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 <akrow...@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?

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

+               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?

+               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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