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....@intel.com>
Cc: Jacob Pan <jacob.jun....@linux.intel.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: sta...@vger.kernel.org
Reported-by: Jis Ben <jis...@google.com>
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Tested-by: James Dong <xmd...@google.com>
---
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
