linux-stable.git/arch/powerpc, branch v3.2.39

KVM: PPC: Emulate dcbf

2013-02-06T04:33:37+00:00

commit d3286144c92ec876da9e30320afa875699b7e0f1 upstream.

Guests can trigger MMIO exits using dcbf. Since we don't emulate cache
incoherent MMIO, just do nothing and move on.

Reported-by: Ben Collins 
Signed-off-by: Alexander Graf 
Tested-by: Ben Collins 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

powerpc: Add missing NULL terminator to avoid boot panic on PPC40x

2013-01-16T01:13:16+00:00

commit e6449c9b2d90c1bd9a5985bf05ddebfd1631cd6b upstream.

The missing NULL terminator can cause a panic on
PPC405 boards during boot:

  Linux/PowerPC load: console=ttyS0,115200 root=/dev/mtdblock1 rootfstype=squashfs,jffs2 noinitrd init=/etc/preinit
  Finalizing device tree... flat tree at 0x6a5160
  bootconsole [udbg0] enabled
  Page fault in user mode with in_atomic() = 1 mm = (null)
  NIP = c0275f50  MSR = fffffffe
  Oops: Weird page fault, sig: 11 [#1]
  PowerPC 40x Platform
  Modules linked in:
  NIP: c0275f50 LR: c0275f60 CTR: c0280000
  REGS: c0275eb0 TRAP: 636f7265   Not tainted  (3.7.1)
  MSR: fffffffe  CR: c06a6190  XER: 00000001
  TASK = c02662a8[0] 'swapper' THREAD: c0274000
  GPR00: c0275ec0 c000c658 c027c4bf 00000000 c0275ee0 c000a0ec c020a1a8 c020a1f0
  GPR08: c020f631 c020f404 c025f078 c025f080 c0275f10
   Call Trace:
   ---[ end trace 31fd0ba7d8756001 ]---

  Kernel panic - not syncing: Attempted to kill the idle task!

The panic happens since commit 9597abe00c1bab2aedce6b49866bf6d1e81c9eed
(sections: fix section conflicts in arch/powerpc), however the root
cause of this is that the NULL terminator were not added in commit
a4f740cf33f7f6c164bbde3c0cdbcc77b0c4997c (of/flattree: Add of_flat_dt_match()
helper function).

Cc: Grant Likely 
Signed-off-by: Gabor Juhos 
Signed-off-by: Benjamin Herrenschmidt 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

powerpc/vdso: Remove redundant locking in update_vsyscall_tz()

2013-01-16T01:13:16+00:00

commit ce73ec6db47af84d1466402781ae0872a9e7873c upstream.

The locking in update_vsyscall_tz() is not only unnecessary because the vdso
code copies the data unproteced in __kernel_gettimeofday() but also
introduces a hard to reproduce race condition between update_vsyscall()
and update_vsyscall_tz(), which causes user space process to loop
forever in vdso code.

The following patch removes the locking from update_vsyscall_tz().

Locking is not only unnecessary because the vdso code copies the data
unprotected in __kernel_gettimeofday() but also erroneous because updating
the tb_update_count is not atomic and introduces a hard to reproduce race
condition between update_vsyscall() and update_vsyscall_tz(), which further
causes user space process to loop forever in vdso code.

The below scenario describes the race condition,
x==0	Boot CPU			other CPU
	proc_P: x==0
	    timer interrupt
		update_vsyscall
x==1		    x++;sync		settimeofday
					    update_vsyscall_tz
x==2						x++;sync
x==3		    sync;x++
						sync;x++
	proc_P: x==3 (loops until x becomes even)

Because the ++ operator would be implemented as three instructions and not
atomic on powerpc.

A similar change was made for x86 in commit 6c260d58634
("x86: vdso: Remove bogus locking in update_vsyscall_tz")

Signed-off-by: Shan Hai 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

powerpc: Fix CONFIG_RELOCATABLE=y CONFIG_CRASH_DUMP=n build

2013-01-03T03:33:09+00:00

commit 11ee7e99f35ecb15f59b21da6a82d96d2cd3fcc8 upstream.

If we build a kernel with CONFIG_RELOCATABLE=y CONFIG_CRASH_DUMP=n,
the kernel fails when we run at a non zero offset. It turns out
we were incorrectly wrapping some of the relocatable kernel code
with CONFIG_CRASH_DUMP.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

KVM: PPC: 44x: fix DCR read/write

2013-01-03T03:32:59+00:00

commit e43a028752fed049e4bd94ef895542f96d79fa74 upstream.

When remembering the direction of a DCR transaction, we should write
to the same variable that we interpret on later when doing vcpu_run
again.

Signed-off-by: Alexander Graf 
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings

powerpc: fix wii_memory_fixups() compile error on 3.0.y tree

2013-01-03T03:32:55+00:00

Fix wii_memory_fixups() the following compile error on 3.0.y tree with
wii_defconfig on 3.0.y tree.

  CC      arch/powerpc/platforms/embedded6xx/wii.o
arch/powerpc/platforms/embedded6xx/wii.c: In function ‘wii_memory_fixups’:
arch/powerpc/platforms/embedded6xx/wii.c:88:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 2 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:88:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:90:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 2 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:90:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘phys_addr_t’ [-Werror=format]
cc1: all warnings being treated as errors
make[2]: *** [arch/powerpc/platforms/embedded6xx/wii.o] Error 1
make[1]: *** [arch/powerpc/platforms/embedded6xx] Error 2
make: *** [arch/powerpc/platforms] Error 2

Signed-off-by: Shuah Khan 
Signed-off-by: Ben Hutchings

powerpc/eeh: Lock module while handling EEH event

2012-10-17T02:48:32+00:00

commit feadf7c0a1a7c08c74bebb4a13b755f8c40e3bbc upstream.

