nvme-pci: try function level reset on init failure

NVMe devices from multiple vendors appear to get stuck in a reset state
that we can't get out of with an NVMe level Controller Reset. The kernel
would report these with messages that look like:

  Device not ready; aborting reset, CSTS=0x1

These have historically required a power cycle to make them usable
again, but in many cases, a PCIe FLR is sufficient to restart operation
without a power cycle. Try it if the initial controller reset fails
during any nvme reset attempt.

Signed-off-by: Keith Busch <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Nitesh Shetty <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>

Author: keithbusch

drivers/nvme/host/pci.c

@@ -2064,8 +2064,28 @@ static int nvme_pci_configure_admin_queue(struct nvme_dev *dev)
 	 * might be pointing at!
 	 */
 	result = nvme_disable_ctrl(&dev->ctrl, false);
-	if (result < 0)
-		return result;
+	if (result < 0) {
+		struct pci_dev *pdev = to_pci_dev(dev->dev);
+
+		/*
+		 * The NVMe Controller Reset method did not get an expected
+		 * CSTS.RDY transition, so something with the device appears to
+		 * be stuck. Use the lower level and bigger hammer PCIe
+		 * Function Level Reset to attempt restoring the device to its
+		 * initial state, and try again.
+		 */
+		result = pcie_reset_flr(pdev, false);
+		if (result < 0)
+			return result;
+
+		pci_restore_state(pdev);
+		result = nvme_disable_ctrl(&dev->ctrl, false);
+		if (result < 0)
+			return result;
+
+		dev_info(dev->ctrl.device,
+			"controller reset completed after pcie flr\n");
+	}
 
 	result = nvme_alloc_queue(dev, 0, NVME_AQ_DEPTH);
 	if (result)