Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760748Ab2EJRgn (ORCPT ); Thu, 10 May 2012 13:36:43 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:53504 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760618Ab2EJRgj (ORCPT ); Thu, 10 May 2012 13:36:39 -0400 Message-Id: <20120510173136.725265629@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Thu, 10 May 2012 10:32:16 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Alex Williamson , Marcelo Tosatti Subject: [ 44/52] KVM: lock slots_lock around device assignment In-Reply-To: <20120510173229.GA5678@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2492 Lines: 86 3.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Williamson (cherry picked from commit 21a1416a1c945c5aeaeaf791b63c64926018eb77) 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 Signed-off-by: Greg Kroah-Hartman --- virt/kvm/iommu.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) --- a/virt/kvm/iommu.c +++ b/virt/kvm/iommu.c @@ -240,9 +240,13 @@ int kvm_iommu_map_guest(struct kvm *kvm) return -ENODEV; } + mutex_lock(&kvm->slots_lock); + kvm->arch.iommu_domain = iommu_domain_alloc(&pci_bus_type); - if (!kvm->arch.iommu_domain) - return -ENOMEM; + if (!kvm->arch.iommu_domain) { + r = -ENOMEM; + goto out_unlock; + } if (!allow_unsafe_assigned_interrupts && !iommu_domain_has_cap(kvm->arch.iommu_domain, @@ -253,17 +257,16 @@ int kvm_iommu_map_guest(struct kvm *kvm) " module option.\n", __func__); iommu_domain_free(kvm->arch.iommu_domain); kvm->arch.iommu_domain = NULL; - return -EPERM; + r = -EPERM; + 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; } @@ -340,7 +343,11 @@ int kvm_iommu_unmap_guest(struct kvm *kv 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; } -- 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/