litmus-rt-ext-res.git/drivers/misc/cxl, branch EXT-RES

cxl: Route eeh events to all drivers in cxl_pci_error_detected()

2017-05-25T13:44:37+00:00

commit 4f58f0bf155e87dda31a3088b1e107fa9dd79f0e upstream.

Fix a boundary condition where in some cases an eeh event that results
in card reset isn't passed on to a driver attached to the virtual PCI
device associated with a slice. This will happen in case when a slice
attached device driver returns a value other than
PCI_ERS_RESULT_NEED_RESET from the eeh error_detected() callback. This
would result in an early return from cxl_pci_error_detected() and
other drivers attached to other AFUs on the card wont be notified.

The patch fixes this by making sure that all slice attached
device-drivers are notified and the return values from
error_detected() callback are aggregated in a scheme where request for
'disconnect' trumps all and 'none' trumps 'need_reset'.

Fixes: 9e8df8a21963 ("cxl: EEH support")
Signed-off-by: Vaibhav Jain 
Reviewed-by: Andrew Donnellan 
Acked-by: Frederic Barrat 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

cxl: Force context lock during EEH flow

2017-05-25T13:44:36+00:00

commit ea9a26d117cf0637c71d3e0076f4a124bf5859df upstream.

During an eeh event when the cxl card is fenced and card sysfs attr
perst_reloads_same_image is set following warning message is seen in the
kernel logs:

  Adapter context unlocked with 0 active contexts
  ------------[ cut here ]------------
  WARNING: CPU: 12 PID: 627 at
  ../drivers/misc/cxl/main.c:325 cxl_adapter_context_unlock+0x60/0x80 [cxl]

Even though this warning is harmless, it clutters the kernel log
during an eeh event. This warning is triggered as the EEH callback
cxl_pci_error_detected doesn't obtain a context-lock before forcibly
detaching all active context and when context-lock is released during
call to cxl_configure_adapter from cxl_pci_slot_reset, a warning in
cxl_adapter_context_unlock is triggered.

To fix this warning, we acquire the adapter context-lock via
cxl_adapter_context_lock() in the eeh callback
cxl_pci_error_detected() once all the virtual AFU PHBs are notified
and their contexts detached. The context-lock is released in
cxl_pci_slot_reset() after the adapter is successfully reconfigured
and before the we call the slot_reset callback on slice attached
device-drivers.

Fixes: 70b565bbdb91 ("cxl: Prevent adapter reset if an active context exists")
Reported-by: Andrew Donnellan 
Signed-off-by: Vaibhav Jain 
Acked-by: Frederic Barrat 
Reviewed-by: Matthew R. Ochs 
Tested-by: Uma Krishnan 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

cxl: fix nested locking hang during EEH hotplug

2017-03-15T02:02:42+00:00

commit 171ed0fcd8966d82c45376f1434678e7b9d4d9b1 upstream.

Commit 14a3ae34bfd0 ("cxl: Prevent read/write to AFU config space while AFU
not configured") introduced a rwsem to fix an invalid memory access that
occurred when someone attempts to access the config space of an AFU on a
vPHB whilst the AFU is deconfigured, such as during EEH recovery.

It turns out that it's possible to run into a nested locking issue when EEH
recovery fails and a full device hotplug is required.
cxl_pci_error_detected() deconfigures the AFU, taking a writer lock on
configured_rwsem. When EEH recovery fails, the EEH code calls
pci_hp_remove_devices() to remove the device, which in turn calls
cxl_remove() -> cxl_pci_remove_afu() -> pci_deconfigure_afu(), which tries
to grab the writer lock that's already held.

Standard rwsem semantics don't express what we really want to do here and
don't allow for nested locking. Fix this by replacing the rwsem with an
atomic_t which we can control more finely. Allow the AFU to be locked
multiple times so long as there are no readers.

Fixes: 14a3ae34bfd0 ("cxl: Prevent read/write to AFU config space while AFU not configured")
Signed-off-by: Andrew Donnellan 
Acked-by: Frederic Barrat 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

cxl: Prevent read/write to AFU config space while AFU not configured

2017-03-15T02:02:42+00:00

commit 14a3ae34bfd0bcb1cc12d55b06a8584c11fac6fc upstream.

During EEH recovery, we deconfigure all AFUs whilst leaving the
corresponding vPHB and virtual PCI device in place.

If something attempts to interact with the AFU's PCI config space (e.g.
running lspci) after the AFU has been deconfigured and before it's
reconfigured, cxl_pcie_{read,write}_config() will read invalid values from
the deconfigured struct cxl_afu and proceed to Oops when they try to
dereference pointers that have been set to NULL during deconfiguration.

