Messages in this thread |  | | Subject | Re: [PATCH v4 05/15] KVM: s390: enable/disable AP interpretive execution | From | Pierre Morel <> | Date | Wed, 18 Apr 2018 10:31:08 +0200 |
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On 17/04/2018 20:11, Tony Krowiak wrote: > On 04/17/2018 12:55 PM, Pierre Morel wrote: >> On 17/04/2018 18:22, Tony Krowiak wrote: >>> On 04/17/2018 12:13 PM, Pierre Morel wrote: >>>> On 17/04/2018 17:02, Tony Krowiak wrote: >>>>> On 04/16/2018 06:51 AM, Pierre Morel wrote: >>>>>> On 15/04/2018 23:22, Tony Krowiak wrote: >>>>>>> The VFIO AP device model exploits interpretive execution of AP >>>>>>> instructions (APIE) to provide guests passthrough access to AP >>>>>>> devices. This patch introduces a new interface to enable and >>>>>>> disable APIE. >>>>>>> >>>>>>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com> >>>>>>> --- >>>>>>> arch/s390/include/asm/kvm-ap.h | 16 ++++++++++++++++ >>>>>>> arch/s390/include/asm/kvm_host.h | 1 + >>>>>>> arch/s390/kvm/kvm-ap.c | 20 ++++++++++++++++++++ >>>>>>> arch/s390/kvm/kvm-s390.c | 9 +++++++++ >>>>>>> 4 files changed, 46 insertions(+), 0 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/s390/include/asm/kvm-ap.h >>>>>>> b/arch/s390/include/asm/kvm-ap.h >>>>>>> index 736e93e..a6c092e 100644 >>>>>>> --- a/arch/s390/include/asm/kvm-ap.h >>>>>>> +++ b/arch/s390/include/asm/kvm-ap.h >>>>>>> @@ -35,4 +35,20 @@ >>>>>>> */ >>>>>>> void kvm_ap_build_crycbd(struct kvm *kvm); >>>>>>> >>>>>>> +/** >>>>>>> + * kvm_ap_interpret_instructions >>>>>>> + * >>>>>>> + * Indicate whether AP instructions shall be interpreted. If >>>>>>> they are not >>>>>>> + * interpreted, all AP instructions will be intercepted and >>>>>>> routed back to >>>>>>> + * userspace. >>>>>>> + * >>>>>>> + * @kvm: the virtual machine attributes >>>>>>> + * @enable: indicates whether AP instructions are to be >>>>>>> interpreted (true) or >>>>>>> + * or not (false). >>>>>>> + * >>>>>>> + * Returns 0 if completed successfully; otherwise, returns >>>>>>> -EOPNOTSUPP >>>>>>> + * indicating that AP instructions are not installed on the guest. >>>>>>> + */ >>>>>>> +int kvm_ap_interpret_instructions(struct kvm *kvm, bool enable); >>>>>>> + >>>>>>> #endif /* _ASM_KVM_AP */ >>>>>>> diff --git a/arch/s390/include/asm/kvm_host.h >>>>>>> b/arch/s390/include/asm/kvm_host.h >>>>>>> index 3162783..5470685 100644 >>>>>>> --- a/arch/s390/include/asm/kvm_host.h >>>>>>> +++ b/arch/s390/include/asm/kvm_host.h >>>>>>> @@ -715,6 +715,7 @@ struct kvm_s390_crypto { >>>>>>> __u32 crycbd; >>>>>>> __u8 aes_kw; >>>>>>> __u8 dea_kw; >>>>>>> + __u8 apie; >>>>>>> }; >>>>>>> >>>>>>> #define APCB0_MASK_SIZE 1 >>>>>>> diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c >>>>>>> index 991bae4..55d11b5 100644 >>>>>>> --- a/arch/s390/kvm/kvm-ap.c >>>>>>> +++ b/arch/s390/kvm/kvm-ap.c >>>>>>> @@ -58,3 +58,23 @@ void kvm_ap_build_crycbd(struct kvm *kvm) >>>>>>> } >>>>>>> } >>>>>>> EXPORT_SYMBOL(kvm_ap_build_crycbd); >>>>>>> + >>>>>>> +int kvm_ap_interpret_instructions(struct kvm *kvm, bool enable) >>>>>>> +{ >>>>>>> + int ret = 0; >>>>>>> + >>>>>>> + mutex_lock(&kvm->lock); >>>>>>> + >>>>>>> + if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) { >>>>>> >>>>>> Do we really need to test CPU_FEAT_AP? >>>>> >>>>> Yes we do. >>>> >>>> really? why? >>> >>> The KVM_S390_VM_CPU_FEAT_AP will not be enabled by KVM if the AP >>> instructions are not installed on the host. I assume - but have >>> no way of verifying - that if the AP instructions are not installed >>> on the host, that interpretation would fail. Do you know what would >>> happen if AP instructions are interpreted when not installed on >>> the host? >> >> If the host has no AP instructions (his ECA.28=0) but it set ECA.28 >> for a guest, >> there will be no AP instructions available in the guest. > > Then there's the answer to your question; this is why we to test > CPU_FEAT_AP.
