From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753326AbaBXPmj (ORCPT ); Mon, 24 Feb 2014 10:42:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:9250 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753294AbaBXPmh (ORCPT ); Mon, 24 Feb 2014 10:42:37 -0500 From: Andrew Jones To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: mtosatti@redhat.com, pbonzini@redhat.com Subject: [PATCH] x86: kvm: fix unstable_tsc boot Date: Mon, 24 Feb 2014 16:42:29 +0100 Message-Id: <1393256549-7743-1-git-send-email-drjones@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the tsc is marked unstable on the host it causes global clock updates to be requested each time a vcpu is loaded, nearly halting all progress on guests with a large number of vcpus. Fix this by only requesting a local clock update unless the vcpu is migrating to another cpu. Signed-off-by: Andrew Jones --- arch/x86/kvm/x86.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6530019116b0d..ea716a162b4a3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2781,15 +2781,18 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vcpu->arch.last_guest_tsc); kvm_x86_ops->write_tsc_offset(vcpu, offset); vcpu->arch.tsc_catchup = 1; + set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests); } + } + + if (unlikely(vcpu->cpu != cpu)) { /* * On a host with synchronized TSC, there is no need to update * kvmclock on vcpu->cpu migration */ if (!vcpu->kvm->arch.use_master_clock || vcpu->cpu == -1) kvm_make_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu); - if (vcpu->cpu != cpu) - kvm_migrate_timers(vcpu); + kvm_migrate_timers(vcpu); vcpu->cpu = cpu; } -- 1.8.1.4