From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Krowiak Subject: Re: [PATCH v2 04/15] KVM: s390: CPU model support for AP virtualization Date: Wed, 28 Feb 2018 10:59:17 -0500 Message-ID: <06f77e0c-a99f-b8c8-750e-7ba148d374ed@linux.vnet.ibm.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> <10cfdb2a-304c-989b-4765-84e19fcd423f@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <10cfdb2a-304c-989b-4765-84e19fcd423f@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: David Hildenbrand , Christian Borntraeger , 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 02/28/2018 06:58 AM, David Hildenbrand wrote: > 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! All true. >