From: Frederic Barrat <fbarrat@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Reviewed-by: Sam Bobroff <sbobroff@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191016162833.22509-1-fbarrat@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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));
