powerpc/powernv: Fix the state of root PE

The PE for root bus (root PE) can be removed because of PCI hot
remove in EEH recovery path for fenced PHB error. We need update
@phb->root_pe_populated accordingly so that the root PE can be
populated again in forthcoming PCI hot add path. Also, the PE
shouldn't be destroyed as it's global and reserved resource.

Fixes: c5f7700bbd2e ("powerpc/powernv: Dynamically release PE")
Reported-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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

@@ -3426,7 +3426,17 @@ static void pnv_ioda_release_pe(struct pnv_ioda_pe *pe)
 		}
 	}
 
-	pnv_ioda_free_pe(pe);
+	/*
+	 * The PE for root bus can be removed because of hotplug in EEH
+	 * recovery for fenced PHB error. We need to mark the PE dead so
+	 * that it can be populated again in PCI hot add path. The PE
+	 * shouldn't be destroyed as it's the global reserved resource.
+	 */
+	if (phb->ioda.root_pe_populated &&
+	    phb->ioda.root_pe_idx == pe->pe_number)
+		phb->ioda.root_pe_populated = false;
+	else
+		pnv_ioda_free_pe(pe);
 }
 
 static void pnv_pci_release_device(struct pci_dev *pdev)