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.we...@intel.com>
---
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;