• Michael Neuling's avatar
    powerpc/eeh: Fix enabling bridge MMIO windows · 13a83eac
    Michael Neuling authored
    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.
    
    Fixes: 652defed ("powerpc/eeh: Check PCIe link after reset")
    Cc: stable@vger.kernel.org # v3.11+
    Reported-by: default avatarPridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
    Acked-by: default avatarRussell Currey <ruscur@russell.cc>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    13a83eac
eeh_pe.c 23.8 KB