[PATCH v2] PCI/PM: Avoid suspending the device with errors

[Raag Jadav <raag.jadav@intel.com>]

If an error is triggered before or during system suspend, any bus level
power state transition will result in unpredictable behaviour by the
device with failed recovery. Avoid suspending such a device and leave
it in its existing power state.

This only covers the devices that rely on PCI core PM for their power
state transition.

Signed-off-by: Raag Jadav <raag.jadav@intel.com>
---

v2: Synchronize AER handling with PCI PM (Rafael)

More discussion on [1].
[1] https://lore.kernel.org/all/CAJZ5v0g-aJXfVH+Uc=9eRPuW08t-6PwzdyMXsC6FZRKYJtY03Q@mail.gmail.com/

 drivers/pci/pci-driver.c |  3 ++-
 drivers/pci/pcie/aer.c   | 11 +++++++++++
 include/linux/aer.h      |  2 ++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index f57ea36d125d..289a1fa7cb2d 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -884,7 +884,8 @@ static int pci_pm_suspend_noirq(struct device *dev)
 		}
 	}
 
-	if (!pci_dev->state_saved) {
+	/* Avoid suspending the device with errors */
+	if (!pci_aer_in_progress(pci_dev) && !pci_dev->state_saved) {
 		pci_save_state(pci_dev);
 
 		/*
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 508474e17183..b70f5011d4f5 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -233,6 +233,17 @@ int pcie_aer_is_native(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_NS_GPL(pcie_aer_is_native, "CXL");
 
+bool pci_aer_in_progress(struct pci_dev *dev)
+{
+	u16 reg16;
+
+	if (!pcie_aer_is_native(dev))
+		return false;
+
+	pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &reg16);
+	return !!(reg16 & PCI_EXP_AER_FLAGS);
+}
+
 static int pci_enable_pcie_error_reporting(struct pci_dev *dev)
 {
 	int rc;
diff --git a/include/linux/aer.h b/include/linux/aer.h
index 947b63091902..68ae5378256e 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -48,12 +48,14 @@ struct aer_capability_regs {
 #if defined(CONFIG_PCIEAER)
 int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
 int pcie_aer_is_native(struct pci_dev *dev);
+bool pci_aer_in_progress(struct pci_dev *dev);
 #else
 static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
 {
 	return -EINVAL;
 }
 static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
+static inline bool pci_aer_in_progress(struct pci_dev *dev) { return false; }
 #endif
 
 void pci_print_aer(struct pci_dev *dev, int aer_severity,
-- 
2.34.1