[PATCH 3.16 074/305] powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism

Ben Hutchings
2016-08-14T11:00:11Z

From: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>

commit 8445a87f7092bc8336ea1305be9306f26b846d93 upstream.

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")
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/powerpc/platforms/pseries/iommu.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -826,7 +826,8 @@ machine_arch_initcall(pseries, find_exis
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;
@@ -837,11 +838,10 @@ static int query_ddw(struct pci_dev *dev
* 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));
@@ -855,7 +855,8 @@ static int create_ddw(struct pci_dev *de
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;
@@ -866,11 +867,10 @@ static int create_ddw(struct pci_dev *de
* 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) */