On 6/25/26 4:04 AM, Anisa Su wrote:
> From: Ira Weiny <[email protected]>
>
> Extend cxl_validate_extent() — the per-extent check of the add pipeline
> to check partition membership.
>
> Resolves an extent's DPA to its containing DC partition. Sharability is
> a property of the partition (part->shareable), taken from its CDAT DSMAS
> entry.
>
> An extent from a sharable partition must carry a non-null tag, since hosts
> sharing the allocation key on that tag. A null tag there is a device
> firmware bug; reject the extent.
>
> shared_extn_seq validation is checked in cxl_check_group_seq() once the
> whole tag group is collected.
>
> Based on patches by John Groves.
>
> Signed-off-by: Ira Weiny <[email protected]>
> Signed-off-by: John Groves <[email protected]>
> Signed-off-by: Anisa Su <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
>
> ---
> Changes:
> 1. cxl_extent_dc_partition() declared static — it is only called
> from extent.c at this point. A subsequent commit ("cxl/mem: Enforce
> tag-group semantics") drops static and adds the declaration to core.h
> when mbox.c starts calling it.
> 2. In cxl_validate_extent(), declare the local uuid as a struct
> (uuid_t uuid) and fill it via import_uuid(&uuid, extent->uuid) instead
> of casting (uuid_t *)extent->uuid.
> ---
> drivers/cxl/core/extent.c | 85 +++++++++++++++++++++++++++++++++++++--
> 1 file changed, 82 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cxl/core/extent.c b/drivers/cxl/core/extent.c
> index 6e67e787d14d..2e770c5279c2 100644
> --- a/drivers/cxl/core/extent.c
> +++ b/drivers/cxl/core/extent.c
> @@ -76,11 +76,67 @@ alloc_tag_group(struct cxl_dax_region *cxlr_dax, uuid_t
> *uuid)
> return no_free_ptr(group);
> }
>
> +/*
> + * Find the DC (Dynamic Capacity) partition that fully contains @ext_range,
> + * or NULL if the extent falls outside every DC partition on this memdev.
> + * The returned pointer is owned by mds->cxlds.part[] and lives for the
> + * lifetime of the memdev.
> + */
> +static const struct cxl_dpa_partition *
> +cxl_extent_dc_partition(struct cxl_memdev_state *mds,
> + struct cxl_extent *extent,
> + struct range *ext_range)
> +{
> + struct cxl_dev_state *cxlds = &mds->cxlds;
> + struct device *dev = mds->cxlds.dev;
> +
> + /*
> + * A device-side error could cause end < start, which range_contains()
> + * would treat as contained in any partition.
> + */
> + if (ext_range->end < ext_range->start) {
> + dev_err_ratelimited(dev,
> + "DC extent DPA %pra (%pU) has invalid
> length (firmware bug)\n",
> + ext_range, extent->uuid);
> + return NULL;
> + }
> +
> + for (int i = 0; i < cxlds->nr_partitions; i++) {
> + struct cxl_dpa_partition *part = &cxlds->part[i];
> + struct range partition_range = {
> + .start = part->res.start,
> + .end = part->res.end,
> + };
> +
> + if (part->mode != CXL_PARTMODE_DYNAMIC_RAM_1)
> + continue;
> +
> + if (range_contains(&partition_range, ext_range)) {
> + dev_dbg(dev, "DC extent DPA %pra (DCR:%pra)(%pU)\n",
> + ext_range, &partition_range, extent->uuid);
> + return part;
> + }
> + }
> +
> + dev_err_ratelimited(dev,
> + "DC extent DPA %pra (%pU) is not in a valid DC
> partition\n",
> + ext_range, extent->uuid);
> + return NULL;
> +}
> +
> /*
> * Stage 1 of the add pipeline: pure, no allocation. Resolve the extent
> - * to its region/endpoint decoder and ext_range, and verify the range
> - * fits in the resolved endpoint decoder's DPA resource. Further
> - * per-extent invariants layer into this function in subsequent commits.
> + * to its region/endpoint decoder and ext_range, and enforce every
> + * per-extent invariant the device must satisfy:
> + *
> + * - DPA falls inside a Dynamic Capacity partition
> (cxl_extent_dc_partition).
> + * - Sharability is a property of the partition (part->shareable), not of
> + * the shared_extn_seq value: a sharable-partition extent must carry a
> + * non-null tag, and a non-sharable-partition extent must leave
> + * shared_extn_seq reserved (zero). The dense 0..n-1 numbering within a
> + * sharable tag group is validated separately (cxl_check_group_seq()).
> + * - DPA resolves to an endpoint decoder attached to a region.
> + * - The extent's range is fully contained in that ED's DPA resource.
> *
> * Caller must hold cxl_rwsem.region for read (cxl_dpa_to_region()).
> * On success, @out_cxled / @out_cxlr_dax / @out_ext_range carry the
> @@ -94,6 +150,8 @@ static int cxl_validate_extent(struct cxl_memdev_state
> *mds,
> {
> u64 start_dpa = le64_to_cpu(extent->start_dpa);
> struct cxl_memdev *cxlmd = mds->cxlds.cxlmd;
> + struct device *dev = mds->cxlds.dev;
> + const struct cxl_dpa_partition *part;
> struct cxl_endpoint_decoder *cxled;
> struct cxl_region *cxlr;
> struct range ext_range = (struct range) {
> @@ -101,6 +159,27 @@ static int cxl_validate_extent(struct cxl_memdev_state
> *mds,
> .end = start_dpa + le64_to_cpu(extent->length) - 1,
> };
> struct range ed_range;
> + uuid_t uuid;
> +
> + import_uuid(&uuid, extent->uuid);
> +
> + part = cxl_extent_dc_partition(mds, extent, &ext_range);
> + if (!part)
> + return -ENXIO;
> +
> + if (part->shareable) {
> + if (uuid_is_null(&uuid)) {
> + dev_err_ratelimited(dev,
> + "DC extent DPA %pra: sharable-partition extent
> has null tag (firmware bug)\n",
> + &ext_range);
> + return -ENXIO;
> + }
> + } else if (le16_to_cpu(extent->shared_extn_seq)) {
> + dev_err_ratelimited(dev,
> + "DC extent DPA %pra (%pU): non-sharable partition but
> shared_extn_seq=%u (firmware bug)\n",
> + &ext_range, &uuid,
> le16_to_cpu(extent->shared_extn_seq));
> + return -ENXIO;
> + }
>
> cxlr = cxl_dpa_to_region(cxlmd, start_dpa, &cxled);
> if (!cxlr || !cxlr->cxlr_dax)
