Commit 89a51df5ab1d ("powerpc/eeh: Fix crash in eeh_add_device_early() on Cell") added a check on function eeh_add_device_early(): since in Cell arch eeh_ops is NULL, that code used to crash on Cell. The commit's approach was validate if EEH was available by checking the result of function eeh_enabled().
Since the function eeh_add_device_early() is used to perform EEH initialization in devices added later on the system, like in hotplug/DLPAR scenarios, we might reach a case in which no PCI devices are present on boot and so EEH is not initialized. Then, if a device is added via DLPAR for example, eeh_add_device_early() fails because eeh_enabled() is false. We can hit a kernel oops on pSeries arch if eeh_add_device_early() fails: if we have no PCI devices on machine at boot time, and then we add a PCI device via DLPAR operation, the function query_ddw() triggers the oops on NULL pointer dereference in the line "cfg_addr = edev->config_addr;". It happens because config_addr in edev is NULL, since the function eeh_add_device_early() was not completed successfully. This patch just changes the way the arch checking is done in function eeh_add_device_early(): we use no more eeh_enabled(), but instead we check the running architecture by using the macro machine_is(). If we are running on pSeries or PowerNV, the EEH mechanism can be enabled; otherwise, we bail out the function. This way, we don't enable EEH on Cell and we don't hit the oops on DLPAR either. Fixes: 89a51df5ab1d ("powerpc/eeh: Fix crash in eeh_add_device_early() on Cell") Signed-off-by: Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com> --- arch/powerpc/kernel/eeh.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c index 40e4d4a..81e2d3e 100644 --- a/arch/powerpc/kernel/eeh.c +++ b/arch/powerpc/kernel/eeh.c @@ -1072,7 +1072,13 @@ void eeh_add_device_early(struct pci_dn *pdn) struct pci_controller *phb; struct eeh_dev *edev = pdn_to_eeh_dev(pdn); - if (!edev || !eeh_enabled()) + if (!edev) + return; + + /* Some platforms (like Cell) don't have EEH capabilities, so we + * need to abort here. In case of pseries or powernv, we have EEH + * so we can continue. */ + if (!machine_is(pseries) && !machine_is(powernv)) return; if (!eeh_has_flag(EEH_PROBE_MODE_DEVTREE)) -- 2.1.0 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev