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SubjectRe: [PATCH v2 08/15] KVM: s390: interface to enable AP execution mode
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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?
>

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