Re: [PATCH v11 3/4] cxl/core, EINJ: Add EINJ CXL debugfs files and EINJ helper functions

[Ben Cheatham <benjamin.cheatham@amd.com>]

On 2/14/24 11:46 AM, Jonathan Cameron wrote:
> On Wed, 14 Feb 2024 10:41:00 -0600
> Ben Cheatham <benjamin.cheatham@amd.com> wrote:
> 
>> On 2/14/24 9:27 AM, Jonathan Cameron wrote:
>>> On Thu, 8 Feb 2024 14:00:41 -0600
>>> Ben Cheatham <Benjamin.Cheatham@amd.com> wrote:
>>>   
>>>> Implement CXL helper functions in the EINJ module for getting/injecting
>>>> available CXL protocol error types and export them 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 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.
>>>>
>>>> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>>>> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>  
>>> Hi Ben,
>>>
>>> Sorry I've not looked at this sooner.
>>>
>>> Anyhow, some comments inline. Mostly looks good to me.
>>>
>>> Jonathan
>>>   
>>>> ---
>>>>  Documentation/ABI/testing/debugfs-cxl |  22 ++++
>>>>  MAINTAINERS                           |   1 +
>>>>  drivers/acpi/apei/einj.c              | 158 ++++++++++++++++++++++++--
>>>>  drivers/cxl/core/port.c               |  39 +++++++
>>>>  include/linux/einj-cxl.h              |  45 ++++++++
>>>>  5 files changed, 255 insertions(+), 10 deletions(-)
>>>>  create mode 100644 include/linux/einj-cxl.h
>>>>
>>>> diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
>>>> index fe61d372e3fa..bcd985cca66a 100644
>>>> --- a/Documentation/ABI/testing/debugfs-cxl
>>>> +++ b/Documentation/ABI/testing/debugfs-cxl
>>>> @@ -33,3 +33,25 @@ 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 <error number> can be written to einj_inject to inject
>>>> +		<error type> into a chosen dport.  
>>>
>>> I think it's a limited set, so docs could include what the error_type values can
>>> be?  From this description it's not obvious they are human readable strings.
>>>   
>>
>> It is a limited set, but that set has 6 variants. It may make the description
>> a bit long to include all of them, but I could include an example string instead?
>> If length isn't an issue then I can add them all in.
> 
> Example works.
> 

I tried adding them all in and it didn't make the description too long, so I went
ahead and did that instead of an example.

