[dpdk-dev] [PATCH v3 10/17] dma/idxd: add data-path job submission functions

[Conor Walsh]

> Add data path functions for enqueuing and submitting operations to DSA
> devices.
>
> Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
> Signed-off-by: Kevin Laatz <kevin.laatz at intel.com>

<snip>

> +static __rte_always_inline int
> +__idxd_write_desc(struct rte_dmadev *dev,
> +		const uint32_t op_flags,
> +		const rte_iova_t src,
> +		const rte_iova_t dst,
> +		const uint32_t size,
> +		const uint32_t flags)
> +{
> +	struct idxd_dmadev *idxd = dev->dev_private;
> +	uint16_t mask = idxd->desc_ring_mask;
> +	uint16_t job_id = idxd->batch_start + idxd->batch_size;
> +	/* we never wrap batches, so we only mask the start and allow start+size to overflow */
> +	uint16_t write_idx = (idxd->batch_start & mask) + idxd->batch_size;
> +
> +	/* first check batch ring space then desc ring space */
> +	if ((idxd->batch_idx_read == 0 && idxd->batch_idx_write == idxd->max_batches) ||
> +			idxd->batch_idx_write + 1 == idxd->batch_idx_read)
> +		goto failed;
> +	if (((write_idx + 1) & mask) == (idxd->ids_returned & mask))
> +		goto failed;
> +
> +	/* write desc. Note: descriptors don't wrap, but the completion address does */
> +	const uint64_t op_flags64 = (uint64_t)(op_flags | IDXD_FLAG_COMPLETION_ADDR_VALID) << 32;
> +	const uint64_t comp_addr = __desc_idx_to_iova(idxd, write_idx & mask);
> +	_mm256_store_si256((void *)&idxd->desc_ring[write_idx],
> +			_mm256_set_epi64x(dst, src, comp_addr, op_flags64));
> +	_mm256_store_si256((void *)&idxd->desc_ring[write_idx].size,
> +			_mm256_set_epi64x(0, 0, 0, size));
> +
> +	idxd->batch_size++;
> +
> +	rte_prefetch0_write(&idxd->desc_ring[write_idx + 1]);
> +
> +	if (flags & RTE_DMA_OP_FLAG_SUBMIT)
> +		__submit(idxd);
> +
> +	return job_id;
> +
> +failed:
> +	return -1;
> +}

If the failed goto just returns -1 it would probably be better to remove 
it and just return -1 in the 2 spots above.

Reviewed-by: Conor Walsh <conor.walsh at intel.com>