linux-toradex.git/arch/powerpc/kernel/eeh.c, branch v4.4.89

powerpc/eeh: Enable IO path on permanent error

2017-07-05T12:37:18+00:00

[ Upstream commit 387bbc974f6adf91aa635090f73434ed10edd915 ]

We give up recovery on permanent error, simply shutdown the affected
devices and remove them. If the devices can't be put into quiet state,
they spew more traffic that is likely to cause another unexpected EEH
error. This was observed on "p8dtu2u" machine:

   0002:00:00.0 PCI bridge: IBM Device 03dc
   0002:01:00.0 Ethernet controller: Intel Corporation \
                Ethernet Controller X710/X557-AT 10GBASE-T (rev 02)
   0002:01:00.1 Ethernet controller: Intel Corporation \
                Ethernet Controller X710/X557-AT 10GBASE-T (rev 02)
   0002:01:00.2 Ethernet controller: Intel Corporation \
                Ethernet Controller X710/X557-AT 10GBASE-T (rev 02)
   0002:01:00.3 Ethernet controller: Intel Corporation \
                Ethernet Controller X710/X557-AT 10GBASE-T (rev 02)

On P8 PowerNV platform, the IO path is frozen when shutdowning the
devices, meaning the memory registers are inaccessible. It is why
the devices can't be put into quiet state before removing them.
This fixes the issue by enabling IO path prior to putting the devices
into quiet state.

Reported-by: Pridhiviraj Paidipeddi 
Signed-off-by: Gavin Shan 
Acked-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: eeh_pci_enable(): fix checking of post-request state

2016-09-07T06:32:36+00:00

commit 949e9b827eb4736d96df520c67d07a54c64e99b8 upstream.

In eeh_pci_enable(), after making the request to set the new options, we
call eeh_ops->wait_state() to check that the request finished successfully.

At the moment, if eeh_ops->wait_state() returns 0, we return 0 without
checking that it reflects the expected outcome. This can lead to callers
further up the chain incorrectly assuming the slot has been successfully
unfrozen and continuing to attempt recovery.

On powernv, this will occur if pnv_eeh_get_pe_state() or
pnv_eeh_get_phb_state() return 0, which in turn occurs if the relevant OPAL
call returns OPAL_EEH_STOPPED_MMIO_DMA_FREEZE or
OPAL_EEH_PHB_ERROR respectively.

On pseries, this will occur if pseries_eeh_get_state() returns 0, which in
turn occurs if RTAS reports that the PE is in the MMIO Stopped and DMA
Stopped states.

Obviously, none of these cases represent a successful completion of a
request to thaw MMIO or DMA.

Fix the check so that a wait_state() return value of 0 won't be considered
successful for the EEH_OPT_THAW_MMIO or EEH_OPT_THAW_DMA cases.

Signed-off-by: Andrew Donnellan 
Acked-by: Gavin Shan 
Reviewed-by: Daniel Axtens 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"

2016-06-08T01:14:35+00:00

commit c2078d9ef600bdbe568c89e5ddc2c6f15b7982c8 upstream.

This reverts commit 89a51df5ab1d38b257300b8ac940bbac3bb0eb9b.

The function eeh_add_device_early() is used to perform EEH
initialization in devices added later on the system, like in
hotplug/DLPAR scenarios. Since the commit 89a51df5ab1d ("powerpc/eeh:
Fix crash in eeh_add_device_early() on Cell") a new check was introduced
in this function - Cell has no EEH capabilities which led to kernel oops
if hotplug was performed, so checking for eeh_enabled() was introduced
to avoid the issue.

However, in architectures that EEH is present like pSeries or PowerNV,
we might reach a case in which no PCI devices are present on boot time
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,
and EEH end up not being enabled at all.

This reverts the aforementioned patch since a new verification was
introduced by the commit d91dafc02f42 ("powerpc/eeh: Delay probing EEH
device during hotplug") and so the original Cell issue does not happen
anymore.

Reviewed-by: Gavin Shan 
Signed-off-by: Guilherme G. Piccoli 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: More relaxed condition for enabled IO path

2015-10-21T09:41:43+00:00

When one or both of the below two flags are marked in the PE state, the
PE's IO path is regarded as enabled: EEH_STATE_MMIO_ACTIVE or
EEH_STATE_MMIO_ENABLED.

Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/eeh: atomic_dec_if_positive() to update passthru count

2015-10-15T09:31:58+00:00

No need to have two atomic opertions (update and fetch/check) when
decreasing PE's number of passed devices as one atomic operation
is enough.

Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/mm: Differentiate between hugetlb and THP during page walk

2015-10-12T04:30:09+00:00

We need to properly identify whether a hugepage is an explicit or
a transparent hugepage in follow_huge_addr(). We used to depend
on hugepage shift argument to do that. But in some case that can
result in wrong results. For ex:

On finding a transparent hugepage we set hugepage shift to PMD_SHIFT.
But we can end up clearing the thp pte, via pmdp_huge_get_and_clear.
We do prevent reusing the pfn page via the usage of
kick_all_cpus_sync(). But that happens after we updated the pte to 0.
Hence in follow_huge_addr() we can find hugepage shift set, but transparent
huge page check fail for a thp pte.

NOTE: We fixed a variant of this race against thp split in commit
691e95fd7396905a38d98919e9c150dbc3ea21a3
("powerpc/mm/thp: Make page table walk safe against thp split/collapse")

Without this patch, we may hit the BUG_ON(flags & FOLL_GET) in
follow_page_mask occasionally.

In the long term, we may want to switch ppc64 64k page size config to
enable CONFIG_ARCH_WANT_GENERAL_HUGETLB

Reported-by: David Gibson 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/eeh: Fix fenced PHB caused by eeh_slot_error_detail()

2015-08-28T03:26:31+00:00

The config space of some PCI devices can't be accessed when their
PEs are in frozen state. Otherwise, fenced PHB might be seen.
Those PEs are identified with flag EEH_PE_CFG_RESTRICTED, meaing
EEH_PE_CFG_BLOCKED is set automatically when the PE is put to
frozen state (EEH_PE_ISOLATED). eeh_slot_error_detail() restores
PCI device BARs with eeh_pe_restore_bars(), which then calls
eeh_ops->restore_config() to reinitialize the PCI device in
(OPAL) firmware. eeh_ops->restore_config() produces PCI config
access that causes fenced PHB. The problem was reported on below
adapter:

   0001:01:00.0 0200: 14e4:168e (rev 10)
   0001:01:00.0 Ethernet controller: Broadcom Corporation \
                NetXtreme II BCM57810 10 Gigabit Ethernet (rev 10)

This fixes the issue by skipping eeh_pe_restore_bars() in
eeh_slot_error_detail() when EEH_PE_CFG_BLOCKED is set for the PE.

Fixes: b6541db1 ("powerpc/eeh: Block PCI config access upon frozen PE")
Cc: stable@vger.kernel.org # v4.0+
Reported-by: Manvanthara B. Puttashankar 
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/eeh: Disable automatically blocked PCI config

2015-08-18T09:34:42+00:00

pcibios_set_pcie_reset_state() could be called to complete
reset request when passing through PCI device, flag
EEH_PE_ISOLATED is set before saving the PCI config sapce.
On some Broadcom adapters, EEH_PE_CFG_BLOCKED is automatically
set when the flag EEH_PE_ISOLATED is marked. It caused bogus
data saved from the PCI config space, which will be restored
to the PCI adapter after the reset. Eventually, the hardware
can't work with corrupted data in PCI config space.

The patch fixes the issue with eeh_pe_state_mark_no_cfg(), which
doesn't set EEH_PE_CFG_BLOCKED when seeing EEH_PE_ISOLATED on the
PE, in order to avoid the bogus data saved and restored to the PCI
config space.

Reported-by: Rajanikanth H. Adaveeshaiah 
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/eeh: Probe after unbalanced kref check

2015-08-14T11:31:49+00:00

In the complete hotplug case, EEH PEs are supposed to be released
and set to NULL. Normally, this is done by eeh_remove_device(),
which is called from pcibios_release_device().

However, if something is holding a kref to the device, it will not
be released, and the PE will remain. eeh_add_device_late() has
a check for this which will explictly destroy the PE in this case.

This check in eeh_add_device_late() occurs after a call to
eeh_ops->probe(). On PowerNV, probe is a pointer to pnv_eeh_probe(),
which will exit without probing if there is an existing PE.

This means that on PowerNV, devices with outstanding krefs will not
be rediscovered by EEH correctly after a complete hotplug. This is
affecting CXL (CAPI) devices in the field.

Put the probe after the kref check so that the PE is destroyed
and affected devices are correctly rediscovered by EEH.

Fixes: d91dafc02f42 ("powerpc/eeh: Delay probing EEH device during hotplug")
Cc: stable@vger.kernel.org
Cc: Gavin Shan 
Signed-off-by: Daniel Axtens 
Acked-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/eeh/ioda2: Use device::iommu_group to check IOMMU group

2015-06-11T05:14:54+00:00

This relies on the fact that a PCI device always has an IOMMU table
which may not be the case when we get dynamic DMA windows so
let's use more reliable check for IOMMU group here.

As we do not rely on the table presence here, remove the workaround
from pnv_pci_ioda2_set_bypass(); also remove the @add_to_iommu_group
parameter from pnv_ioda_setup_bus_dma().

Signed-off-by: Alexey Kardashevskiy 
Acked-by: Gavin Shan 
Reviewed-by: David Gibson 
Signed-off-by: Michael Ellerman