Re: [RFC PATCH v9 06/11] cxl/mbox: Add SET_FEATURE mailbox command

[nifan.cxl@gmail.com]

On Tue, Jul 16, 2024 at 04:03:30PM +0100, shiju.jose@huawei.com wrote:
> From: Shiju Jose <shiju.jose@huawei.com>
> 
> Add support for SET_FEATURE mailbox command.
> 
> CXL spec 3.1 section 8.2.9.6 describes optional device specific features.
> CXL devices supports features with changeable attributes.
> The settings of a feature can be optionally modified using Set Feature
> command.

Add more specific spec reference to the command here: 8.2.9.6.3.
The same suggestions for get supported features and get feature commands.

> 
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
> ---
>  drivers/cxl/core/mbox.c | 71 +++++++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxlmem.h    | 33 +++++++++++++++++++
>  2 files changed, 104 insertions(+)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index b1eeed508459..50ecd2bd7372 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1388,6 +1388,77 @@ size_t cxl_get_feature(struct cxl_memdev_state *mds,
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_get_feature, CXL);
>  
> +/*
> + * FEAT_DATA_MIN_PAYLOAD_SIZE - min extra number of bytes should be
> + * available in the mailbox for storing the actual feature data so that
> + * the feature data transfer would work as expected.
> + */
> +#define FEAT_DATA_MIN_PAYLOAD_SIZE 10
> +int cxl_set_feature(struct cxl_memdev_state *mds,
> +		    const uuid_t feat_uuid, u8 feat_version,
> +		    void *feat_data, size_t feat_data_size,
> +		    u8 feat_flag)
> +{
> +	struct cxl_memdev_set_feat_pi {
> +		struct cxl_mbox_set_feat_hdr hdr;
> +		u8 feat_data[];
> +	}  __packed;
> +	size_t data_in_size, data_sent_size = 0;
> +	struct cxl_mbox_cmd mbox_cmd;
> +	size_t hdr_size;
> +	int rc = 0;
> +
> +	struct cxl_memdev_set_feat_pi *pi __free(kfree) =
> +					kmalloc(mds->payload_size, GFP_KERNEL);
> +	pi->hdr.uuid = feat_uuid;
> +	pi->hdr.version = feat_version;
> +	feat_flag &= ~CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK;

Although we may not support it yet, should we set bit[3] (saved across reset) 
since we already defined CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET and
it is not used?

Fan
> +	hdr_size = sizeof(pi->hdr);
> +	/*
> +	 * Check minimum mbox payload size is available for
> +	 * the feature data transfer.
> +	 */
> +	if (hdr_size + FEAT_DATA_MIN_PAYLOAD_SIZE > mds->payload_size)
> +		return -ENOMEM;
> +
> +	if ((hdr_size + feat_data_size) <= mds->payload_size) {
> +		pi->hdr.flags = cpu_to_le32(feat_flag |
> +				       CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER);
> +		data_in_size = feat_data_size;
> +	} else {
> +		pi->hdr.flags = cpu_to_le32(feat_flag |
> +				       CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER);
> +		data_in_size = mds->payload_size - hdr_size;
> +	}
> +
> +	do {
> +		pi->hdr.offset = cpu_to_le16(data_sent_size);
> +		memcpy(pi->feat_data, feat_data + data_sent_size, data_in_size);
> +		mbox_cmd = (struct cxl_mbox_cmd) {
> +			.opcode = CXL_MBOX_OP_SET_FEATURE,
> +			.size_in = hdr_size + data_in_size,
> +			.payload_in = pi,
> +		};
> +		rc = cxl_internal_send_cmd(mds, &mbox_cmd);
> +		if (rc < 0)
> +			return rc;
> +
> +		data_sent_size += data_in_size;
> +		if (data_sent_size >= feat_data_size)
> +			return 0;
> +
> +		if ((feat_data_size - data_sent_size) <= (mds->payload_size - hdr_size)) {
> +			data_in_size = feat_data_size - data_sent_size;
> +			pi->hdr.flags = cpu_to_le32(feat_flag |
> +					       CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER);
> +		} else {
> +			pi->hdr.flags = cpu_to_le32(feat_flag |
> +					       CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER);
> +		}
> +	} while (true);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_set_feature, 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 25698a6fbe66..c3cb8e2736b5 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -532,6 +532,7 @@ enum cxl_opcode {
>  	CXL_MBOX_OP_GET_SUP_LOG_SUBLIST = 0x0405,
>  	CXL_MBOX_OP_GET_SUPPORTED_FEATURES	= 0x0500,
>  	CXL_MBOX_OP_GET_FEATURE		= 0x0501,
> +	CXL_MBOX_OP_SET_FEATURE		= 0x0502,
>  	CXL_MBOX_OP_IDENTIFY		= 0x4000,
>  	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,
>  	CXL_MBOX_OP_SET_PARTITION_INFO	= 0x4101,
> @@ -780,6 +781,34 @@ struct cxl_mbox_get_feat_in {
>  	u8 selection;
>  }  __packed;
>  
> +/*
> + * Set Feature CXL 3.1 Spec 8.2.9.6.3
> + */
> +
> +/*
> + * Set Feature input payload
> + * CXL rev 3.1 section 8.2.9.6.3 Table 8-101
> + */
> +/* Set Feature : Payload in flags */
> +#define CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK	GENMASK(2, 0)
> +enum cxl_set_feat_flag_data_transfer {
> +	CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER,
> +	CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER,
> +	CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER,
> +	CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER,
> +	CXL_SET_FEAT_FLAG_ABORT_DATA_TRANSFER,
> +	CXL_SET_FEAT_FLAG_DATA_TRANSFER_MAX
> +};
> +#define CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET	BIT(3)
> +
> +struct cxl_mbox_set_feat_hdr {
> +	uuid_t uuid;
> +	__le32 flags;
> +	__le16 offset;
> +	u8 version;
> +	u8 rsvd[9];
> +}  __packed;
> +
>  /* Get Poison List  CXL 3.0 Spec 8.2.9.8.4.1 */
>  struct cxl_mbox_poison_in {
>  	__le64 offset;
> @@ -918,6 +947,10 @@ size_t cxl_get_feature(struct cxl_memdev_state *mds,
>  		       const uuid_t feat_uuid, void *feat_out,
>  		       size_t feat_out_size,
>  		       enum cxl_get_feat_selection selection);
> +int cxl_set_feature(struct cxl_memdev_state *mds,
> +		    const uuid_t feat_uuid, u8 feat_version,
> +		    void *feat_data, size_t feat_data_size,
> +		    u8 feat_flag);
>  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);
> -- 
> 2.34.1
>