[PATCH v19 13/14] PCI/CXL: Mask/Unmask CXL protocol errors

[Terry Bowman <terry.bowman@amd.com>]

CXL protocol errors must be unmasked to be reported. Add
pci_aer_mask_internal_errors() as the symmetric counterpart to
pci_aer_unmask_internal_errors() and export both for cxl_core.

Unmask CXL internal errors in cxl_dport_map_ras() and
devm_cxl_port_ras_setup() after the RAS register block is
successfully mapped. Register a devm action to restore the mask
on teardown. The unmask/mask helpers gate on dev_is_pci() and
pcie_aer_is_native() internally so callers need no special-casing.

Remove the dev_is_pci(dport->dport_dev) guard in
devm_cxl_dport_rch_ras_setup(). On RCH systems dport->dport_dev
is the pci_host_bridge device which is not on pci_bus_type, so
this guard blocked real hardware. The caller already gates on
dport->rch.

Co-developed-by: Dan Williams <djbw@kernel.org>
Signed-off-by: Dan Williams <djbw@kernel.org>
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

---

Changes in v18 -> v19:
- Reworded commit message to be more concise.
- Use pci_clear_and_set_config_dword() in pci_aer_mask_internal_errors()
- Add review-by for DaveJ and Jonathan

Changes in v17->v18:
- Make cxl_unmask_proto_interrupts() and cxl_mask_proto_interrupts() static
- Remove dev_is_pci() guard from devm_cxl_dport_rch_ras_setup(); the guard
  blocked real RCH hardware because pci_host_bridge is not on pci_bus_type

Changes in v16->v17:
- Drop redundant cxl_mask_proto_interrupts() calls from unregister_port()
  and cxl_dport_remove(); the devres action registered alongside the unmask
  is the sole mask path.
- Update title
- Remove unnecessary check for aer_capabilities
- Gate cxl_unmask_proto_interrupts() on pcie_aer_is_native()
- Add pci_aer_mask_internal_errors() and cxl_mask_proto_interrupts()
- Only unmask on successful cxl_map_component_regs()
- NULL-check @dev in cxl_{un,}mask_proto_interrupts()
- Drop static and declare in core/core.h

Change in v15 -> v16:
- None

Change in v14 -> v15:
- None

Changes in v13->v14:
- Update commit title's prefix (Bjorn)

Changes in v12->v13:
- Add dev and dev_is_pci() NULL checks in cxl_unmask_proto_interrupts() (Terry)
- Add Dave Jiang's and Ben's review-by

Changes in v11->v12:
- None
---
 drivers/cxl/core/ras.c        | 73 +++++++++++++++++++++++++++++++----
 drivers/pci/pcie/aer.c        | 22 +++++++++--
 include/linux/aer.h           |  2 +
 tools/testing/cxl/Kbuild      |  1 +
 tools/testing/cxl/test/mock.c | 12 ++++++
 5 files changed, 99 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
index 0254b7ec64c30..40a8a03070652 100644
--- a/drivers/cxl/core/ras.c
+++ b/drivers/cxl/core/ras.c
@@ -114,16 +114,64 @@ static void cxl_cper_prot_err_work_fn(struct work_struct *work)
 }
 static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
 
+static void cxl_unmask_proto_interrupts(struct device *dev)
+{
+	struct pci_dev *pdev;
+
+	if (!dev || !dev_is_pci(dev))
+		return;
+
+	pdev = to_pci_dev(dev);
+	if (!pcie_aer_is_native(pdev))
+		return;
+
+	pci_aer_unmask_internal_errors(pdev);
+}
+
+static void cxl_mask_proto_interrupts(struct device *dev)
+{
+	struct pci_dev *pdev;
+
+	if (!dev || !dev_is_pci(dev))
+		return;
+
+	pdev = to_pci_dev(dev);
+	if (!pcie_aer_is_native(pdev))
+		return;
+
+	pci_aer_mask_internal_errors(pdev);
+}
+
+static void cxl_mask_proto_irqs(void *dev)
+{
+	cxl_mask_proto_interrupts(dev);
+}
+
 static void cxl_dport_map_ras(struct cxl_dport *dport)
 {
 	struct cxl_register_map *map = &dport->reg_map;
 	struct device *dev = dport->dport_dev;
 
-	if (!map->component_map.ras.valid)
+	if (!map->component_map.ras.valid) {
 		dev_dbg(dev, "RAS registers not found\n");
-	else if (cxl_map_component_regs(map, &dport->regs.component,
-					BIT(CXL_CM_CAP_CAP_ID_RAS)))
+		return;
+	}
+
+	if (cxl_map_component_regs(map, &dport->regs.component,
+				   BIT(CXL_CM_CAP_CAP_ID_RAS))) {
 		dev_dbg(dev, "Failed to map RAS capability.\n");
+		return;
+	}
+
+	if (!dev_is_pci(dev))
+		return;
+
+	cxl_unmask_proto_interrupts(dev);
+	if (devm_add_action_or_reset(dport_to_host(dport),
+				     cxl_mask_proto_irqs, dev)) {
+		dev_warn(dev, "failed to defer CXL proto-irq mask; CXL protocol error reporting disabled\n");
+		dport->regs.component.ras = NULL;
+	}
 }
 
 /**
@@ -140,9 +188,6 @@ void devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport)
 {
 	struct pci_host_bridge *host_bridge;
 
