GenWQE: Add support for EEH error recovery

This patch implements the callbacks and functions necessary to have EEH
recovery support.

It adds a config option to enable or disable explicit calls to trigger
platform specific mechanisms on error recovery paths. This option is
enabled by default only on PPC64 systems and can be overritten via
debugfs. If this option is enabled, on the error recovery path the
driver will call pci_channel_offline() to check for error condition and
issue non-raw MMIO reads to trigger early EEH detection in case of
hardware failures. This is necessary since the driver MMIO helper
funtions use raw accessors.

Signed-off-by: Kleber Sacilotto de Souza <[e-mail]>
Acked-by: Frank Haverkamp <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/genwqe/Kconfig

···
 	  Enables PCIe card driver for IBM GenWQE accelerators.
 	  The user-space interface is described in
 	  include/linux/genwqe/genwqe_card.h.
+
+config GENWQE_PLATFORM_ERROR_RECOVERY
+	int "Use platform recovery procedures (0=off, 1=on)"
+	depends on GENWQE
+	default 1 if PPC64
+	default 0

drivers/misc/genwqe/card_base.c

···
 	cd->class_genwqe = class_genwqe;
 	cd->debugfs_genwqe = debugfs_genwqe;
 
+	/*
+	 * This comes from kernel config option and can be overritten via
+	 * debugfs.
+	 */
+	cd->use_platform_recovery = CONFIG_GENWQE_PLATFORM_ERROR_RECOVERY;
+
 	init_waitqueue_head(&cd->queue_waitq);
 
 	spin_lock_init(&cd->file_lock);
···
 	return 0;
 
  fatal_error:
+	if (cd->use_platform_recovery) {
+		/*
+		 * Since we use raw accessors, EEH errors won't be detected
+		 * by the platform until we do a non-raw MMIO or config space
+		 * read
+		 */
+		readq(cd->mmio + IO_SLC_CFGREG_GFIR);
+
+		/* We do nothing if the card is going over PCI recovery */
+		if (pci_channel_offline(pci_dev))
+			return -EIO;
+	}
+
 	dev_err(&pci_dev->dev,
 		"[%s] card unusable. Please trigger unbind!\n", __func__);
 
···
 
 	pci_set_master(pci_dev);
 	pci_enable_pcie_error_reporting(pci_dev);
+
+	/* EEH recovery requires PCIe fundamental reset */
+	pci_dev->needs_freset = 1;
 
 	/* request complete BAR-0 space (length = 0) */
 	cd->mmio_len = pci_resource_len(pci_dev, 0);
···
 
 	dev_err(&pci_dev->dev, "[%s] state=%d\n", __func__, state);
 
-	if (pci_dev == NULL)
-		return PCI_ERS_RESULT_NEED_RESET;
-
 	cd = dev_get_drvdata(&pci_dev->dev);
 	if (cd == NULL)
-		return PCI_ERS_RESULT_NEED_RESET;
+		return PCI_ERS_RESULT_DISCONNECT;
 
-	switch (state) {
-	case pci_channel_io_normal:
-		return PCI_ERS_RESULT_CAN_RECOVER;
-	case pci_channel_io_frozen:
+	/* Stop the card */
+	genwqe_health_check_stop(cd);
+	genwqe_stop(cd);
+
+	/*
+	 * On permanent failure, the PCI code will call device remove
+	 * after the return of this function.
+	 * genwqe_stop() can be called twice.
+	 */
+	if (state == pci_channel_io_perm_failure) {
+		return PCI_ERS_RESULT_DISCONNECT;
+	} else {
+		genwqe_pci_remove(cd);
 		return PCI_ERS_RESULT_NEED_RESET;
-	case pci_channel_io_perm_failure:
+	}
+}
+
+static pci_ers_result_t genwqe_err_slot_reset(struct pci_dev *pci_dev)
+{
+	int rc;
+	struct genwqe_dev *cd = dev_get_drvdata(&pci_dev->dev);
+
+	rc = genwqe_pci_setup(cd);
+	if (!rc) {
+		return PCI_ERS_RESULT_RECOVERED;
+	} else {
+		dev_err(&pci_dev->dev,
+			"err: problems with PCI setup (err=%d)\n", rc);
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
-
-	return PCI_ERS_RESULT_NEED_RESET;
 }
 
 static pci_ers_result_t genwqe_err_result_none(struct pci_dev *dev)
···
 	return PCI_ERS_RESULT_NONE;
 }
 
