powerpc: Add optional smp_ops->prepare_cpu SMP callback

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Some platforms (will) need to perform allocations before bringing
a new CPU online. Doing it from smp_ops->setup_cpu is the wrong
thing to do:

 - It has no useful failure path (too late)
 - Calling any allocator will enable interrupts prematurely
   causing problems with large decrementer among others

Instead, add a new callback that is called from __cpu_up (so from
the context trying to online the new CPU) at a point where we
can safely allocate and handle failures.

This will be used by XIVE support.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Benjamin Herrenschmidt 2017-04-05 17:54:48 +10:00 • committed by Michael Ellerman

parent 22bd64a621

commit 14d4ae5c4c

2 changed files with 11 additions and 0 deletions

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1

arch/powerpc/include/asm/smp.h

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10

arch/powerpc/kernel/smp.c

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