cxl: Add endpoint decoder flags clear when PCI reset happens

When a PCI reset happens, the lock and enable flags of the CXL device
should be cleared to avoid stale state flags after reset. Add flag
clearing during cxl_reset_done() to clear the relevant endpoint
decoder flags for all decoders of the endpoint device.

Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260319152541.2739343-1-dave.jiang@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: davejiang

drivers/cxl/cxl.h

@@ -333,6 +333,7 @@ int cxl_dport_map_rcd_linkcap(struct pci_dev *pdev, struct cxl_dport *dport);
 #define CXL_DECODER_F_LOCK  BIT(4)
 #define CXL_DECODER_F_ENABLE    BIT(5)
 #define CXL_DECODER_F_NORMALIZED_ADDRESSING BIT(6)
+#define CXL_DECODER_F_RESET_MASK (CXL_DECODER_F_ENABLE | CXL_DECODER_F_LOCK)
 
 enum cxl_decoder_type {
 	CXL_DECODER_DEVMEM = 2,

drivers/cxl/pci.c

@@ -1030,6 +1030,19 @@ static void cxl_error_resume(struct pci_dev *pdev)
 		 dev->driver ? "successful" : "failed");
 }
 
+static int cxl_endpoint_decoder_clear_reset_flags(struct device *dev, void *data)
+{
+	struct cxl_endpoint_decoder *cxled;
+
+	if (!is_endpoint_decoder(dev))
+		return 0;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	cxled->cxld.flags &= ~CXL_DECODER_F_RESET_MASK;
+
+	return 0;
+}
+
 static void cxl_reset_done(struct pci_dev *pdev)
 {
 	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
@@ -1045,6 +1058,9 @@ static void cxl_reset_done(struct pci_dev *pdev)
 	guard(device)(&cxlmd->dev);
 	if (cxlmd->endpoint &&
 	    cxl_endpoint_decoder_reset_detected(cxlmd->endpoint)) {
+		device_for_each_child(&cxlmd->endpoint->dev, NULL,
+				      cxl_endpoint_decoder_clear_reset_flags);
+
 		dev_crit(dev, "SBR happened without memory regions removal.\n");
 		dev_crit(dev, "System may be unstable if regions hosted system memory.\n");
 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);