From: Dan Williams <dan.j.williams@xxxxxxxxx> [ 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> --- drivers/cxl/core/region.c | 12 ++++++++++++ drivers/cxl/cxl.h | 8 ++++++++ 2 files changed, 20 insertions(+) diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 594ce3c2565df..fa29bd2ec3227 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; } @@ -2864,6 +2869,13 @@ 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 -- 2.39.2
