From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lu Baolu Subject: [PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices Date: Mon, 25 Feb 2019 10:46:36 +0800 Message-ID: <20190225024636.32418-1-baolu.lu@linux.intel.com> Return-path: Sender: stable-owner@vger.kernel.org To: joro@8bytes.org, dwmw2@infradead.org Cc: ashok.raj@intel.com, jacob.jun.pan@linux.intel.com, jisben@google.com, xmdong@google.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Lu Baolu , Fenghua Yu , stable@vger.kernel.org List-Id: iommu@lists.linux-foundation.org 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, hot-added devices are not 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 Cc: Fenghua Yu Cc: stable@vger.kernel.org Reported-by: Jis Ben Signed-off-by: Lu Baolu Tested-by: James Dong --- drivers/iommu/intel-iommu.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index af23cfc2a05e..4f77657a9c25 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4564,16 +4564,19 @@ 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