linux-stable.git/arch/powerpc/kernel/eeh_driver.c, branch linux-4.4.y

powerpc/eeh: Avoid use after free in eeh_handle_special_event()

2017-06-14T11:16:25+00:00

commit daeba2956f32f91f3493788ff6ee02fb1b2f02fa upstream.

eeh_handle_special_event() is called when an EEH event is detected but
can't be narrowed down to a specific PE.  This function looks through
every PE to find one in an erroneous state, then calls the regular event
handler eeh_handle_normal_event() once it knows which PE has an error.

However, if eeh_handle_normal_event() found that the PE cannot possibly
be recovered, it will free it, rendering the passed PE stale.
This leads to a use after free in eeh_handle_special_event() as it attempts to
clear the "recovering" state on the PE after eeh_handle_normal_event() returns.

Thus, make sure the PE is valid when attempting to clear state in
eeh_handle_special_event().

Fixes: 8a6b1bc70dbb ("powerpc/eeh: EEH core to handle special event")
Reported-by: Alexey Kardashevskiy 
Signed-off-by: Russell Currey 
Reviewed-by: Gavin Shan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix wrong flag passed to eeh_unfreeze_pe()

2017-02-09T07:02:45+00:00

commit f05fea5b3574a5926c53865eea27139bb40b2f2b upstream.

In __eeh_clear_pe_frozen_state(), we should pass the flag's value
instead of its address to eeh_unfreeze_pe(). The isolated flag is
cleared if no error returned from __eeh_clear_pe_frozen_state(). We
never observed the error from the function. So the isolated flag should
have been always cleared, no real issue is caused because of the misused
@flag.

This fixes the code by passing the value of @flag to eeh_unfreeze_pe().

Fixes: 5cfb20b96f6 ("powerpc/eeh: Emulate EEH recovery for VFIO devices")
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix deadlock when PE frozen state can't be cleared

2016-12-15T16:49:21+00:00

commit 409bf7f8a02ef88db5a0f2cdcf9489914f4b8508 upstream.

In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after
after we call eeh_reset_pe() to reset the PCI controller. We then call
eeh_clear_pe_frozen_state(), which can return an error. In this case, we
bail out of eeh_reset_device() without calling pci_unlock_rescan_remove().

Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state()
error path so that we don't cause a deadlock later on.

Reported-by: Pradipta Ghosh 
Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset")
Signed-off-by: Andrew Donnellan 
Acked-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Null check uses of eeh_pe_bus_get

2016-10-31T10:13:59+00:00

commit 04fec21c06e35b169a83e75a84a015ab4606bf5e upstream.

eeh_pe_bus_get() can return NULL if a PCI bus isn't found for a given PE.
Some callers don't check this, and can cause a null pointer dereference
under certain circumstances.

Fix this by checking NULL everywhere eeh_pe_bus_get() is called.

Fixes: 8a6b1bc70dbb ("powerpc/eeh: EEH core to handle special event")
Cc: stable@vger.kernel.org # v3.11+
Signed-off-by: Russell Currey 
Reviewed-by: Andrew Donnellan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Restore initial state in eeh_pe_reset_and_recover()

2016-06-08T01:14:36+00:00

commit 5a0cdbfd17b90a89c64a71d8aec9773ecdb20d0d upstream.

The function eeh_pe_reset_and_recover() is used to recover EEH
error when the passthrou device are transferred to guest and
backwards. The content in the device's config space will be lost
on PE reset issued in the middle of the recovery. The function
saves/restores it before/after the reset. However, config access
to some adapters like Broadcom BCM5719 at this point will causes
fenced PHB. The config space is always blocked and we save 0xFF's
that are restored at late point. The memory BARs are totally
corrupted, causing another EEH error upon access to one of the
memory BARs.

This restores the config space on those adapters like BCM5719
from the content saved to the EEH device when it's populated,
to resolve above issue.

Fixes: 5cfb20b9 ("powerpc/eeh: Emulate EEH recovery for VFIO devices")
Signed-off-by: Gavin Shan 
Reviewed-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Don't report error in eeh_pe_reset_and_recover()

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

commit affeb0f2d3a9af419ad7ef4ac782e1540b2f7b28 upstream.

The function eeh_pe_reset_and_recover() is used to recover EEH
error when the passthrough device are transferred to guest and
backwards, meaning the device's driver is vfio-pci or none.
When the driver is vfio-pci that provides error_detected() error
handler only, the handler simply stops the guest and it's not
expected behaviour. On the other hand, no error handlers will
be called if we don't have a bound driver.

