e3e53c5af5
[ Upstream commit 9e272ed69ad6f6952fafd0599d6993575512408e ]
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: e93df0108579 ("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.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.