>>
>>>> +
>>>> +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/MAINTAINERS b/MAINTAINERS
>>>> index 9104430e148e..02d7feb2ed1f 100644
>>>> --- a/MAINTAINERS
>>>> +++ b/MAINTAINERS
>>>> @@ -5246,6 +5246,7 @@ L:	linux-cxl@vger.kernel.org
>>>>  S:	Maintained
>>>>  F:	drivers/cxl/
>>>>  F:	include/uapi/linux/cxl_mem.h
>>>> +F:  include/linux/einj-cxl.h
>>>>  F:	tools/testing/cxl/
>>>>  
>>>>  COMPUTE EXPRESS LINK PMU (CPMU)
>>>> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
>>>> index 73dde21d3e89..9137cc01f791 100644
>>>> --- a/drivers/acpi/apei/einj.c
>>>> +++ b/drivers/acpi/apei/einj.c
>>>> @@ -21,6 +21,7 @@
>>>>  #include <linux/nmi.h>
>>>>  #include <linux/delay.h>
>>>>  #include <linux/mm.h>
>>>> +#include <linux/einj-cxl.h>
>>>>  #include <linux/platform_device.h>
>>>>  #include <asm/unaligned.h>
>>>>  
>>>> @@ -37,6 +38,20 @@
>>>>  #define MEM_ERROR_MASK		(ACPI_EINJ_MEMORY_CORRECTABLE | \
>>>>  				ACPI_EINJ_MEMORY_UNCORRECTABLE | \
>>>>  				ACPI_EINJ_MEMORY_FATAL)
>>>> +#ifndef ACPI_EINJ_CXL_CACHE_CORRECTABLE
>>>> +#define ACPI_EINJ_CXL_CACHE_CORRECTABLE     BIT(12)
>>>> +#define ACPI_EINJ_CXL_CACHE_UNCORRECTABLE   BIT(13)
>>>> +#define ACPI_EINJ_CXL_CACHE_FATAL           BIT(14)
>>>> +#define ACPI_EINJ_CXL_MEM_CORRECTABLE       BIT(15)
>>>> +#define ACPI_EINJ_CXL_MEM_UNCORRECTABLE     BIT(16)
>>>> +#define ACPI_EINJ_CXL_MEM_FATAL             BIT(17)
>>>> +#endif
>>>> +#define CXL_ERROR_MASK		(ACPI_EINJ_CXL_CACHE_CORRECTABLE | \
>>>> +				ACPI_EINJ_CXL_CACHE_UNCORRECTABLE | \
>>>> +				ACPI_EINJ_CXL_CACHE_FATAL | \
>>>> +				ACPI_EINJ_CXL_MEM_CORRECTABLE | \
>>>> +				ACPI_EINJ_CXL_MEM_UNCORRECTABLE | \
>>>> +				ACPI_EINJ_CXL_MEM_FATAL)
>>>>  
>>>>  /*
>>>>   * ACPI version 5 provides a SET_ERROR_TYPE_WITH_ADDRESS action.
>>>> @@ -543,8 +558,11 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
>>>>  	if (type & ACPI5_VENDOR_BIT) {
>>>>  		if (vendor_flags != SETWA_FLAGS_MEM)
>>>>  			goto inject;
>>>> -	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM))
>>>> +	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM)) {
>>>>  		goto inject;
>>>> +	} else if ((type & CXL_ERROR_MASK) && (flags & SETWA_FLAGS_MEM)) {
>>>> +		goto inject;
>>>> +	}
>>>>  
>>>>  	/*
>>>>  	 * Disallow crazy address masks that give BIOS leeway to pick
>>>> @@ -596,6 +614,9 @@ static const char * const einj_error_type_string[] = {
>>>>  	"0x00000200\tPlatform Correctable\n",
>>>>  	"0x00000400\tPlatform Uncorrectable non-fatal\n",
>>>>  	"0x00000800\tPlatform Uncorrectable fatal\n",
>>>> +};
>>>> +
>>>> +static const char * const einj_cxl_error_type_string[] = {
>>>>  	"0x00001000\tCXL.cache Protocol Correctable\n",
>>>>  	"0x00002000\tCXL.cache Protocol Uncorrectable non-fatal\n",
>>>>  	"0x00004000\tCXL.cache Protocol Uncorrectable fatal\n",
>>>> @@ -621,29 +642,44 @@ static int available_error_type_show(struct seq_file *m, void *v)
>>>>  
>>>>  DEFINE_SHOW_ATTRIBUTE(available_error_type);
>>>>  
>>>> -static int error_type_get(void *data, u64 *val)
>>>> +int einj_cxl_available_error_type_show(struct seq_file *m, void *v)
>>>>  {
>>>> -	*val = error_type;
>>>> +	int cxl_err, rc;
>>>> +	u32 available_error_type = 0;
>>>> +
>>>> +	if (!einj_initialized)
>>>> +		return -ENXIO;
>>>> +
>>>> +	rc = einj_get_available_error_type(&available_error_type);
>>>> +	if (rc)
>>>> +		return rc;
>>>> +
>>>> +	for (int pos = 0; pos < ARRAY_SIZE(einj_cxl_error_type_string); pos++) {  
>>>
>>> Trivial so feel free to ignore but, I'd stick to local styles and have pos
>>> declared in more traditional c style.
>>>   
>>
>> Will do.
>>
>>>> +		cxl_err = ACPI_EINJ_CXL_CACHE_CORRECTABLE << pos;  
>>>
>>> Maybe clearer as
>>> 		cxl_err = FIELD_PREP(CXL_ERROR_MASK, BIT(pos));
>>>   
>>
>> I'll think about it. I think I agree with you, but I've seen a good amount of
>> people who aren't familiar with the FIELD_* macros in which case it isn't much clearer.
> 
> Lets teach them ;)
> 

Sounds good!

Thanks,
Ben