From: David Woodhouse Date: Mon, 11 May 2015 13:59:20 +0000 (+0100) Subject: iommu/vt-d: Fix passthrough mode with translation-disabled devices X-Git-Tag: firefly_0821_release~176^2~1661^2~2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4ed6a540fab8ea4388c1703b73ecfed68a2009d1;p=firefly-linux-kernel-4.4.55.git iommu/vt-d: Fix passthrough mode with translation-disabled devices When we use 'intel_iommu=igfx_off' to disable translation for the graphics, and when we discover that the BIOS has misconfigured the DMAR setup for I/OAT, we use a special DUMMY_DEVICE_DOMAIN_INFO value in dev->archdata.iommu to indicate that translation is disabled. With passthrough mode, we were attempting to dereference that as a normal pointer to a struct device_domain_info when setting up an identity mapping for the affected device. This fixes the problem by making device_to_iommu() explicitly check for the special value and indicate that no IOMMU was found to handle the devices in question. Signed-off-by: David Woodhouse Cc: stable@vger.kernel.org (which means you can pick up 18436afdc now too) --- diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 68d43beccb7e..2ffe58969944 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -696,6 +696,11 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu return &context[devfn]; } +static int iommu_dummy(struct device *dev) +{ + return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO; +} + static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn) { struct dmar_drhd_unit *drhd = NULL; @@ -705,6 +710,9 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf u16 segment = 0; int i; + if (iommu_dummy(dev)) + return NULL; + if (dev_is_pci(dev)) { pdev = to_pci_dev(dev); segment = pci_domain_nr(pdev->bus); @@ -2969,11 +2977,6 @@ static inline struct dmar_domain *get_valid_domain_for_dev(struct device *dev) return __get_valid_domain_for_dev(dev); } -static int iommu_dummy(struct device *dev) -{ - return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO; -} - /* Check if the dev needs to go through non-identity map and unmap process.*/ static int iommu_no_mapping(struct device *dev) {