[PATCH 1/2] PCI: Add per-device flag to disable native PCIe port services

[Han Gao <gaohan@iscas.ac.cn>]

Add PCI_DEV_FLAGS_NO_PORT_SERVICES to allow quirks to prevent the PCIe
port service driver from probing specific devices. This provides a
per-device equivalent of the global pcie_ports=compat kernel parameter.

Some platforms have PCIe root ports that break MSI delivery to downstream
devices when native port services (AER, PME, bwctrl, etc.) are active.
The existing pci_host_bridge native_* flags do not cover all services
(notably bwctrl), so a mechanism to skip port driver probing entirely
on a per-device basis is needed.

Cc: stable@vger.kernel.org
Signed-off-by: Han Gao <gaohan@iscas.ac.cn>
---
 drivers/pci/pcie/portdrv.c | 3 +++
 include/linux/pci.h        | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 2d6aa488fe7b..3386818d200d 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -685,6 +685,9 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
 static int pcie_portdrv_probe(struct pci_dev *dev,
 					const struct pci_device_id *id)
 {
+	if (dev->dev_flags & PCI_DEV_FLAGS_NO_PORT_SERVICES)
+		return -ENODEV;
+
 	int type = pci_pcie_type(dev);
 	int status;
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1c270f1d5123..e038fe14ef78 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -253,6 +253,8 @@ enum pci_dev_flags {
 	 * integrated with the downstream devices and doesn't use real PCI.
 	 */
 	PCI_DEV_FLAGS_PCI_BRIDGE_NO_ALIAS = (__force pci_dev_flags_t) (1 << 14),
+	/* Do not use native PCIe port services (equivalent to pcie_ports=compat) */
+	PCI_DEV_FLAGS_NO_PORT_SERVICES = (__force pci_dev_flags_t) (1 << 15),
 };
 
 enum pci_irq_reroute_variant {
-- 
2.47.3