? >> >> Thomas >=20 > No, KVM doesn't report stfle facilities in protected mode and we would > need to add it again in normal mode so just clearing it would be > pointless. In protected mode 8-10 do not intercept, so there's nothing > we need to do. Ah, ok, that's what I've missed. Maybe replace "the VM will loose the facility bit" with "the ultravisor will conceal the facility bit" ? Thomas