[PATCH v2] cxl: Add endpoint decoder flags clear when PCI reset happens

[Dave Jiang <dave.jiang@intel.com>]

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>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Rename CLEAR_MASK to RESET_MASK (Alison)
- Make the helper function take a mask argument to specify which flags
  to clear (Alison)
---
 drivers/cxl/cxl.h |  1 +
 drivers/cxl/pci.c | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 9b947286eb9b..d09c84bcc015 100644
--- a/drivers/cxl/cxl.h
+++ b/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,
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index fbb300a01830..a0bba4b4db92 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -1030,6 +1030,20 @@ static void cxl_error_resume(struct pci_dev *pdev)
 		 dev->driver ? "successful" : "failed");
 }
 
+static int cxl_decoder_clear_flags(struct device *dev, void *data)
+{
+	struct cxl_endpoint_decoder *cxled;
+	unsigned long *flags = data;
+
+	if (!is_endpoint_decoder(dev))
+		return 0;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	cxled->cxld.flags &= ~(*flags);
+
+	return 0;
+}
+
 static void cxl_reset_done(struct pci_dev *pdev)
 {
 	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
@@ -1045,6 +1059,11 @@ static void cxl_reset_done(struct pci_dev *pdev)
 	guard(device)(&cxlmd->dev);
 	if (cxlmd->endpoint &&
 	    cxl_endpoint_decoder_reset_detected(cxlmd->endpoint)) {
+		unsigned long flags = CXL_DECODER_F_RESET_MASK;
+
+		device_for_each_child(&cxlmd->endpoint->dev, &flags,
+				      cxl_decoder_clear_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);

base-commit: f338e77383789c0cae23ca3d48adcc5e9e137e3c
-- 
2.53.0