Re: [PATCH v2 4/4] cxl: Add mce notifier to emit aliased address for extended linear cache

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Fri, 10 Jan 2025 08:17:47 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Below is a setup with extended linear cache configuration with an example
> layout of memory region shown below presented as a single memory region
> consists of 256G memory where there's 128G of DRAM and 128G of CXL memory.
> The kernel sees a region of total 256G of system memory.
> 
>               128G DRAM                          128G CXL memory
> |-----------------------------------|-------------------------------------|
> 
> Data resides in either DRAM or far memory (FM) with no replication. Hot
> data is swapped into DRAM by the hardware behind the scenes. When error is
> detected in one location, it is possible that error also resides in the
> aliased location. Therefore when a memory location that is flagged by MCE
> is part of the special region, the aliased memory location needs to be
> offlined as well.
> 
> Add an mce notify callback to identify if the MCE address location is part
> of an extended linear cache region and handle accordingly.
> 
> Added symbol export to set_mce_nospec() in x86 code in order to call
> set_mce_nospec() from the CXL MCE notify callback.
> 
> Link: https://lore.kernel.org/linux-cxl/668333b17e4b2_5639294fd@dwillia2-xfh.jf.intel.com.notmuch/
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Update new EXPORT_SYMOBOL_() input. (Jonathan)

typo  Though this get dropped anyway so not important!

> - Remove unnecessary pointer cast. (Jonathan)
> - Introduce CONFIG_CXL_MCE to shield from missing CONFIG_MEMORY_FAILURE kbuilds.
> - Emit alias address0 (Jonathan)