cxl/region: Move coherence tracking into cxl_region_attach()

Each time the contents of a given HPA are potentially changed in a cache
incoherent manner the CXL core sets CXL_REGION_F_INCOHERENT to
invalidate CPU caches before the region is used.

Successful invocation of attach_target() indicates that DPA has been
newly assigned to a given HPA in the dynamic region creation flow.
However, attach_target() is also reused in the autodiscovery flow where
the region was activated by platform firmware. In that case there is no
need to invalidate caches because that region is already in active use
and nothing about the autodiscovery flow modifies the HPA-to-DPA
relationship.

In the autodiscovery case cxl_region_attach() exits early after
determining the endpoint decoder is already correctly attached to the
region.

Fixes: a32320b71f08 ("cxl/region: Add region autodiscovery")
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/168002858817.50647.1217607907088920888.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 52bbf6268d5fb8b004aadb846bac7a12ecfaac5b..b2fd67fcebfb5742ce2095d062b7201075e4b10f 100644 (file)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1674,6 +1674,7 @@ static int cxl_region_attach(struct cxl_region *cxlr,
                if (rc)
                        goto err_decrement;
                p->state = CXL_CONFIG_ACTIVE;
+               set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
        }
 
        cxled->cxld.interleave_ways = p->interleave_ways;
@@ -1775,8 +1776,6 @@ static int attach_target(struct cxl_region *cxlr,
 
        down_read(&cxl_dpa_rwsem);
        rc = cxl_region_attach(cxlr, cxled, pos);
-       if (rc == 0)
-               set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
        up_read(&cxl_dpa_rwsem);
        up_write(&cxl_region_rwsem);
        return rc;