KVM: s390: Add support for channel I/O instructions.
Add a new capability, KVM_CAP_S390_CSS_SUPPORT, which will pass
intercepts for channel I/O instructions to userspace. Only I/O
instructions interacting with I/O interrupts need to be handled
in-kernel:
- TEST PENDING INTERRUPTION (tpi) dequeues and stores pending
interrupts entirely in-kernel.
- TEST SUBCHANNEL (tsch) dequeues pending interrupts in-kernel
and exits via KVM_EXIT_S390_TSCH to userspace for subchannel-
related processing.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 5ff2603..5b01f09 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -141,6 +141,7 @@
case KVM_CAP_SYNC_REGS:
case KVM_CAP_ONE_REG:
case KVM_CAP_ENABLE_CAP:
+ case KVM_CAP_S390_CSS_SUPPORT:
r = 1;
break;
case KVM_CAP_NR_VCPUS:
@@ -235,6 +236,9 @@
if (!kvm->arch.gmap)
goto out_nogmap;
}
+
+ kvm->arch.css_support = 0;
+
return 0;
out_nogmap:
debug_unregister(kvm->arch.dbf);
@@ -658,6 +662,7 @@
case KVM_EXIT_INTR:
case KVM_EXIT_S390_RESET:
case KVM_EXIT_S390_UCONTROL:
+ case KVM_EXIT_S390_TSCH:
break;
default:
BUG();
@@ -818,6 +823,13 @@
return -EINVAL;
switch (cap->cap) {
+ case KVM_CAP_S390_CSS_SUPPORT:
+ if (!vcpu->kvm->arch.css_support) {
+ vcpu->kvm->arch.css_support = 1;
+ trace_kvm_s390_enable_css(vcpu->kvm);
+ }
+ r = 0;
+ break;
default:
r = -EINVAL;
break;