powerpc/pci: Mask linkDown on resetting PCI bus

The problem was initially reported by Wendy who tried pass through
IPR adapter, which was connected to PHB root port directly, to KVM
based guest. When doing that, pci_reset_bridge_secondary_bus() was
called by VFIO driver and linkDown was detected by the root port.
That caused all PEs to be frozen.

The patch fixes the issue by routing the reset for the secondary bus
of root port to underly firmware. For that, one more weak function
pci_reset_secondary_bus() is introduced so that the individual platforms
can override that and do specific reset for bridge's secondary bus.

Reported-by: Wendy Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 38 insertions, 2 deletions

diff --git a/arch/powerpc/platforms/powernv/eeh-ioda.c b/arch/powerpc/platforms/powernv/eeh-ioda.c
index 268cd46af8f1..58ef80987eed 100644
--- a/arch/powerpc/platforms/powernv/eeh-ioda.c
+++ b/arch/powerpc/platforms/powernv/eeh-ioda.c
@@ -474,6 +474,8 @@ static int ioda_eeh_bridge_reset(struct pci_dev *dev, int option)
 
 {
         struct device_node *dn = pci_device_to_OF_node(dev);
+        struct eeh_dev *edev = of_node_to_eeh_dev(dn);
+        int aer = edev ? edev->aer_cap : 0;
         u32 ctrl;
 
         pr_debug("%s: Reset PCI bus %04x:%02x with option %d\n",
@@ -483,24 +485,56 @@ static int ioda_eeh_bridge_reset(struct pci_dev *dev, int option)
         switch (option) {
         case EEH_RESET_FUNDAMENTAL:
         case EEH_RESET_HOT:
+                /* Don't report linkDown event */
+                if (aer) {
+                        eeh_ops->read_config(dn, aer + PCI_ERR_UNCOR_MASK,
+                                             4, &ctrl);
+                        ctrl |= PCI_ERR_UNC_SURPDN;
+                        eeh_ops->write_config(dn, aer + PCI_ERR_UNCOR_MASK,
+                                              4, ctrl);
+                }
+
                 eeh_ops->read_config(dn, PCI_BRIDGE_CONTROL, 2, &ctrl);
                 ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
                 eeh_ops->write_config(dn, PCI_BRIDGE_CONTROL, 2, ctrl);
-
                 msleep(EEH_PE_RST_HOLD_TIME);
+
                 break;
         case EEH_RESET_DEACTIVATE:
                 eeh_ops->read_config(dn, PCI_BRIDGE_CONTROL, 2, &ctrl);
                 ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
                 eeh_ops->write_config(dn, PCI_BRIDGE_CONTROL, 2, ctrl);
-
                 msleep(EEH_PE_RST_SETTLE_TIME);
+
+                /* Continue reporting linkDown event */
+                if (aer) {
+                        eeh_ops->read_config(dn, aer + PCI_ERR_UNCOR_MASK,
+                                             4, &ctrl);
+                        ctrl &= ~PCI_ERR_UNC_SURPDN;
+                        eeh_ops->write_config(dn, aer + PCI_ERR_UNCOR_MASK,
+                                              4, ctrl);
+                }
+
                 break;
         }
 
         return 0;
 }
 
+void pnv_pci_reset_secondary_bus(struct pci_dev *dev)
+{
+        struct pci_controller *hose;
+
+        if (pci_is_root_bus(dev->bus)) {
+                hose = pci_bus_to_host(dev->bus);
+                ioda_eeh_root_reset(hose, EEH_RESET_HOT);
+                ioda_eeh_root_reset(hose, EEH_RESET_DEACTIVATE);
+        } else {
+                ioda_eeh_bridge_reset(dev, EEH_RESET_HOT);
+                ioda_eeh_bridge_reset(dev, EEH_RESET_DEACTIVATE);
+        }
+}
+
 /**
  * ioda_eeh_reset - Reset the indicated PE
  * @pe: EEH PE
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 98824aa99173..a179ff00be3e 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1386,6 +1386,7 @@ void __init pnv_pci_init_ioda_phb(struct device_node *np,
         ppc_md.pcibios_fixup = pnv_pci_ioda_fixup;
         ppc_md.pcibios_enable_device_hook = pnv_pci_enable_device_hook;
         ppc_md.pcibios_window_alignment = pnv_pci_window_alignment;
+        ppc_md.pcibios_reset_secondary_bus = pnv_pci_reset_secondary_bus;
         pci_add_flags(PCI_REASSIGN_ALL_RSRC);
 
         /* Reset IODA tables to a clean state */
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 39ec6978e809..34a09740aad3 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -204,5 +204,6 @@ extern void pnv_pci_init_ioda_hub(struct device_node *np);
 extern void pnv_pci_init_ioda2_phb(struct device_node *np);
 extern void pnv_pci_ioda_tce_invalidate(struct iommu_table *tbl,
                                         __be64 *startp, __be64 *endp, bool rm);
+extern void pnv_pci_reset_secondary_bus(struct pci_dev *dev);
 
 #endif /* __POWERNV_PCI_H */