Messages in this thread | | | Subject | Re: [PATCH v2 08/15] KVM: s390: interface to enable AP execution mode | From | Tony Krowiak <> | Date | Fri, 2 Mar 2018 14:54:34 -0500 |
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On 03/01/2018 04:35 AM, David Hildenbrand wrote: > On 28.02.2018 21:39, Tony Krowiak wrote: >> On 02/28/2018 04:44 AM, David Hildenbrand wrote: >>> On 27.02.2018 15:28, Tony Krowiak wrote: >>>> Introduces a new interface to enable AP interpretive >>>> execution (IE) mode for the KVM guest. When running >>>> with IE mode enabled, AP instructions executed on the >>>> KVM guest will be interpreted by the firmware and >>>> passed directly through to an AP device installed on >>>> the system. The CPU model feature for AP must >>>> be enabled for the KVM guest in order to enable >>>> interpretive execution mode. >>>> >>>> This interface will be used in a subsequent patch >>>> by the VFIO AP device driver. >>>> >>>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com> >>>> --- >>>> arch/s390/include/asm/kvm-ap.h | 2 ++ >>>> arch/s390/include/asm/kvm_host.h | 1 + >>>> arch/s390/kvm/kvm-ap.c | 27 +++++++++++++++++++++++++++ >>>> arch/s390/kvm/kvm-s390.h | 1 + >>>> 4 files changed, 31 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/arch/s390/include/asm/kvm-ap.h b/arch/s390/include/asm/kvm-ap.h >>>> index 46e7c5b..6bd6bfb 100644 >>>> --- a/arch/s390/include/asm/kvm-ap.h >>>> +++ b/arch/s390/include/asm/kvm-ap.h >>>> @@ -51,4 +51,6 @@ struct kvm_ap_matrix { >>>> >>>> void kvm_ap_deconfigure_matrix(struct kvm *kvm); >>>> >>>> +int kvm_ap_enable_ie_mode(struct kvm *kvm); >>>> + >>>> #endif /* _ASM_KVM_AP */ >>>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >>>> index a4c77d3..1eebdd6 100644 >>>> --- a/arch/s390/include/asm/kvm_host.h >>>> +++ b/arch/s390/include/asm/kvm_host.h >>>> @@ -186,6 +186,7 @@ struct kvm_s390_sie_block { >>>> #define ECA_AIV 0x00200000 >>>> #define ECA_VX 0x00020000 >>>> #define ECA_PROTEXCI 0x00002000 >>>> +#define ECA_APIE 0x00000008 >>>> #define ECA_SII 0x00000001 >>>> __u32 eca; /* 0x004c */ >>>> #define ICPT_INST 0x04 >>>> diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c >>>> index bb29045..862e54b 100644 >>>> --- a/arch/s390/kvm/kvm-ap.c >>>> +++ b/arch/s390/kvm/kvm-ap.c >>>> @@ -307,3 +307,30 @@ void kvm_ap_deconfigure_matrix(struct kvm *kvm) >>>> kvm_ap_clear_crycb_masks(kvm); >>>> } >>>> EXPORT_SYMBOL(kvm_ap_deconfigure_matrix); >>>> + >>>> +/** >>>> + * kvm_ap_enable_ie_mode >>>> + * >>>> + * Enable interpretrive execution of AP instructions for the guest. When >>>> + * enabled, AP instructions executed on the guest will be interpreted and >>>> + * passed through to an AP installed on the host system. >>>> + * >>>> + * Returns 0 if interpretrive execution is enabled. Returns -EOPNOTSUPP >>>> + * if AP facilities are not installed for the guest. >>>> + * >>>> + * @kvm: the guest's kvm structure >>>> + */ >>>> +int kvm_ap_enable_ie_mode(struct kvm *kvm) >>>> +{ >>>> + int i; >>>> + struct kvm_vcpu *vcpu; >>>> + >>>> + if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) >>>> + return -EOPNOTSUPP; >>>> + >>>> + kvm_for_each_vcpu(i, vcpu, kvm) >>>> + vcpu->arch.sie_block->eca |= ECA_APIE; >>>> + >>>> + return 0; >>>> +} >>>> +EXPORT_SYMBOL(kvm_ap_enable_ie_mode); >>>> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h >>>> index 1b5621f..3142541 100644 >>>> --- a/arch/s390/kvm/kvm-s390.h >>>> +++ b/arch/s390/kvm/kvm-s390.h >>>> @@ -18,6 +18,7 @@ >>>> #include <asm/facility.h> >>>> #include <asm/processor.h> >>>> #include <asm/sclp.h> >>>> +#include <asm/ap.h> >>>> >>>> /* Transactional Memory Execution related macros */ >>>> #define IS_TE_ENABLED(vcpu) ((vcpu->arch.sie_block->ecb & ECB_TE)) >>>> >>> And also, what about hot-plugged CPUs? >> I haven't considered that, do you have any suggestions? > You should handle the KVM_S390_VM_CPU_FEAT_AP feature instead during > kvm_arch_vcpu_setup(), independent of any configured AP devices. > > This avoids the races I mentioned in regards to this series and also > will handle hotplugged CPUs properly. > > If KVM_S390_VM_CPU_FEAT_AP is configured for a guest -> each CPU sets > ECA_APIE during kvm_arch_vcpu_setup(). We talked about this in a couple of other patches, but I am on board with this. To make things clearer, Should we rename the feature to KVM_S390_VM_CPU_FEAT_APIE so its purpose is more clear? > > > (In the vSIE code, simply allow to set ECA_APIE in the shadow SCB in > case KVM_S390_VM_CPU_FEAT_AP is enabled) >
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