This is a note to let you know that I've just added the patch titled
cxl/region: Flag partially torn down regions as unusable
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cxl-region-flag-partially-torn-down-regions-as-unusa.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit efed36881a583c305bceaebe7dbb055edd141ff9
Author: Dan Williams <dan.j.williams@xxxxxxxxx>
Date: Fri Jun 16 18:24:34 2023 -0700
cxl/region: Flag partially torn down regions as unusable
[ Upstream commit 2ab47045ac96a605e3037d479a7d5854570ee5bf ]
cxl_region_decode_reset() walks all the decoders associated with a given
region and disables them. Due to decoder ordering rules it is possible
that a switch in the topology notices that a given decoder can not be
shutdown before another region with a higher HPA is shutdown first. That
can leave the region in a partially committed state.
Capture that state in a new CXL_REGION_F_NEEDS_RESET flag and require
that a successful cxl_region_decode_reset() attempt must be completed
before cxl_region_probe() accepts the region.
This is a corollary for the bug that Jonathan identified in "CXL/region
: commit reset of out of order region appears to succeed." [1].
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Link: http://lore.kernel.org/r/20230316171441.0000205b@xxxxxxxxxx [1]
Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware")
Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Link: https://lore.kernel.org/r/168696507423.3590522.16254212607926684429.stgit@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 3b3bbd98e99d5..c1422167ab02b 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -182,14 +182,19 @@ static int cxl_region_decode_reset(struct cxl_region *cxlr, int count)
rc = cxld->reset(cxld);
if (rc)
return rc;
+ set_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags);
}
endpoint_reset:
rc = cxled->cxld.reset(&cxled->cxld);
if (rc)
return rc;
+ set_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags);
}
+ /* all decoders associated with this region have been torn down */
+ clear_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags);
+
return 0;
}
@@ -2740,6 +2745,13 @@ static int cxl_region_probe(struct device *dev)
goto out;
}
+ if (test_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags)) {
+ dev_err(&cxlr->dev,
+ "failed to activate, re-commit region and retry\n");
+ rc = -ENXIO;
+ goto out;
+ }
+
/*
* From this point on any path that changes the region's state away from
* CXL_CONFIG_COMMIT is also responsible for releasing the driver.
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 70ab8fcd0377c..dcebe48bb5bb5 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -469,6 +469,14 @@ struct cxl_region_params {
*/
#define CXL_REGION_F_AUTO 0
+/*
+ * Require that a committed region successfully complete a teardown once
+ * any of its associated decoders have been torn down. This maintains
+ * the commit state for the region since there are committed decoders,
+ * but blocks cxl_region_probe().
+ */
+#define CXL_REGION_F_NEEDS_RESET 1
+
/**
* struct cxl_region - CXL region
* @dev: This region's device
