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, 182 insertions, 0 deletions

diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
new file mode 100644
index 000000000..6d2b3cf12
--- /dev/null
+++ b/migration/postcopy-ram.h
@@ -0,0 +1,182 @@
+/*
+ * Postcopy migration for RAM
+ *
+ * Copyright 2013 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ *  Dave Gilbert  <dgilbert@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#ifndef QEMU_POSTCOPY_RAM_H
+#define QEMU_POSTCOPY_RAM_H
+
+/* Return true if the host supports everything we need to do postcopy-ram */
+bool postcopy_ram_supported_by_host(MigrationIncomingState *mis);
+
+/*
+ * Make all of RAM sensitive to accesses to areas that haven't yet been written
+ * and wire up anything necessary to deal with it.
+ */
+int postcopy_ram_incoming_setup(MigrationIncomingState *mis);
+
+/*
+ * Initialise postcopy-ram, setting the RAM to a state where we can go into
+ * postcopy later; must be called prior to any precopy.
+ * called from ram.c's similarly named ram_postcopy_incoming_init
+ */
+int postcopy_ram_incoming_init(MigrationIncomingState *mis);
+
+/*
+ * At the end of a migration where postcopy_ram_incoming_init was called.
+ */
+int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
+
+/*
+ * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
+ * however leaving it until after precopy means that most of the precopy
+ * data is still THPd
+ */
+int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
+
+/*
+ * Called at the start of each RAMBlock by the bitmap code.
+ */
+void postcopy_discard_send_init(MigrationState *ms, const char *name);
+
+/*
+ * Called by the bitmap code for each chunk to discard.
+ * May send a discard message, may just leave it queued to
+ * be sent later.
+ * @start,@length: a range of pages in the migration bitmap in the
+ *  RAM block passed to postcopy_discard_send_init() (length=1 is one page)
+ */
+void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
+                                 unsigned long length);
+
+/*
+ * Called at the end of each RAMBlock by the bitmap code.
+ * Sends any outstanding discard messages.
+ */
+void postcopy_discard_send_finish(MigrationState *ms);
+
+/*
+ * Place a page (from) at (host) efficiently
+ *    There are restrictions on how 'from' must be mapped, in general best
+ *    to use other postcopy_ routines to allocate.
+ * returns 0 on success
+ */
+int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
+                        RAMBlock *rb);
+
+/*
+ * Place a zero page at (host) atomically
+ * returns 0 on success
+ */
+int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
+                             RAMBlock *rb);
+
+/* The current postcopy state is read/set by postcopy_state_get/set
+ * which update it atomically.
+ * The state is updated as postcopy messages are received, and
+ * in general only one thread should be writing to the state at any one
+ * time, initially the main thread and then the listen thread;
+ * Corner cases are where either thread finishes early and/or errors.
+ * The state is checked as messages are received to ensure that
+ * the source is sending us messages in the correct order.
+ * The state is also used by the RAM reception code to know if it
+ * has to place pages atomically, and the cleanup code at the end of
+ * the main thread to know if it has to delay cleanup until the end
+ * of postcopy.
+ */
+typedef enum {
+    POSTCOPY_INCOMING_NONE = 0,  /* Initial state - no postcopy */
+    POSTCOPY_INCOMING_ADVISE,
+    POSTCOPY_INCOMING_DISCARD,
+    POSTCOPY_INCOMING_LISTENING,
+    POSTCOPY_INCOMING_RUNNING,
+    POSTCOPY_INCOMING_END
+} PostcopyState;
+
+PostcopyState postcopy_state_get(void);
+/* Set the state and return the old state */
+PostcopyState postcopy_state_set(PostcopyState new_state);
+
+void postcopy_fault_thread_notify(MigrationIncomingState *mis);
+
+/*
+ * To be called once at the start before any device initialisation
+ */
+void postcopy_infrastructure_init(void);
+
+/* Add a notifier to a list to be called when checking whether the devices
+ * can support postcopy.
+ * It's data is a *PostcopyNotifyData
+ * It should return 0 if OK, or a negative value on failure.
+ * On failure it must set the data->errp to an error.
+ *
+ */
+enum PostcopyNotifyReason {
+    POSTCOPY_NOTIFY_PROBE = 0,
+    POSTCOPY_NOTIFY_INBOUND_ADVISE,
+    POSTCOPY_NOTIFY_INBOUND_LISTEN,
+    POSTCOPY_NOTIFY_INBOUND_END,
+};
+
+struct PostcopyNotifyData {
+    enum PostcopyNotifyReason reason;
+    Error **errp;
+};
+
+void postcopy_add_notifier(NotifierWithReturn *nn);
+void postcopy_remove_notifier(NotifierWithReturn *n);
+/* Call the notifier list set by postcopy_add_start_notifier */
+int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
+
+struct PostCopyFD;
+
+/* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
+typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
+/* Notification to wake, either on place or on reception of
+ * a fault on something that's already arrived (race)
+ */
+typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
+
+struct PostCopyFD {
+    int fd;
+    /* Data to pass to handler */
+    void *data;
+    /* Handler to be called whenever we get a poll event */
+    pcfdhandler handler;
+    /* Notification to wake shared client */
+    pcfdwake waker;
+    /* A string to use in error messages */
+    const char *idstr;
+};
+
+/* Register a userfaultfd owned by an external process for
+ * shared memory.
+ */
+void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
+void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
+/* Call each of the shared 'waker's registered telling them of
+ * availability of a block.
+ */
+int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
+/* postcopy_wake_shared: Notify a client ufd that a page is available
+ *
+ * Returns 0 on success
+ *
+ * @pcfd: Structure with fd, handler and name as above
+ * @client_addr: Address in the client program, not QEMU
+ * @rb: The RAMBlock the page is in
+ */
+int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
+                         RAMBlock *rb);
+/* Callback from shared fault handlers to ask for a page */
+int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
+                                 uint64_t client_addr, uint64_t offset);
+
+#endif