powerpc/eeh: sysfs entries lost

The sysfs entries are lost because of commit 2213fb1 ("powerpc/eeh:
Skip eeh sysfs when eeh is disabled"). That commit added condition
to create sysfs entries with EEH_ENABLED, which isn't populated
when trying to create sysfs entries on PowerNV platform during system
boot time. The patch fixes the issue by:

   * Reoder EEH initialization functions so that they're same on
     PowerNV/pSeries.
   * Cache PE's primary bus by PowerNV platform instead of EEH core
     to avoid kernel crash caused by the function reorder. Another
     benefit with this is to avoid one eeh_probe_mode_dev() in EEH
     core.

Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
Acked-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/eeh_pe.c

@@ -350,17 +350,6 @@ int eeh_add_to_parent_pe(struct eeh_dev *edev)
 	pe->addr	= edev->pe_config_addr;
 	pe->config_addr	= edev->config_addr;
 
-	/*
-	 * While doing PE reset, we probably hot-reset the
-	 * upstream bridge. However, the PCI devices including
-	 * the associated EEH devices might be removed when EEH
-	 * core is doing recovery. So that won't safe to retrieve
-	 * the bridge through downstream EEH device. We have to
-	 * trace the parent PCI bus, then the upstream bridge.
-	 */
-	if (eeh_probe_mode_dev())
-		pe->bus = eeh_dev_to_pci_dev(edev)->bus;
-
 	/*
 	 * Put the new EEH PE into hierarchy tree. If the parent
 	 * can't be found, the newly created PE will be attached

arch/powerpc/platforms/powernv/eeh-powernv.c

@@ -107,6 +107,7 @@ static int powernv_eeh_dev_probe(struct pci_dev *dev, void *flag)
 	struct pnv_phb *phb = hose->private_data;
 	struct device_node *dn = pci_device_to_OF_node(dev);
 	struct eeh_dev *edev = of_node_to_eeh_dev(dn);
+	int ret;
 
 	/*
 	 * When probing the root bridge, which doesn't have any
@@ -143,7 +144,21 @@ static int powernv_eeh_dev_probe(struct pci_dev *dev, void *flag)
 	edev->pe_config_addr	= phb->bdfn_to_pe(phb, dev->bus, dev->devfn & 0xff);
 
 	/* Create PE */
-	eeh_add_to_parent_pe(edev);
+	ret = eeh_add_to_parent_pe(edev);
+	if (ret) {
+		pr_warn("%s: Can't add PCI dev %s to parent PE (%d)\n",
+			__func__, pci_name(dev), ret);
+		return ret;
+	}
+
+	/*
+	 * Cache the PE primary bus, which can't be fetched when
+	 * full hotplug is in progress. In that case, all child
+	 * PCI devices of the PE are expected to be removed prior
+	 * to PE reset.
+	 */
+	if (!edev->pe->bus)
+		edev->pe->bus = dev->bus;
 
 	/*
 	 * Enable EEH explicitly so that we will do EEH check

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -1145,8 +1145,8 @@ static void pnv_pci_ioda_fixup(void)
 
 #ifdef CONFIG_EEH
 	eeh_probe_mode_set(EEH_PROBE_MODE_DEV);
-	eeh_addr_cache_build();
 	eeh_init();
+	eeh_addr_cache_build();
 #endif
 }