postcopy: helper for waking shared

Provide a helper to send a 'wake' request on a userfaultfd for
a shared process.
The address in the clients address space is specified together
with the RAMBlock it was resolved to.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index d7afab07d7..fcd53b8295 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -164,6 +164,16 @@ struct PostCopyFD {
  */
 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
+/* 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);