On Tue, Aug 18, 2026 at 12:26:12PM +0800, Jia Jia wrote:
Clear the device IOTLB when userspace clears VIRTIO_F_ACCESS_PLATFORM.
Otherwise descriptor translation can continue to use mappings installed
before the feature change.

The common helper invalidates cached vring access and applies the
transition even while a backend is attached. The backend remains attached,
but userspace must configure the vring addresses for the new address mode
after a successful live transition.

Fixes: e13a6915a03f ("vhost/vsock: add IOTLB API support")

Suggested-by: Michael S. Tsirkin <[email protected]>

In v5 there weren't any blank lines there, why are you adding them?
Please remove them.


Signed-off-by: Jia Jia <[email protected]>
---
drivers/vhost/vsock.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 9aaab6bb8061..77a5a6775c86 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -854,6 +854,7 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, 
u64 guest_cid)
static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
{
        struct vhost_virtqueue *vq;
+       int ret = -EFAULT;

This is a return value used only in the error path IIUC, better to call it `err` or something like that IMO.

        int i;

        if (features & ~VHOST_VSOCK_FEATURES)
@@ -865,9 +866,12 @@ static int vhost_vsock_set_features(struct vhost_vsock 
*vsock, u64 features)
                goto err;
        }

-       if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
-               if (vhost_init_device_iotlb(&vsock->dev))
+       if (features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)) {
+               ret = vhost_init_device_iotlb(&vsock->dev);
+               if (ret)

Is this change related to this fix?

Stefano

                        goto err;
+       } else {
+               vhost_clear_device_iotlb(&vsock->dev);
        }

        vsock->seqpacket_allow = features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET);
@@ -883,7 +887,7 @@ static int vhost_vsock_set_features(struct vhost_vsock 
*vsock, u64 features)

err:
        mutex_unlock(&vsock->dev.mutex);
-       return -EFAULT;
+       return ret;
}

static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,



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