RE: [PATCH v11 04/14] cxl/mbox: Add GET_SUPPORTED_FEATURES mailbox command

[Shiju Jose <shiju.jose@huawei.com>]

Hi Dave,

>-----Original Message-----
>From: Dave Jiang <dave.jiang@intel.com>
>Sent: 20 August 2024 23:46
>To: Shiju Jose <shiju.jose@huawei.com>; linux-edac@vger.kernel.org; linux-
>cxl@vger.kernel.org; linux-acpi@vger.kernel.org; linux-mm@kvack.org; linux-
>kernel@vger.kernel.org
>Cc: bp@alien8.de; tony.luck@intel.com; rafael@kernel.org; lenb@kernel.org;
>mchehab@kernel.org; dan.j.williams@intel.com; dave@stgolabs.net; Jonathan
>Cameron <jonathan.cameron@huawei.com>; alison.schofield@intel.com;
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><prime.zeng@hisilicon.com>; Roberto Sassu <roberto.sassu@huawei.com>;
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>Linuxarm <linuxarm@huawei.com>
>Subject: Re: [PATCH v11 04/14] cxl/mbox: Add GET_SUPPORTED_FEATURES
>mailbox command
>
>
>
>On 8/16/24 9:42 AM, shiju.jose@huawei.com wrote:
>> From: Shiju Jose <shiju.jose@huawei.com>
>>
>> Add support for GET_SUPPORTED_FEATURES mailbox command.
>>
>> CXL spec 3.1 section 8.2.9.6 describes optional device specific features.
>> CXL devices support features with changeable attributes.
>>
>> CXL spec 3.1 section 8.2.9.6.1 describes Get Supported features command.
>> Get Supported Features retrieves the list of supported device specific
>> features. The settings of a feature can be retrieved using Get Feature
>> and optionally modified using Set Feature.
>>
>> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
>> ---
>>  drivers/cxl/core/mbox.c | 68
>+++++++++++++++++++++++++++++++++++++++++
>>  drivers/cxl/cxlmem.h    | 63 ++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 131 insertions(+)
>>
>> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index
>> 2626f3fff201..760fa3e1075f 100644
>> --- a/drivers/cxl/core/mbox.c
>> +++ b/drivers/cxl/core/mbox.c
>> @@ -1324,6 +1324,74 @@ int cxl_set_timestamp(struct cxl_memdev_state
>> *mds)  }  EXPORT_SYMBOL_NS_GPL(cxl_set_timestamp, CXL);
>>
>> +int cxl_get_supported_features(struct cxl_memdev_state *mds,
>> +			       u32 count, u16 start_index,
>> +			       struct cxl_mbox_get_supp_feats_out *feats_out) {
>> +	struct cxl_mbox_get_supp_feats_in pi;
>> +	struct cxl_mbox_cmd mbox_cmd;
>> +	int rc;
>> +
>> +	pi.count = cpu_to_le32(count);
>> +	pi.start_index = cpu_to_le16(start_index);
>> +
>> +	mbox_cmd = (struct cxl_mbox_cmd) {
>> +		.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
>> +		.size_in = sizeof(pi),
>> +		.payload_in = &pi,
>> +		.size_out = count,
>> +		.payload_out = feats_out,
>> +		.min_out = sizeof(*feats_out),
>> +	};
>> +	rc = cxl_internal_send_cmd(mds, &mbox_cmd);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_get_supported_features, CXL);
>> +
>> +int cxl_get_supported_feature_entry(struct cxl_memdev_state *mds, const
>uuid_t *feat_uuid,
>> +				    struct cxl_mbox_supp_feat_entry
>*feat_entry_out)
>
>Hi Shiju,
>thoughts on storing all the supported features meta info from
>GET_SUPPORTED_FEATURES command in the cxl core driver during device
>enumeration and the CXL EDAC code can just query the core instead of reading
>from the device? Just looking forward to supporting other read/set features
>operations in the future and avoiding going through this entire read and find
>routine for each feature.
Thanks for the suggestion.
I saw you have implementation for storing all the supported features meta info from GET_SUPPORTED_FEATURES command  here. 
https://patchwork.kernel.org/project/cxl/patch/20240718213446.1750135-5-dave.jiang@intel.com/
I am fine basing on it if this patch is ready to go?
>
>DJ

