vhost: invalidate vring access on IOTLB transitions

When ACCESS_PLATFORM changes, the addresses cached in desc, avail, and
used change meaning with the address space. Clear the cached vring access
state when the device IOTLB is installed or removed so stale IOVAs cannot
be reused as direct userspace addresses.

Keep device IOTLB initialization idempotent and apply the mode change even
when a virtqueue backend is attached. Drop the device-wide IOTLB first,
then clear each VQ state under its own mutex, and keep the old table alive
until every VQ has completed the handoff.

A successful live mode change leaves the backend attached but invalidates
the cached vring addresses. Userspace must configure the vring addresses
for the new address mode before data processing can resume.

Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
Signed-off-by: Jia Jia <physicalmtea@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260820080332.313933-2-physicalmtea@gmail.com>

0 files changed, 0 insertions, 0 deletions