[PATCH Wily SRU] powerpc/powernv: Fix stale PE primary bus

[tim.gardner at canonical.com]

From: Gavin Shan <gwshan at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1546145

When PCI bus is unplugged during full hotplug for EEH recovery,
the platform PE instance (struct pnv_ioda_pe) isn't released and
it dereferences the stale PCI bus that has been released. It leads
to kernel crash when referring to the stale PCI bus.

This fixes the issue by correcting the PE's primary bus when it's
oneline at plugging time, in pnv_pci_dma_bus_setup() which is to
be called by pcibios_fixup_bus().

Cc: stable at vger.kernel.org # v4.1+
Reported-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
Reported-by: Pradipta Ghosh <pradghos at in.ibm.com>
Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Tested-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
(cherry picked from linux-next commit 1bc74f1ccd457832dc515fc1febe6655985fdcd2)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c |  1 +
 arch/powerpc/platforms/powernv/pci.c      | 20 ++++++++++++++++++++
 arch/powerpc/platforms/powernv/pci.h      |  1 +
 3 files changed, 22 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index e3edd4b..da0a5f2 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3064,6 +3064,7 @@ static void pnv_pci_ioda_shutdown(struct pci_controller *hose)
 
 static const struct pci_controller_ops pnv_pci_ioda_controller_ops = {
        .dma_dev_setup = pnv_pci_dma_dev_setup,
+       .dma_bus_setup = pnv_pci_dma_bus_setup,
 #ifdef CONFIG_PCI_MSI
        .setup_msi_irqs = pnv_setup_msi_irqs,
        .teardown_msi_irqs = pnv_teardown_msi_irqs,
diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index bcbe2bf..5e9e0dd 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -762,6 +762,26 @@ void pnv_pci_dma_dev_setup(struct pci_dev *pdev)
 		phb->dma_dev_setup(phb, pdev);
 }
 
+void pnv_pci_dma_bus_setup(struct pci_bus *bus)
+{
+	struct pci_controller *hose = bus->sysdata;
+	struct pnv_phb *phb = hose->private_data;
+	struct pnv_ioda_pe *pe;
+
+	list_for_each_entry(pe, &phb->ioda.pe_list, list) {
+		if (!(pe->flags & (PNV_IODA_PE_BUS | PNV_IODA_PE_BUS_ALL)))
+			continue;
+
+		if (!pe->pbus)
+			continue;
+
+		if (bus->number == ((pe->rid >> 8) & 0xFF)) {
+			pe->pbus = bus;
+			break;
+		}
+	}
+}
+
 void pnv_pci_shutdown(void)
 {
 	struct pci_controller *hose;
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 93a319a..aa127cd 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -234,6 +234,7 @@ extern void pnv_pci_reset_secondary_bus(struct pci_dev *dev);
 extern int pnv_eeh_phb_reset(struct pci_controller *hose, int option);
 
 extern void pnv_pci_dma_dev_setup(struct pci_dev *pdev);
+extern void pnv_pci_dma_bus_setup(struct pci_bus *bus);
 extern int pnv_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type);
 extern void pnv_teardown_msi_irqs(struct pci_dev *pdev);
 
-- 
2.7.0