Thanks,
Shiju
>
>> +{
>> +	struct cxl_mbox_supp_feat_entry *feat_entry;
>> +	int feat_index, feats_out_size;
>> +	int nentries, count;
>> +	int ret;
>> +
>> +	feat_index = 0;
>> +	feats_out_size = sizeof(struct cxl_mbox_get_supp_feats_out) +
>> +				sizeof(struct cxl_mbox_supp_feat_entry);
>> +	struct cxl_mbox_get_supp_feats_out *feats_out __free(kfree) =
>> +					kmalloc(feats_out_size, GFP_KERNEL);
>> +	if (!feats_out)
>> +		return -ENOMEM;
>> +
>> +	while (true) {
>> +		memset(feats_out, 0, feats_out_size);
>> +		ret = cxl_get_supported_features(mds, feats_out_size,
>> +						 feat_index, feats_out);
>> +		if (ret)
>> +			return ret;
>> +
>> +		nentries = feats_out->nr_entries;
>> +		if (!nentries)
>> +			return -EOPNOTSUPP;
>> +
>> +		/* Check CXL memdev supports the feature */
>> +		feat_entry = feats_out->feat_entries;
>> +		for (count = 0; count < nentries; count++, feat_entry++) {
>> +			if (uuid_equal(&feat_entry->uuid, feat_uuid)) {
>> +				memcpy(feat_entry_out, feat_entry,
>> +				       sizeof(*feat_entry_out));
>> +				return 0;
>> +			}
>> +		}
>> +		feat_index += nentries;
>> +	}
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_get_supported_feature_entry, CXL);
>> +
>>  int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
>>  		       struct cxl_region *cxlr)
>>  {
>> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index
>> af8169ccdbc0..9939c771f642 100644
>> --- a/drivers/cxl/cxlmem.h
>> +++ b/drivers/cxl/cxlmem.h
>> @@ -531,6 +531,7 @@ enum cxl_opcode {
>>  	CXL_MBOX_OP_GET_LOG_CAPS	= 0x0402,
>>  	CXL_MBOX_OP_CLEAR_LOG           = 0x0403,
>>  	CXL_MBOX_OP_GET_SUP_LOG_SUBLIST = 0x0405,
>> +	CXL_MBOX_OP_GET_SUPPORTED_FEATURES	= 0x0500,
>>  	CXL_MBOX_OP_IDENTIFY		= 0x4000,
>>  	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,
>>  	CXL_MBOX_OP_SET_PARTITION_INFO	= 0x4101,
>> @@ -700,6 +701,63 @@ struct cxl_mbox_set_timestamp_in {
>>
>>  } __packed;
>>
>> +/*
>> + * Get Supported Features CXL 3.1 Spec 8.2.9.6.1  */
>> +
>> +/*
>> + * Get Supported Features input payload
>> + * CXL rev 3.1 section 8.2.9.6.1 Table 8-95  */ struct
>> +cxl_mbox_get_supp_feats_in {
>> +	__le32 count;
>> +	__le16 start_index;
>> +	u8 rsvd[2];
>> +} __packed;
>> +
>> +/*
>> + * Get Supported Features Supported Feature Entry
>> + * CXL rev 3.1 section 8.2.9.6.1 Table 8-97  */
>> +/* Supported Feature Entry : Payload out attribute flags */
>> +#define CXL_FEAT_ENTRY_FLAG_CHANGABLE	BIT(0)
>> +#define CXL_FEAT_ENTRY_FLAG_DEEPEST_RESET_PERSISTENCE_MASK
>	GENMASK(3, 1)
>> +#define CXL_FEAT_ENTRY_FLAG_PERSIST_ACROSS_FIRMWARE_UPDATE
>	BIT(4)
>> +#define CXL_FEAT_ENTRY_FLAG_SUPPORT_DEFAULT_SELECTION	BIT(5)
>> +#define CXL_FEAT_ENTRY_FLAG_SUPPORT_SAVED_SELECTION	BIT(6)
>> +
>> +enum cxl_feat_attr_value_persistence {
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_NONE,
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_CXL_RESET,
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_HOT_RESET,
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_WARM_RESET,
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_COLD_RESET,
>> +	CXL_FEAT_ATTR_VALUE_PERSISTENCE_MAX
>> +};
>> +
>> +struct cxl_mbox_supp_feat_entry {
>> +	uuid_t uuid;
>> +	__le16 index;
>> +	__le16 get_size;
>> +	__le16 set_size;
>> +	__le32 attr_flags;
>> +	u8 get_version;
>> +	u8 set_version;
>> +	__le16 set_effects;
>> +	u8 rsvd[18];
>> +}  __packed;
>> +
>> +/*
>> + * Get Supported Features output payload
>> + * CXL rev 3.1 section 8.2.9.6.1 Table 8-96  */ struct
>> +cxl_mbox_get_supp_feats_out {
>> +	__le16 nr_entries;
>> +	__le16 nr_supported;
>> +	u8 rsvd[4];
>> +	struct cxl_mbox_supp_feat_entry feat_entries[]; } __packed;
>> +
>>  /* Get Poison List  CXL 3.0 Spec 8.2.9.8.4.1 */  struct
>> cxl_mbox_poison_in {
>>  	__le64 offset;
>> @@ -831,6 +889,11 @@ void cxl_event_trace_record(const struct
>cxl_memdev *cxlmd,
>>  			    enum cxl_event_type event_type,
>>  			    const uuid_t *uuid, union cxl_event *evt);  int
>> cxl_set_timestamp(struct cxl_memdev_state *mds);
>> +int cxl_get_supported_features(struct cxl_memdev_state *mds,
>> +			       u32 count, u16 start_index,
>> +			       struct cxl_mbox_get_supp_feats_out *feats_out);
>int
>> +cxl_get_supported_feature_entry(struct cxl_memdev_state *mds, const
>uuid_t *feat_uuid,
>> +				    struct cxl_mbox_supp_feat_entry
>*feat_entry_out);
>>  int cxl_poison_state_init(struct cxl_memdev_state *mds);  int
>> cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
>>  		       struct cxl_region *cxlr);