linux-stable.git/arch/powerpc/kernel/setup_64.c, branch v4.9.77

Revert "powerpc/numa: Fix percpu allocations to be NUMA aware"

2017-08-07T01:59:41+00:00

This reverts commit b4624ff952ec7d268a9651cd9184a1995befc271 which is
commit ba4a648f12f4cd0a8003dd229b6ca8a53348ee4b upstream.

Michal Hocko writes:

JFYI. We have encountered a regression after applying this patch on a
large ppc machine. While the patch is the right thing to do it doesn't
work well with the current vmalloc area size on ppc and large machines
where NUMA nodes are very far from each other. Just for the reference
the boot fails on such a machine with bunch of warning preceeding it.
See http://lkml.kernel.org/r/20170724134240.GL25221@dhcp22.suse.cz

It seems the right thing to do is to enlarge the vmalloc space on ppc
but this is not the case in the upstream kernel yet AFAIK. It is also
questionable whether that is a stable material but I will decision on
you here.

We have reverted this patch from our 4.4 based kernel.

Newer kernels do not have enlarged vmalloc space yet AFAIK so they won't
work properly eiter. This bug is quite rare though because you need a
specific HW configuration to trigger the issue - namely NUMA nodes have
to be far away from each other in the physical memory space.

Cc: Michal Hocko 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Signed-off-by: Greg Kroah-Hartman

powerpc/numa: Fix percpu allocations to be NUMA aware

2017-06-14T13:06:03+00:00

commit ba4a648f12f4cd0a8003dd229b6ca8a53348ee4b upstream.

In commit 8c272261194d ("powerpc/numa: Enable USE_PERCPU_NUMA_NODE_ID"), we
switched to the generic implementation of cpu_to_node(), which uses a percpu
variable to hold the NUMA node for each CPU.

Unfortunately we neglected to notice that we use cpu_to_node() in the allocation
of our percpu areas, leading to a chicken and egg problem. In practice what
happens is when we are setting up the percpu areas, cpu_to_node() reports that
all CPUs are on node 0, so we allocate all percpu areas on node 0.

This is visible in the dmesg output, as all pcpu allocs being in group 0:

  pcpu-alloc: [0] 00 01 02 03 [0] 04 05 06 07
  pcpu-alloc: [0] 08 09 10 11 [0] 12 13 14 15
  pcpu-alloc: [0] 16 17 18 19 [0] 20 21 22 23
  pcpu-alloc: [0] 24 25 26 27 [0] 28 29 30 31
  pcpu-alloc: [0] 32 33 34 35 [0] 36 37 38 39
  pcpu-alloc: [0] 40 41 42 43 [0] 44 45 46 47

To fix it we need an early_cpu_to_node() which can run prior to percpu being
setup. We already have the numa_cpu_lookup_table we can use, so just plumb it
in. With the patch dmesg output shows two groups, 0 and 1:

  pcpu-alloc: [0] 00 01 02 03 [0] 04 05 06 07
  pcpu-alloc: [0] 08 09 10 11 [0] 12 13 14 15
  pcpu-alloc: [0] 16 17 18 19 [0] 20 21 22 23
  pcpu-alloc: [1] 24 25 26 27 [1] 28 29 30 31
  pcpu-alloc: [1] 32 33 34 35 [1] 36 37 38 39
  pcpu-alloc: [1] 40 41 42 43 [1] 44 45 46 47

We can also check the data_offset in the paca of various CPUs, with the fix we
see:

  CPU 0:  data_offset = 0x0ffe8b0000
  CPU 24: data_offset = 0x1ffe5b0000

And we can see from dmesg that CPU 24 has an allocation on node 1:

  node   0: [mem 0x0000000000000000-0x0000000fffffffff]
  node   1: [mem 0x0000001000000000-0x0000001fffffffff]

Fixes: 8c272261194d ("powerpc/numa: Enable USE_PERCPU_NUMA_NODE_ID")
Signed-off-by: Michael Ellerman 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc: Disable HFSCR[TM] if TM is not supported

2017-04-12T10:41:13+00:00

commit 7ed23e1bae8bf7e37fd555066550a00b95a3a98b upstream.

