From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758201Ab2JKBDo (ORCPT ); Wed, 10 Oct 2012 21:03:44 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:49308 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758086Ab2JKBDj (ORCPT ); Wed, 10 Oct 2012 21:03:39 -0400 X-Sasl-enc: qPdlf95UAtt9g1DJlFOg9yIl5LZOLaf7AZ1qkEljYyg3 1349917417 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Alex Williamson , Donald Dutile , Chris Wright , Joerg Roedel Subject: [ 005/120] intel-iommu: Default to non-coherent for domains unattached to iommus Date: Thu, 11 Oct 2012 09:59:17 +0900 Message-Id: <20121011005826.327862190@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121011005825.364610894@linuxfoundation.org> References: <20121011005825.364610894@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Williamson commit 2e12bc29fc5a12242d68e11875db3dd58efad9ff upstream. domain_update_iommu_coherency() currently defaults to setting domains as coherent when the domain is not attached to any iommus. This allows for a window in domain_context_mapping_one() where such a domain can update context entries non-coherently, and only after update the domain capability to clear iommu_coherency. This can be seen using KVM device assignment on VT-d systems that do not support coherency in the ecap register. When a device is added to a guest, a domain is created (iommu_coherency = 0), the device is attached, and ranges are mapped. If we then hot unplug the device, the coherency is updated and set to the default (1) since no iommus are attached to the domain. A subsequent attach of a device makes use of the same dmar domain (now marked coherent) updates context entries with coherency enabled, and only disables coherency as the last step in the process. To fix this, switch domain_update_iommu_coherency() to use the safer, non-coherent default for domains not attached to iommus. Signed-off-by: Alex Williamson Tested-by: Donald Dutile Acked-by: Donald Dutile Acked-by: Chris Wright Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/intel-iommu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -588,7 +588,9 @@ static void domain_update_iommu_coherenc { int i; - domain->iommu_coherency = 1; + i = find_first_bit(domain->iommu_bmp, g_num_of_iommus); + + domain->iommu_coherency = i < g_num_of_iommus ? 1 : 0; for_each_set_bit(i, domain->iommu_bmp, g_num_of_iommus) { if (!ecap_coherent(g_iommus[i]->ecap)) {