This ignores the error handler in eeh_pe_reset_and_recover()
that reports the error to device driver to avoid the exceptional
behaviour.

Fixes: 5cfb20b9 ("powerpc/eeh: Emulate EEH recovery for VFIO devices")
Signed-off-by: Gavin Shan 
Reviewed-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix partial hotplug criterion

2016-03-03T23:07:29+00:00

commit f6bf0fa14cf848ae770e0b7842c9b11ce2f01645 upstream.

During error recovery, the device could be removed as part of the
partial hotplug. The criterion used to come with partial hotplug
is: if the device driver provides error_detected(), slot_reset()
and resume() callbacks, it's immune from hotplug. Otherwise,
it's going to experience partial hotplug during EEH recovery. But
the criterion isn't correct enough: mlx4_core driver for Mellanox
adapters provides error_detected(), slot_reset() callbacks, but
resume() isn't there. Those Mellanox adapters won't be to involved
in the partial hotplug.

This fixes the criterion to a practical one: adpater with driver
that provides error_detected(), slot_reset() will be immune from
partial hotplug. resume() isn't mandatory.

Fixes: f2da4ccf ("powerpc/eeh: More relaxed hotplug criterion")
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix stale cached primary bus

2016-02-25T20:01:18+00:00

commit 05ba75f848647135f063199dc0e9f40fee769724 upstream.

When PE is created, its primary bus is cached to pe->bus. At later
point, the cached primary bus is returned from eeh_pe_bus_get().
However, we could get stale cached primary bus and run into kernel
crash in one case: full hotplug as part of fenced PHB error recovery
releases all PCI busses under the PHB at unplugging time and recreate
them at plugging time. pe->bus is still dereferencing the PCI bus
that was released.

This adds another PE flag (EEH_PE_PRI_BUS) to represent the validity
of pe->bus. pe->bus is updated when its first child EEH device is
online and the flag is set. Before unplugging in full hotplug for
error recovery, the flag is cleared.

Fixes: 8cdb2833 ("powerpc/eeh: Trace PCI bus from PE")
Reported-by: Andrew Donnellan 
Reported-by: Pradipta Ghosh 
Signed-off-by: Gavin Shan 
Tested-by: Andrew Donnellan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

Revert "powerpc/eeh: Don't unfreeze PHB PE after reset"

2015-12-09T03:05:10+00:00

This reverts commit 527d10ef3a315d3cb9dc098dacd61889a6c26439.

The reverted commit breaks cxlflash devices following an EEH reset (and
possibly other cxl devices, however this has not been tested).

The reverted commit changed the behaviour of eeh_reset_device() so that PHB
PEs are not unfrozen following the completion of the reset. This should not
be problematic, as no device resources should have been associated with the
PHB PE.

However, when attempting to load the cxlflash driver after a reset, the
driver attempts to read Vital Product Data through a call to
pci_read_vpd() (which is called on the physical cxl device, not on the
virtual AFU device). pci_read_vpd() in turn attempts to read from the cxl
device's config space. This fails, as the PE it's trying to read from is
still frozen. In turn, the driver gets an -ENODEV and fails to initialise.

It appears this issue only affects some parts of the VPD area, as "lspci
-vvv", which only reads a subset of the VPD bytes, is not broken by the
original patch.

At this stage, we don't fully understand why we're trying to read a frozen
PE, and we don't know how this affects other cxl devices. It is possible
that there is an underlying bug in the cxl driver or the powerpc CAPI
support code, or alternatively a bug in the PCI resource allocation/mapping
code that is incorrectly mapping resources to PE#0.

As such, this fix is incomplete, however it is necessary to prevent a
serious regression in CAPI support.

In the meantime, revert the commit, especially as it was intended to be a
non-functional change.

Cc: Gavin Shan 
Cc: Ian Munsie 
Cc: Daniel Axtens 
Signed-off-by: Andrew Donnellan 
Signed-off-by: Michael Ellerman

powerpc/eeh: Force reset on fenced PHB

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

On fenced PHB, the error handlers in the drivers of its subordinate
devices could return PCI_ERS_RESULT_CAN_RECOVER, indicating no reset
will be issued during the recovery. It's conflicting with the fact
that fenced PHB won't be recovered without reset.

This limits the return value from the error handlers in the drivers
of the fenced PHB's subordinate devices to PCI_ERS_RESULT_NEED_NONE
or PCI_ERS_RESULT_NEED_RESET, to ensure reset will be issued during
recovery.

Signed-off-by: Gavin Shan 
Reviewed-by: Daniel Axtens 
Signed-off-by: Michael Ellerman