On Fri, 14 Feb 2025 17:36:44 +0000, Nicolas Saenz Julienne wrote:
> x86 is the only architecture that defines set/clear_bit() as non-atomic.
> This makes it incompatible with arch-agnostic code that might implicitly
> require atomicity. And it was observed to corrupt the 'online_cpus'
> bitmap, as non BSP CPUs perform RmWs on the bitmap concurrently during
> bring up. See:
>
> ap_start64()
> save_id()
> set_bit(apic_id(), online_cpus)
>
> [...]
Applied to kvm-x86 next (and now pulled by Paolo), thanks!
[1/1] x86: Make set/clear_bit() atomic
https://github.com/kvm-x86/kvm-unit-tests/commit/2f3c02862e03
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https://github.com/kvm-x86/kvm-unit-tests/tree/next
