powerpc/eeh: Reenable PCI devices after reset

The PCI devices that have been passed through are enabled before
reset, we need restore to the enabled state after reset. Otherwise,
MMIO access might be issued to disabled devices after reset and
causes exceptional recursive EEH error.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/eeh.c

@@ -1342,6 +1342,53 @@ int eeh_pe_get_state(struct eeh_pe *pe)
 }
 EXPORT_SYMBOL_GPL(eeh_pe_get_state);
 
+static int eeh_pe_reenable_devices(struct eeh_pe *pe)
+{
+	struct eeh_dev *edev, *tmp;
+	struct pci_dev *pdev;
+	int ret = 0;
+
+	/* Restore config space */
+	eeh_pe_restore_bars(pe);
+
+	/*
+	 * Reenable PCI devices as the devices passed
+	 * through are always enabled before the reset.
+	 */
+	eeh_pe_for_each_dev(pe, edev, tmp) {
+		pdev = eeh_dev_to_pci_dev(edev);
+		if (!pdev)
+			continue;
+
+		ret = pci_reenable_device(pdev);
+		if (ret) {
+			pr_warn("%s: Failure %d reenabling %s\n",
+				__func__, ret, pci_name(pdev));
+			return ret;
+		}
+	}
+
+	/* The PE is still in frozen state */
+	ret = eeh_ops->set_option(pe, EEH_OPT_THAW_MMIO);
+	if (ret) {
+		pr_warn("%s: Failure %d enabling MMIO for PHB#%x-PE#%x\n",
+			__func__, ret, pe->phb->global_number, pe->addr);
+		return ret;
+	}
+
+	ret = eeh_ops->set_option(pe, EEH_OPT_THAW_DMA);
+	if (ret) {
+		pr_warn("%s: Failure %d enabling DMA for PHB#%x-PE#%x\n",
+			__func__, ret, pe->phb->global_number, pe->addr);
+		return ret;
+	}
+
+	/* Clear software isolated state */
+	eeh_pe_state_clear(pe, EEH_PE_ISOLATED);
+
+	return ret;
+}
+
 /**
  * eeh_pe_reset - Issue PE reset according to specified type
  * @pe: EEH PE
@@ -1368,17 +1415,7 @@ int eeh_pe_reset(struct eeh_pe *pe, int option)
 		if (ret)
 			break;
 
-		/*
-		 * The PE is still in frozen state and we need to clear
-		 * that. It's good to clear frozen state after deassert
-		 * to avoid messy IO access during reset, which might
-		 * cause recursive frozen PE.
-		 */
-		ret = eeh_ops->set_option(pe, EEH_OPT_THAW_MMIO);
-		if (!ret)
-			ret = eeh_ops->set_option(pe, EEH_OPT_THAW_DMA);
-		if (!ret)
-			eeh_pe_state_clear(pe, EEH_PE_ISOLATED);
+		ret = eeh_pe_reenable_devices(pe);
 		break;
 	case EEH_RESET_HOT:
 	case EEH_RESET_FUNDAMENTAL:
@@ -1417,9 +1454,6 @@ int eeh_pe_configure(struct eeh_pe *pe)
 	if (!pe)
 		return -ENODEV;
 
-	/* Restore config space for the affected devices */
-	eeh_pe_restore_bars(pe);
-
 	return ret;
 }
 EXPORT_SYMBOL_GPL(eeh_pe_configure);