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[qemu-s390x] [PULL 4/8] s390x/kvm: enable AP instruction interpretation

From: Cornelia Huck
Subject: [qemu-s390x] [PULL 4/8] s390x/kvm: enable AP instruction interpretation for guest
Date: Fri, 12 Oct 2018 12:00:57 +0200

From: Tony Krowiak <address@hidden>

Let's use the KVM_SET_DEVICE_ATTR ioctl to enable hardware
interpretation of AP instructions executed on the guest.
If the S390_FEAT_AP feature is switched on for the guest,
AP instructions must be interpreted by default; otherwise,
they will be intercepted.

This attribute setting may be overridden by a device. For example,
a device may want to provide AP instructions to the guest (i.e.,
S390_FEAT_AP turned on), but it may want to emulate them. In this
case, the AP instructions executed on the guest must be
intercepted; so when the device is realized, it must disable

Signed-off-by: Tony Krowiak <address@hidden>
Tested-by: Pierre Morel <address@hidden>
Reviewed-by: David Hildenbrand <address@hidden>
Reviewed-by: Thomas Huth <address@hidden>
Reviewed-by: Christian Borntraeger <address@hidden>
Acked-by: Halil Pasic <address@hidden>
Tested-by: Christian Borntraeger <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Cornelia Huck <address@hidden>
 target/s390x/kvm.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 78d39b34d0..2ebf26adfe 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -2299,11 +2299,26 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, 
Error **errp)
         error_setg(errp, "KVM: host CPU model could not be identified");
+    /* for now, we can only provide the AP feature with HW support */
+    if (kvm_vm_check_attr(kvm_state, KVM_S390_VM_CRYPTO,
+        set_bit(S390_FEAT_AP, model->features);
+    }
     /* strip of features that are not part of the maximum model */
     bitmap_and(model->features, model->features, model->def->full_feat,
+static void kvm_s390_configure_apie(bool interpret)
+    uint64_t attr = interpret ? KVM_S390_VM_CRYPTO_ENABLE_APIE :
+                                KVM_S390_VM_CRYPTO_DISABLE_APIE;
+    if (kvm_vm_check_attr(kvm_state, KVM_S390_VM_CRYPTO, attr)) {
+        kvm_s390_set_attr(attr);
+    }
 void kvm_s390_apply_cpu_model(const S390CPUModel *model, Error **errp)
     struct kvm_s390_vm_cpu_processor prop  = {
@@ -2353,6 +2368,10 @@ void kvm_s390_apply_cpu_model(const S390CPUModel *model, 
Error **errp)
     if (test_bit(S390_FEAT_CMM, model->features)) {
+    if (test_bit(S390_FEAT_AP, model->features)) {
+        kvm_s390_configure_apie(true);
+    }
 void kvm_s390_restart_interrupt(S390CPU *cpu)

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