postcopy: postcopy_notify_shared_wake

Add a hook to allow a client userfaultfd to be 'woken' when a page arrives, and a walker that calls that hook for relevant clients given a RAMBlock and offset. Signed-off-by: Dr. David Alan Gilbert <[email protected]> Reviewed-by: Peter Xu <[email protected]> Reviewed-by: Marc-André Lureau <[email protected]> Reviewed-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]>
dreddy · Mar 20, 2018 · d488b34 · d488b34
1 parent 5efc356
commit d488b34
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diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
@@ -827,6 +827,22 @@ static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
     return ret;
 }
 
+int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset)
+{
+    int i;
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    GArray *pcrfds = mis->postcopy_remote_fds;
+
+    for (i = 0; i < pcrfds->len; i++) {
+        struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
+        int ret = cur->waker(cur, rb, offset);
+        if (ret) {
+            return ret;
+        }
+    }
+    return 0;
+}
+
 /*
  * Place a host page (from) at (host) atomically
  * returns 0 on success

diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
@@ -148,13 +148,19 @@ 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;
 };
@@ -164,6 +170,10 @@ struct PostCopyFD {
  */
 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
+/* Call each of the shared 'waker's registerd 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