RE: [PATCH v15 04/15] cxl: Add Get Supported Features command for kernel usage

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

>-----Original Message-----
>From: Dave Jiang <dave.jiang@intel.com>
>Sent: 06 November 2024 23:35
>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>; gregkh@linuxfoundation.org;
>sudeep.holla@arm.com; jassisinghbrar@gmail.com; alison.schofield@intel.com;
>vishal.l.verma@intel.com; ira.weiny@intel.com; david@redhat.com;
>Vilas.Sridharan@amd.com; leo.duran@amd.com; Yazen.Ghannam@amd.com;
>rientjes@google.com; jiaqiyan@google.com; Jon.Grimm@amd.com;
>dave.hansen@linux.intel.com; naoya.horiguchi@nec.com;
>james.morse@arm.com; jthoughton@google.com; somasundaram.a@hpe.com;
>erdemaktas@google.com; pgonda@google.com; duenwen@google.com;
>gthelen@google.com; wschwartz@amperecomputing.com;
>dferguson@amperecomputing.com; wbs@os.amperecomputing.com;
>nifan.cxl@gmail.com; tanxiaofei <tanxiaofei@huawei.com>; Zengtao (B)
><prime.zeng@hisilicon.com>; Roberto Sassu <roberto.sassu@huawei.com>;
>kangkang.shen@futurewei.com; wanghuiqiang <wanghuiqiang@huawei.com>;
>Linuxarm <linuxarm@huawei.com>
>Subject: Re: [PATCH v15 04/15] cxl: Add Get Supported Features command for
>kernel usage
>
>
>
>On 11/1/24 2:17 AM, shiju.jose@huawei.com wrote:
>> From: Dave Jiang <dave.jiang@intel.com>
>>
>> CXL spec r3.1 8.2.9.6.1 Get Supported Features (Opcode 0500h) The
>> command retrieve the list of supported device-specific features
>> (identified by UUID) and general information about each Feature.
>>
>> The driver will retrieve the feature entries in order to make checks
>> and provide information for the Get Feature and Set Feature command.
>> One of the main piece of information retrieved are the effects a Set
>> Feature command would have for a particular feature.
>>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> Co-developed-by: Shiju Jose <shiju.jose@huawei.com>
>> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
>
>Found couple endien conversion changes below:
Hi Dave,

Thanks for pointing these errors. Fixed now.

Thanks,
Shiju
>
>> ---
>>  drivers/cxl/core/mbox.c      | 175 +++++++++++++++++++++++++++++++++++
>>  drivers/cxl/cxlmem.h         |  47 ++++++++++
>>  drivers/cxl/pci.c            |   4 +
>>  include/cxl/mailbox.h        |   4 +
>>  include/uapi/linux/cxl_mem.h |   1 +
>>  5 files changed, 231 insertions(+)
>>
>> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index
>> 5175138c4fb7..5045960e3bfe 100644
>> --- a/drivers/cxl/core/mbox.c
>> +++ b/drivers/cxl/core/mbox.c
>> @@ -67,6 +67,7 @@ static struct cxl_mem_command
>cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
>>  	CXL_CMD(SET_SHUTDOWN_STATE, 0x1, 0, 0),
>>  	CXL_CMD(GET_SCAN_MEDIA_CAPS, 0x10, 0x4, 0),
>>  	CXL_CMD(GET_TIMESTAMP, 0, 0x8, 0),
>> +	CXL_CMD(GET_SUPPORTED_FEATURES, 0x8, CXL_VARIABLE_PAYLOAD,
>0),
>>  };
>>
>>  /*
>> @@ -795,6 +796,180 @@ static const uuid_t log_uuid[] = {
>>  	[VENDOR_DEBUG_UUID] = DEFINE_CXL_VENDOR_DEBUG_UUID,  };
>>
>> +static void cxl_free_features(void *features) {
>> +	kvfree(features);
>> +}
>> +
>> +static int cxl_get_supported_features_count(struct cxl_dev_state
>> +*cxlds) {
>> +	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
>> +	struct cxl_mbox_get_sup_feats_out mbox_out;
>> +	struct cxl_mbox_get_sup_feats_in mbox_in;
>> +	struct cxl_mbox_cmd mbox_cmd;
>> +	int rc;
>> +
>> +	memset(&mbox_in, 0, sizeof(mbox_in));
