Re: [added to the 3.18 stable tree] powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism

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Hi Sasha, thanks for letting me know.

Unfortunately, this patch has an issue; the proposed fix is simple and was already sent to linuxppc-dev list by Gavin Shan.

Link to the proposed fix (already tested): https://patchwork.ozlabs.org/patch/626492

Thanks, and sorry for the inconvenience.
Cheers,


Guilherme

On 06/03/2016 06:46 PM, Sasha Levin wrote:
From: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxxxxxxxxxx>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 8445a87f7092bc8336ea1305be9306f26b846d93 ]

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@xxxxxxxxxxxxxxx # v3.4+
Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
  arch/powerpc/platforms/pseries/iommu.c | 24 ++++++++++++------------
  1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index e32e009..4046df9 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -825,7 +825,8 @@ 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;
@@ -836,11 +837,10 @@ 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));
@@ -854,7 +854,8 @@ 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;
@@ -865,11 +866,10 @@ 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) */


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