1 files changed, 32 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/s390x/ucall.c b/tools/testing/selftests/kvm/lib/s390x/ucall.c
new file mode 100644
index 000000000..a7f02dc37
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/s390x/ucall.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ucall support. A ucall is a "hypercall to userspace".
+ *
+ * Copyright (C) 2019 Red Hat, Inc.
+ */
+#include "kvm_util.h"
+
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
+{
+}
+
+void ucall_arch_do_ucall(vm_vaddr_t uc)
+{
+	/* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
+	asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory");
+}
+
+void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+
+	if (run->exit_reason == KVM_EXIT_S390_SIEIC &&
+	    run->s390_sieic.icptcode == 4 &&
+	    (run->s390_sieic.ipa >> 8) == 0x83 &&    /* 0x83 means DIAGNOSE */
+	    (run->s390_sieic.ipb >> 16) == 0x501) {
+		int reg = run->s390_sieic.ipa & 0xf;
+
+		return (void *)run->s.regs.gprs[reg];
+	}
+	return NULL;
+}