>> +	mbox_in.count = sizeof(mbox_out);
>
>mbox_in.count = cpu_to_le32(sizeof(mbox_out));
>
>> +	memset(&mbox_out, 0, sizeof(mbox_out));
>> +	mbox_cmd = (struct cxl_mbox_cmd) {
>> +		.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
>> +		.size_in = sizeof(mbox_in),
>> +		.payload_in = &mbox_in,
>> +		.size_out = sizeof(mbox_out),
>> +		.payload_out = &mbox_out,
>> +		.min_out = sizeof(mbox_out),
>> +	};
>> +	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	cxl_mbox->num_features = le16_to_cpu(mbox_out.supported_feats);
>> +	if (!cxl_mbox->num_features)
>> +		return -ENOENT;
>> +
>> +	return 0;
>> +}
>> +
>> +int cxl_get_supported_features(struct cxl_memdev_state *mds) {
>> +	int remain_feats, max_size, max_feats, start, rc;
>> +	struct cxl_dev_state *cxlds = &mds->cxlds;
>> +	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
>> +	int feat_size = sizeof(struct cxl_feat_entry);
>> +	struct cxl_mbox_get_sup_feats_out *mbox_out;
>> +	struct cxl_mbox_get_sup_feats_in mbox_in;
>> +	int hdr_size = sizeof(*mbox_out);
>> +	struct cxl_mbox_cmd mbox_cmd;
>> +	struct cxl_mem_command *cmd;
>> +	void *ptr;
>> +
>> +	/* Get supported features is optional, need to check */
>> +	cmd =
>cxl_mem_find_command(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
>> +	if (!cmd)
>> +		return -EOPNOTSUPP;
>> +	if (!test_bit(cmd->info.id, mds->enabled_cmds))
>> +		return -EOPNOTSUPP;
>> +
>> +	rc = cxl_get_supported_features_count(cxlds);
>> +	if (rc)
>> +		return rc;
>> +
>> +	struct cxl_feat_entry *entries __free(kvfree) =
>> +		kvmalloc(cxl_mbox->num_features * feat_size, GFP_KERNEL);
>> +
>> +	if (!entries)
>> +		return -ENOMEM;
>> +
>> +	cxl_mbox->entries = no_free_ptr(entries);
>> +	rc = devm_add_action_or_reset(cxl_mbox->host, cxl_free_features,
>> +				      cxl_mbox->entries);
>> +	if (rc)
>> +		return rc;
>> +
>> +	max_size = cxl_mbox->payload_size - hdr_size;
>> +	/* max feat entries that can fit in mailbox max payload size */
>> +	max_feats = max_size / feat_size;
>> +	ptr = &cxl_mbox->entries[0];
>> +
>> +	mbox_out = kvmalloc(cxl_mbox->payload_size, GFP_KERNEL);
>> +	if (!mbox_out)
>> +		return -ENOMEM;
>> +
>> +	start = 0;
>> +	remain_feats = cxl_mbox->num_features;
>> +	do {
>> +		int retrieved, alloc_size, copy_feats;
>  +		int num_entries;
>> +
>> +		if (remain_feats > max_feats) {
>> +			alloc_size = sizeof(*mbox_out) + max_feats * feat_size;
>> +			remain_feats = remain_feats - max_feats;
>> +			copy_feats = max_feats;
>> +		} else {
>> +			alloc_size = sizeof(*mbox_out) + remain_feats *
>feat_size;
>> +			copy_feats = remain_feats;
>> +			remain_feats = 0;
>> +		}
>> +
>> +		memset(&mbox_in, 0, sizeof(mbox_in));
>> +		mbox_in.count = alloc_size;
>> +		mbox_in.start_idx = start;
>mbox_in.count = cpu_to_le32(alloc_size); mbox_in.start_idx =
>cpu_to_le16(start);
>
>
>> +		memset(mbox_out, 0, alloc_size);
>> +		mbox_cmd = (struct cxl_mbox_cmd) {
>> +			.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
>> +			.size_in = sizeof(mbox_in),
>> +			.payload_in = &mbox_in,
>> +			.size_out = alloc_size,
>> +			.payload_out = mbox_out,
>> +			.min_out = hdr_size,
>> +		};
>> +		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
>> +		if (rc < 0)
>> +			goto err;
>> +		if (mbox_cmd.size_out <= hdr_size) {
>> +			rc = -ENXIO;
>> +			goto err;
>> +		}
>> +
>> +		/*
>> +		 * Make sure retrieved out buffer is multiple of feature
>> +		 * entries.
