linux-toradex.git/arch/powerpc/kernel, branch v4.9.100

powerpc/eeh: Fix race with driver un/bind

2018-05-01T22:13:10+00:00

commit f0295e047fcf52ccb42561fb7de6942f5201b676 upstream.

The current EEH callbacks can race with a driver unbind. This can
result in a backtraces like this:

  EEH: Frozen PHB#0-PE#1fc detected
  EEH: PE location: S000009, PHB location: N/A
  CPU: 2 PID: 2312 Comm: kworker/u258:3 Not tainted 4.15.6-openpower1 #2
  Workqueue: nvme-wq nvme_reset_work [nvme]
  Call Trace:
    dump_stack+0x9c/0xd0 (unreliable)
    eeh_dev_check_failure+0x420/0x470
    eeh_check_failure+0xa0/0xa4
    nvme_reset_work+0x138/0x1414 [nvme]
    process_one_work+0x1ec/0x328
    worker_thread+0x2e4/0x3a8
    kthread+0x14c/0x154
    ret_from_kernel_thread+0x5c/0xc8
  nvme nvme1: Removing after probe failure status: -19
  
  cpu 0x23: Vector: 300 (Data Access) at [c000000ff50f3800]
      pc: c0080000089a0eb0: nvme_error_detected+0x4c/0x90 [nvme]
      lr: c000000000026564: eeh_report_error+0xe0/0x110
      sp: c000000ff50f3a80
     msr: 9000000000009033
     dar: 400
   dsisr: 40000000
    current = 0xc000000ff507c000
    paca    = 0xc00000000fdc9d80   softe: 0        irq_happened: 0x01
      pid   = 782, comm = eehd
  Linux version 4.15.6-openpower1 (smc@smc-desktop) (gcc version 6.4.0 (Buildroot 2017.11.2-00008-g4b6188e)) #2 SM                                             P Tue Feb 27 12:33:27 PST 2018
  enter ? for help
    eeh_report_error+0xe0/0x110
    eeh_pe_dev_traverse+0xc0/0xdc
    eeh_handle_normal_event+0x184/0x4c4
    eeh_handle_event+0x30/0x288
    eeh_event_handler+0x124/0x170
    kthread+0x14c/0x154
    ret_from_kernel_thread+0x5c/0xc8

The first part is an EEH (on boot), the second half is the resulting
crash. nvme probe starts the nvme_reset_work() worker thread. This
worker thread starts touching the device which see a device error
(EEH) and hence queues up an event in the powerpc EEH worker
thread. nvme_reset_work() then continues and runs
nvme_remove_dead_ctrl_work() which results in unbinding the driver
from the device and hence releases all resources. At the same time,
the EEH worker thread starts doing the EEH .error_detected() driver
callback, which no longer works since the resources have been freed.

This fixes the problem in the same way the generic PCIe AER code (in
drivers/pci/pcie/aer/aerdrv_core.c) does. It makes the EEH code hold
the device_lock() while performing the driver EEH callbacks and
associated code. This ensures either the callbacks are no longer
register, or if they are registered the driver will not be removed
from underneath us.

This has been broken forever. The EEH call backs were first introduced
in 2005 (in 77bd7415610) but it's not clear if a lock was needed back
then.

Fixes: 77bd74156101 ("[PATCH] powerpc: PCI Error Recovery: PPC64 core recovery routines")
Cc: stable@vger.kernel.org # v2.6.16+
Signed-off-by: Michael Neuling 
Reviewed-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix enabling bridge MMIO windows

2018-04-24T07:34:17+00:00

commit 13a83eac373c49c0a081cbcd137e79210fe78acd upstream.

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: 652defed4875 ("powerpc/eeh: Check PCIe link after reset")
Cc: stable@vger.kernel.org # v3.11+
Reported-by: Pridhiviraj Paidipeddi 
Signed-off-by: Michael Neuling 
Acked-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE]

2018-04-13T17:48:12+00:00

[ Upstream commit 6e2f03e292ef46eed2b31b0a344a91d514f9cd81 ]

Prevent a kernel panic caused by unintentionally clearing TCR watchdog
bits. At this point in the kernel boot, the watchdog may have already
been enabled by u-boot. The original code's attempt to write to the TCR
register results in an inadvertent clearing of the watchdog
configuration bits, causing the 476 to reset.

Signed-off-by: Ivan Mikhaylov 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

2018-04-08T10:12:42+00:00

commit 52396500f97c53860164debc7d4f759077853423 upstream.

The SLB bad address handler's trap number fixup does not preserve the
low bit that indicates nonvolatile GPRs have not been saved. This
leads save_nvgprs to skip saving them, and subsequent functions and
return from interrupt will think they are saved.