We can postpone this discussion when we discuss on VSIE. For this specific call I just wanted to point out that obviously this function should not be called if the guest has no AP instructions.
> >> >> >>> >>>> >>>> >>>>> >>>>>> >>>>>> >>>>>> I understand that KVM_S390_VM_CPU_FEAT_AP means AP instructions >>>>>> are interpreted. >>>>>> shouldn't we add this information in the name? >>>>>> like KVM_S390_VM_CPU_FEAT_APIE >>>>> >>>>> KVM_S390_VM_CPU_FEAT_AP does NOT mean AP instructions are >>>>> interpreted, it means >>>>> AP instructions are installed. >>>> >>>> Right same error I made all along this review. >>>> But AFAIK it means AP instructions are provided to the guest. >>>> Then should this function be called if the guest has no AP >>>> instructions ? >>>> >>>> >>>>> >>>>>> >>>>>>> + ret = -EOPNOTSUPP; >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + kvm->arch.crypto.apie = enable; >>>>>>> + kvm_s390_vcpu_crypto_reset_all(kvm); >>>>>>> + >>>>>>> +done: >>>>>>> + mutex_unlock(&kvm->lock); >>>>>>> + return ret; >>>>>>> +} >>>>>>> +EXPORT_SYMBOL(kvm_ap_interpret_instructions); >>>>>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>>>>>> index 55cd897..1dc8566 100644 >>>>>>> --- a/arch/s390/kvm/kvm-s390.c >>>>>>> +++ b/arch/s390/kvm/kvm-s390.c >>>>>>> @@ -1901,6 +1901,9 @@ static void kvm_s390_crypto_init(struct >>>>>>> kvm *kvm) >>>>>>> kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb; >>>>>>> kvm_ap_build_crycbd(kvm); >>>>>>> >>>>>>> + /* Default setting indicating SIE shall interpret AP >>>>>>> instructions */ >>>>>>> + kvm->arch.crypto.apie = 1; >>>>>>> + >>>>>>> if (!test_kvm_facility(kvm, 76)) >>>>>>> return; >>>>>>> >>>>>>> @@ -2434,6 +2437,12 @@ static void >>>>>>> kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu) >>>>>>> { >>>>>>> vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd; >>>>>>> >>>>>>> + vcpu->arch.sie_block->eca &= ~ECA_APIE; >>>>>>> + if (vcpu->kvm->arch.crypto.apie && >>>>>>> + test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP)) >>>>>> >>>>>> Do we call xxx_crypto_setup() if KVM does not support AP >>>>>> interpretation? >>>>> >>>>> Yes, kvm_s390_vcpu_crypto_setup(vcpu) is called by >>>>> kvm_arch_vcpu_setup(vcpu) >>>>> as well as from kvm_s390_vcpu_crypto_reset_all(kvm). Calling it >>>>> has nothing >>>>> to do with whether AP interpretation is supported or not as it >>>>> does much >>>>> more than that, including setting up of wrapping keys and the CRYCBD. >>>> >>>> Sorry, still the same error I made about CPU_FEAT_AP meaning AP >>>> instructions in the guest >>>> and not AP interpretation available. >>>> Could apie be set if AP instruction are not supported? >>>> >>>>> >>>>>> >>>>>>> + vcpu->arch.sie_block->eca |= ECA_APIE; >>>>>>> + >>>>>>> + >>>>>>> if (!test_kvm_facility(vcpu->kvm, 76)) >>>>>>> return; >>>>>>> >>>>>> >>>>> >>>> >>> >> >
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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