Add a rwsem to struct cxl_afu so we can prevent interaction with config
space while the AFU is deconfigured.

Reported-by: Pradipta Ghosh 
Suggested-by: Frederic Barrat 
Signed-off-by: Andrew Donnellan 
Signed-off-by: Vaibhav Jain 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

cxl: Fix leaking pid refs in some error paths

2016-10-24T00:38:27+00:00

In some error paths in functions cxl_start_context and
afu_ioctl_start_work pid references to the current & group-leader tasks
can leak after they are taken. This patch fixes these error paths to
release these pid references before exiting the error path.

Fixes: 7b8ad495d592 ("cxl: Fix DSI misses when the context owning task exits")
Cc: stable@vger.kernel.org # v4.5+
Reviewed-by: Andrew Donnellan 
Reported-by: Frederic Barrat 
Signed-off-by: Vaibhav Jain 
Acked-by: Frederic Barrat 
Signed-off-by: Michael Ellerman

cxl: Prevent adapter reset if an active context exists

2016-10-19T09:35:39+00:00

This patch prevents resetting the cxl adapter via sysfs in presence of
one or more active cxl_context on it. This protects against an
unrecoverable error caused by PSL owning a dirty cache line even after
reset and host tries to touch the same cache line. In case a force reset
of the card is required irrespective of any active contexts, the int
value -1 can be stored in the 'reset' sysfs attribute of the card.

The patch introduces a new atomic_t member named contexts_num inside
struct cxl that holds the number of active context attached to the card
, which is checked against '0' before proceeding with the reset. To
prevent against a race condition where a context is activated just after
reset check is performed, the contexts_num is atomically set to '-1'
after reset-check to indicate that no more contexts can be activated on
the card anymore.

Before activating a context we atomically test if contexts_num is
non-negative and if so, increment its value by one. In case the value of
contexts_num is negative then it indicates that the card is about to be
reset and context activation is error-ed out at that point.

Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card")
Cc: stable@vger.kernel.org # v4.0+
Acked-by: Frederic Barrat 
Reviewed-by: Andrew Donnellan 
Signed-off-by: Vaibhav Jain 
Signed-off-by: Michael Ellerman

cxl: replace loop with for_each_child_of_node(), remove unneeded of_node_put()

2016-10-04T05:19:23+00:00

Rewrite the cxl_guest_init_afu() loop in cxl_of_probe() to use
for_each_child_of_node() rather than a hand-coded for loop.

Remove the useless of_node_put(afu_np) call after the loop, where it's
guaranteed that afu_np == NULL.

Reported-by: SF Markus Elfring 
Reported-by: Julia Lawall 
Signed-off-by: Andrew Donnellan 
Reviewed-by: Frederic Barrat 
Signed-off-by: Michael Ellerman

cxl: Flush PSL cache before resetting the adapter

2016-10-04T05:16:42+00:00

If the capi link is going down while the PSL owns a dirty cache line,
any access from the host for that data could lead to an Uncorrectable
Error.

So when resetting the capi adapter through sysfs, make sure the PSL
cache is flushed. It won't help if there are any active Process
Elements on the card, as the cache would likely get new dirty cache
lines immediately, but if resetting an idle adapter, it should avoid
any bad surprises from data left over from terminated Process Elements.

Signed-off-by: Frederic Barrat 
Reviewed-by: Andrew Donnellan 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

cxl: Fix informational message

2016-09-13T07:37:11+00:00

When set_sl_ops() is called, the adapter data structure is not fully
initialized yet. Therefore the device name is not showing up in the
trace. Fix is simply to get the device name from the pci_dev
structure.

Fixes: 6d382616ac22 ("cxl: Abstract the differences between the PSL and XSL")
Signed-off-by: Frederic Barrat 
Signed-off-by: Michael Ellerman

cxl: use pcibios_free_controller_deferred() when removing vPHBs

2016-08-22T01:09:33+00:00

When cxl removes a vPHB, it's possible that the pci_controller may be freed
before all references to the devices on the vPHB have been released. This
in turn causes an invalid memory access when the devices are eventually
released, as pcibios_release_device() attempts to call the phb's
release_device hook.

In cxl_pci_vphb_remove(), remove the existing call to
pcibios_free_controller(). Instead, use
pcibios_free_controller_deferred() to free the pci_controller after all
devices have been released. Export pci_set_host_bridge_release() so we can
do this.

Cc: stable@vger.kernel.org
Signed-off-by: Andrew Donnellan 
Reviewed-by: Matthew R. Ochs 
Acked-by: Ian Munsie 
Signed-off-by: Benjamin Herrenschmidt