powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism

Commit 39baadbf36ce ("powerpc/eeh: Remove eeh information from pci_dn")
changed the pci_dn struct by removing its EEH-related members.
As part of this clean-up, DDW mechanism was modified to read the device
configuration address from eeh_dev struct.

As a consequence, now if we disable EEH mechanism on kernel command-line
for example, the DDW mechanism will fail, generating a kernel oops by
dereferencing a NULL pointer (which turns to be the eeh_dev pointer).

This patch just changes the configuration address calculation on DDW
functions to a manual calculation based on pci_dn members instead of
using eeh_dev-based address.

No functional changes were made. This was tested on pSeries, both
in PHyp and qemu guest.

Fixes: 39baadbf36ce ("powerpc/eeh: Remove eeh information from pci_dn")
Cc: stable@vger.kernel.org # v3.4+
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index bd98ce2be17b766182b4b5df4358c8d731b8c305..b7dfc1359d0113d570fe9ea7f702c728814dc66f 100644 (file)
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -912,7 +912,8 @@ machine_arch_initcall(pseries, find_existing_ddw_windows);
 static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
                        struct ddw_query_response *query)
 {
-       struct eeh_dev *edev;
+       struct device_node *dn;
+       struct pci_dn *pdn;
        u32 cfg_addr;
        u64 buid;
        int ret;
@@ -923,11 +924,10 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
         * Retrieve them from the pci device, not the node with the
         * dma-window property
         */
-       edev = pci_dev_to_eeh_dev(dev);
-       cfg_addr = edev->config_addr;
-       if (edev->pe_config_addr)
-               cfg_addr = edev->pe_config_addr;
-       buid = edev->phb->buid;
+       dn = pci_device_to_OF_node(dev);
+       pdn = PCI_DN(dn);
+       buid = pdn->phb->buid;
+       cfg_addr = (pdn->busno << 8) | pdn->devfn;
 
        ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
                  cfg_addr, BUID_HI(buid), BUID_LO(buid));
@@ -941,7 +941,8 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
                        struct ddw_create_response *create, int page_shift,
                        int window_shift)
 {
-       struct eeh_dev *edev;
+       struct device_node *dn;
+       struct pci_dn *pdn;
        u32 cfg_addr;
        u64 buid;
        int ret;
@@ -952,11 +953,10 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
         * Retrieve them from the pci device, not the node with the
         * dma-window property
         */
-       edev = pci_dev_to_eeh_dev(dev);
-       cfg_addr = edev->config_addr;
-       if (edev->pe_config_addr)
-               cfg_addr = edev->pe_config_addr;
-       buid = edev->phb->buid;
+       dn = pci_device_to_OF_node(dev);
+       pdn = PCI_DN(dn);
+       buid = pdn->phb->buid;
+       cfg_addr = (pdn->busno << 8) | pdn->devfn;
 
        do {
                /* extra outputs are LIOBN and dma-addr (hi, lo) */