6.5-stable review patch. If anyone has any objections, please let me know.
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From: Alison Schofield alison.schofield@intel.com
[ Upstream commit 9e4edf1a2196fa4bea6e8201f166785bd066446a ]
Currently, when the region driver attaches a region to a port, it selects the ports next available decoder to program.
With the addition of auto-discovered regions, a port decoder has already been programmed so grabbing the next available decoder can be a mismatch when there is more than one region using the port.
The failure appears like this with CXL DEBUG enabled:
[] cxl_core:alloc_region_ref:754: cxl region0: endpoint9: HPA order violation region0:[mem 0x14780000000-0x1478fffffff flags 0x200] vs [mem 0x880000000-0x185fffffff flags 0x200] [] cxl_core:cxl_port_attach_region:972: cxl region0: endpoint9: failed to allocate region reference
When CXL DEBUG is not enabled, there is no failure message. The region just never materializes. Users can suspect this issue if they know their firmware has programmed decoders so that more than one region is using a port. Note that the problem may appear intermittently, ie not on every reboot.
Add a matching method for auto-discovered regions that finds a decoder based on an HPA range. The decoder range must exactly match the region resource parameter.
Fixes: a32320b71f08 ("cxl/region: Add region autodiscovery") Signed-off-by: Alison Schofield alison.schofield@intel.com Reviewed-by: Dave Jiang dave.jiang@intel.com Reviewed-by: Davidlohr Bueso dave@stgolabs.net Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com Link: https://lore.kernel.org/r/20230905211007.256385-1-alison.schofield@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cxl/core/region.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index e115ba382e044..b4c6a749406f1 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -717,13 +717,35 @@ static int match_free_decoder(struct device *dev, void *data) return 0; }
+static int match_auto_decoder(struct device *dev, void *data) +{ + struct cxl_region_params *p = data; + struct cxl_decoder *cxld; + struct range *r; + + if (!is_switch_decoder(dev)) + return 0; + + cxld = to_cxl_decoder(dev); + r = &cxld->hpa_range; + + if (p->res && p->res->start == r->start && p->res->end == r->end) + return 1; + + return 0; +} + static struct cxl_decoder *cxl_region_find_decoder(struct cxl_port *port, struct cxl_region *cxlr) { struct device *dev; int id = 0;
- dev = device_find_child(&port->dev, &id, match_free_decoder); + if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags)) + dev = device_find_child(&port->dev, &cxlr->params, + match_auto_decoder); + else + dev = device_find_child(&port->dev, &id, match_free_decoder); if (!dev) return NULL; /*