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/kvm/book3s_hv_rmhandlers.S | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/powerpc/kvm/book3s_hv_rmhandlers.S') diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index cb44065e2946..eacf3d06eb75 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -149,9 +149,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) subf r4, r4, r3 mtspr SPRN_DEC, r4 +BEGIN_FTR_SECTION /* hwthread_req may have got set by cede or no vcpu, so clear it */ li r0, 0 stb r0, HSTATE_HWTHREAD_REQ(r13) +END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) /* * For external interrupts we need to call the Linux @@ -314,6 +316,7 @@ kvm_novcpu_exit: * Relocation is off and most register values are lost. * r13 points to the PACA. * r3 contains the SRR1 wakeup value, SRR1 is trashed. + * This is not used by ISAv3.0B processors. */ .globl kvm_start_guest kvm_start_guest: @@ -432,6 +435,9 @@ kvm_secondary_got_guest: * While waiting we also need to check if we get given a vcpu to run. */ kvm_no_guest: +BEGIN_FTR_SECTION + twi 31,0,0 +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) lbz r3, HSTATE_HWTHREAD_REQ(r13) cmpwi r3, 0 bne 53f @@ -2466,8 +2472,10 @@ kvm_do_nap: clrrdi r0, r0, 1 mtspr SPRN_CTRLT, r0 +BEGIN_FTR_SECTION li r0,1 stb r0,HSTATE_HWTHREAD_REQ(r13) +END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) mfspr r5,SPRN_LPCR ori r5,r5,LPCR_PECE0 | LPCR_PECE1 BEGIN_FTR_SECTION -- cgit v1.2.3