Re: [PATCH v9 04/19] cxl/core: Enforce partition order/simplify partition calls

[Davidlohr Bueso]

On Sun, 13 Apr 2025, Ira Weiny wrote:

> Device partitions have an implied order which is made more complex by
> the addition of a dynamic partition.
>
> Remove the ram special case information calls in favor of generic calls
> with a check ahead of time to ensure the preservation of the implied
> partition order.
>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
> drivers/cxl/core/hdm.c    | 11 ++++++++++-
> drivers/cxl/core/memdev.c | 32 +++++++++-----------------------
> drivers/cxl/cxl.h         |  1 +
> drivers/cxl/cxlmem.h      |  9 +++------
> drivers/cxl/mem.c         |  2 +-
> 5 files changed, 24 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index c5f8a17d00f1..92e1a24e2109 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -470,6 +470,7 @@ static const char *cxl_mode_name(enum cxl_partition_mode mode)
> int cxl_dpa_setup(struct cxl_dev_state *cxlds, const struct cxl_dpa_info *info)
> {
> 	struct device *dev = cxlds->dev;
> +	int i;
>
> 	guard(rwsem_write)(&cxl_dpa_rwsem);
>
> @@ -482,9 +483,17 @@ int cxl_dpa_setup(struct cxl_dev_state *cxlds, const struct cxl_dpa_info *info)
> 		return 0;
> 	}
>
> +	/* Verify partitions are in expected order. */
> +	for (i = 1; i < info->nr_partitions; i++) {
> +		if (cxlds->part[i].mode < cxlds->part[i-1].mode) {
> +			dev_err(dev, "Partition order mismatch\n");
> +			return 0;

return -EINVAL?

> +		}
> +	}
> +
> 	cxlds->dpa_res = DEFINE_RES_MEM(0, info->size);
>
> -	for (int i = 0; i < info->nr_partitions; i++) {
> +	for (i = 0; i < info->nr_partitions; i++) {
> 		const struct cxl_dpa_part_info *part = &info->part[i];
> 		int rc;