The EEH core is talking with the PCI device driver to determine the
action (purely reset, or PCI device removal). During the period, the
driver might be unloaded and in turn causes kernel crash as follows:

EEH: Detected PCI bus error on PHB#4-PE#10000
EEH: This PCI device has failed 3 times in the last hour
lpfc 0004:01:00.0: 0:2710 PCI channel disable preparing for reset
Unable to handle kernel paging request for data at address 0x00000490
Faulting instruction address: 0xd00000000e682c90
cpu 0x1: Vector: 300 (Data Access) at [c000000fc75ffa20]
    pc: d00000000e682c90: .lpfc_io_error_detected+0x30/0x240 [lpfc]
    lr: d00000000e682c8c: .lpfc_io_error_detected+0x2c/0x240 [lpfc]
    sp: c000000fc75ffca0
   msr: 8000000000009032
   dar: 490
 dsisr: 40000000
  current = 0xc000000fc79b88b0
  paca    = 0xc00000000edb0380	 softe: 0	 irq_happened: 0x00
    pid   = 3386, comm = eehd
enter ? for help
[c000000fc75ffca0] c000000fc75ffd30 (unreliable)
[c000000fc75ffd30] c00000000004fd3c .eeh_report_error+0x7c/0xf0
[c000000fc75ffdc0] c00000000004ee00 .eeh_pe_dev_traverse+0xa0/0x180
[c000000fc75ffe70] c00000000004ffd8 .eeh_handle_event+0x68/0x300
[c000000fc75fff00] c0000000000503a0 .eeh_event_handler+0x130/0x1a0
[c000000fc75fff90] c000000000020138 .kernel_thread+0x54/0x70
1:mon>

The patch increases the reference of the corresponding driver modules
while EEH core does the negotiation with PCI device driver so that the
corresponding driver modules can't be unloaded during the period and
we're safe to refer the callbacks.

Reported-by: Alexey Kardashevskiy 
Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt 
[bwh: Backported to 3.2:
 - Adjust context
 - Reporting functions return int (success = 0), not void * (success = NULL)
 - Assume that the 'dev' arguments are non-null]
Signed-off-by: Ben Hutchings

powerpc: Make sure IPI handlers see data written by IPI senders

2012-09-19T14:04:42+00:00

commit 9fb1b36ca1234e64a5d1cc573175303395e3354d upstream.

We have been observing hangs, both of KVM guest vcpu tasks and more
generally, where a process that is woken doesn't properly wake up and
continue to run, but instead sticks in TASK_WAKING state.  This
happens because the update of rq->wake_list in ttwu_queue_remote()
is not ordered with the update of ipi_message in
smp_muxed_ipi_message_pass(), and the reading of rq->wake_list in
scheduler_ipi() is not ordered with the reading of ipi_message in
smp_ipi_demux().  Thus it is possible for the IPI receiver not to see
the updated rq->wake_list and therefore conclude that there is nothing
for it to do.

In order to make sure that anything done before smp_send_reschedule()
is ordered before anything done in the resulting call to scheduler_ipi(),
this adds barriers in smp_muxed_message_pass() and smp_ipi_demux().
The barrier in smp_muxed_message_pass() is a full barrier to ensure that
there is a full ordering between the smp_send_reschedule() caller and
scheduler_ipi().  In smp_ipi_demux(), we use xchg() rather than
xchg_local() because xchg() includes release and acquire barriers.
Using xchg() rather than xchg_local() makes sense given that
ipi_message is not just accessed locally.

This moves the barrier between setting the message and calling the
cause_ipi() function into the individual cause_ipi implementations.
Most of them -- those that used outb, out_8 or similar -- already had
a full barrier because out_8 etc. include a sync before the MMIO
store.  This adds an explicit barrier in the two remaining cases.

These changes made no measurable difference to the speed of IPIs as
measured using a simple ping-pong latency test across two CPUs on
different cores of a POWER7 machine.

The analysis of the reason why processes were not waking up properly
is due to Milton Miller.

Reported-by: Milton Miller 
Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

powerpc/xics: Harden xics hypervisor backend

2012-09-19T14:04:42+00:00

commit 3ce21cdfe93efffa4ffba9cf3ca2576d3d60d6dc upstream.

During kdump stress testing I sometimes see the kdump kernel panic
with:

  Interrupt 0x306 (real) is invalid, disabling it.
  Kernel panic - not syncing: bad return code EOI - rc = -4, value=ff000306

Instead of panicing print the error message, dump the stack the first
time it happens and continue on. Add some more information to the
debug messages as well.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

powerpc: Restore correct DSCR in context switch

2012-09-19T14:04:42+00:00

commit 714332858bfd40dcf8f741498336d93875c23aa7 upstream.

During a context switch we always restore the per thread DSCR value.
If we aren't doing explicit DSCR management
(ie thread.dscr_inherit == 0) and the default DSCR changed while
the process has been sleeping we end up with the wrong value.

Check thread.dscr_inherit and select the default DSCR or per thread
DSCR as required.

This was found with the following test case, when running with
more threads than CPUs (ie forcing context switching):

http://ozlabs.org/~anton/junkcode/dscr_default_test.c

With the four patches applied I can run a combination of all
test cases successfully at the same time:

http://ozlabs.org/~anton/junkcode/dscr_default_test.c
http://ozlabs.org/~anton/junkcode/dscr_explicit_test.c
http://ozlabs.org/~anton/junkcode/dscr_inherit_test.c

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings