Re: [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management
From: Paul Mackerras <hidden>
Date: 2017-08-29 00:20:52
On Fri, Aug 25, 2017 at 02:30:33PM +1000, Nicholas Piggin wrote:
POWER9 CPUs have independent MMU contexts per thread, so KVM does not need to quiesce secondary threads, so the hwthread_req/hwthread_state protocol does not have to be used. So patch it away on POWER9, and patch away the branch from the Linux idle wakeup to kvm_start_guest that is never used. Add a warning and error out of kvmppc_grab_hwthread in case it is ever called on POWER9. This avoids a hwsync in the idle wakeup path on POWER9. Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Some of the feature sections seem a little unnecessary except for documentation purposes (e.g. the second one added after the kvm_no_guest label), but they won't actually hurt, so: Acked-by: Paul Mackerras <redacted>