linux-stable.git/arch/powerpc/kernel/eeh.c, branch linux-4.1.y

powerpc/eeh: Enable IO path on permanent error

2017-07-31T17:37:50+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

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

2016-08-23T15:03:35+00:00

[ Upstream commit 949e9b827eb4736d96df520c67d07a54c64e99b8 ]

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: Sasha Levin

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

2016-06-06T23:12:19+00:00

[ Upstream commit c2078d9ef600bdbe568c89e5ddc2c6f15b7982c8 ]

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.

Cc: stable@vger.kernel.org # v4.1+
Reviewed-by: Gavin Shan 
Signed-off-by: Guilherme G. Piccoli 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

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

2015-09-29T17:26:04+00:00

commit 259800135c654a098d9f0adfdd3d1f20eef1f231 upstream.

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")
Reported-by: Manvanthara B. Puttashankar 
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Probe after unbalanced kref check

2015-09-29T17:26:03+00:00

commit e642d11bdbfe8eb10116ab3959a2b5d75efda832 upstream.

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

powerpc/eeh: Delay probing EEH device during hotplug

2015-05-01T03:52:32+00:00

Commit 1c509148b ("powerpc/eeh: Do probe on pci_dn") probes EEH
devices in early stage, which is reasonable to pSeries platform.
However, it's wrong for PowerNV platform because the PE# isn't
determined until the resources (IO and MMIO) are assigned to
PE in hotplug case. So we have to delay probing EEH devices
for PowerNV platform until the PE# is assigned.

Fixes: ff57b454ddb9 ("powerpc/eeh: Do probe on pci_dn")
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/eeh: Fix race condition in pcibios_set_pcie_reset_state()

2015-05-01T03:52:09+00:00

When asserting reset in pcibios_set_pcie_reset_state(), the PE
is enforced to (hardware) frozen state in order to drop unexpected
PCI transactions (except PCI config read/write) automatically by
hardware during reset, which would cause recursive EEH error.
However, the (software) frozen state EEH_PE_ISOLATED is missed.
When users get 0xFF from PCI config or MMIO read, EEH_PE_ISOLATED
is set in PE state retrival backend. Unfortunately, nobody (the
reset handler or the EEH recovery functinality in host) will clear
EEH_PE_ISOLATED when the PE has been passed through to guest.

The patch sets and clears EEH_PE_ISOLATED properly during reset
in function pcibios_set_pcie_reset_state() to fix the issue.

Fixes: 28158cd ("Enhance pcibios_set_pcie_reset_state()")
Reported-by: Carol L. Soto 
Signed-off-by: Gavin Shan 
Tested-by: Carol L. Soto 
Signed-off-by: Michael Ellerman

powerpc/mm/thp: Make page table walk safe against thp split/collapse

2015-04-17T01:23:39+00:00

We can disable a THP split or a hugepage collapse by disabling irq.
We do send IPI to all the cpus in the early part of split/collapse,
and disabling local irq ensure we don't make progress with
split/collapse. If the THP is getting split we return NULL from
find_linux_pte_or_hugepte(). For all the current callers it should be ok.
We need to be careful if we want to use returned pte_t pointer outside
the irq disabled region. W.r.t to THP split, the pfn remains the same,
but then a hugepage collapse will result in a pfn change. There are
few steps we can take to avoid a hugepage collapse.One way is to take page
reference inside the irq disable region. Other option is to take
mmap_sem so that a parallel collapse will not happen. We can also
disable collapse by taking pmd_lock. Another method used by kvm
subsystem is to check whether we had a mmu_notifer update in between
using mmu_notifier_retry().

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

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

2015-04-14T07:13:31+00:00

The recent change to the EEH probing causes a crash on Cell because
eeh_ops is NULL.

Check if EEH is enabled and if not bail out.

Fixes: ff57b454ddb9 ("powerpc/eeh: Do probe on pci_dn")
Signed-off-by: Michael Ellerman

powerpc/eeh: Remove device_node dependency

2015-03-24T02:15:53+00:00

The patch removes struct eeh_dev::dn and the corresponding helper
functions: eeh_dev_to_of_node() and of_node_to_eeh_dev(). Instead,
eeh_dev_to_pdn() and pdn_to_eeh_dev() should be used to get the
pdn, which might contain device_node on PowerNV platform.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt