[PATCH v2] KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception

[Michael Ellerman]

On Mon, 15 Apr 2024 09:27:29 +0530, Vaibhav Jain wrote:
> This reverts commit 180c6b072bf3 ("KVM: PPC: Book3S HV nestedv2: Do not
> cancel pending decrementer exception") [1] which prevented canceling a
> pending HDEC exception for nestedv2 KVM guests. It was done to avoid
> overhead of a H_GUEST_GET_STATE hcall to read the 'DEC expiry TB' register
> which was higher compared to handling extra decrementer exceptions.
> 
> However recent benchmarks indicate that overhead of not handling 'DECR'
> expiry for Nested KVM Guest(L2) is higher and results in much larger exits
> to Pseries Host(L1) as indicated by the Unixbench-arithoh bench[2]
> 
> [...]

Applied to powerpc/topic/ppc-kvm.

[1/1] KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception
      https://git.kernel.org/powerpc/c/7be6ce7043b4cf293c8826a48fd9f56931cef2cf

cheers