linux-stable.git/arch/powerpc/kernel/setup_64.c, branch v4.4.232

powerpc/fsl: Enable runtime patching if nospectre_v2 boot arg is used

2019-05-16T17:44:52+00:00

commit 3bc8ea8603ae4c1e09aca8de229ad38b8091fcb3 upstream.

If the user choses not to use the mitigations, replace
the code sequence with nops.

Signed-off-by: Diana Craciun 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Call setup_barrier_nospec() from setup_arch()

2019-05-16T17:44:49+00:00

commit af375eefbfb27cbb5b831984e66d724a40d26b5c upstream.

Currently we require platform code to call setup_barrier_nospec(). But
if we add an empty definition for the !CONFIG_PPC_BARRIER_NOSPEC case
then we can call it in setup_arch().

Signed-off-by: Diana Craciun 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Fix section mismatch warnings from setup_rfi_flush()

2019-05-16T17:44:47+00:00

commit 501a78cbc17c329fabf8e9750a1e9ab810c88a0e upstream.

The recent LPM changes to setup_rfi_flush() are causing some section
mismatch warnings because we removed the __init annotation on
setup_rfi_flush():

  The function setup_rfi_flush() references
  the function __init ppc64_bolted_size().
  the function __init memblock_alloc_base().

The references are actually in init_fallback_flush(), but that is
inlined into setup_rfi_flush().

These references are safe because:
 - only pseries calls setup_rfi_flush() at runtime
 - pseries always passes L1D_FLUSH_FALLBACK at boot
 - so the fallback flush area will always be allocated
 - so the check in init_fallback_flush() will always return early:
   /* Only allocate the fallback flush area once (at boot time). */
   if (l1d_flush_fallback_area)
   	return;

 - and therefore we won't actually call the freed init routines.

We should rework the code to make it safer by default rather than
relying on the above, but for now as a quick-fix just add a __ref
annotation to squash the warning.

Fixes: abf110f3e1ce ("powerpc/rfi-flush: Make it possible to call setup_rfi_flush() again")
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Move cpu_show_meltdown()

2019-05-16T17:44:46+00:00

commit 8ad33041563a10b34988800c682ada14b2612533 upstream.

This landed in setup_64.c for no good reason other than we had nowhere
else to put it. Now that we have a security-related file, that is a
better place for it so move it.

Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/rfi-flush: Differentiate enabled and patched flush types

2019-05-16T17:44:45+00:00

commit 0063d61ccfc011f379a31acaeba6de7c926fed2c upstream.

Currently the rfi-flush messages print 'Using  flush' for all
enabled_flush_types, but that is not necessarily true -- as now the
fallback flush is always enabled on pseries, but the fixup function
overwrites its nop/branch slot with other flush types, if available.

So, replace the 'Using  flush' messages with ' flush is
available'.

Also, print the patched flush types in the fixup function, so users
can know what is (not) being used (e.g., the slower, fallback flush,
or no flush type at all if flush is disabled via the debugfs switch).

Suggested-by: Michael Ellerman 
Signed-off-by: Mauricio Faria de Oliveira 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/rfi-flush: Make it possible to call setup_rfi_flush() again

2019-05-16T17:44:45+00:00

commit abf110f3e1cea40f5ea15e85f5d67c39c14568a7 upstream.

For PowerVM migration we want to be able to call setup_rfi_flush()
again after we've migrated the partition.

To support that we need to check that we're not trying to allocate the
fallback flush area after memblock has gone away (i.e., boot-time only).

Signed-off-by: Michael Ellerman 
Signed-off-by: Mauricio Faria de Oliveira 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/rfi-flush: Move the logic to avoid a redo into the debugfs code

2019-05-16T17:44:45+00:00

commit 1e2a9fc7496955faacbbed49461d611b704a7505 upstream.

rfi_flush_enable() includes a check to see if we're already
enabled (or disabled), and in that case does nothing.

But that means calling setup_rfi_flush() a 2nd time doesn't actually
work, which is a bit confusing.

Move that check into the debugfs code, where it really belongs.

Signed-off-by: Michael Ellerman 
Signed-off-by: Mauricio Faria de Oliveira 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

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

2019-05-16T17:44:44+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 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Fix RFI flush dependency on HARDLOCKUP_DETECTOR

2018-02-28T09:17:21+00:00

The backport of commit aa8a5e0062ac ("powerpc/64s: Add support for RFI
flush of L1-D cache"), incorrectly placed the new RFI flush code
inside an existing #ifdef CONFIG_HARDLOCKUP_DETECTOR block.

This has the obvious effect of requiring HARDLOCKUP_DETECTOR to be
enabled in order for RFI flush to be enabled, which is a bug.

Fix it by moving the #endif up to where it belongs.

Fixes: c3892946315e ("powerpc/64s: Add support for RFI flush of L1-D cache")
Reported-by: Bernhard Kaindl 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Allow control of RFI flush via debugfs

2018-02-16T19:09:36+00:00

commit 236003e6b5443c45c18e613d2b0d776a9f87540e upstream.

Expose the state of the RFI flush (enabled/disabled) via debugfs, and
allow it to be enabled/disabled at runtime.

eg: $ cat /sys/kernel/debug/powerpc/rfi_flush
    1
    $ echo 0 > /sys/kernel/debug/powerpc/rfi_flush
    $ cat /sys/kernel/debug/powerpc/rfi_flush
    0

Signed-off-by: Michael Ellerman 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Greg Kroah-Hartman