On 1/22/24 04:27, Hao Chen wrote:
In a nested virtualization environment, running dpdk-vdpa in QEMU-L1 for
software live migration will result in a deadlock between dpdke-vdpa and
QEMU-L2 processes.
'rte_vdpa_relay_vring_used'->
'__vhost_iova_to_vva'->
'vhost_user_iotlb_rd_unlock(vq)'->
'vhost_user_iotlb_miss'-> send vhost message 'VHOST_USER_SLAVE_IOTLB_MSG'
to QEMU-L2's vdpa socket,
then call 'vhost_user_iotlb_rd_lock(vq)' to hold the read lock `iotlb_lock`.
But there is no place to release this read lock.
QEMU-L2 get the 'VHOST_USER_SLAVE_IOTLB_MSG',
then call 'vhost_user_send_device_iotlb_msg' to send 'VHOST_USER_IOTLB_MSG'
messages to dpdk-vdpa.
Dpdk-vdpa will call vhost_user_iotlb_msg->
vhost_user_iotlb_cache_insert, here, will obtain the write lock
`iotlb_lock`, but the read lock `iotlb_lock` has not been released and
will block here.
This patch add lock and unlock function to fix the deadlock.
Fixes: b13ad2decc83 ("vhost: provide helpers for virtio ring relay")
Cc: sta...@dpdk.org
Signed-off-by: Hao Chen <ch...@yusur.tech>
---
Changes v1 ... v2:
- protect the vhost_alloc_copy_ind_table() call too.
Applied to next-virtio tree with reworked commit message.
Thanks,
Maxime
