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From: Steve Sistare <steven.sistare@oracle.com>
To: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>,
        Si-Wei Liu <si-wei.liu@oracle.com>,
        Eugenio Perez Martin <eperezma@redhat.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        Dragos Tatulea <dtatulea@nvidia.com>, Eli Cohen <elic@nvidia.com>,
        Xie Yongji <xieyongji@bytedance.com>,
        Steve Sistare <steven.sistare@oracle.com>
Subject: [RFC V1 10/13] vdpa_sim: flush workers on suspend
Date: Wed, 10 Jan 2024 12:40:12 -0800
Message-Id: <1704919215-91319-11-git-send-email-steven.sistare@oracle.com>
In-Reply-To: <1704919215-91319-1-git-send-email-steven.sistare@oracle.com>
References: <1704919215-91319-1-git-send-email-steven.sistare@oracle.com>
Precedence: bulk

To pass ownership of a live vdpa device to a new process, the user
suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
mm.  Flush workers in suspend to guarantee that no worker sees the new
mm and old VA in between.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vdpa/vdpa_sim/vdpa_sim.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 6304cb0b4770..8734834983cb 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -74,6 +74,17 @@ static void vdpasim_worker_change_mm_sync(struct vdpasim *vdpasim,
 	kthread_flush_work(work);
 }
 
+static void flush_work_fn(struct kthread_work *work) {}
+
+static void vdpasim_flush_work(struct vdpasim *vdpasim)
+{
+	struct kthread_work work;
+
+	kthread_init_work(&work, flush_work_fn);
+	kthread_queue_work(vdpasim->worker, &work);
+	kthread_flush_work(&work);
+}
+
 static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
 {
 	return container_of(vdpa, struct vdpasim, vdpa);
@@ -512,6 +523,8 @@ static int vdpasim_suspend(struct vdpa_device *vdpa)
 	vdpasim->running = false;
 	mutex_unlock(&vdpasim->mutex);
 
+	vdpasim_flush_work(vdpasim);
+
 	return 0;
 }
 
-- 
2.39.3