1 files changed, 32 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/x86_64/ucall.c b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
new file mode 100644
index 000000000..4d41dc63c
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ucall support. A ucall is a "hypercall to userspace".
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ */
+#include "kvm_util.h"
+
+#define UCALL_PIO_PORT ((uint16_t)0x1000)
+
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
+{
+}
+
+void ucall_arch_do_ucall(vm_vaddr_t uc)
+{
+	asm volatile("in %[port], %%al"
+		: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax", "memory");
+}
+
+void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+
+	if (run->exit_reason == KVM_EXIT_IO && run->io.port == UCALL_PIO_PORT) {
+		struct kvm_regs regs;
+
+		vcpu_regs_get(vcpu, &regs);
+		return (void *)regs.rdi;
+	}
+	return NULL;
+}