KVM: s390: protvirt: Add SCLP interrupt handling

The sclp interrupt is kind of special. The ultravisor polices that we
do not inject an sclp interrupt with payload if no sccb is outstanding.
On the other hand we have "asynchronous" event interrupts, e.g. for
console input.
We separate both variants into sclp interrupt and sclp event interrupt.
The sclp interrupt is masked until a previous servc instruction has
finished (sie exit 108).

[frankja@linux.ibm.com: factoring out write_sclp]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 9966c43c6035..00a79442a428 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -444,8 +444,35 @@ static int handle_operexc(struct kvm_vcpu *vcpu)
 	return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
 }
 
+static int handle_pv_sclp(struct kvm_vcpu *vcpu)
+{
+	struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
+
+	spin_lock(&fi->lock);
+	/*
+	 * 2 cases:
+	 * a: an sccb answering interrupt was already pending or in flight.
+	 *    As the sccb value is not known we can simply set some value to
+	 *    trigger delivery of a saved SCCB. UV will then use its saved
+	 *    copy of the SCCB value.
+	 * b: an error SCCB interrupt needs to be injected so we also inject
+	 *    a fake SCCB address. Firmware will use the proper one.
+	 * This makes sure, that both errors and real sccb returns will only
+	 * be delivered after a notification intercept (instruction has
+	 * finished) but not after others.
+	 */
+	fi->srv_signal.ext_params |= 0x43000;
+	set_bit(IRQ_PEND_EXT_SERVICE, &fi->pending_irqs);
+	clear_bit(IRQ_PEND_EXT_SERVICE, &fi->masked_irqs);
+	spin_unlock(&fi->lock);
+	return 0;
+}
+
 static int handle_pv_notification(struct kvm_vcpu *vcpu)
 {
+	if (vcpu->arch.sie_block->ipa == 0xb220)
+		return handle_pv_sclp(vcpu);
+
 	return handle_instruction(vcpu);
 }