linux-kernel - [RFC PATCH 0/3] soc: Enable cache lockdown for HiSilicon L3 cache

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Message-ID: <20251125080542.3721829-1-wangyushan12@huawei.com>
Date: Tue, 25 Nov 2025 16:05:39 +0800
From: Yushan Wang <wangyushan12@...wei.com>
To: <xuwei5@...ilicon.com>, <Jonathan.Cameron@...wei.com>,
	<wanghuiqiang@...wei.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linuxarm@...wei.com>
CC: <prime.zeng@...ilicon.com>, <fanghao11@...wei.com>,
	<wangyushan12@...wei.com>
Subject: [RFC PATCH 0/3] soc: Enable cache lockdown for HiSilicon L3 cache

Cache has been playing the transparent yet crucial role of performance
for modern computers. To fully exploit the potential of SoC cache, we
made an attempt to lockdown the HiSilicon L3 cache.

Cache lockdown means to make a memory region locked inside the L3 cache
for better access latency. The data stored in L3 cache will behave like
any other data (i.e. it still follows cache coherency protocol etc.)
except it won't be evicted unless explicitly asked to by deallocation.

Ideally locked data will have stable low access latency despite high
background stress. It is also useful for scenarios that have especially
high cache miss penalty. However, while enhancing some processes,
reserving cache resource will raise the performance problem to other
processes running on the CPUs that share the L3 cache that carries
locked data, users should be careful to do so.

I would like to ask for opinions about the possibility to make this
driver upstream, and the possible usecase of L3 cache lock within
kernel. Further tests are needed to obtain the performance benefits and
impact we get from L3 cache lock on such usecases.

Yushan Wang (3):
  soc cache: L3 cache driver for HiSilicon SoC
  soc cache: L3 cache lockdown support for HiSilicon SoC
  Documentation: soc cache: Add documentation to HiSilicon SoC cache

 Documentation/driver-api/hisi-soc-cache.rst   |  62 ++
 Documentation/driver-api/index.rst            |   1 +
 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 drivers/soc/hisilicon/Kconfig                 |  10 +
 drivers/soc/hisilicon/Makefile                |   2 +
 drivers/soc/hisilicon/hisi_soc_l3c.c          | 877 ++++++++++++++++++
 include/uapi/misc/hisi_l3c.h                  |  28 +
 7 files changed, 981 insertions(+)
 create mode 100644 Documentation/driver-api/hisi-soc-cache.rst
 create mode 100644 drivers/soc/hisilicon/hisi_soc_l3c.c
 create mode 100644 include/uapi/misc/hisi_l3c.h

-- 
2.33.0