-static void genwqe_err_resume(struct pci_dev *dev)
+static void genwqe_err_resume(struct pci_dev *pci_dev)
 {
+	int rc;
+	struct genwqe_dev *cd = dev_get_drvdata(&pci_dev->dev);
+
+	rc = genwqe_start(cd);
+	if (!rc) {
+		rc = genwqe_health_check_start(cd);
+		if (rc)
+			dev_err(&pci_dev->dev,
+				"err: cannot start health checking! (err=%d)\n",
+				rc);
+	} else {
+		dev_err(&pci_dev->dev,
+			"err: cannot start card services! (err=%d)\n", rc);
+	}
 }
 
 static int genwqe_sriov_configure(struct pci_dev *dev, int numvfs)
···
 	.error_detected = genwqe_err_error_detected,
 	.mmio_enabled	= genwqe_err_result_none,
 	.link_reset	= genwqe_err_result_none,
-	.slot_reset	= genwqe_err_result_none,
+	.slot_reset	= genwqe_err_slot_reset,
 	.resume		= genwqe_err_resume,
 };
 

drivers/misc/genwqe/card_base.h

···
 	struct task_struct *health_thread;
 	wait_queue_head_t health_waitq;
 
+	int use_platform_recovery;	/* use platform recovery mechanisms */
+
 	/* char device */
 	dev_t  devnum_genwqe;		/* major/minor num card */
 	struct class *class_genwqe;	/* reference to class object */

drivers/misc/genwqe/card_ddcb.c

···
 	 * safer, but slower for the good-case ... See above.
 	 */
 	gfir = __genwqe_readq(cd, IO_SLC_CFGREG_GFIR);
-	if ((gfir & GFIR_ERR_TRIGGER) != 0x0) {
+	if (((gfir & GFIR_ERR_TRIGGER) != 0x0) &&
+	    !pci_channel_offline(pci_dev)) {
+
+		if (cd->use_platform_recovery) {
+			/*
+			 * Since we use raw accessors, EEH errors won't be
+			 * detected by the platform until we do a non-raw
+			 * MMIO or config space read
+			 */
+			readq(cd->mmio + IO_SLC_CFGREG_GFIR);
+
+			/* Don't do anything if the PCI channel is frozen */
+			if (pci_channel_offline(pci_dev))
+				goto exit;
+		}
 
 		wake_up_interruptible(&cd->health_waitq);
 
···
 		 * By default GFIRs causes recovery actions. This
 		 * count is just for debug when recovery is masked.
 		 */
-		printk_ratelimited(KERN_ERR
-				   "%s %s: [%s] GFIR=%016llx\n",
-				   GENWQE_DEVNAME, dev_name(&pci_dev->dev),
-				   __func__, gfir);
+		dev_err_ratelimited(&pci_dev->dev,
+				    "[%s] GFIR=%016llx\n",
+				    __func__, gfir);
 	}
 
+ exit:
 	return IRQ_HANDLED;
 }
 

drivers/misc/genwqe/card_debugfs.c

···
 		goto err1;
 	}
 
+	file = debugfs_create_u32("use_platform_recovery", 0666, root,
+				  &cd->use_platform_recovery);
+	if (!file) {
+		ret = -ENOMEM;
+		goto err1;
+	}
+
 	cd->debugfs_root = root;
 	return 0;
 err1:

drivers/misc/genwqe/card_dev.c

···
 	int rc = 0;
 	struct genwqe_file *cfile = (struct genwqe_file *)filp->private_data;
 	struct genwqe_dev *cd = cfile->cd;
+	struct pci_dev *pci_dev = cd->pci_dev;
 	struct genwqe_reg_io __user *io;
 	u64 val;
 	u32 reg_offs;
+
+	/* Return -EIO if card hit EEH */
+	if (pci_channel_offline(pci_dev))
+		return -EIO;
 
 	if (_IOC_TYPE(cmd) != GENWQE_IOC_CODE)
 		return -EINVAL;

drivers/misc/genwqe/card_utils.c

···
  */
 int __genwqe_writeq(struct genwqe_dev *cd, u64 byte_offs, u64 val)
 {
+	struct pci_dev *pci_dev = cd->pci_dev;
+
 	if (cd->err_inject & GENWQE_INJECT_HARDWARE_FAILURE)
 		return -EIO;
 
 	if (cd->mmio == NULL)
+		return -EIO;
+
+	if (pci_channel_offline(pci_dev))
 		return -EIO;
 
 	__raw_writeq((__force u64)cpu_to_be64(val), cd->mmio + byte_offs);
···
  */
 int __genwqe_writel(struct genwqe_dev *cd, u64 byte_offs, u32 val)
 {
+	struct pci_dev *pci_dev = cd->pci_dev;
+
 	if (cd->err_inject & GENWQE_INJECT_HARDWARE_FAILURE)
 		return -EIO;
 
 	if (cd->mmio == NULL)
+		return -EIO;
+
+	if (pci_channel_offline(pci_dev))
 		return -EIO;
 
 	__raw_writel((__force u32)cpu_to_be32(val), cd->mmio + byte_offs);