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, 248 insertions, 0 deletions

diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
new file mode 100644
index 000000000..d6336a9c9
--- /dev/null
+++ b/accel/tcg/tcg-all.c
@@ -0,0 +1,248 @@
+/*
+ * QEMU System Emulator, accelerator interfaces
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2014 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "sysemu/tcg.h"
+#include "sysemu/cpu-timers.h"
+#include "tcg/tcg.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "qemu/accel.h"
+#include "qapi/qapi-builtin-visit.h"
+#include "qemu/units.h"
+#if !defined(CONFIG_USER_ONLY)
+#include "hw/boards.h"
+#endif
+#include "internal.h"
+
+struct TCGState {
+    AccelState parent_obj;
+
+    bool mttcg_enabled;
+    int splitwx_enabled;
+    unsigned long tb_size;
+};
+typedef struct TCGState TCGState;
+
+#define TYPE_TCG_ACCEL ACCEL_CLASS_NAME("tcg")
+
+DECLARE_INSTANCE_CHECKER(TCGState, TCG_STATE,
+                         TYPE_TCG_ACCEL)
+
+/*
+ * We default to false if we know other options have been enabled
+ * which are currently incompatible with MTTCG. Otherwise when each
+ * guest (target) has been updated to support:
+ *   - atomic instructions
+ *   - memory ordering primitives (barriers)
+ * they can set the appropriate CONFIG flags in ${target}-softmmu.mak
+ *
+ * Once a guest architecture has been converted to the new primitives
+ * there are two remaining limitations to check.
+ *
+ * - The guest can't be oversized (e.g. 64 bit guest on 32 bit host)
+ * - The host must have a stronger memory order than the guest
+ *
+ * It may be possible in future to support strong guests on weak hosts
+ * but that will require tagging all load/stores in a guest with their
+ * implicit memory order requirements which would likely slow things
+ * down a lot.
+ */
+
+static bool check_tcg_memory_orders_compatible(void)
+{
+#if defined(TCG_GUEST_DEFAULT_MO) && defined(TCG_TARGET_DEFAULT_MO)
+    return (TCG_GUEST_DEFAULT_MO & ~TCG_TARGET_DEFAULT_MO) == 0;
+#else
+    return false;
+#endif
+}
+
+static bool default_mttcg_enabled(void)
+{
+    if (icount_enabled() || TCG_OVERSIZED_GUEST) {
+        return false;
+    } else {
+#ifdef TARGET_SUPPORTS_MTTCG
+        return check_tcg_memory_orders_compatible();
+#else
+        return false;
+#endif
+    }
+}
+
+static void tcg_accel_instance_init(Object *obj)
+{
+    TCGState *s = TCG_STATE(obj);
+
+    s->mttcg_enabled = default_mttcg_enabled();
+
+    /* If debugging enabled, default "auto on", otherwise off. */
+#if defined(CONFIG_DEBUG_TCG) && !defined(CONFIG_USER_ONLY)
+    s->splitwx_enabled = -1;
+#else
+    s->splitwx_enabled = 0;
+#endif
+}
+
+bool mttcg_enabled;
+
+static int tcg_init_machine(MachineState *ms)
+{
+    TCGState *s = TCG_STATE(current_accel());
+#ifdef CONFIG_USER_ONLY
+    unsigned max_cpus = 1;
+#else
+    unsigned max_cpus = ms->smp.max_cpus;
+#endif
+
+    tcg_allowed = true;
+    mttcg_enabled = s->mttcg_enabled;
+
+    page_init();
+    tb_htable_init();
+    tcg_init(s->tb_size * MiB, s->splitwx_enabled, max_cpus);
+
+#if defined(CONFIG_SOFTMMU)
+    /*
+     * There's no guest base to take into account, so go ahead and
+     * initialize the prologue now.
+     */
+    tcg_prologue_init(tcg_ctx);
+#endif
+
+    return 0;
+}
+
+static char *tcg_get_thread(Object *obj, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+
+    return g_strdup(s->mttcg_enabled ? "multi" : "single");
+}
+
+static void tcg_set_thread(Object *obj, const char *value, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+
+    if (strcmp(value, "multi") == 0) {
+        if (TCG_OVERSIZED_GUEST) {
+            error_setg(errp, "No MTTCG when guest word size > hosts");
+        } else if (icount_enabled()) {
+            error_setg(errp, "No MTTCG when icount is enabled");
+        } else {
+#ifndef TARGET_SUPPORTS_MTTCG
+            warn_report("Guest not yet converted to MTTCG - "
+                        "you may get unexpected results");
+#endif
+            if (!check_tcg_memory_orders_compatible()) {
+                warn_report("Guest expects a stronger memory ordering "
+                            "than the host provides");
+                error_printf("This may cause strange/hard to debug errors\n");
+            }
+            s->mttcg_enabled = true;
+        }
+    } else if (strcmp(value, "single") == 0) {
+        s->mttcg_enabled = false;
+    } else {
+        error_setg(errp, "Invalid 'thread' setting %s", value);
+    }
+}
+
+static void tcg_get_tb_size(Object *obj, Visitor *v,
+                            const char *name, void *opaque,
+                            Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    uint32_t value = s->tb_size;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void tcg_set_tb_size(Object *obj, Visitor *v,
+                            const char *name, void *opaque,
+                            Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    uint32_t value;
+
+    if (!visit_type_uint32(v, name, &value, errp)) {
+        return;
+    }
+
+    s->tb_size = value;
+}
+
+static bool tcg_get_splitwx(Object *obj, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    return s->splitwx_enabled;
+}
+
+static void tcg_set_splitwx(Object *obj, bool value, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    s->splitwx_enabled = value;
+}
+
+static void tcg_accel_class_init(ObjectClass *oc, void *data)
+{
+    AccelClass *ac = ACCEL_CLASS(oc);
+    ac->name = "tcg";
+    ac->init_machine = tcg_init_machine;
+    ac->allowed = &tcg_allowed;
+
+    object_class_property_add_str(oc, "thread",
+                                  tcg_get_thread,
+                                  tcg_set_thread);
+
+    object_class_property_add(oc, "tb-size", "int",
+        tcg_get_tb_size, tcg_set_tb_size,
+        NULL, NULL);
+    object_class_property_set_description(oc, "tb-size",
+        "TCG translation block cache size");
+
+    object_class_property_add_bool(oc, "split-wx",
+        tcg_get_splitwx, tcg_set_splitwx);
+    object_class_property_set_description(oc, "split-wx",
+        "Map jit pages into separate RW and RX regions");
+}
+
+static const TypeInfo tcg_accel_type = {
+    .name = TYPE_TCG_ACCEL,
+    .parent = TYPE_ACCEL,
+    .instance_init = tcg_accel_instance_init,
+    .class_init = tcg_accel_class_init,
+    .instance_size = sizeof(TCGState),
+};
+module_obj(TYPE_TCG_ACCEL);
+
+static void register_accel_types(void)
+{
+    type_register_static(&tcg_accel_type);
+}
+
+type_init(register_accel_types);