Re: [PATCH v2 2/8] generic: Support ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 24, 2025 at 04:47:58PM +0100, Jonathan Cameron wrote:
> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION provides the mechanism for
> invalidate certain memory regions in a cache-incoherent manner.
> Currently is used by NVIDMM adn CXL memory. This is mainly done
> by the system component and is implementation define per spec.
> Provides a method for the platforms register their own invalidate
> method and implement ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION.
> 
> Architectures can opt in for this support via
> CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION.
> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
>  drivers/base/Kconfig             |  3 +++
>  drivers/base/Makefile            |  1 +
>  drivers/base/cache.c             | 46 ++++++++++++++++++++++++++++++++
>  include/asm-generic/cacheflush.h | 12 +++++++++
>  4 files changed, 62 insertions(+)
> 
> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
> index 064eb52ff7e2..cc6df87a0a96 100644
> --- a/drivers/base/Kconfig
> +++ b/drivers/base/Kconfig
> @@ -181,6 +181,9 @@ config SYS_HYPERVISOR
>  	bool
>  	default n
>  
> +config GENERIC_CPU_CACHE_INVALIDATE_MEMREGION
> +	bool
> +
>  config GENERIC_CPU_DEVICES
>  	bool
>  	default n
> diff --git a/drivers/base/Makefile b/drivers/base/Makefile
> index 8074a10183dc..0fbfa4300b98 100644
> --- a/drivers/base/Makefile
> +++ b/drivers/base/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
>  obj-$(CONFIG_GENERIC_MSI_IRQ) += platform-msi.o
>  obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
>  obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
> +obj-$(CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION) += cache.o
>  obj-$(CONFIG_ACPI) += physical_location.o
>  
>  obj-y			+= test/
> diff --git a/drivers/base/cache.c b/drivers/base/cache.c
> new file mode 100644
> index 000000000000..8d351657bbef
> --- /dev/null
> +++ b/drivers/base/cache.c
> @@ -0,0 +1,46 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Generic support for CPU Cache Invalidate Memregion
> + */
> +
> +#include <linux/spinlock.h>
> +#include <linux/export.h>
> +#include <asm/cacheflush.h>
> +
> +
> +static const struct system_cache_flush_method *scfm_data;
> +DEFINE_SPINLOCK(scfm_lock);

Shouldn't this lock be static?  I don't see it being used outside of
this file, and it's not exported.

thanks,

greg k-h