[PATCH v2 07/15] cxl/region: Use translated HPA ranges to find the port's decoder

Robert Richter
2025-02-18T13:25:01Z

This is the second step to find the port's decoder with address
translation enabled. The translated HPA range must be used to find a
decoder. The port's HPA range is determined by applying address
translation when crossing memory domains for the HPA range to each
port while traversing the topology from the endpoint up to the port.

Introduce a function cxl_find_auto_decoder() that calculates the
port's translated address range to determine the corresponding
decoder. Use the existing helper function cxl_port_calc_hpa() for HPA
range calculation.

Signed-off-by: Robert Richter <rrichter@amd.com>
---
drivers/cxl/core/region.c | 60 +++++++++++++++++++++++++++++++++++++--
1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 5048511f9de5..6d5ede5b4c43 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -887,6 +887,63 @@ static int match_auto_decoder(struct device *dev, const void *data)
return 0;
}

+static struct device *
+cxl_find_auto_decoder(struct cxl_port *port, struct cxl_endpoint_decoder *cxled,
+ struct cxl_region *cxlr)
+{
+ struct cxl_port *parent, *iter = cxled_to_port(cxled);
+ struct cxl_decoder *cxld = &cxled->cxld;
+ struct range hpa = cxld->hpa_range;
+ struct cxl_region_ref *rr;
+
+ while (iter != port) {
+ parent = parent_port_of(iter);
+ if (!parent) {
+ dev_warn(&port->dev,
+ "port not a parent of endpoint decoder %s\n",
+ dev_name(&cxled->cxld.dev));
+ return NULL;
+ }
+
+ if (!parent->to_hpa) {
+ iter = parent;
+ continue;
+ }
+
+ /* Lower domain decoders are already attached. */
+ rr = cxl_rr_load(iter, cxlr);
+ cxld = rr ? rr->decoder : NULL;
+ if (!cxld) {
+ dev_warn(&iter->dev,
+ "no decoder found for region %s\n",
+ dev_name(&cxlr->dev));
+ return NULL;
+ }
+
+ /* Check switch decoder range. */
+ if (cxld != &cxled->cxld &&
+ !match_auto_decoder(&cxld->dev, &hpa)) {
+ dev_warn(&iter->dev,
+ "decoder %s out of range %#llx-%#llx:%#llx-%#llx(%s)\n",
+ dev_name(&cxld->dev), cxld->hpa_range.start,
+ cxld->hpa_range.end, hpa.start, hpa.end,
+ dev_name(&cxled->cxld.dev));
+ return NULL;
+ }
+
+ if (cxl_port_calc_hpa(parent, cxld, &hpa) < 0)
+ return NULL;
+
+ iter = parent;
+ }
+
+ dev_dbg(cxld->dev.parent, "%s: range: %#llx-%#llx iw: %d ig: %d\n",
+ dev_name(&cxld->dev), hpa.start, hpa.end,
+ cxld->interleave_ways, cxld->interleave_granularity);
+
+ return device_find_child(&port->dev, &hpa, match_auto_decoder);
+}
+
/*
* Use cxl_find_decoder_early() only during region setup in the early
* setup stage. Once a port is attached to a region, the region
@@ -905,8 +962,7 @@ cxl_find_decoder_early(struct cxl_port *port,
return &cxled->cxld;

if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags))
- dev = device_find_child(&port->dev, &cxled->cxld.hpa_range,
- match_auto_decoder);
+ dev = cxl_find_auto_decoder(port, cxled, cxlr);
else
dev = device_find_child(&port->dev, NULL, match_free_decoder);
if (!dev)
--
2.39.5