Re: (subset) [PATCH v3 1/2] arm64: add an MTE support check to the top of mte_thread_switch()

On Wed, 15 Sep 2021 12:03:35 -0700, Peter Collingbourne wrote:

This lets us avoid doing unnecessary work on hardware that does
not support MTE, and will allow us to freely use MTE instructions
in the code called by mte_thread_switch().

Since this would mean that we do a redundant check in
mte_check_tfsr_el1(), remove it and add two checks now required in
its callers.

I applied the first patch to arm64 (for-next/fixes), it should appear in
5.15-rc3. It looks to me more like a performance regression with the
additional dsb+isb on the syscall path for hw not supporting MTE (and I
added a Fixes tag). I'll leave the second patch to Will for 5.16.

Thanks!

[1/2] arm64: add an MTE support check to the top of mte_thread_switch()
      https://git.kernel.org/arm64/c/8c8a3b5bd960

-- 
Catalin


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