From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [PATCH] iommu/intel: GAW only gets smaller by adding devices Date: Thu, 29 May 2014 14:23:17 -0600 Message-ID: <20140529202304.10925.20871.stgit@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: David Woodhouse , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mspeder-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: iommu@lists.linux-foundation.org As analyzed in https://bugzilla.kernel.org/show_bug.cgi?id=76331 we can have multiple DRHDs in a system and each may support different guest address widths. We can add a device behind a less capable DRHD to a domain so long as the lesser DRHD can map the existing domain page table. We should never increase the address width as a result of adding a device to the domain. The current code simply updates the width to the last added device. Change to keep it at the minumum DRHD width. Reported-by: mspeder-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Signed-off-by: Alex Williamson Cc: David Woodhouse --- drivers/iommu/intel-iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index e68f44b..cd41d8d 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4276,7 +4276,7 @@ static int intel_iommu_attach_device(struct iommu_domain *domain, __func__, addr_width, dmar_domain->max_addr); return -EFAULT; } - dmar_domain->gaw = addr_width; + dmar_domain->gaw = min(addr_width, dmar_domain->gaw); /* * Knock out extra levels of page tables if necessary