From: Frederic Barrat fbarrat@linux.ibm.com
commit a8a30219ba78b1abb92091102b632f8e9bbdbf03 upstream.
Recent cleanup in the way EEH support is added to a device causes a kernel oops when the cxl driver probes a device and creates virtual devices discovered on the FPGA:
BUG: Kernel NULL pointer dereference at 0x000000a0 Faulting instruction address: 0xc000000000048070 Oops: Kernel access of bad area, sig: 7 [#1] ... NIP eeh_add_device_late.part.9+0x50/0x1e0 LR eeh_add_device_late.part.9+0x3c/0x1e0 Call Trace: _dev_info+0x5c/0x6c (unreliable) pnv_pcibios_bus_add_device+0x60/0xb0 pcibios_bus_add_device+0x40/0x60 pci_bus_add_device+0x30/0x100 pci_bus_add_devices+0x64/0xd0 cxl_pci_vphb_add+0xe0/0x130 [cxl] cxl_probe+0x504/0x5b0 [cxl] local_pci_probe+0x6c/0x110 work_for_cpu_fn+0x38/0x60
The root cause is that those cxl virtual devices don't have a representation in the device tree and therefore no associated pci_dn structure. In eeh_add_device_late(), pdn is NULL, so edev is NULL and we oops.
We never had explicit support for EEH for those virtual devices. Instead, EEH events are reported to the (real) pci device and handled by the cxl driver. Which can then forward to the virtual devices and handle dependencies. The fact that we try adding EEH support for the virtual devices is new and a side-effect of the recent cleanup.
This patch fixes it by skipping adding EEH support on powernv for devices which don't have a pci_dn structure.
The cxl driver doesn't create virtual devices on pseries so this patch doesn't fix it there intentionally.
Fixes: b905f8cdca77 ("powerpc/eeh: EEH for pSeries hot plug") Signed-off-by: Frederic Barrat fbarrat@linux.ibm.com Reviewed-by: Sam Bobroff sbobroff@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20191016162833.22509-1-fbarrat@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/platforms/powernv/eeh-powernv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/platforms/powernv/eeh-powernv.c +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c @@ -47,7 +47,7 @@ void pnv_pcibios_bus_add_device(struct p { struct pci_dn *pdn = pci_get_pdn(pdev);
- if (eeh_has_flag(EEH_FORCE_DISABLED)) + if (!pdn || eeh_has_flag(EEH_FORCE_DISABLED)) return;
pr_debug("%s: EEH: Setting up device %s.\n", __func__, pci_name(pdev));