Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966359AbcCPIOw (ORCPT ); Wed, 16 Mar 2016 04:14:52 -0400 Received: from mail.kernel.org ([198.145.29.136]:60949 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966534AbcCPINp (ORCPT ); Wed, 16 Mar 2016 04:13:45 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Marcelo Tosatti , Paolo Bonzini , Zefan Li Subject: [PATCH 3.4 107/107] KVM: x86: move steal time initialization to vcpu entry time Date: Wed, 16 Mar 2016 16:06:41 +0800 Message-Id: <1458115601-5762-107-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1458115541-5712-1-git-send-email-lizf@kernel.org> References: <1458115541-5712-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1786 Lines: 64 From: Marcelo Tosatti 3.4.111-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 7cae2bedcbd4680b155999655e49c27b9cf020fa upstream. As reported at https://bugs.launchpad.net/qemu/+bug/1494350, it is possible to have vcpu->arch.st.last_steal initialized from a thread other than vcpu thread, say the iothread, via KVM_SET_MSRS. Which can cause an overflow later (when subtracting from vcpu threads sched_info.run_delay). To avoid that, move steal time accumulation to vcpu entry time, before copying steal time data to guest. Signed-off-by: Marcelo Tosatti Reviewed-by: David Matlack Signed-off-by: Paolo Bonzini Signed-off-by: Zefan Li --- arch/x86/kvm/x86.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4ad2b7b..9cc83e2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1545,6 +1545,8 @@ static void accumulate_steal_time(struct kvm_vcpu *vcpu) static void record_steal_time(struct kvm_vcpu *vcpu) { + accumulate_steal_time(vcpu); + if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) return; @@ -1665,12 +1667,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) if (!(data & KVM_MSR_ENABLED)) break; - vcpu->arch.st.last_steal = current->sched_info.run_delay; - - preempt_disable(); - accumulate_steal_time(vcpu); - preempt_enable(); - kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); break; @@ -2327,7 +2323,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vcpu->cpu = cpu; } - accumulate_steal_time(vcpu); kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); } -- 1.9.1