Re: [PATCH v14 2/4] EINJ: Add CXL error type support

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

On 2/28/24 12:00 AM, Dan Williams wrote:
> Ben Cheatham wrote:
>> This patch had an outdated commit message, so here's the patch with an updated description.
>>
>> I also realized that I was wrong about letting CXL 2.0+ error types (discussed a revision
>> or two ago) and I wasn't actually letting them through. I've went ahead and added
>> the ability to inject CXL 2.0+ error through the legacy interface. This pretty
>> much amounts to returning an error for CXL 1.0/1.1 injection types in einj_error_inject()
>> and instead routing them through a new einj_cxl_rch_error_inject() function called
>> in einj-cxl.c
>>
>> If this change is too big I can send in another revision, I just wanted to avoid
>> spamming the list(s).
>>
>> From eea1cf991dc2a551f6db2e3bb9510ed43c86762d Mon Sep 17 00:00:00 2001
>> From: Ben Cheatham <Benjamin.Cheatham@amd.com>
>> Date: Fri, 16 Feb 2024 11:12:51 -0600
>> Subject: [PATCH v14 2/4] EINJ: Add CXL error type support
>>
>> Move CXL protocol error types from einj.c (now einj-core.c) to einj-cxl.c.
>> einj-cxl.c implements the necessary handling for CXL protocol error
>> injection and exposes an API for the CXL core to use said functionality,
>> while also allowing the EINJ module to be built without CXL support.
>> Because CXL error types targeting CXL 1.0/1.1 ports require special
>> handling, only allow them to be injected through the new cxl debugfs
>> interface (next commit) and return an error when attempting to inject
>> through the legacy interface.
>>
>> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
>> ---
>>  MAINTAINERS                               |   1 +
>>  drivers/acpi/apei/Kconfig                 |  12 +++
>>  drivers/acpi/apei/Makefile                |   2 +
>>  drivers/acpi/apei/apei-internal.h         |  18 ++++
>>  drivers/acpi/apei/{einj.c => einj-core.c} |  85 +++++++++++----
>>  drivers/acpi/apei/einj-cxl.c              | 121 ++++++++++++++++++++++
>>  include/linux/einj-cxl.h                  |  40 +++++++
>>  7 files changed, 257 insertions(+), 22 deletions(-)
>>  rename drivers/acpi/apei/{einj.c => einj-core.c} (94%)
>>  create mode 100644 drivers/acpi/apei/einj-cxl.c
>>  create mode 100644 include/linux/einj-cxl.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 2ecaaec6a6bf..90cf8403dd17 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -5289,6 +5289,7 @@ M:	Dan Williams <dan.j.williams@intel.com>
>>  L:	linux-cxl@vger.kernel.org
>>  S:	Maintained
>>  F:	drivers/cxl/
>> +F:	include/linux/cxl-einj.h
>>  F:	include/linux/cxl-event.h
>>  F:	include/uapi/linux/cxl_mem.h
>>  F:	tools/testing/cxl/
>> diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
>> index 6b18f8bc7be3..f01afa2805be 100644
>> --- a/drivers/acpi/apei/Kconfig
>> +++ b/drivers/acpi/apei/Kconfig
>> @@ -60,6 +60,18 @@ config ACPI_APEI_EINJ
>>  	  mainly used for debugging and testing the other parts of
>>  	  APEI and some other RAS features.
>>  
>> +config ACPI_APEI_EINJ_CXL
>> +	bool "CXL Error INJection Support"
>> +	default ACPI_APEI_EINJ
>> +	depends on ACPI_APEI_EINJ && CXL_BUS <= ACPI_APEI_EINJ
>> +	help
>> +	  Support for CXL protocol Error INJection through debugfs/cxl.
>> +	  Availability and which errors are supported is dependent on
>> +	  the host platform. Look to ACPI v6.5 section 18.6.4 and kernel
>> +	  EINJ documentation for more information.
>> +
>> +	  If unsure say 'n'
>> +
>>  config ACPI_APEI_ERST_DEBUG
>>  	tristate "APEI Error Record Serialization Table (ERST) Debug Support"
>>  	depends on ACPI_APEI
>> diff --git a/drivers/acpi/apei/Makefile b/drivers/acpi/apei/Makefile
>> index 4dfac2128737..2c474e6477e1 100644
>> --- a/drivers/acpi/apei/Makefile
>> +++ b/drivers/acpi/apei/Makefile
>> @@ -2,6 +2,8 @@
