Thread (3 messages) 3 messages, 2 authors, 2021-05-15

Re: [PATCH v2 1/2] powerpc/64s: Fix crashes when toggling stf barrier

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From: Michael Ellerman <hidden>
Date: 2021-05-15 22:48:08

On Thu, 6 May 2021 14:49:58 +1000, Michael Ellerman wrote:
The STF (store-to-load forwarding) barrier mitigation can be
enabled/disabled at runtime via a debugfs file (stf_barrier), which
causes the kernel to patch itself to enable/disable the relevant
mitigations.

However depending on which mitigation we're using, it may not be safe to
do that patching while other CPUs are active. For example the following
crash:

[...]
Applied to powerpc/fixes.

[1/2] powerpc/64s: Fix crashes when toggling stf barrier
      https://git.kernel.org/powerpc/c/8ec7791bae1327b1c279c5cd6e929c3b12daaf0a
[2/2] powerpc/64s: Fix crashes when toggling entry flush barrier
      https://git.kernel.org/powerpc/c/aec86b052df6541cc97c5fca44e5934cbea4963b

cheers
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