RE: [PATCH v13 3/4] cxl/core: Add CXL EINJ debugfs files

[Dan Williams <dan.j.williams@intel.com>]

Ben Cheatham wrote:
> Export CXL helper functions in the einj_cxl module for getting/injecting
> available CXL protocol error types to sysfs under kernel/debug/cxl.
> 
> The kernel/debug/cxl/einj_types file will print the available CXL
> protocol errors in the same format as the available_error_types
> file provided by the einj_cxl module. The
> kernel/debug/cxl/$dport_dev/einj_inject is functionally the same as the
> error_type and error_inject files provided by the EINJ module, i.e.:
> writing an error type into $dport_dev/einj_inject will inject said error
> type into the CXL dport represented by $dport_dev.
> 
> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
> ---
>  Documentation/ABI/testing/debugfs-cxl | 30 ++++++++++++++++++++
>  drivers/cxl/Kconfig                   |  1 +
>  drivers/cxl/core/port.c               | 41 +++++++++++++++++++++++++++
>  3 files changed, 72 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
> index fe61d372e3fa..4c0f62f881ca 100644
> --- a/Documentation/ABI/testing/debugfs-cxl
> +++ b/Documentation/ABI/testing/debugfs-cxl
> @@ -33,3 +33,33 @@ Description:
>  		device cannot clear poison from the address, -ENXIO is returned.
>  		The clear_poison attribute is only visible for devices
>  		supporting the capability.
> +
> +What:		/sys/kernel/debug/cxl/einj_types
> +Date:		January, 2024
> +KernelVersion:	v6.9
> +Contact:	linux-cxl@vger.kernel.org
> +Description:
> +		(RO) Prints the CXL protocol error types made available by
> +		the platform in the format "0x<error number>	<error type>".
> +		The possible error types are (as of ACPI v6.5):
> +			0x1000	CXL.cache Protocol Correctable
> +			0x2000	CXL.cache Protocol Uncorrectable non-fatal
> +			0x4000	CXL.cache Protocol Uncorrectable fatal
> +			0x8000	CXL.mem Protocol Correctable
> +			0x10000	CXL.mem Protocol Uncorrectable non-fatal
> +			0x20000	CXL.mem Protocol Uncorrectable fatal
> +
> +		The <error number> can be written to einj_inject to inject
> +		<error type> into a chosen dport.
> +
> +What:		/sys/kernel/debug/cxl/$dport_dev/einj_inject
> +Date:		January, 2024
> +KernelVersion:	v6.9
> +Contact:	linux-cxl@vger.kernel.org
> +Description:
> +		(WO) Writing an integer to this file injects the corresponding
> +		CXL protocol error into $dport_dev ($dport_dev will be a device
> +		name from /sys/bus/pci/devices). The integer to type mapping for
> +		injection can be found by reading from einj_types. If the dport
> +		was enumerated in RCH mode, a CXL 1.1 error is injected, otherwise
> +		a CXL 2.0 error is injected.
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index 67998dbd1d46..c86ae4c65c03 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -2,6 +2,7 @@
>  menuconfig CXL_BUS
>  	tristate "CXL (Compute Express Link) Devices Support"
>  	depends on PCI
> +	depends on ACPI_APEI_EINJ_CXL || !ACPI_APEI_EINJ_CXL

This statement is always true "x || !x"

I mentioned in the other patch that ACPI_APEI_EINJ_CXL needs to have a
dependency on CXL_BUS.