From d942e60557fc7ea6fee535fb9a0a7d334d65b636 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Sun, 24 Feb 2019 10:01:03 +0800 Subject: [PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices The Intel IOMMU driver will put devices into a static identity mapped domain during boot if the kernel parameter "iommu=pt" is used. That means the IOMMU hardware will translate a DMA address into the same memory address. Unfortunately, a hot-added device doesn't subject to this. That results in some devices not working properly after hot added. A quick way to reproduce this issue is to boot a system with iommu=pt and, remove then readd the pci device with echo 1 > /sys/bus/pci/devices/[pci_source_id]/remove echo 1 > /sys/bus/pci/rescan You will find the identity mapped domain was replaced with a normal domain. Cc: Ashok Raj Cc: Jacob Pan Signed-off-by: Lu Baolu --- drivers/iommu/intel-iommu.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 6ecdcf8fc8c0..730ee29d561b 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -3001,9 +3001,9 @@ static int iommu_should_identity_map(struct device *dev, int startup) } /* - * At boot time, we don't yet know if devices will be 64-bit capable. - * Assume that they will — if they turn out not to be, then we can - * take them out of the 1:1 domain later. + * At boot time or hot added, we don't yet know if devices will be + * 64-bit capable. Assume that they will — if they turn out not to + * be, then we can take them out of the 1:1 domain later. */ if (!startup) { /* @@ -4807,16 +4807,19 @@ static int device_notifier(struct notifier_block *nb, if (iommu_dummy(dev)) return 0; - if (action != BUS_NOTIFY_REMOVED_DEVICE) - return 0; - - domain = find_domain(dev); - if (!domain) - return 0; + if (action == BUS_NOTIFY_REMOVED_DEVICE) { + domain = find_domain(dev); + if (!domain) + return 0; - dmar_remove_one_dev_info(dev); - if (!domain_type_is_vm_or_si(domain) && list_empty(&domain->devices)) - domain_exit(domain); + dmar_remove_one_dev_info(dev); + if (!domain_type_is_vm_or_si(domain) && + list_empty(&domain->devices)) + domain_exit(domain); + } else if (action == BUS_NOTIFY_ADD_DEVICE) { + if (iommu_should_identity_map(dev, 1)) + domain_add_dev_info(si_domain, dev); + } return 0; } -- 2.17.1