From: Paul Mackerras <paulus@xxxxxxxxx> The global_invalidates() function contains a check that is intended to tell whether we are currently executing in the context of a hypercall issued by the guest. The reason is that the optimization of using a local TLB invalidate instruction is only valid in that context. The check was testing local_paca->kvm_hstate.kvm_vcore, which gets set when entering the guest but no longer gets cleared when exiting the guest. To fix this, we use the kvm_vcpu field instead, which does get cleared when exiting the guest, by the kvmppc_release_hwthread() calls inside kvmppc_run_core(). The effect of having the check wrong was that when kvmppc_do_h_remove() got called from htab_write() on the destination machine during a migration, it cleared the current cpu's bit in kvm->arch.need_tlb_flush. This meant that when the guest started running in the destination VM, it may miss out on doing a complete TLB flush, and therefore may end up using stale TLB entries from a previous guest that used the same LPID value. This should make migration more reliable. Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> Signed-off-by: Alexander Graf <agraf@xxxxxxx> --- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c index 1d6c56a..ac840c6 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c @@ -42,13 +42,14 @@ static int global_invalidates(struct kvm *kvm, unsigned long flags) /* * If there is only one vcore, and it's currently running, + * as indicated by local_paca->kvm_hstate.kvm_vcpu being set, * we can use tlbiel as long as we mark all other physical * cores as potentially having stale TLB entries for this lpid. * If we're not using MMU notifiers, we never take pages away * from the guest, so we can use tlbiel if requested. * Otherwise, don't use tlbiel. */ - if (kvm->arch.online_vcores == 1 && local_paca->kvm_hstate.kvm_vcore) + if (kvm->arch.online_vcores == 1 && local_paca->kvm_hstate.kvm_vcpu) global = 0; else if (kvm->arch.using_mmu_notifiers) global = 1; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
