Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 41 insertions, 0 deletions

diff --git a/hw/s390x/s390-virtio-hcall.c b/hw/s390x/s390-virtio-hcall.c
new file mode 100644
index 000000000..ec7cf8beb
--- /dev/null
+++ b/hw/s390x/s390-virtio-hcall.c
@@ -0,0 +1,41 @@
+/*
+ * Support for virtio hypercalls on s390
+ *
+ * Copyright 2012 IBM Corp.
+ * Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "hw/s390x/s390-virtio-hcall.h"
+
+#define MAX_DIAG_SUBCODES 255
+
+static s390_virtio_fn s390_diag500_table[MAX_DIAG_SUBCODES];
+
+void s390_register_virtio_hypercall(uint64_t code, s390_virtio_fn fn)
+{
+    assert(code < MAX_DIAG_SUBCODES);
+    assert(!s390_diag500_table[code]);
+
+    s390_diag500_table[code] = fn;
+}
+
+int s390_virtio_hypercall(CPUS390XState *env)
+{
+    s390_virtio_fn fn;
+
+    if (env->regs[1] < MAX_DIAG_SUBCODES) {
+        fn = s390_diag500_table[env->regs[1]];
+        if (fn) {
+            env->regs[2] = fn(&env->regs[2]);
+            return 0;
+        }
+    }
+
+    return -EINVAL;
+}