cxl/region: Add memory hotplug notifier for cxl region

When the CXL region is formed, the driver computes the performance data
for the region. However this data is not available at the node data
collection that has been populated by the HMAT during kernel
initialization. Add a memory hotplug notifier to update the access
coordinates to the 'struct memory_target' context kept by the
HMAT_REPORTING code.

Add CXL_CALLBACK_PRI for a memory hotplug callback priority. Set the
priority number to be called before HMAT_CALLBACK_PRI. The CXL update must
happen before hmat_callback().

A new HMAT_REPORTING helper hmat_update_target_coordinates() is added in
order to allow CXL to update the memory_target access coordinates.

A new ext_updated member is added to the memory_target to indicate that
the access coordinates within the memory_target has been updated by an
external agent such as CXL. This prevents data being overwritten by the
hmat_update_target_attrs() triggered by hmat_callback().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Huang, Ying <ying.huang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20240308220055.2172956-12-dave.jiang@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index 40052666ebf1..ee1bc8fa396b 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -580,3 +580,9 @@ void cxl_region_perf_data_calculate(struct cxl_region *cxlr,
 			DIV_ROUND_UP(cxlr->coord[i].write_latency, 1000);
 	}
 }
+
+int cxl_update_hmat_access_coordinates(int nid, struct cxl_region *cxlr,
+				       enum access_coordinate_class access)
+{
+	return hmat_update_target_coordinates(nid, &cxlr->coord[access], access);
+}