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, 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 <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: stable@vger.kernel.org
Reported-by: Jis Ben <jisben@google.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: James Dong <xmdong@google.com>
Fixes: 99dcadede42f ('intel-iommu: Support PCIe hot-plug')
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 00f4602..c30b73d 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4567,16 +4567,19 @@ 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;
 }