-	if (!dev_is_pci(dport->dport_dev))
-		return;
-
 	devm_cxl_dport_ras_setup(dport);
 
 	host_bridge = to_pci_host_bridge(dport->dport_dev);
@@ -157,6 +202,7 @@ EXPORT_SYMBOL_NS_GPL(devm_cxl_dport_rch_ras_setup, "CXL");
 void devm_cxl_port_ras_setup(struct cxl_port *port)
 {
 	struct cxl_register_map *map = &port->reg_map;
+	struct device *dev;
 
 	if (!map->component_map.ras.valid) {
 		dev_dbg(&port->dev, "RAS registers not found\n");
@@ -165,8 +211,21 @@ void devm_cxl_port_ras_setup(struct cxl_port *port)
 
 	map->host = &port->dev;
 	if (cxl_map_component_regs(map, &port->regs,
-				   BIT(CXL_CM_CAP_CAP_ID_RAS)))
+				   BIT(CXL_CM_CAP_CAP_ID_RAS))) {
 		dev_dbg(&port->dev, "Failed to map RAS capability\n");
+		return;
+	}
+
+	dev = is_cxl_endpoint(port) ? port->uport_dev->parent : port->uport_dev;
+	if (!dev_is_pci(dev))
+		return;
+
+	cxl_unmask_proto_interrupts(dev);
+	if (devm_add_action_or_reset(&port->dev, cxl_mask_proto_irqs, dev)) {
+		dev_warn(&port->dev,
+			 "failed to defer CXL proto-irq mask; CXL protocol error reporting disabled\n");
+		port->regs.ras = NULL;
+	}
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_port_ras_setup, "CXL");
 
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 0155f3923c1fd..d461f281e5372 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -1143,12 +1143,26 @@ void pci_aer_unmask_internal_errors(struct pci_dev *dev)
 	mask &= ~PCI_ERR_COR_INTERNAL;
 	pci_write_config_dword(dev, aer + PCI_ERR_COR_MASK, mask);
 }
+EXPORT_SYMBOL_FOR_MODULES(pci_aer_unmask_internal_errors, "cxl_core");
 
-/*
- * Internal errors are too device-specific to enable generally, however for CXL
- * their behavior is standardized for conveying CXL protocol errors.
+/**
+ * pci_aer_mask_internal_errors - mask internal errors
+ * @dev: pointer to the pci_dev data structure
+ *
+ * Mask internal errors in the Uncorrectable and Correctable Error
+ * Mask registers.
+ *
+ * Note: AER must be enabled and supported by the device which must be
+ * checked in advance, e.g. with pcie_aer_is_native().
  */
-EXPORT_SYMBOL_FOR_MODULES(pci_aer_unmask_internal_errors, "cxl_core");
+void pci_aer_mask_internal_errors(struct pci_dev *dev)
+{
+	pci_clear_and_set_config_dword(dev, dev->aer_cap + PCI_ERR_UNCOR_MASK,
+				       0, PCI_ERR_UNC_INTN);
+	pci_clear_and_set_config_dword(dev, dev->aer_cap + PCI_ERR_COR_MASK,
+				       0, PCI_ERR_COR_INTERNAL);
+}
+EXPORT_SYMBOL_FOR_MODULES(pci_aer_mask_internal_errors, "cxl_core");
 
 /**
  * pci_aer_handle_error - handle logging error into an event log
diff --git a/include/linux/aer.h b/include/linux/aer.h
index 8eba3192e2d15..b3657b80564b9 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -58,6 +58,7 @@ struct aer_capability_regs {
 int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
 int pcie_aer_is_native(struct pci_dev *dev);
 void pci_aer_unmask_internal_errors(struct pci_dev *dev);
+void pci_aer_mask_internal_errors(struct pci_dev *dev);
 #else
 static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
 {
@@ -65,6 +66,7 @@ static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
 }
 static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
 static inline void pci_aer_unmask_internal_errors(struct pci_dev *dev) { }
+static inline void pci_aer_mask_internal_errors(struct pci_dev *dev) { }
 #endif
 
 #ifdef CONFIG_CXL_RAS
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 2be1df80fcc93..957945201f04d 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -6,6 +6,7 @@ ldflags-y += --wrap=acpi_pci_find_root
 ldflags-y += --wrap=nvdimm_bus_register
 ldflags-y += --wrap=cxl_await_media_ready
 ldflags-y += --wrap=devm_cxl_add_rch_dport
+ldflags-y += --wrap=devm_cxl_dport_rch_ras_setup
 ldflags-y += --wrap=cxl_endpoint_parse_cdat
 ldflags-y += --wrap=devm_cxl_endpoint_decoders_setup
 ldflags-y += --wrap=hmat_get_extended_linear_cache_size
diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
index 6454b868b122c..5ad3243da8d29 100644
--- a/tools/testing/cxl/test/mock.c
+++ b/tools/testing/cxl/test/mock.c
@@ -220,6 +220,18 @@ struct cxl_dport *__wrap_devm_cxl_add_rch_dport(struct cxl_port *port,
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_add_rch_dport, "CXL");
 
+void __wrap_devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport)
+{
+	int index;
+	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
+
+	if (!ops || !ops->is_mock_port(dport->dport_dev))
+		devm_cxl_dport_rch_ras_setup(dport);
+
+	put_cxl_mock_ops(index);
+}
+EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_dport_rch_ras_setup, "CXL");
+
 void __wrap_cxl_endpoint_parse_cdat(struct cxl_port *port)
 {
 	int index;
-- 
2.34.1