>> +		 */
>> +		retrieved = mbox_cmd.size_out - hdr_size;
>> +		if (retrieved % feat_size) {
>> +			rc = -ENXIO;
>> +			goto err;
>> +		}
>> +
>
>  +		num_entries = le16_to_cpu(mbox_out->num_entries);
>> +		/*
>> +		 * If the reported output entries * defined entry size !=
>> +		 * retrieved output bytes, then the output package is incorrect.
>> +		 */
>> +		if (mbox_out->num_entries * feat_size != retrieved) {
>if (num_entries * feat_size != retrieved) {
>> +			rc = -ENXIO;
>> +			goto err;
>> +		}
>> +
>> +		memcpy(ptr, mbox_out->ents, retrieved);
>> +		ptr += retrieved;
>> +		/*
>> +		 * If the number of output entries is less than expected, add the
>> +		 * remaining entries to the next batch.
>> +		 */
>> +		remain_feats += copy_feats - mbox_out->num_entries;
>> +		start += mbox_out->num_entries;
>remain_feat += copy_feats - num_entries; start += num_entries;
>
>> +	} while (remain_feats);
>> +
>> +	kfree(mbox_out);
>> +	return 0;
>> +
>> +err:
>> +	kfree(mbox_out);
>> +	cxl_mbox->num_features = 0;
>> +	return rc;
>> +}
>> +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_feat_entry *feat_entry_out) {
>> +	struct cxl_dev_state *cxlds = &mds->cxlds;
>> +	struct cxl_feat_entry *feat_entry;
>> +	int count;
>> +
>> +	/* Check CXL dev supports the feature */
>> +	feat_entry = &cxlds->cxl_mbox.entries[0];
>> +	for (count = 0; count < cxlds->cxl_mbox.num_features; count++,
>feat_entry++) {
>> +		if (uuid_equal(&feat_entry->uuid, feat_uuid)) {
>> +			memcpy(feat_entry_out, feat_entry,
>sizeof(*feat_entry_out));
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	return -EOPNOTSUPP;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_get_supported_feature_entry, CXL);
>> +
>>  /**
>>   * cxl_enumerate_cmds() - Enumerate commands for a device.
