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SubjectRe: [PATCH v5 2/9] x86/split_lock: Avoid runtime reads of the TEST_CTRL MSR
On Sun, Mar 15, 2020 at 01:05:10PM +0800, Xiaoyao Li wrote:
> In a context switch from a task that is detecting split locks
> to one that is not (or vice versa) we need to update the TEST_CTRL
> MSR. Currently this is done with the common sequence:
> read the MSR
> flip the bit
> write the MSR
> in order to avoid changing the value of any reserved bits in the MSR.
> Cache the value of the TEST_CTRL MSR when we read it during initialization
> so we can avoid an expensive RDMSR instruction during context switch.
> Suggested-by: Sean Christopherson <>
> Originally-by: Tony Luck <>
> Signed-off-by: Xiaoyao Li <>

Is it bad form to Ack/Review patches originally by oneself?


Acked-by: Tony Luck <>

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