Commit fdc9be90 authored by Li Ming's avatar Li Ming Committed by Dave Jiang
Browse files

cxl/edac: Fix the min_scrub_cycle of a region miscalculation 



When trying to update the scrub_cycle value of a cxl region, which means
updating the scrub_cycle value of each memdev under a cxl region. cxl
driver needs to guarantee the new scrub_cycle value is greater than the
min_scrub_cycle value of a memdev, otherwise the updating operation will
fail(Per Table 8-223 in CXL r3.2 section 8.2.10.9.11.1).

Current implementation logic of getting the min_scrub_cycle value of a
cxl region is that getting the min_scrub_cycle value of each memdevs
under the cxl region, then using the minimum min_scrub_cycle value as
the region's min_scrub_cycle. Checking if the new scrub_cycle value is
greater than this value. If yes, updating the new scrub_cycle value to
each memdevs. The issue is that the new scrub_cycle value is possibly
greater than the minimum min_scrub_cycle value of all memdevs but less
than the maximum min_scrub_cycle value of all memdevs if memdevs have
a different min_scrub_cycle value. The updating operation will always
fail on these memdevs which have a greater min_scrub_cycle than the new
scrub_cycle.

The correct implementation logic is to get the maximum value of these
memdevs' min_scrub_cycle, check if the new scrub_cycle value is greater
than the value. If yes, the new scrub_cycle value is fit for the region.

The change also impacts the result of
cxl_patrol_scrub_get_min_scrub_cycle(), the interface returned the
minimum min_scrub_cycle value among all memdevs under the region before
the change. The interface will return the maximum min_scrub_cycle value
among all memdevs under the region with the change.

Signed-off-by: default avatarLi Ming <ming.li@zohomail.com>
Reviewed-by: default avatarJonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: default avatarDave Jiang <dave.jiang@intel.com>
Reviewed-by: default avatarShiju Jose <shiju.jose@huawei.com>
Reviewed-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Link: https://patch.msgid.link/20250603104314.25569-1-ming.li@zohomail.com


Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
parent 87b42c11

drivers/cxl/core/edac.c

+6 −2
Original line number Diff line number Diff line
@@ -103,10 +103,10 @@ static int cxl_scrub_get_attrbs(struct cxl_patrol_scrub_context *cxl_ps_ctx, 
				u8 *cap, u16 *cycle, u8 *flags, u8 *min_cycle)

{

	struct cxl_mailbox *cxl_mbox;

	u8 min_scrub_cycle = U8_MAX;

	struct cxl_region_params *p;

	struct cxl_memdev *cxlmd;

	struct cxl_region *cxlr;

	u8 min_scrub_cycle = 0;

	int i, ret;



	if (!cxl_ps_ctx->cxlr) {
@@ -133,8 +133,12 @@ static int cxl_scrub_get_attrbs(struct cxl_patrol_scrub_context *cxl_ps_ctx, 
		if (ret)

			return ret;



		/*

		 * The min_scrub_cycle of a region is the max of minimum scrub

		 * cycles supported by memdevs that back the region.

		 */

		if (min_cycle)

			min_scrub_cycle = min(*min_cycle, min_scrub_cycle);

			min_scrub_cycle = max(*min_cycle, min_scrub_cycle);

	}



	if (min_cycle)