From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH v2 04/15] KVM: s390: CPU model support for AP virtualization Date: Wed, 28 Feb 2018 12:58:42 +0100 Message-ID: <10cfdb2a-304c-989b-4765-84e19fcd423f@redhat.com> References: <1519741693-17440-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1519741693-17440-5-git-send-email-akrowiak@linux.vnet.ibm.com> <38deecae-53b4-c5cb-3dba-24bdfab3d9d0@redhat.com> <3a3ff176-4e6b-963c-7831-cdcd10b556eb@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <3a3ff176-4e6b-963c-7831-cdcd10b556eb@de.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Christian Borntraeger , Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com List-ID: On 28.02.2018 12:40, Christian Borntraeger wrote: > > > On 02/28/2018 10:48 AM, David Hildenbrand wrote: >> On 27.02.2018 15:28, 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 the >>> AP facilities are installed on the KVM guest. This >>> feature will be enabled by the kernel only if the AP >>> facilities are installed on the linux host. This feature >>> must be specifically turned on for the KVM guest from >>> userspace to allow guest access to AP devices installed >>> on the linux host. >>> >>> 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/uapi/asm/kvm.h | 1 + >>> arch/s390/kvm/kvm-s390.c | 4 ++++ >>> arch/s390/tools/gen_facilities.c | 2 ++ >>> 3 files changed, 7 insertions(+), 0 deletions(-) >>> >>> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h >>> index 4cdaa55..a580dec 100644 >>> --- a/arch/s390/include/uapi/asm/kvm.h >>> +++ b/arch/s390/include/uapi/asm/kvm.h >>> @@ -130,6 +130,7 @@ struct kvm_s390_vm_cpu_machine { >>> #define KVM_S390_VM_CPU_FEAT_PFMFI 11 >>> #define KVM_S390_VM_CPU_FEAT_SIGPIF 12 >>> #define KVM_S390_VM_CPU_FEAT_KSS 13 >>> +#define KVM_S390_VM_CPU_FEAT_AP 14 >>> struct kvm_s390_vm_cpu_feat { >>> __u64 feat[16]; >>> }; >>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>> index de1e299..c68ca86 100644 >>> --- a/arch/s390/kvm/kvm-s390.c >>> +++ b/arch/s390/kvm/kvm-s390.c >>> @@ -347,6 +347,10 @@ 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); >> >> Don't we have a SIE specific AP feature? So is it true, that once we >> have AP instructions, we are allowed to use them for SIE? Isn't there a >> "AP interpretation facility" or anything like that? (that unlocks ECA_APIE) > > This seems to be coupled to the AP facility and there is no facility or scp bit. > AP is too old to have that (predates STFLE) > Interesting, so we (I :) ) didn't implement vSIE support back then because we never indicated the AP facility (sensed by executing the instruction) to the guest. So ECA_APIE can be used when we sense the AP facility. Thanks! -- Thanks, David / dhildenb