From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753940AbcFPIXZ (ORCPT ); Thu, 16 Jun 2016 04:23:25 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:34824 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbcFPIXV (ORCPT ); Thu, 16 Jun 2016 04:23:21 -0400 Subject: Re: [PATCH 0/3] KVM: do not use kvm->online_vcpus to check "has one VCPU been created?" To: Cornelia Huck References: <1465824332-10628-1-git-send-email-pbonzini@redhat.com> <20160613164421.77b70bee.cornelia.huck@de.ibm.com> <26948b73-1233-8515-24ac-7557837230b2@redhat.com> <5762559A.1090604@de.ibm.com> <20160616095946.35cc57e8.cornelia.huck@de.ibm.com> Cc: Christian Borntraeger , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Christian Borntraeger From: Paolo Bonzini Message-ID: Date: Thu, 16 Jun 2016 10:23:17 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <20160616095946.35cc57e8.cornelia.huck@de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/06/2016 09:59, Cornelia Huck wrote: > On Thu, 16 Jun 2016 09:30:34 +0200 > Christian Borntraeger wrote: > >> On 06/16/2016 12:00 AM, Paolo Bonzini wrote: >>> >>> >>> On 13/06/2016 16:44, Cornelia Huck wrote: >>>>>> arch/s390/kvm/kvm-s390.c | 10 +++++----- >>>>>> arch/x86/kvm/Kconfig | 1 - >>>>>> arch/x86/kvm/x86.c | 11 +++-------- >>>>>> include/linux/kvm_host.h | 14 ++++++++------ >>>>>> virt/kvm/Kconfig | 3 --- >>>>>> virt/kvm/kvm_main.c | 27 +++++++++++++++++---------- >>>>>> 6 files changed, 33 insertions(+), 33 deletions(-) >>>>>> >>>> Looks like a sane approach, only two inversions in the s390 patch :) >>> >>> So it's okay to push patch 3 to kvm/next? >> >> >> With the 2 fixes that Conny requested, yes. > > I had been waiting for a v2 ;) This is the patch I've pushed: -------------------- 8< --------------------- >>From a03825bbd0c39feeba605912cdbc28e79e4e01e1 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 13 Jun 2016 14:50:04 +0200 Subject: [PATCH] KVM: s390: use kvm->created_vcpus The new created_vcpus field avoids possible races between enabling capabilities and creating VCPUs. Acked-by: Christian Borntraeger Signed-off-by: Paolo Bonzini diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 49c60393a15c..0dcf9b8fc12c 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -422,7 +422,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) break; case KVM_CAP_S390_VECTOR_REGISTERS: mutex_lock(&kvm->lock); - if (atomic_read(&kvm->online_vcpus)) { + if (kvm->created_vcpus) { r = -EBUSY; } else if (MACHINE_HAS_VX) { set_kvm_facility(kvm->arch.model.fac_mask, 129); @@ -437,7 +437,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) case KVM_CAP_S390_RI: r = -EINVAL; mutex_lock(&kvm->lock); - if (atomic_read(&kvm->online_vcpus)) { + if (kvm->created_vcpus) { r = -EBUSY; } else if (test_facility(64)) { set_kvm_facility(kvm->arch.model.fac_mask, 64); @@ -492,7 +492,7 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att ret = -EBUSY; VM_EVENT(kvm, 3, "%s", "ENABLE: CMMA support"); mutex_lock(&kvm->lock); - if (atomic_read(&kvm->online_vcpus) == 0) { + if (!kvm->created_vcpus) { kvm->arch.use_cmma = 1; ret = 0; } @@ -536,7 +536,7 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att ret = -EBUSY; mutex_lock(&kvm->lock); - if (atomic_read(&kvm->online_vcpus) == 0) { + if (!kvm->created_vcpus) { /* gmap_alloc will round the limit up */ struct gmap *new = gmap_alloc(current->mm, new_limit); @@ -713,7 +713,7 @@ static int kvm_s390_set_processor(struct kvm *kvm, struct kvm_device_attr *attr) int ret = 0; mutex_lock(&kvm->lock); - if (atomic_read(&kvm->online_vcpus)) { + if (kvm->created_vcpus) { ret = -EBUSY; goto out; }