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, 159 insertions, 0 deletions

diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c
new file mode 100644
index 000000000..29632bd4c
--- /dev/null
+++ b/accel/tcg/tcg-accel-ops-mttcg.c
@@ -0,0 +1,159 @@
+/*
+ * QEMU TCG Multi Threaded vCPUs implementation
+ *
+ * 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/replay.h"
+#include "qemu/main-loop.h"
+#include "qemu/notify.h"
+#include "qemu/guest-random.h"
+#include "exec/exec-all.h"
+#include "hw/boards.h"
+
+#include "tcg-accel-ops.h"
+#include "tcg-accel-ops-mttcg.h"
+
+typedef struct MttcgForceRcuNotifier {
+    Notifier notifier;
+    CPUState *cpu;
+} MttcgForceRcuNotifier;
+
+static void do_nothing(CPUState *cpu, run_on_cpu_data d)
+{
+}
+
+static void mttcg_force_rcu(Notifier *notify, void *data)
+{
+    CPUState *cpu = container_of(notify, MttcgForceRcuNotifier, notifier)->cpu;
+
+    /*
+     * Called with rcu_registry_lock held, using async_run_on_cpu() ensures
+     * that there are no deadlocks.
+     */
+    async_run_on_cpu(cpu, do_nothing, RUN_ON_CPU_NULL);
+}
+
+/*
+ * In the multi-threaded case each vCPU has its own thread. The TLS
+ * variable current_cpu can be used deep in the code to find the
+ * current CPUState for a given thread.
+ */
+
+static void *mttcg_cpu_thread_fn(void *arg)
+{
+    MttcgForceRcuNotifier force_rcu;
+    CPUState *cpu = arg;
+
+    assert(tcg_enabled());
+    g_assert(!icount_enabled());
+
+    rcu_register_thread();
+    force_rcu.notifier.notify = mttcg_force_rcu;
+    force_rcu.cpu = cpu;
+    rcu_add_force_rcu_notifier(&force_rcu.notifier);
+    tcg_register_thread();
+
+    qemu_mutex_lock_iothread();
+    qemu_thread_get_self(cpu->thread);
+
+    cpu->thread_id = qemu_get_thread_id();
+    cpu->can_do_io = 1;
+    current_cpu = cpu;
+    cpu_thread_signal_created(cpu);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
+
+    /* process any pending work */
+    cpu->exit_request = 1;
+
+    do {
+        if (cpu_can_run(cpu)) {
+            int r;
+            qemu_mutex_unlock_iothread();
+            r = tcg_cpus_exec(cpu);
+            qemu_mutex_lock_iothread();
+            switch (r) {
+            case EXCP_DEBUG:
+                cpu_handle_guest_debug(cpu);
+                break;
+            case EXCP_HALTED:
+                /*
+                 * during start-up the vCPU is reset and the thread is
+                 * kicked several times. If we don't ensure we go back
+                 * to sleep in the halted state we won't cleanly
+                 * start-up when the vCPU is enabled.
+                 *
+                 * cpu->halted should ensure we sleep in wait_io_event
+                 */
+                g_assert(cpu->halted);
+                break;
+            case EXCP_ATOMIC:
+                qemu_mutex_unlock_iothread();
+                cpu_exec_step_atomic(cpu);
+                qemu_mutex_lock_iothread();
+            default:
+                /* Ignore everything else? */
+                break;
+            }
+        }
+
+        qatomic_mb_set(&cpu->exit_request, 0);
+        qemu_wait_io_event(cpu);
+    } while (!cpu->unplug || cpu_can_run(cpu));
+
+    tcg_cpus_destroy(cpu);
+    qemu_mutex_unlock_iothread();
+    rcu_remove_force_rcu_notifier(&force_rcu.notifier);
+    rcu_unregister_thread();
+    return NULL;
+}
+
+void mttcg_kick_vcpu_thread(CPUState *cpu)
+{
+    cpu_exit(cpu);
+}
+
+void mttcg_start_vcpu_thread(CPUState *cpu)
+{
+    char thread_name[VCPU_THREAD_NAME_SIZE];
+
+    g_assert(tcg_enabled());
+    tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
+
+    cpu->thread = g_malloc0(sizeof(QemuThread));
+    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
+    qemu_cond_init(cpu->halt_cond);
+
+    /* create a thread per vCPU with TCG (MTTCG) */
+    snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
+             cpu->cpu_index);
+
+    qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
+                       cpu, QEMU_THREAD_JOINABLE);
+
+#ifdef _WIN32
+    cpu->hThread = qemu_thread_get_handle(cpu->thread);
+#endif
+}