Re: [RFC PATCH 2/9] cxl/mem: Implement Clear Event Records command

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

On Fri, 12 Aug 2022 22:32:36 -0700
ira.weiny@intel.com wrote:

> From: Ira Weiny <ira.weiny@intel.com>
> 
> CXL v3.0 section 8.2.9.2.3 defines the Clear Event Records mailbox
> command.  After an event record is read it needs to be cleared from the
> event log.
> 
> Implement cxl_clear_event_record() and call it for each record retrieved
> from the device.
> 
> Each record is cleared individually.  A clear all bit is specified but
> events could arrive between a get and the final clear all operation.
> Therefore each event is cleared specifically.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Trivial suggestions inline, but other than that LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/cxl/core/mbox.c      | 31 ++++++++++++++++++++++++++++---
>  drivers/cxl/cxlmem.h         | 15 +++++++++++++++
>  include/uapi/linux/cxl_mem.h |  1 +
>  3 files changed, 44 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 2cceed8608dc..493f5ceb5d1c 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -52,6 +52,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
>  #endif
>  	CXL_CMD(GET_SUPPORTED_LOGS, 0, CXL_VARIABLE_PAYLOAD, CXL_CMD_FLAG_FORCE_ENABLE),
>  	CXL_CMD(GET_EVENT_RECORD, 1, CXL_VARIABLE_PAYLOAD, 0),
> +	CXL_CMD(CLEAR_EVENT_RECORD, CXL_VARIABLE_PAYLOAD, 0, 0),
>  	CXL_CMD(GET_FW_INFO, 0, 0x50, 0),
>  	CXL_CMD(GET_PARTITION_INFO, 0, 0x20, 0),
>  	CXL_CMD(GET_LSA, 0x8, CXL_VARIABLE_PAYLOAD, 0),
> @@ -708,6 +709,26 @@ int cxl_enumerate_cmds(struct cxl_dev_state *cxlds)
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL);
>  
> +static int cxl_clear_event_record(struct cxl_dev_state *cxlds,
> +				  enum cxl_event_log_type log,
> +				  __le16 handle)
> +{
> +	struct cxl_mbox_clear_event_payload payload;
> +	int rc;
> +
> +	memset(&payload, 0, sizeof(payload));

Could just do payload = {};

Thouch as you are setting stuff, why not just do

payload = {
	.event_log = log,
	.nr_recs = 1,
	.handle = handle,
};
and let the compiler zero anything else (I think there are no holes to complicate
things).

> +	payload.event_log = log;
> +	payload.nr_recs = 1;
> +	payload.handle = handle;
> +
> +	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_CLEAR_EVENT_RECORD,
> +			       &payload, sizeof(payload), NULL, 0);

return cxl_mbox_send_cmd() and drop rc definition.


> +	if (rc)
> +		return rc;
> +
> +	return 0;
> +}
> +
>  static int cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
>  				   enum cxl_event_log_type type)
>  {
> @@ -725,9 +746,12 @@ static int cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
>  			return rc;
>  
>  		record_count = le16_to_cpu(payload.record_count);
> -		if (record_count > 0)
> +		if (record_count > 0) {
>  			trace_cxl_event(dev_name(cxlds->dev), type,
>  					&payload.record);
> +			cxl_clear_event_record(cxlds, type,
> +					       payload.record.hdr.handle);
> +		}
>  
>  		if (payload.flags & CXL_GET_EVENT_FLAG_OVERFLOW)
>  			trace_cxl_event_overflow(dev_name(cxlds->dev), type,
> @@ -742,10 +766,11 @@ static int cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
>   * cxl_mem_get_event_records - Get Event Records from the device
>   * @cxlds: The device data for the operation
>   *
> - * Retrieve all event records available on the device and report them as trace
> - * events.
> + * Retrieve all event records available on the device, report them as trace
> + * events, and clear them.
>   *
>   * See CXL v3.0 @8.2.9.2.2 Get Event Records
> + * See CXL v3.0 @8.2.9.2.3 Clear Event Records
>   */
>  void cxl_mem_get_event_records(struct cxl_dev_state *cxlds)
>  {
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index f83634f3bc8d..5506e7210cf6 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -255,6 +255,7 @@ enum cxl_opcode {
>  	CXL_MBOX_OP_INVALID		= 0x0000,
>  	CXL_MBOX_OP_RAW			= CXL_MBOX_OP_INVALID,
>  	CXL_MBOX_OP_GET_EVENT_RECORD	= 0x0100,
> +	CXL_MBOX_OP_CLEAR_EVENT_RECORD	= 0x0101,
>  	CXL_MBOX_OP_GET_FW_INFO		= 0x0200,
>  	CXL_MBOX_OP_ACTIVATE_FW		= 0x0202,
>  	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
> @@ -387,6 +388,20 @@ static inline char *cxl_event_log_type_str(enum cxl_event_log_type type)
>  	return "<unknown>";
>  }
>  
> +/*
> + * Clear Event Records input payload
> + * CXL v3.0 section 8.2.9.2.3; Table 8-51
> + *
> + * Space given for 1 record
> + */
> +struct cxl_mbox_clear_event_payload {
> +	u8 event_log;		/* enum cxl_event_log_type */
> +	u8 clear_flags;
> +	u8 nr_recs;		/* 1 for this struct */
> +	u8 reserved[3];
> +	__le16 handle;
> +};
> +
>  struct cxl_mbox_get_partition_info {
>  	__le64 active_volatile_cap;
>  	__le64 active_persistent_cap;
> diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
> index 70459be5bdd4..7c1ad8062792 100644
> --- a/include/uapi/linux/cxl_mem.h
> +++ b/include/uapi/linux/cxl_mem.h
> @@ -25,6 +25,7 @@
>  	___C(RAW, "Raw device command"),                                  \
>  	___C(GET_SUPPORTED_LOGS, "Get Supported Logs"),                   \
>  	___C(GET_EVENT_RECORD, "Get Event Record"),                       \
> +	___C(CLEAR_EVENT_RECORD, "Clear Event Record"),                   \
>  	___C(GET_FW_INFO, "Get FW Info"),                                 \
>  	___C(GET_PARTITION_INFO, "Get Partition Information"),            \
>  	___C(GET_LSA, "Get Label Storage Area"),                          \