Patch "powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-iommu-remove-the-dependency-on-eeh-struct-in-ddw-mechanism.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Guilherme G. Piccoli" <[email protected]>
Date: Mon, 11 Apr 2016 16:17:23 -0300
Subject: powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism

From: Guilherme G. Piccoli <[email protected]>

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.

---
 arch/powerpc/platforms/pseries/iommu.c |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

@@ -912,7 +912,8 @@ 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;

@@ -923,11 +924,10 @@ 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));

@@ -941,7 +941,8 @@ 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;

@@ -952,11 +953,10 @@ 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) */

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/powerpc-iommu-remove-the-dependency-on-eeh-struct-in-ddw-mechanism.patch queue-4.6/powerpc-pseries-fix-pci-config-address-for-ddw.patch