This is a note to let you know that I've just added the patch titled iommu: Don't use lazy flush for untrusted device to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: iommu-don-t-use-lazy-flush-for-untrusted-device.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 20fea533163e9c65a14ceacf50678691f2fb8ac2 Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> Date: Thu Feb 25 14:14:54 2021 +0800 iommu: Don't use lazy flush for untrusted device [ Upstream commit 82c3cefb9f1652e7470f442ff96c613e8c8ed8f4 ] The lazy IOTLB flushing setup leaves a time window, in which the device can still access some system memory, which has already been unmapped by the device driver. It's not suitable for untrusted devices. A malicious device might use this to attack the system by obtaining data that it shouldn't obtain. Fixes: c588072bba6b5 ("iommu/vt-d: Convert intel iommu driver to the iommu ops") Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210225061454.2864009-1-baolu.lu@xxxxxxxxxxxxxxx Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 4078358ed66e..00fbc591a142 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -309,6 +309,11 @@ static void iommu_dma_flush_iotlb_all(struct iova_domain *iovad) domain->ops->flush_iotlb_all(domain); } +static bool dev_is_untrusted(struct device *dev) +{ + return dev_is_pci(dev) && to_pci_dev(dev)->untrusted; +} + /** * iommu_dma_init_domain - Initialise a DMA mapping domain * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie() @@ -363,8 +368,9 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, init_iova_domain(iovad, 1UL << order, base_pfn); - if (!cookie->fq_domain && !iommu_domain_get_attr(domain, - DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE, &attr) && attr) { + if (!cookie->fq_domain && (!dev || !dev_is_untrusted(dev)) && + !iommu_domain_get_attr(domain, DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE, &attr) && + attr) { if (init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all, iommu_dma_entry_dtor)) pr_warn("iova flush queue initialization failed\n"); @@ -521,11 +527,6 @@ static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr, iova_align(iovad, size), dir, attrs); } -static bool dev_is_untrusted(struct device *dev) -{ - return dev_is_pci(dev) && to_pci_dev(dev)->untrusted; -} - static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys, size_t size, int prot, u64 dma_mask) {