From: Sungho Bae <[email protected]> After a device reset in noirq context the existing vrings must be re-initialized without any memory allocation, because GFP_KERNEL is not available.
The internal helpers virtqueue_reset_split() and virtqueue_reset_packed() already reset vring indices and descriptor state in place. Add a thin exported wrapper, virtqueue_reinit_vring(), that dispatches to the appropriate helper based on the ring layout. This will be used by a subsequent patch that adds noirq system-sleep PM callbacks for virtio-mmio. Signed-off-by: Sungho Bae <[email protected]> --- drivers/virtio/virtio_ring.c | 58 ++++++++++++++++++++++++++++++++++++ include/linux/virtio_ring.h | 3 ++ 2 files changed, 61 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index fbca7ce1c6bf..d3339b820f6b 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -506,6 +506,15 @@ static void virtqueue_init(struct vring_virtqueue *vq, u32 num) vq->event_triggered = false; vq->num_added = 0; + /* + * Keep IN_ORDER state aligned with a freshly initialized/reset queue. + * For packed IN_ORDER, free_head is unused but harmlessly reset. + */ + if (virtqueue_is_in_order(vq)) { + vq->free_head = 0; + vq->batch_last.id = UINT_MAX; + } + #ifdef DEBUG vq->in_use = false; vq->last_add_time_valid = false; @@ -3936,5 +3945,54 @@ void virtqueue_map_sync_single_range_for_device(const struct virtqueue *_vq, } EXPORT_SYMBOL_GPL(virtqueue_map_sync_single_range_for_device); +/** + * virtqueue_reinit_vring - reinitialize vring state without reallocation + * @_vq: the virtqueue + * + * Reset the avail/used indices and descriptor state of an existing + * virtqueue so it can be reused after a device reset. No memory is + * allocated or freed, making this safe for use in noirq context. + * + * Preconditions for callers: + * 1) The vq must be fully quiesced (no concurrent add/get/kick/IRQ callback). + * 2) Transport/device side must already have stopped/reset this queue. + * 3) All in-flight buffers must already be completed or detached. + * + * If called with outstanding descriptors, free-list state can be corrupted: + * num_free is restored to full capacity while desc_extra next-chain/free_head + * may still represent a partially consumed list. + * + * Return: + * 0 on success, or -EBUSY if preconditions are not met. + */ +int virtqueue_reinit_vring(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + unsigned int num = virtqueue_is_packed(vq) ? + vq->packed.vring.num : vq->split.vring.num; + + /* All in-flight descriptors must be completed or detached */ + if (WARN_ON(vq->vq.num_free != num)) + return -EBUSY; + + if (virtqueue_is_packed(vq)) { + virtqueue_reset_packed(vq); + } else { + /* + * Split queue shadow index should match the visible avail + * index when the queue is fully quiesced. + */ + if (WARN_ON(vq->split.avail_idx_shadow != + virtio16_to_cpu(vq->vq.vdev, + vq->split.vring.avail->idx))) + return -EBUSY; + + virtqueue_reset_split(vq); + } + + return 0; +} +EXPORT_SYMBOL_GPL(virtqueue_reinit_vring); + MODULE_DESCRIPTION("Virtio ring implementation"); MODULE_LICENSE("GPL"); diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index c97a12c1cda3..8b421fef4fef 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -118,6 +118,9 @@ void vring_del_virtqueue(struct virtqueue *vq); /* Filter out transport-specific feature bits. */ void vring_transport_features(struct virtio_device *vdev); +/* Reinitialize a virtqueue without reallocation (safe in noirq context) */ +int virtqueue_reinit_vring(struct virtqueue *_vq); + irqreturn_t vring_interrupt(int irq, void *_vq); u32 vring_notification_data(struct virtqueue *_vq); -- 2.43.0
