Merge branch 'pci/cxl'

- Lock the upstream bridge while using it to perform a Secondary Bus Reset
  (Dave Jiang)

- Return failure when attempting Secondary Bus Reset below a CXL Port that
  has SBR masked (Dave Jiang)

- Add a "cxl_bus" reset method that temporarily unmasks SBR (Dave Jiang)

- Add a warning if we reset a CXL type 3 memory device that was in use
  while being reset (Dave Jiang)

* pci/cxl:
  cxl: Add post-reset warning if reset results in loss of previously committed HDM decoders
  PCI/CXL: Add 'cxl_bus' reset method for devices below CXL Ports
  PCI/CXL: Fail bus reset if upstream CXL Port has SBR masked
  PCI: Lock upstream bridge for pci_reset_function()
  PCI/CXL: Move CXL Vendor ID to pci_ids.h

1 files changed, 94 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e5f243dd4288..13605261a881 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4879,6 +4879,7 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
  */
 int pci_bridge_secondary_bus_reset(struct pci_dev *dev)
 {
+	lock_map_assert_held(&dev->cfg_access_lock);
 	pcibios_reset_secondary_bus(dev);
 
 	return pci_bridge_wait_for_secondary_bus(dev, "bus reset");
@@ -4927,16 +4928,96 @@ static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe)
 	return pci_reset_hotplug_slot(dev->slot->hotplug, probe);
 }
 
+static u16 cxl_port_dvsec(struct pci_dev *dev)
+{
+	return pci_find_dvsec_capability(dev, PCI_VENDOR_ID_CXL,
+					 PCI_DVSEC_CXL_PORT);
+}
+
+static bool cxl_sbr_masked(struct pci_dev *dev)
+{
+	u16 dvsec, reg;
+	int rc;
+
+	dvsec = cxl_port_dvsec(dev);
+	if (!dvsec)
+		return false;
+
+	rc = pci_read_config_word(dev, dvsec + PCI_DVSEC_CXL_PORT_CTL, &reg);
+	if (rc || PCI_POSSIBLE_ERROR(reg))
+		return false;
+
+	/*
+	 * Per CXL spec r3.1, sec 8.1.5.2, when "Unmask SBR" is 0, the SBR
+	 * bit in Bridge Control has no effect.  When 1, the Port generates
+	 * hot reset when the SBR bit is set to 1.
+	 */
+	if (reg & PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR)
+		return false;
+
+	return true;
+}
+
 static int pci_reset_bus_function(struct pci_dev *dev, bool probe)
 {
+	struct pci_dev *bridge = pci_upstream_bridge(dev);
 	int rc;
 
+	/*
+	 * If "dev" is below a CXL port that has SBR control masked, SBR
+	 * won't do anything, so return error.
+	 */
+	if (bridge && cxl_sbr_masked(bridge)) {
+		if (probe)
+			return 0;
+
+		return -ENOTTY;
+	}
+
 	rc = pci_dev_reset_slot_function(dev, probe);
 	if (rc != -ENOTTY)
 		return rc;
 	return pci_parent_bus_reset(dev, probe);
 }
 
+static int cxl_reset_bus_function(struct pci_dev *dev, bool probe)
+{
+	struct pci_dev *bridge;
+	u16 dvsec, reg, val;
+	int rc;
+
+	bridge = pci_upstream_bridge(dev);
+	if (!bridge)
+		return -ENOTTY;
+
+	dvsec = cxl_port_dvsec(bridge);
+	if (!dvsec)
+		return -ENOTTY;
+
+	if (probe)
+		return 0;
+
+	rc = pci_read_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, &reg);
+	if (rc)
+		return -ENOTTY;
+
+	if (reg & PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR) {
+		val = reg;
+	} else {
+		val = reg | PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR;
+		pci_write_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL,
+				      val);
+	}
+
+	rc = pci_reset_bus_function(dev, probe);
+
+	if (reg != val)
+		pci_write_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL,
+				      reg);
+
+	return rc;
+}
+
 void pci_dev_lock(struct pci_dev *dev)
 {
 	/* block PM suspend, driver probe, etc. */
@@ -5021,6 +5102,7 @@ static const struct pci_reset_fn_method pci_reset_fn_methods[] = {
 	{ pci_af_flr, .name = "af_flr" },
 	{ pci_pm_reset, .name = "pm" },
 	{ pci_reset_bus_function, .name = "bus" },
+	{ cxl_reset_bus_function, .name = "cxl_bus" },
 };
 
 static ssize_t reset_method_show(struct device *dev,
@@ -5245,11 +5327,20 @@ void pci_init_reset_methods(struct pci_dev *dev)
  */
 int pci_reset_function(struct pci_dev *dev)
 {
+	struct pci_dev *bridge;
 	int rc;
 
 	if (!pci_reset_supported(dev))
 		return -ENOTTY;
 
+	/*
+	 * If there's no upstream bridge, no locking is needed since there is
+	 * no upstream bridge configuration to hold consistent.
+	 */
+	bridge = pci_upstream_bridge(dev);
+	if (bridge)
+		pci_dev_lock(bridge);
+
 	pci_dev_lock(dev);
 	pci_dev_save_and_disable(dev);
 
@@ -5258,6 +5349,9 @@ int pci_reset_function(struct pci_dev *dev)
 	pci_dev_restore(dev);
 	pci_dev_unlock(dev);
 
+	if (bridge)
+		pci_dev_unlock(bridge);
+
 	return rc;
 }
 EXPORT_SYMBOL_GPL(pci_reset_function);