Re: [PATCH] powerpc/eeh: Fix enabling bridge MMIO windows

[Russell Currey <ruscur@russell.cc>]

On Wed, 2018-04-11 at 13:37 +1000, Michael Neuling wrote:
> On boot we save the configuration space of PCIe bridges. We do this
> so
> when we get an EEH event and everything gets reset that we can
> restore
> them.
> 
> Unfortunately we save this state before we've enabled the MMIO space
> on the bridges. Hence if we have to reset the bridge when we come
> back
> MMIO is not enabled and we end up taking an PE freeze when the driver
> starts accessing again.
> 
> This patch forces the memory/MMIO and bus mastering on when restoring
> bridges on EEH. Ideally we'd do this correctly by saving the
> configuration space writes later, but that will have to come later in
> a larger EEH rewrite. For now we have this simple fix.
> 
> The original bug can be triggered on a boston machine by doing:
>   echo 0x8000000000000000 >
> /sys/kernel/debug/powerpc/PCI0001/err_injct_outbound
> On boston, this PHB has a PCIe switch on it.  Without this patch,
> you'll see two EEH events, 1 expected and 1 the failure we are fixing
> here. The second EEH event causes the anything under the PHB to
> disappear (i.e. the i40e eth).
> 
> With this patch, only 1 EEH event occurs and devices properly
> recover.
> 
> Reported-by: Pridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> Cc: stable@vger.kernel.org

Acked-by: Russell Currey <ruscur@russell.cc>