This causes kernel branch-to-garbage debugging to not have correct
registers, can also cause userspace to have its registers clobbered
after a segfault.

Fixes: f0f558b131db ("powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Fix lost pending interrupt due to race causing lost update to irq_happened

2018-04-08T10:12:42+00:00

commit ff6781fd1bb404d8a551c02c35c70cec1da17ff1 upstream.

force_external_irq_replay() can be called in the do_IRQ path with
interrupts hard enabled and soft disabled if may_hard_irq_enable() set
MSR[EE]=1. It updates local_paca->irq_happened with a load, modify,
store sequence. If a maskable interrupt hits during this sequence, it
will go to the masked handler to be marked pending in irq_happened.
This update will be lost when the interrupt returns and the store
instruction executes. This can result in unpredictable latencies,
timeouts, lockups, etc.

Fix this by ensuring hard interrupts are disabled before modifying
irq_happened.

This could cause any maskable asynchronous interrupt to get lost, but
it was noticed on P9 SMP system doing RDMA NVMe target over 100GbE,
so very high external interrupt rate and high IPI rate. The hang was
bisected down to enabling doorbell interrupts for IPIs. These provided
an interrupt type that could run at high rates in the do_IRQ path,
stressing the race.

Fixes: 1d607bb3bd60 ("powerpc/irq: Add mechanism to force a replay of interrupts")
Cc: stable@vger.kernel.org # v4.8+
Reported-by: Carol L. Soto 
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/modules: Don't try to restore r2 after a sibling call

2018-03-22T08:17:57+00:00

[ Upstream commit b9eab08d012fa093947b230f9a87257c27fb829b ]

When attempting to load a livepatch module, I got the following error:

  module_64: patch_module: Expect noop after relocate, got 3c820000

The error was triggered by the following code in
unregister_netdevice_queue():

  14c:   00 00 00 48     b       14c 
                         14c: R_PPC64_REL24      net_set_todo
  150:   00 00 82 3c     addis   r4,r2,0

GCC didn't insert a nop after the branch to net_set_todo() because it's
a sibling call, so it never returns.  The nop isn't needed after the
branch in that case.

Signed-off-by: Josh Poimboeuf 
Acked-by: Naveen N. Rao 
Reviewed-and-tested-by: Kamalesh Babulal 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Improve RFI L1-D cache flush fallback

2018-02-25T10:05:50+00:00

commit bdcb1aefc5b3f7d0f1dc8b02673602bca2ff7a4b upstream.

The fallback RFI flush is used when firmware does not provide a way
to flush the cache. It's a "displacement flush" that evicts useful
data by displacing it with an uninteresting buffer.

The flush has to take care to work with implementation specific cache
replacment policies, so the recipe has been in flux. The initial
slow but conservative approach is to touch all lines of a congruence
class, with dependencies between each load. It has since been
determined that a linear pattern of loads without dependencies is
sufficient, and is significantly faster.

Measuring the speed of a null syscall with RFI fallback flush enabled
gives the relative improvement:

P8 - 1.83x
P9 - 1.75x

The flush also becomes simpler and more adaptable to different cache
geometries.

Signed-off-by: Nicholas Piggin 
[mpe: Backport to 4.9]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Simple RFI macro conversions

2018-02-25T10:05:50+00:00

commit 222f20f140623ef6033491d0103ee0875fe87d35 upstream.

This commit does simple conversions of rfi/rfid to the new macros that
include the expected destination context. By simple we mean cases
where there is a single well known destination context, and it's
simply a matter of substituting the instruction for the appropriate
macro.

Signed-off-by: Nicholas Piggin 
[mpe: Backport to 4.9, use RFI_TO_KERNEL in idle_book3s.S]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Fix conversion of slb_miss_common to use RFI_TO_USER/KERNEL

2018-02-25T10:05:50+00:00

The back port of commit c7305645eb0c ("powerpc/64s: Convert
slb_miss_common to use RFI_TO_USER/KERNEL") missed a hunk needed to
restore cr6.

Fixes: 48cc95d4e4d6 ("powerpc/64s: Convert slb_miss_common to use RFI_TO_USER/KERNEL")
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc: fix build errors in stable tree

2018-02-22T14:43:51+00:00

This is just the first chunk of commit
222f20f140623ef6033491d0103ee0875fe87d35 upstream.

to fix a build error in the powerpc tree due to other backports
happening (and this full patch not being backported).

Reported-by: Guenter Roeck 
Reported-by: Yves-Alexis Perez 
Cc: Nicholas Piggin 
Cc: Michael Ellerman 
Cc: Yves-Alexis Perez 
Signed-off-by: Greg Kroah-Hartman