Both vhost-vsock and vhost-net can leave the device IOTLB attached when userspace clears VIRTIO_F_ACCESS_PLATFORM. They also replace an existing IOTLB with a new empty table when a later feature update keeps ACCESS_PLATFORM enabled, for example when updating logging.
The stale IOTLB can keep old translations active after a memory table change, while replacing an existing table discards valid translations and causes avoidable IOTLB misses. Patch 1 makes device IOTLB initialization idempotent and adds a common teardown helper. The helper detaches the table from every virtqueue, resets metadata caches, clears queued IOTLB miss messages, and frees the old table after the virtqueue handoff. It is a no-op when no device IOTLB is installed. Patches 2 and 3 use the common helper when vhost-vsock and vhost-net clear ACCESS_PLATFORM. The backend-specific code continues to update acked_features in its own virtqueue loop. Changes since v4: - move the existing-IOTLB check into vhost_init_device_iotlb() - remove the vhost-vsock-specific keep-IOTLB patch - add the corresponding ACCESS_PLATFORM teardown to vhost-net - make vhost_clear_device_iotlb() handle an absent device IOTLB Jia Jia (3): vhost: add helpers for device IOTLB lifecycle vhost/vsock: discard IOTLB when ACCESS_PLATFORM is cleared vhost/net: discard IOTLB when ACCESS_PLATFORM is cleared drivers/vhost/net.c | 4 ++++ drivers/vhost/vhost.c | 28 ++++++++++++++++++++++++++++ drivers/vhost/vhost.h | 1 + drivers/vhost/vsock.c | 4 ++++ 4 files changed, 36 insertions(+), 3 deletions(-) -- 2.34.1
