From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:56709 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932378AbcCMDuH (ORCPT ); Sat, 12 Mar 2016 22:50:07 -0500 Subject: Patch "KVM: x86: move steal time initialization to vcpu entry time" has been added to the 3.10-stable tree To: mtosatti@redhat.com, dmatlack@google.com, gregkh@linuxfoundation.org, pbonzini@redhat.com Cc: , From: Date: Sat, 12 Mar 2016 19:49:46 -0800 Message-ID: <14578409867077@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled KVM: x86: move steal time initialization to vcpu entry time to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-move-steal-time-initialization-to-vcpu-entry-time.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 7cae2bedcbd4680b155999655e49c27b9cf020fa Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Wed, 14 Oct 2015 19:33:09 -0300 Subject: KVM: x86: move steal time initialization to vcpu entry time From: Marcelo Tosatti 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: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1941,6 +1941,8 @@ static void accumulate_steal_time(struct static void record_steal_time(struct kvm_vcpu *vcpu) { + accumulate_steal_time(vcpu); + if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) return; @@ -2074,12 +2076,6 @@ int kvm_set_msr_common(struct kvm_vcpu * 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; @@ -2758,7 +2754,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu vcpu->cpu = cpu; } - accumulate_steal_time(vcpu); kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); } Patches currently in stable-queue which might be from mtosatti@redhat.com are queue-3.10/kvm-x86-move-steal-time-initialization-to-vcpu-entry-time.patch