From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751187AbeC0LXF (ORCPT ); Tue, 27 Mar 2018 07:23:05 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:37094 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750898AbeC0LXD (ORCPT ); Tue, 27 Mar 2018 07:23:03 -0400 Subject: Re: [PATCH v3 03/14] KVM: s390: CPU model support for AP virtualization To: Cornelia Huck , Tony Krowiak Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com References: <1521051954-25715-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1521051954-25715-4-git-send-email-akrowiak@linux.vnet.ibm.com> <20180327125911.5c7ecf34.cohuck@redhat.com> From: Pierre Morel Date: Tue, 27 Mar 2018 13:22:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180327125911.5c7ecf34.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18032711-0044-0000-0000-0000054057AF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18032711-0045-0000-0000-0000287F72B0 Message-Id: <327f20bc-741d-ac0a-8e3f-929e8ad73159@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-27_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803270116 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/03/2018 12:59, Cornelia Huck wrote: > On Wed, 14 Mar 2018 14:25:43 -0400 > Tony Krowiak wrote: > >> Introduces a new CPU model feature and two CPU model >> facilities to support AP virtualization for KVM guests. >> >> CPU model feature: >> >> The KVM_S390_VM_CPU_FEAT_AP feature indicates that >> AP instructions are available on the guest. This >> feature will be enabled by the kernel only if the AP >> instructions are installed on the linux host. This feature >> must be specifically turned on for the KVM guest from >> userspace to use the VFIO AP device driver for guest >> access to AP devices. >> >> CPU model facilities: >> >> 1. AP Query Configuration Information (QCI) facility is installed. >> >> This is indicated by setting facilities bit 12 for >> the guest. The kernel will not enable this facility >> for the guest if it is not set on the host. This facility >> must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP >> feature is not installed. >> >> 2. AP Facilities Test facility (APFT) is installed. >> >> This is indicated by setting facilities bit 15 for >> the guest. The kernel will not enable this facility for >> the guest if it is not set on the host. This facility >> must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP >> feature is not installed. >> >> Reviewed-by: Christian Borntraeger >> Reviewed-by: Halil Pasic >> Signed-off-by: Tony Krowiak >> --- >> arch/s390/include/asm/kvm_host.h | 1 + >> arch/s390/include/uapi/asm/kvm.h | 1 + >> arch/s390/kvm/kvm-s390.c | 4 ++++ >> arch/s390/tools/gen_facilities.c | 2 ++ >> 4 files changed, 8 insertions(+), 0 deletions(-) >> >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index c47731d..a60c45b 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -350,6 +350,10 @@ static void kvm_s390_cpu_feat_init(void) >> >> if (MACHINE_HAS_ESOP) >> allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP); >> + >> + if (ap_instructions_installed()) /* AP instructions installed on host */ >> + allow_cpu_feat(KVM_S390_VM_CPU_FEAT_AP); > That's another dependency of the base kvm-s390 module on zcrypt, which > I don't like at all. In fact there is a tricky thing about zcrypt it is that even it is configured a a module CONFIG_ZCRYPT=M, the AP BUS is built statically with the kernel. See drivers/s390/crypto/Makefile " ap-objs := ap_bus.o ap_card.o ap_queue.o obj-$(subst m,y,$(CONFIG_ZCRYPT)) += ap.o " ugly isn't it? > > There are two possibilities here: > - Exposing the features makes sense even if no zcrypt driver is active > in the host. Then, ap_instructions_installed() needs to be moved into > always-built code (see my comments for the interface in patch 1). This is what we need for future enhancement I think. > - Exposing the features makes sense only if we actually want to make > vfio-ap available. Then we should provide the proper check in the > vfio-ap parts (which depends on zcrypt) and stub it out if vfio-ap is > not configured. > >> + >> /* >> * We need SIE support, ESOP (PROT_READ protection for gmap_shadow), >> * 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing). -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany