[RFC PATCH v1 4/6] KVM: s390: Restart IRQ should also block SIGP

[Eric Farman <farman@linux.ibm.com>]

When userspace handles a SIGP Restart, it first looks at the
destination CPU state to determine its next course of action:

  if (cpu is online)
     inject restart IRQ
  else
     set cpu online
     load restart PSW

Since we already have logic for dealing with an in-flight
STOP IRQ when a new SIGP comes in, let's include the RESTART
IRQ in the same logic, so we don't race with that work.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 7 +++++++
 arch/s390/kvm/kvm-s390.h  | 1 +
 arch/s390/kvm/sigp.c      | 5 +++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 10722455fd02..77c5d73ff0e2 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2108,6 +2108,13 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int,
 	return 0;
 }
 
+int kvm_s390_is_restart_irq_pending(struct kvm_vcpu *vcpu)
+{
+	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
+
+	return test_bit(IRQ_PEND_RESTART, &li->pending_irqs);
+}
+
 int kvm_s390_is_stop_irq_pending(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 52bc8fbaa60a..57c5e9369d65 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -417,6 +417,7 @@ int psw_extint_disabled(struct kvm_vcpu *vcpu);
 void kvm_s390_destroy_adapters(struct kvm *kvm);
 int kvm_s390_ext_call_pending(struct kvm_vcpu *vcpu);
 extern struct kvm_device_ops kvm_flic_ops;
+int kvm_s390_is_restart_irq_pending(struct kvm_vcpu *vcpu);
 int kvm_s390_is_stop_irq_pending(struct kvm_vcpu *vcpu);
 void kvm_s390_clear_stop_irq(struct kvm_vcpu *vcpu);
 int kvm_s390_set_irq_state(struct kvm_vcpu *vcpu,
diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
index 0c08927ca7c9..c64e37f4347d 100644
--- a/arch/s390/kvm/sigp.c
+++ b/arch/s390/kvm/sigp.c
@@ -412,10 +412,11 @@ static int handle_sigp_order_is_blocked(struct kvm_vcpu *vcpu, u8 order_code,
 	 * Any other SIGP order could race with an existing SIGP order
 	 * on the destination CPU, and thus encounter a busy condition
 	 * on the CPU processing the SIGP order. Reject the order at
-	 * this point, rather than racing with the STOP IRQ injection.
+	 * this point, rather than racing with any IRQ injection.
 	 */
 	spin_lock(&dst_vcpu->arch.local_int.lock);
-	if (kvm_s390_is_stop_irq_pending(dst_vcpu)) {
+	if (kvm_s390_is_stop_irq_pending(dst_vcpu) ||
+	    kvm_s390_is_restart_irq_pending(dst_vcpu)) {
 		kvm_s390_set_psw_cc(vcpu, SIGP_CC_BUSY);
 		rc = 1;
 	}
-- 
2.25.1