vhost/net: Clear the pending messages when the backend is removed

[ Upstream commit 9526f9a2b762af16be94a72aca5d65c677d28f50 ]

When the vhost iotlb is used along with a guest virtual iommu
and the guest gets rebooted, some MISS messages may have been
recorded just before the reboot and spuriously executed by
the virtual iommu after the reboot.

As vhost does not have any explicit reset user API,
VHOST_NET_SET_BACKEND looks a reasonable point where to clear
the pending messages, in case the backend is removed.

Export vhost_clear_msg() and call it in vhost_net_set_backend()
when fd == -1.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Message-Id: <20230117151518.44725-3-eric.auger@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 297b5db474545e37619181549618c845a19ba51a..32148f0112004d5afed0f8020d3050e78d27fa5f 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1517,6 +1517,9 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
        nvq = &n->vqs[index];
        mutex_lock(&vq->mutex);
 
+       if (fd == -1)
+               vhost_clear_msg(&n->dev);
+
        /* Verify that ring has been setup correctly. */
        if (!vhost_vq_access_ok(vq)) {
                r = -EFAULT;

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 0a9746bc9228d2d715d8f6c3b08d2fa1b0f4e108..c0f926a9c298f5eaf97770885a22e5fc8a34daaa 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -669,7 +669,7 @@ void vhost_dev_stop(struct vhost_dev *dev)
 }
 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 
-static void vhost_clear_msg(struct vhost_dev *dev)
+void vhost_clear_msg(struct vhost_dev *dev)
 {
        struct vhost_msg_node *node, *n;
 
@@ -687,6 +687,7 @@ static void vhost_clear_msg(struct vhost_dev *dev)
 
        spin_unlock(&dev->iotlb_lock);
 }
+EXPORT_SYMBOL_GPL(vhost_clear_msg);
 
 void vhost_dev_cleanup(struct vhost_dev *dev)
 {

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 638bb640d6b4b5f7d0ce20b2bab5461ba8b2cfbd..f2675c0aa08ee408f5b5ac0546d97e6691537472 100644 (file)
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -182,6 +182,7 @@ long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp);
 bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
 bool vhost_log_access_ok(struct vhost_dev *);
+void vhost_clear_msg(struct vhost_dev *dev);
 
 int vhost_get_vq_desc(struct vhost_virtqueue *,
                      struct iovec iov[], unsigned int iov_count,