Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932496AbaBEVRs (ORCPT ); Wed, 5 Feb 2014 16:17:48 -0500 Received: from mail1.windriver.com ([147.11.146.13]:47857 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753296AbaBEUD0 (ORCPT ); Wed, 5 Feb 2014 15:03:26 -0500 From: Paul Gortmaker To: , CC: Alex Williamson , Marcelo Tosatti , Paul Gortmaker Subject: [v2.6.34-stable 008/213] KVM: lock slots_lock around device assignment Date: Wed, 5 Feb 2014 14:59:23 -0500 Message-ID: <1391630568-49251-9-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.8.5.2 In-Reply-To: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> References: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alex Williamson ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 21a1416a1c945c5aeaeaf791b63c64926018eb77 upstream. As pointed out by Jason Baron, when assigning a device to a guest we first set the iommu domain pointer, which enables mapping and unmapping of memory slots to the iommu. This leaves a window where this path is enabled, but we haven't synchronized the iommu mappings to the existing memory slots. Thus a slot being removed at that point could send us down unexpected code paths removing non-existent pinnings and iommu mappings. Take the slots_lock around creating the iommu domain and initial mappings as well as around iommu teardown to avoid this race. Signed-off-by: Alex Williamson Signed-off-by: Marcelo Tosatti [PG: drop goto for EPERM check, 2.6.34 doesn't have that code] Signed-off-by: Paul Gortmaker --- virt/kvm/iommu.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c index ac765f648218..8c510edca9c9 100644 --- a/virt/kvm/iommu.c +++ b/virt/kvm/iommu.c @@ -174,18 +174,20 @@ int kvm_iommu_map_guest(struct kvm *kvm) return -ENODEV; } + mutex_lock(&kvm->slots_lock); + kvm->arch.iommu_domain = iommu_domain_alloc(); - if (!kvm->arch.iommu_domain) - return -ENOMEM; + if (!kvm->arch.iommu_domain) { + r = -ENOMEM; + goto out_unlock; + } r = kvm_iommu_map_memslots(kvm); if (r) - goto out_unmap; - - return 0; + kvm_iommu_unmap_memslots(kvm); -out_unmap: - kvm_iommu_unmap_memslots(kvm); +out_unlock: + mutex_unlock(&kvm->slots_lock); return r; } @@ -239,7 +241,11 @@ int kvm_iommu_unmap_guest(struct kvm *kvm) if (!domain) return 0; + mutex_lock(&kvm->slots_lock); kvm_iommu_unmap_memslots(kvm); + kvm->arch.iommu_domain = NULL; + mutex_unlock(&kvm->slots_lock); + iommu_domain_free(domain); return 0; } -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/