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@xxxxxxxxxxxxxxxxxx> >>> --- >>> 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(). (In the vSIE code, simply allow to set ECA_APIE in the shadow SCB in case KVM_S390_VM_CPU_FEAT_AP is enabled) -- Thanks, David / dhildenb -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html