From 35480cbfcb73143af66c8de4b444d686a46c2e88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
Date: Tue, 29 Aug 2017 17:27:50 +0200
Subject: [PATCH] libvhost-user: support resuming vq->last_avail_idx based on
used_idx
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This is the same workaround as commit 523b018dde3b765, which was lost
with libvhost-user transition in commit e10e798c85c2331.
Signed-off-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>
---
contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
contrib/libvhost-user/libvhost-user.h | 7 +++++++
2 files changed, 20 insertions(+)
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 35fa0c5e56..d27d6303db 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -521,6 +521,19 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
vq->used_idx = vq->vring.used->idx;
+ if (vq->last_avail_idx != vq->used_idx) {
+ bool resume = dev->iface->queue_is_processed_in_order &&
+ dev->iface->queue_is_processed_in_order(dev, index);
+
+ DPRINT("Last avail index != used index: %u != %u%s\n",
+ vq->last_avail_idx, vq->used_idx,
+ resume ? ", resuming" : "");
+
+ if (resume) {
+ vq->shadow_avail_idx = vq->last_avail_idx = vq->used_idx;
+ }
+ }
+
return false;
}
diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index 53ef222c0b..4021f1124e 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -132,6 +132,7 @@ typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
int *do_reply);
typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
+typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
typedef struct VuDevIface {
/* called by VHOST_USER_GET_FEATURES to get the features bitmask */
@@ -148,6 +149,12 @@ typedef struct VuDevIface {
vu_process_msg_cb process_msg;
/* tells when queues can be processed */
vu_queue_set_started_cb queue_set_started;
+ /*
+ * If the queue is processed in order, in which case it will be
+ * resumed to vring.used->idx. This can help to support resuming
+ * on unmanaged exit/crash.
+ */
+ vu_queue_is_processed_in_order_cb queue_is_processed_in_order;
} VuDevIface;
typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);