>>  obj-$(CONFIG_ACPI_APEI)		+= apei.o
>>  obj-$(CONFIG_ACPI_APEI_GHES)	+= ghes.o
>>  obj-$(CONFIG_ACPI_APEI_EINJ)	+= einj.o
>> +einj-y				:= einj-core.o
>> +einj-$(CONFIG_ACPI_APEI_EINJ_CXL) += einj-cxl.o
>>  obj-$(CONFIG_ACPI_APEI_ERST_DEBUG) += erst-dbg.o
>>  
>>  apei-y := apei-base.o hest.o erst.o bert.o
>> diff --git a/drivers/acpi/apei/apei-internal.h b/drivers/acpi/apei/apei-internal.h
>> index 67c2c3b959e1..cd2766c69d78 100644
>> --- a/drivers/acpi/apei/apei-internal.h
>> +++ b/drivers/acpi/apei/apei-internal.h
>> @@ -130,4 +130,22 @@ static inline u32 cper_estatus_len(struct acpi_hest_generic_status *estatus)
>>  }
>>  
>>  int apei_osc_setup(void);
>> +
>> +int einj_get_available_error_type(u32 *type);
>> +int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2, u64 param3,
>> +		      u64 param4);
>> +int einj_cxl_rch_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
>> +			      u64 param3, u64 param4);
>> +bool einj_is_cxl_error_type(u64 type);
>> +int einj_validate_error_type(u64 type);
>> +
>> +#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
>> +
>>  #endif
>> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj-core.c
>> similarity index 94%
>> rename from drivers/acpi/apei/einj.c
>> rename to drivers/acpi/apei/einj-core.c
>> index 937c69844dac..437c13949be7 100644
>> --- a/drivers/acpi/apei/einj.c
>> +++ b/drivers/acpi/apei/einj-core.c
>> @@ -37,6 +37,12 @@
>>  #define MEM_ERROR_MASK		(ACPI_EINJ_MEMORY_CORRECTABLE | \
>>  				ACPI_EINJ_MEMORY_UNCORRECTABLE | \
>>  				ACPI_EINJ_MEMORY_FATAL)
>> +#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.
>> @@ -141,7 +147,7 @@ static DEFINE_MUTEX(einj_mutex);
>>  /*
>>   * Exported APIs use this flag to exit early if einj_probe() failed.
>>   */
>> -static bool einj_initialized __ro_after_init;
>> +bool einj_initialized __ro_after_init;
>>  
>>  static void *einj_param;
>>  
>> @@ -166,7 +172,7 @@ static int __einj_get_available_error_type(u32 *type)
>>  }
>>  
>>  /* Get error injection capabilities of the platform */
>> -static int einj_get_available_error_type(u32 *type)
>> +int einj_get_available_error_type(u32 *type)
>>  {
>>  	int rc;
>>  
>> @@ -536,8 +542,8 @@ static int __einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
>>  }
>>  
>>  /* Inject the specified hardware error */
>> -static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
>> -			     u64 param3, u64 param4)
>> +int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2, u64 param3,
>> +		      u64 param4)
>>  {
>>  	int rc;
>>  	u64 base_addr, size;
>> @@ -560,8 +566,18 @@ 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;
>> +	}
>> +
>> +	/*
>> +	 * Injections targeting a CXL 1.0/1.1 port have to be injected
>> +	 * from the CXL debugfs interface so that we can guarantee a
>> +	 * correct MMIO address.
>> +	 */
> 
> Given that the CXL debugfs is not present in this file I would update
> this comment to give a hints using local references. Something like:
> 
> 	/*
> 	 * Injections targeting a CXL 1.0/1.1 port have to be injected
> 	 * via the einj_cxl_rch_error_inject() path as that does proper
> 	 * input validation that passed address is an RCRB base address.
> 	 */
> 

I agree, I'll change it to something along those lines.

> ...that said, how does this work for the CXL 2.0 path? Does not
> einj_cxl_inject_error() need to use __einj_error_inject() rather than
> einj_error_inject() to get by this check?
> 

The way that the target port type (1.0 vs. 2.0+) is differentiated is whether
we are targeting a memory address, which is what SETWA_FLAGS_MEM indicates.
So for the CXL 2.0+ path, the check will pass. Although the error type
is a CXL error type, the flags variable will be set to SETWA_FLAGS_SBDF
(I'm 90% sure that's what it's called, but it's something along those lines).
Let me know if that doesn't answer your question!