Re: [PATCH 2/2] dmaengine: idxd: Add Max SGL Size Support for DSA3.0

[Dave Jiang <dave.jiang@intel.com>]

On 6/13/25 9:18 AM, Yi Sun wrote:
> Certain DSA 3.0 opcodes, such as Gather copy and Gather reduce requires max
> SGL configured for workqueues prior to support these opcodes.
> 
> Configure the maximum scatter-gather list (SGL) size for workqueues during
> setup on the supported HW. Application can then properly handle the SGL
> size without explicitly setting it.
> 
> Signed-off-by: Yi Sun <yi.sun@intel.com>
> Co-developed-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 5cf419fe6b46..1c10b030bea7 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -375,6 +375,7 @@ static void idxd_wq_disable_cleanup(struct idxd_wq *wq)
>  	memset(wq->name, 0, WQ_NAME_SIZE);
>  	wq->max_xfer_bytes = WQ_DEFAULT_MAX_XFER;
>  	idxd_wq_set_max_batch_size(idxd->data->type, wq, WQ_DEFAULT_MAX_BATCH);
> +	idxd_wq_set_init_max_sgl_size(idxd, wq);
>  	if (wq->opcap_bmap)
>  		bitmap_copy(wq->opcap_bmap, idxd->opcap_bmap, IDXD_MAX_OPCAP_BITS);
>  }
> @@ -974,6 +975,8 @@ static int idxd_wq_config_write(struct idxd_wq *wq)
>  	/* bytes 12-15 */
>  	wq->wqcfg->max_xfer_shift = ilog2(wq->max_xfer_bytes);
>  	idxd_wqcfg_set_max_batch_shift(idxd->data->type, wq->wqcfg, ilog2(wq->max_batch_size));
> +	if (idxd_sgl_supported(idxd))
> +		wq->wqcfg->max_sgl_shift = ilog2(wq->max_sgl_size);
>  
>  	/* bytes 32-63 */
>  	if (idxd->hw.wq_cap.op_config && wq->opcap_bmap) {
> @@ -1152,6 +1155,8 @@ static int idxd_wq_load_config(struct idxd_wq *wq)
>  
>  	wq->max_xfer_bytes = 1ULL << wq->wqcfg->max_xfer_shift;
>  	idxd_wq_set_max_batch_size(idxd->data->type, wq, 1U << wq->wqcfg->max_batch_shift);
> +	if (idxd_sgl_supported(idxd))
> +		wq->max_sgl_size = 1U << wq->wqcfg->max_sgl_shift;
>  
>  	for (i = 0; i < WQCFG_STRIDES(idxd); i++) {
>  		wqcfg_offset = WQCFG_OFFSET(idxd, wq->id, i);
> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> index cc0a3fe1c957..fe5af50b58a4 100644
> --- a/drivers/dma/idxd/idxd.h
> +++ b/drivers/dma/idxd/idxd.h
> @@ -227,6 +227,7 @@ struct idxd_wq {
>  	char name[WQ_NAME_SIZE + 1];
>  	u64 max_xfer_bytes;
>  	u32 max_batch_size;
> +	u32 max_sgl_size;
>  
>  	/* Lock to protect upasid_xa access. */
>  	struct mutex uc_lock;
> @@ -348,6 +349,7 @@ struct idxd_device {
>  
>  	u64 max_xfer_bytes;
>  	u32 max_batch_size;
> +	u32 max_sgl_size;
>  	int max_groups;
>  	int max_engines;
>  	int max_rdbufs;
> @@ -692,6 +694,20 @@ static inline void idxd_wq_set_max_batch_size(int idxd_type, struct idxd_wq *wq,
>  		wq->max_batch_size = max_batch_size;
>  }
>  
> +static bool idxd_sgl_supported(struct idxd_device *idxd)
> +{
> +	return idxd->hw.dsacap0.sgl_formats &&
> +	       idxd->data->type == IDXD_TYPE_DSA &&
> +	       idxd->hw.version >= DEVICE_VERSION_3;
> +}
> +
> +static inline void idxd_wq_set_init_max_sgl_size(struct idxd_device *idxd,
> +						 struct idxd_wq *wq)
> +{
> +	if (idxd_sgl_supported(idxd))
> +		wq->max_sgl_size = 1U << idxd->hw.dsacap0.max_sgl_shift;
> +}
> +
>  static inline void idxd_wqcfg_set_max_batch_shift(int idxd_type, union wqcfg *wqcfg,
>  						  u32 max_batch_shift)
>  {
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index cc8203320d40..f37a7d7b537a 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -217,6 +217,7 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>  		init_completion(&wq->wq_resurrect);
>  		wq->max_xfer_bytes = WQ_DEFAULT_MAX_XFER;
>  		idxd_wq_set_max_batch_size(idxd->data->type, wq, WQ_DEFAULT_MAX_BATCH);
> +		idxd_wq_set_init_max_sgl_size(idxd, wq);
>  		wq->enqcmds_retries = IDXD_ENQCMDS_RETRIES;
>  		wq->wqcfg = kzalloc_node(idxd->wqcfg_size, GFP_KERNEL, dev_to_node(dev));
>  		if (!wq->wqcfg) {
> @@ -585,6 +586,10 @@ static void idxd_read_caps(struct idxd_device *idxd)
>  	idxd->hw.dsacap0.bits = ioread64(idxd->reg_base + IDXD_DSACAP0_OFFSET);
>  	idxd->hw.dsacap1.bits = ioread64(idxd->reg_base + IDXD_DSACAP1_OFFSET);
>  	idxd->hw.dsacap2.bits = ioread64(idxd->reg_base + IDXD_DSACAP2_OFFSET);
> +	if (idxd_sgl_supported(idxd)) {
> +		idxd->max_sgl_size = 1U << idxd->hw.dsacap0.max_sgl_shift;
> +		dev_dbg(dev, "max sgl size: %u\n", idxd->max_sgl_size);
> +	}
>  
>  	/* read iaa cap */
>  	if (idxd->data->type == IDXD_TYPE_IAX && idxd->hw.version >= DEVICE_VERSION_2)
> diff --git a/drivers/dma/idxd/registers.h b/drivers/dma/idxd/registers.h
> index 45485ecd7bb6..0401cfc95f27 100644
> --- a/drivers/dma/idxd/registers.h
> +++ b/drivers/dma/idxd/registers.h
> @@ -385,7 +385,8 @@ union wqcfg {
>  		/* bytes 12-15 */
>  		u32 max_xfer_shift:5;
>  		u32 max_batch_shift:4;
> -		u32 rsvd4:23;
> +		u32 max_sgl_shift:4;
> +		u32 rsvd4:19;
>  
>  		/* bytes 16-19 */
>  		u16 occupancy_inth;
> @@ -585,6 +586,15 @@ union evl_status_reg {
>  
>  #define IDXD_DSACAP0_OFFSET		0x180
>  union dsacap0_reg {
> +	struct {
> +		u64 max_sgl_shift:4;
> +		u64 max_gr_block_shift:4;
> +		u64 ops_inter_domain:7;
> +		u64 rsvd1:17;
> +		u64 sgl_formats:16;
> +		u64 max_sg_process:8;
> +		u64 rsvd2:8;
> +	};
>  	u64 bits;
>  };
>