>>   * @mds: The driver data for the operation diff --git
>> a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index
>> 2a25d1957ddb..f88b10188632 100644
>> --- a/drivers/cxl/cxlmem.h
>> +++ b/drivers/cxl/cxlmem.h
>> @@ -530,6 +530,7 @@ 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,
>> @@ -813,6 +814,48 @@ enum {
>>  	CXL_PMEM_SEC_PASS_USER,
>>  };
>>
>> +/* Get Supported Features (0x500h) CXL r3.1 8.2.9.6.1 */ struct
>> +cxl_mbox_get_sup_feats_in {
>> +	__le32 count;
>> +	__le16 start_idx;
>> +	u8 reserved[2];
>> +} __packed;
>> +
>> +/* 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_feat_entry {
>> +	uuid_t uuid;
>> +	__le16 id;
>> +	__le16 get_feat_size;
>> +	__le16 set_feat_size;
>> +	__le32 attr_flags;
>> +	u8 get_feat_ver;
>> +	u8 set_feat_ver;
>> +	__le16 set_effects;
>> +	u8 reserved[18];
>> +} __packed;
>> +
>> +struct cxl_mbox_get_sup_feats_out {
>> +	__le16 num_entries;
>> +	__le16 supported_feats;
>> +	u8 reserved[4];
>> +	struct cxl_feat_entry ents[] __counted_by_le(supported_feats); }
>> +__packed;
>> +
>>  int cxl_internal_send_cmd(struct cxl_mailbox *cxl_mbox,
>>  			  struct cxl_mbox_cmd *cmd);
>>  int cxl_dev_state_identify(struct cxl_memdev_state *mds); @@ -872,4
>> +915,8 @@ struct cxl_hdm {  struct seq_file;  struct dentry
>> *cxl_debugfs_create_dir(const char *dir);  void cxl_dpa_debug(struct
>> seq_file *file, struct cxl_dev_state *cxlds);
>> +
>> +int cxl_get_supported_features(struct cxl_memdev_state *mds); int
>> +cxl_get_supported_feature_entry(struct cxl_memdev_state *mds, const
>uuid_t *feat_uuid,
>> +				    struct cxl_feat_entry *feat_entry_out);
>>  #endif /* __CXL_MEM_H__ */
>> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index
>> 188412d45e0d..5c2926eec3c3 100644
>> --- a/drivers/cxl/pci.c
>> +++ b/drivers/cxl/pci.c
>> @@ -887,6 +887,10 @@ static int cxl_pci_probe(struct pci_dev *pdev, const
>struct pci_device_id *id)
>>  	if (rc)
>>  		return rc;
>>
>> +	rc = cxl_get_supported_features(mds);
>> +	if (rc)
>> +		dev_dbg(&pdev->dev, "No features enumerated.\n");
>> +
>>  	rc = cxl_set_timestamp(mds);
>>  	if (rc)
>>  		return rc;
>> diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h index
>> bacd111e75f1..cc66afec3473 100644
>> --- a/include/cxl/mailbox.h
>> +++ b/include/cxl/mailbox.h
>> @@ -14,6 +14,8 @@ struct cxl_mbox_cmd;
>>   * @mbox_mutex: mutex protects device mailbox and firmware
>>   * @mbox_wait: rcuwait for mailbox
>>   * @mbox_send: @dev specific transport for transmitting mailbox
>> commands
>> + * @num_features: number of supported features
>> + * @entries: list of supported feature entries.
>>   */
>>  struct cxl_mailbox {
>>  	struct device *host;
>> @@ -21,6 +23,8 @@ struct cxl_mailbox {
>>  	struct mutex mbox_mutex; /* lock to protect mailbox context */
>>  	struct rcuwait mbox_wait;
>>  	int (*mbox_send)(struct cxl_mailbox *cxl_mbox, struct cxl_mbox_cmd
>> *cmd);
>> +	int num_features;
>> +	struct cxl_feat_entry *entries;
>>  };
>>
>>  int cxl_mailbox_init(struct cxl_mailbox *cxl_mbox, struct device
>> *host); diff --git a/include/uapi/linux/cxl_mem.h
>> b/include/uapi/linux/cxl_mem.h index c6c0fe27495d..bd2535962f70 100644
>> --- a/include/uapi/linux/cxl_mem.h
>> +++ b/include/uapi/linux/cxl_mem.h
>> @@ -50,6 +50,7 @@
>>  	___C(GET_LOG_CAPS, "Get Log Capabilities"),			  \
>>  	___C(CLEAR_LOG, "Clear Log"),					  \
>>  	___C(GET_SUP_LOG_SUBLIST, "Get Supported Logs Sub-List"),	  \
>> +	___C(GET_SUPPORTED_FEATURES, "Get Supported Features"),
>	  \
>>  	___C(MAX, "invalid / last command")
>>
>>  #define ___C(a, b) CXL_MEM_COMMAND_ID_##a
>