|
 |
619821 |
From 6b2d5dafa9847ce29e5cddeb369b35db5ce076b1 Mon Sep 17 00:00:00 2001
|
|
|
4f5da8 |
From: Ladi Prosek <lprosek@redhat.com>
|
|
|
4f5da8 |
Date: Thu, 10 Nov 2016 23:00:50 +0100
|
|
|
4f5da8 |
Subject: [PATCH 7/8] virtio: add virtqueue_rewind()
|
|
|
4f5da8 |
|
|
|
4f5da8 |
RH-Author: Ladi Prosek <lprosek@redhat.com>
|
|
|
4f5da8 |
Message-id: <1478797251-10302-1-git-send-email-lprosek@redhat.com>
|
|
|
4f5da8 |
Patchwork-id: 72818
|
|
|
4f5da8 |
O-Subject: [PATCH v2 7/6] virtio: add virtqueue_rewind()
|
|
|
619821 |
Bugzilla: 1377968
|
|
|
4f5da8 |
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
|
|
|
4f5da8 |
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
4f5da8 |
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
|
|
|
4f5da8 |
|
|
|
4f5da8 |
From: Stefan Hajnoczi <stefanha@redhat.com>
|
|
|
4f5da8 |
|
|
|
4f5da8 |
virtqueue_discard() requires a VirtQueueElement but virtio-balloon does
|
|
|
4f5da8 |
not migrate its in-use element. Introduce a new function that is
|
|
|
4f5da8 |
similar to virtqueue_discard() but doesn't require a VirtQueueElement.
|
|
|
4f5da8 |
|
|
|
4f5da8 |
This will allow virtio-balloon to access element again after migration
|
|
|
4f5da8 |
with the usual proviso that the guest may have modified the vring since
|
|
|
4f5da8 |
last time.
|
|
|
4f5da8 |
|
|
|
4f5da8 |
Cc: Michael S. Tsirkin <mst@redhat.com>
|
|
|
4f5da8 |
Cc: Roman Kagan <rkagan@virtuozzo.com>
|
|
|
4f5da8 |
Cc: Stefan Hajnoczi <stefanha@redhat.com>
|
|
|
4f5da8 |
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
|
|
|
4f5da8 |
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
4f5da8 |
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
4f5da8 |
(cherry picked from commit 297a75e6c55d91db2704a3d6e4029d99c7df51fd)
|
|
|
4f5da8 |
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
|
|
|
4f5da8 |
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
|
|
|
4f5da8 |
---
|
|
|
4f5da8 |
hw/virtio/virtio.c | 22 ++++++++++++++++++++++
|
|
|
4f5da8 |
include/hw/virtio/virtio.h | 1 +
|
|
|
4f5da8 |
2 files changed, 23 insertions(+)
|
|
|
4f5da8 |
|
|
|
4f5da8 |
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
|
|
|
4f5da8 |
index cdb21b1..fe6b032 100644
|
|
|
4f5da8 |
--- a/hw/virtio/virtio.c
|
|
|
4f5da8 |
+++ b/hw/virtio/virtio.c
|
|
|
4f5da8 |
@@ -259,6 +259,28 @@ void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
|
|
|
4f5da8 |
virtqueue_unmap_sg(vq, elem, len);
|
|
|
4f5da8 |
}
|
|
|
4f5da8 |
|
|
|
4f5da8 |
+/* virtqueue_rewind:
|
|
|
4f5da8 |
+ * @vq: The #VirtQueue
|
|
|
4f5da8 |
+ * @num: Number of elements to push back
|
|
|
4f5da8 |
+ *
|
|
|
4f5da8 |
+ * Pretend that elements weren't popped from the virtqueue. The next
|
|
|
4f5da8 |
+ * virtqueue_pop() will refetch the oldest element.
|
|
|
4f5da8 |
+ *
|
|
|
4f5da8 |
+ * Use virtqueue_discard() instead if you have a VirtQueueElement.
|
|
|
4f5da8 |
+ *
|
|
|
4f5da8 |
+ * Returns: true on success, false if @num is greater than the number of in use
|
|
|
4f5da8 |
+ * elements.
|
|
|
4f5da8 |
+ */
|
|
|
4f5da8 |
+bool virtqueue_rewind(VirtQueue *vq, unsigned int num)
|
|
|
4f5da8 |
+{
|
|
|
4f5da8 |
+ if (num > vq->inuse) {
|
|
|
4f5da8 |
+ return false;
|
|
|
4f5da8 |
+ }
|
|
|
4f5da8 |
+ vq->last_avail_idx -= num;
|
|
|
4f5da8 |
+ vq->inuse -= num;
|
|
|
4f5da8 |
+ return true;
|
|
|
4f5da8 |
+}
|
|
|
4f5da8 |
+
|
|
|
4f5da8 |
void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
|
|
|
4f5da8 |
unsigned int len, unsigned int idx)
|
|
|
4f5da8 |
{
|
|
|
4f5da8 |
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
|
|
|
4f5da8 |
index de32425..d9bfe4c 100644
|
|
|
4f5da8 |
--- a/include/hw/virtio/virtio.h
|
|
|
4f5da8 |
+++ b/include/hw/virtio/virtio.h
|
|
|
4f5da8 |
@@ -167,6 +167,7 @@ void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
|
|
|
4f5da8 |
void virtqueue_flush(VirtQueue *vq, unsigned int count);
|
|
|
4f5da8 |
void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
|
|
|
4f5da8 |
unsigned int len);
|
|
|
4f5da8 |
+bool virtqueue_rewind(VirtQueue *vq, unsigned int num);
|
|
|
4f5da8 |
void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
|
|
|
4f5da8 |
unsigned int len, unsigned int idx);
|
|
|
4f5da8 |
|
|
|
4f5da8 |
--
|
|
|
4f5da8 |
1.8.3.1
|
|
|
4f5da8 |
|