On 6/25/26 4:04 AM, Anisa Su wrote: > From: Ira Weiny <[email protected]> > > Add an alignment gate to cxl_add_pending(): every extent in a tag group > must have its start_dpa and length aligned to the dax region's mapping > granularity. A misaligned extent makes the resulting dax device unusable, > so drop the whole group rather than accept a partial allocation that would > surface a broken dax_resource. > > 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: > [anisa: gate on the dax region's actual mapping alignment (PMD_SIZE) > instead of a hardcoded SZ_2M] > --- > drivers/cxl/core/mbox.c | 51 +++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 49 insertions(+), 2 deletions(-) > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > index 08f51b8807c0..14ba263044f0 100644 > --- a/drivers/cxl/core/mbox.c > +++ b/drivers/cxl/core/mbox.c > @@ -7,6 +7,8 @@ > #include <linux/unaligned.h> > #include <linux/list.h> > #include <linux/list_sort.h> > +#include <linux/pgtable.h> > +#include <linux/sizes.h> > #include <cxlpci.h> > #include <cxlmem.h> > #include <cxl.h> > @@ -1295,6 +1297,19 @@ static int add_to_pending_list(struct list_head > *pending_list, > return 0; > } > > +/* > + * Extents need to be aligned to dax region's mapping granularity. > + * Use PMD_SIZE, since cxl_dax_region_probe() calls alloc_dax_region with > + * PMD_SIZE for the 'align' parameter. > + */ > +static bool cxl_extent_dcd_aligned(const struct cxl_extent *extent) > +{ > + u64 start = le64_to_cpu(extent->start_dpa); > + u64 len = le64_to_cpu(extent->length); > + > + return IS_ALIGNED(start, PMD_SIZE) && IS_ALIGNED(len, PMD_SIZE); > +} > + > /* > * Compare two extents by shared_extn_seq (ascending). list_sort is > * stable, so extents with equal keys keep their arrival order from > @@ -1395,11 +1410,38 @@ static int cxl_realize_group(struct cxl_memdev_state > *mds, const uuid_t *tag, > return group_cnt; > } > > +/* > + * Validate a tag @group before realizing it. Returns 0 if the group may be > + * added, or a negative errno if it must be dropped. Further gates layer in > + * here in later commits. > + */ > +static int cxl_validate_group(struct cxl_memdev_state *mds, const uuid_t > *tag, > + struct list_head *group) > +{ > + struct device *dev = mds->cxlds.dev; > + struct cxl_extent_list_node *pos; > + > + /* Alignment gate — drop the group if any member fails */ > + list_for_each_entry(pos, group, list) { > + if (!cxl_extent_dcd_aligned(pos->extent)) { > + dev_warn(dev, > + "Tag %pUb: dropping group, extent DPA:%#llx > LEN:%#llx not %#llx-aligned\n", > + tag, > + le64_to_cpu(pos->extent->start_dpa), > + le64_to_cpu(pos->extent->length), > + (u64)PMD_SIZE); > + return -EINVAL; > + } > + } > + > + return 0; > +} > + > /* > * Drive the pending Add-Capacity records through cxl_realize_group(), > * grouped by tag. Per group: extract from pending, stable-sort by > - * shared_extn_seq, realize the group, and on success move it onto the > - * accepted list. Validation gates layer onto this loop in later commits. > + * shared_extn_seq, validate, realize the group, and on success move it onto > + * the accepted list. > */ > static int cxl_add_pending(struct cxl_memdev_state *mds, bool existing) > { > @@ -1425,6 +1467,11 @@ static int cxl_add_pending(struct cxl_memdev_state > *mds, bool existing) > */ > list_sort(NULL, &group, extent_seq_compare); > > + if (cxl_validate_group(mds, &tag, &group)) { > + drop_extent_group(&group); > + continue; > + } > + > cnt = cxl_realize_group(mds, &tag, &group, existing); > if (cnt < 0) { > drop_extent_group(&group);
