block/raw-win32: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext for raw-win32.
Convert the aio-win32 code to support detach/attach and replace
qemu_aio_wait() with aio_poll().

The .bdrv_detach/attach_aio_context() interfaces move the aio-win32
event notifier from the old to the new AioContext.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/block/win32-aio.c b/block/win32-aio.c
index b43b1667ee..8e417f70ae 100644
--- a/block/win32-aio.c
+++ b/block/win32-aio.c
@@ -40,6 +40,7 @@ struct QEMUWin32AIOState {
     HANDLE hIOCP;
     EventNotifier e;
     int count;
+    bool is_aio_context_attached;
 };
 
 typedef struct QEMUWin32AIOCB {
@@ -114,7 +115,7 @@ static void win32_aio_cancel(BlockDriverAIOCB *blockacb)
      * wait for completion.
      */
     while (!HasOverlappedIoCompleted(&waiocb->ov)) {
-        qemu_aio_wait();
+        aio_poll(bdrv_get_aio_context(blockacb->bs), true);
     }
 }
 
@@ -180,6 +181,20 @@ int win32_aio_attach(QEMUWin32AIOState *aio, HANDLE hfile)
     }
 }
 
+void win32_aio_detach_aio_context(QEMUWin32AIOState *aio,
+                                  AioContext *old_context)
+{
+    aio_set_event_notifier(old_context, &aio->e, NULL);
+    aio->is_aio_context_attached = false;
+}
+
+void win32_aio_attach_aio_context(QEMUWin32AIOState *aio,
+                                  AioContext *new_context)
+{
+    aio->is_aio_context_attached = true;
+    aio_set_event_notifier(new_context, &aio->e, win32_aio_completion_cb);
+}
+
 QEMUWin32AIOState *win32_aio_init(void)
 {
     QEMUWin32AIOState *s;
@@ -194,8 +209,6 @@ QEMUWin32AIOState *win32_aio_init(void)
         goto out_close_efd;
     }
 
-    qemu_aio_set_event_notifier(&s->e, win32_aio_completion_cb);
-
     return s;
 
 out_close_efd:
@@ -207,7 +220,7 @@ out_free_state:
 
 void win32_aio_cleanup(QEMUWin32AIOState *aio)
 {
-    qemu_aio_set_event_notifier(&aio->e, NULL);
+    assert(!aio->is_aio_context_attached);
     CloseHandle(aio->hIOCP);
     event_notifier_cleanup(&aio->e);
     g_free(aio);