KVM: s390: interpretive execution of SIGP EXTERNAL CALL

If the sigp interpretation facility is installed, most SIGP EXTERNAL CALL
operations will be interpreted instead of intercepted. A partial execution
interception will occurr at the sending cpu only if the target cpu is in the
wait state ("W" bit in the cpuflags set). Instruction interception will only
happen in error cases (e.g. cpu addr invalid).

As a sending cpu might set the external call interrupt pending flags at the
target cpu at every point in time, we can't handle this kind of interrupt using
our kvm interrupt injection mechanism. The injection will be done automatically
by the SIE when preparing the start of the target cpu.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
CC: Thomas Huth <thuth@linux.vnet.ibm.com>
[Adopt external call injection to check for sigp interpretion]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 26 insertions, 4 deletions

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 75cd321..bf0d9bc 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -148,9 +148,8 @@ static void __unset_cpu_idle(struct kvm_vcpu *vcpu)
 
 static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
 {
-	atomic_clear_mask(CPUSTAT_ECALL_PEND |
-		CPUSTAT_IO_INT | CPUSTAT_EXT_INT | CPUSTAT_STOP_INT,
-		&vcpu->arch.sie_block->cpuflags);
+	atomic_clear_mask(CPUSTAT_IO_INT | CPUSTAT_EXT_INT | CPUSTAT_STOP_INT,
+			  &vcpu->arch.sie_block->cpuflags);
 	vcpu->arch.sie_block->lctl = 0x0000;
 	vcpu->arch.sie_block->ictl &= ~(ICTL_LPSW | ICTL_STCTL | ICTL_PINT);
 
@@ -524,6 +523,20 @@ static void deliver_ckc_interrupt(struct kvm_vcpu *vcpu)
 	}
 }
 
+/* Check whether SIGP interpretation facility has an external call pending */
+int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu)
+{
+	atomic_t *sigp_ctrl = &vcpu->kvm->arch.sca->cpu[vcpu->vcpu_id].ctrl;
+
+	if (!psw_extint_disabled(vcpu) &&
+	    (vcpu->arch.sie_block->gcr[0] & 0x2000ul) &&
+	    (atomic_read(sigp_ctrl) & SIGP_CTRL_C) &&
+	    (atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_ECALL_PEND))
+		return 1;
+
+	return 0;
+}
+
 int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
@@ -554,6 +567,9 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 	if (!rc && kvm_cpu_has_pending_timer(vcpu))
 		rc = 1;
 
+	if (!rc && kvm_s390_si_ext_call_pending(vcpu))
+		rc = 1;
+
 	return rc;
 }
 
@@ -610,7 +626,8 @@ no_timer:
 	while (list_empty(&vcpu->arch.local_int.list) &&
 		list_empty(&vcpu->arch.local_int.float_int->list) &&
 		(!vcpu->arch.local_int.timer_due) &&
-		!signal_pending(current)) {
+		!signal_pending(current) &&
+		!kvm_s390_si_ext_call_pending(vcpu)) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		spin_unlock_bh(&vcpu->arch.local_int.lock);
 		spin_unlock(&vcpu->arch.local_int.float_int->lock);
@@ -667,6 +684,11 @@ void kvm_s390_clear_local_irqs(struct kvm_vcpu *vcpu)
 	}
 	atomic_set(&li->active, 0);
 	spin_unlock_bh(&li->lock);
+
+	/* clear pending external calls set by sigp interpretation facility */
+	atomic_clear_mask(CPUSTAT_ECALL_PEND, &vcpu->arch.sie_block->cpuflags);
+	atomic_clear_mask(SIGP_CTRL_C,
+			  &vcpu->kvm->arch.sca->cpu[vcpu->vcpu_id].ctrl);
 }
 
 void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)