On Power8 & Power9 the early CPU inititialisation in __init_HFSCR()
turns on HFSCR[TM] (Hypervisor Facility Status and Control Register
[Transactional Memory]), but that doesn't take into account that TM
might be disabled by CPU features, or disabled by the kernel being built
with CONFIG_PPC_TRANSACTIONAL_MEM=n.

So later in boot, when we have setup the CPU features, clear HSCR[TM] if
the TM CPU feature has been disabled. We use CPU_FTR_TM_COMP to account
for the CONFIG_PPC_TRANSACTIONAL_MEM=n case.

Without this a KVM guest might try use TM, even if told not to, and
cause an oops in the host kernel. Typically the oops is seen in
__kvmppc_vcore_entry() and may or may not be fatal to the host, but is
always bad news.

In practice all shipping CPU revisions do support TM, and all host
kernels we are aware of build with TM support enabled, so no one should
actually be able to hit this in the wild.

Fixes: 2a3563b023e5 ("powerpc: Setup in HFSCR for POWER8")
Signed-off-by: Benjamin Herrenschmidt 
Tested-by: Sam Bobroff 
[mpe: Rewrite change log with input from Sam, add Fixes/stable]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Fix setting of AIL in hypervisor mode

2016-11-15T09:43:59+00:00

Commit d3cbff1b5 "powerpc: Put exception configuration in a common place"
broke the setting of the AIL bit (which enables taking exceptions with
the MMU still on) on all processors, moving it incorrectly to a function
called only on the boot CPU. This was correct for the guest case but
not when running in hypervisor mode.

This fixes it by partially reverting that commit, putting the setting
back in cpu_ready_for_interrupts()

Fixes: d3cbff1b5a90 ("powerpc: Put exception configuration in a common place")
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman

powerpc/32: Fix crash during static key init

2016-08-10T09:41:58+00:00

We cannot do those initializations from apply_feature_fixups() as
this function runs in a very restricted environment on 32-bit where
the kernel isn't running at its linked address and the PTRRELOC()
macro must be used for any global accesss.

Instead, split them into a separtate steup_feature_keys() function
which is called in a more suitable spot on ppc32.

Fixes: 309b315b6ec6 ("powerpc: Call jump_label_init() in apply_feature_fixups()")
Reported-and-tested-by: Christian Kujau 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman

powerpc/mm: Convert early cpu/mmu feature check to use the new helpers

2016-08-01T01:15:01+00:00

This switches early feature checks to use the non static key variant of
the function. In later patches we will be switching cpu_has_feature()
and mmu_has_feature() to use static keys and we can use them only after
static key/jump label is initialized. Any check for feature before jump
label init should be done using this new helper.

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

powerpc/64: Do feature patching before MMU init

2016-08-01T01:14:56+00:00

Up until now we needed to do the MMU init before feature patching,
because part of the MMU init was scanning the device tree and setting
and/or clearing some MMU feature bits.

Now that we have split that MMU feature modification out into routines
called from early_init_devtree() (called earlier) we can now do feature
patching before calling MMU init.

The advantage of this is it means the remainder of the MMU init runs
with the final set of features which will apply for the rest of the life
of the system. This means we don't have to special case anything called
from MMU init to deal with a changing set of feature bits.

Signed-off-by: Michael Ellerman

powerpc: Merge 32-bit and 64-bit setup_arch()

2016-07-21T09:17:46+00:00

There is little enough differences now.

mpe: Add a/p/k/setup.h to contain the prototypes and empty versions of
functions we need, rather than using weak functions. Add a few other
empty versions to avoid as many #ifdefs as possible in the code.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman

powerpc/64: Make a few boot functions __init

2016-07-21T09:17:25+00:00

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman

powerpc: Re-order setup_panic()

2016-07-21T09:17:23+00:00

Do it right after probe_machine() since it's about testing ppc_md,
and put the test in the common code.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman