KVM: s390: infrastructure to kick vcpus out of guest state

To ensure vcpu's come out of guest context in certain cases this patch adds a
s390 specific way to kick them out of guest context. Currently it kicks them
out to rerun the vcpu_run path in the s390 code, but the mechanism itself is
expandable and with a new flag we could also add e.g. kicks to userspace etc.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 34 insertions, 22 deletions

diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
index 0ef81d6776e..21897b0f8a3 100644
--- a/arch/s390/kvm/sigp.c
+++ b/arch/s390/kvm/sigp.c
@@ -1,7 +1,7 @@
 /*
  * sigp.c - handlinge interprocessor communication
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License (version 2 only)
@@ -9,6 +9,7 @@
  *
  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  *               Christian Borntraeger <borntraeger@de.ibm.com>
+ *               Christian Ehrhardt <ehrhardt@de.ibm.com>
  */
 
 #include <linux/kvm.h>
@@ -107,46 +108,57 @@ unlock:
 	return rc;
 }
 
-static int __sigp_stop(struct kvm_vcpu *vcpu, u16 cpu_addr, int store)
+static int __inject_sigp_stop(struct kvm_s390_local_interrupt *li, int action)
 {
-	struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
-	struct kvm_s390_local_interrupt *li;
 	struct kvm_s390_interrupt_info *inti;
-	int rc;
-
-	if (cpu_addr >= KVM_MAX_VCPUS)
-		return 3; /* not operational */
 
 	inti = kzalloc(sizeof(*inti), GFP_KERNEL);
 	if (!inti)
 		return -ENOMEM;
-
 	inti->type = KVM_S390_SIGP_STOP;
 
-	spin_lock(&fi->lock);
-	li = fi->local_int[cpu_addr];
-	if (li == NULL) {
-		rc = 3; /* not operational */
-		kfree(inti);
-		goto unlock;
-	}
 	spin_lock_bh(&li->lock);
 	list_add_tail(&inti->list, &li->list);
 	atomic_set(&li->active, 1);
 	atomic_set_mask(CPUSTAT_STOP_INT, li->cpuflags);
-	if (store)
-		li->action_bits |= ACTION_STORE_ON_STOP;
-	li->action_bits |= ACTION_STOP_ON_STOP;
+	li->action_bits |= action;
 	if (waitqueue_active(&li->wq))
 		wake_up_interruptible(&li->wq);
 	spin_unlock_bh(&li->lock);
-	rc = 0; /* order accepted */
+
+	return 0; /* order accepted */
+}
+
+static int __sigp_stop(struct kvm_vcpu *vcpu, u16 cpu_addr, int action)
+{
+	struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
+	struct kvm_s390_local_interrupt *li;
+	int rc;
+
+	if (cpu_addr >= KVM_MAX_VCPUS)
+		return 3; /* not operational */
+
+	spin_lock(&fi->lock);
+	li = fi->local_int[cpu_addr];
+	if (li == NULL) {
+		rc = 3; /* not operational */
+		goto unlock;
+	}
+
+	rc = __inject_sigp_stop(li, action);
+
 unlock:
 	spin_unlock(&fi->lock);
 	VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x", cpu_addr);
 	return rc;
 }
 
+int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action)
+{
+	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
+	return __inject_sigp_stop(li, action);
+}
+
 static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter)
 {
 	int rc;
@@ -262,11 +274,11 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
 		break;
 	case SIGP_STOP:
 		vcpu->stat.instruction_sigp_stop++;
-		rc = __sigp_stop(vcpu, cpu_addr, 0);
+		rc = __sigp_stop(vcpu, cpu_addr, ACTION_STOP_ON_STOP);
 		break;
 	case SIGP_STOP_STORE_STATUS:
 		vcpu->stat.instruction_sigp_stop++;
-		rc = __sigp_stop(vcpu, cpu_addr, 1);
+		rc = __sigp_stop(vcpu, cpu_addr, ACTION_STORE_ON_STOP);
 		break;
 	case SIGP_SET_ARCH:
 		vcpu->stat.instruction_sigp_arch++;