commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.9.

During an eeh a kernel-oops is reported if no vPHB is allocated to the AFU. This happens as during AFU init, an error in creation of vPHB is a non-fatal error. Hence afu->phb should always be checked for NULL before iterating over it for the virtual AFU pci devices.

This patch fixes the kenel-oops by adding a NULL pointer check for afu->phb before it is dereferenced.

Fixes: 9e8df8a21963 ("cxl: EEH support") Cc: stable@vger.kernel.org Signed-off-by: Vaibhav Jain vaibhav@linux.vnet.ibm.com Acked-by: Andrew Donnellan andrew.donnellan@au1.ibm.com Acked-by: Frederic Barrat fbarrat@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- Changelog: Rebased the upstream patch over stable 4.9 tree --- drivers/misc/cxl/pci.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c index eef202d4399b..a5422f483ad5 100644 --- a/drivers/misc/cxl/pci.c +++ b/drivers/misc/cxl/pci.c @@ -1758,6 +1758,9 @@ static pci_ers_result_t cxl_vphb_error_detected(struct cxl_afu *afu, /* There should only be one entry, but go through the list * anyway */ + if (afu->phb == NULL) + return result; + list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) { if (!afu_dev->driver) continue; @@ -1801,6 +1804,11 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, /* Only participate in EEH if we are on a virtual PHB */ if (afu->phb == NULL) return PCI_ERS_RESULT_NONE; + + /* + * Tell the AFU drivers; but we don't care what they + * say, we're going away. + */ cxl_vphb_error_detected(afu, state); } return PCI_ERS_RESULT_DISCONNECT; @@ -1941,6 +1949,9 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev) if (cxl_afu_select_best_mode(afu)) goto err;

+ if (afu->phb == NULL) + continue; + list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) { /* Reset the device context. * TODO: make this less disruptive @@ -2003,6 +2014,9 @@ static void cxl_pci_resume(struct pci_dev *pdev) for (i = 0; i < adapter->slices; i++) { afu = adapter->afu[i];

+ if (afu->phb == NULL) + continue; + list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) { if (afu_dev->driver && afu_dev->driver->err_handler && afu_dev->driver->err_handler->resume)