RDMA/hns: Disable local invalidate operation
When function reset and local invalidate are mixed, HNS RoCEE may hang. Before introducing the cause of the problem, two hardware internal concepts need to be introduced: 1. Execution queue: The queue of hardware execution instructions, function reset and local invalidate are queued for execution in this queue. 2.Local queue: A queue that stores local operation instructions. The instructions in the local queue will be sent to the execution queue for execution. The instructions in the local queue will not be removed until the execution is completed. The reason for the problem is as follows: 1. There is a function reset instruction in the execution queue, which is currently being executed. A necessary condition for the successful execution of function reset is: the hardware pipeline needs to empty the instructions that were not completed before; 2. A local invalidate instruction at the head of the local queue is sent to the execution queue. Now there are two instructions in the execution queue, the first is the function reset instruction, and the second is the local invalidate instruction, which will be executed in se quence; 3. The user has issued many local invalidate operations, causing the local queue to be filled up. 4. The user still has a new local operation command and is queuing to enter the local queue. But the local queue is full and cannot receive new instructions, this instruction is temporarily stored at the hardware pipeline. 5. The function reset has been waiting for the instruction before the hardware pipeline stage is drained. The hardware pipeline stage also caches a local invalidate instruction, so the function reset cannot be completed, and the instructions after it cannot be executed. These factors together cause the execution logic deadlock of the hardware, and the consequence is that RoCEE will not have any response. Considering that the local operation command may potentially cause RoCEE to hang, this feature is no longer supported. Fixes: e93df010 ("RDMA/hns: Support local invalidate for hip08 in kernel space") Signed-off-by: Yangyang Li <liyangyang20@huawei.com> Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com> Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com> Link: https://lore.kernel.org/r/20221024083814.1089722-2-xuhaoyue1@hisilicon.comSigned-off-by: Leon Romanovsky <leon@kernel.org>
Showing
Please register or sign in to comment