From 94a04bc25a2c6296bd0c5e82c10e8231c2b11f77 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 25 Aug 2017 14:30:33 +1000 Subject: KVM: PPC: Book3S HV: POWER9 does not require secondary thread management 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 Acked-by: Paul Mackerras [mpe: Use WARN(...) instead of WARN_ON()/pr_err(...)] Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/kvm_book3s_asm.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/powerpc/include/asm/kvm_book3s_asm.h') diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h index 7cea76f11c26..83596f32f50b 100644 --- a/arch/powerpc/include/asm/kvm_book3s_asm.h +++ b/arch/powerpc/include/asm/kvm_book3s_asm.h @@ -104,6 +104,10 @@ struct kvmppc_host_state { u8 napping; #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + /* + * hwthread_req/hwthread_state pair is used to pull sibling threads + * out of guest on pre-ISAv3.0B CPUs where threads share MMU. + */ u8 hwthread_req; u8 hwthread_state; u8 host_ipi; -- cgit v1.2.3