Hi,
On 2/22/19 10:44 AM, James Dong wrote:
With specific Linux command line option such as "iommu=pt", some types
of hotplug devices will be assigned to the static 1:1 iommu domain by
default during kernel init.
If such a hotplug device is rescanned after being removed, for example,
with following sample commands:
echo 1 > /sys/bus/pci/devices/0000\:03\:00.1/remove
echo 1 > /sys/bus/pci/rescan
, an iommu group for this hotplug device will be added without attaching
it to the default static 1:1 domain. As a result, this device's I/O
operation won't work.
What does "I/O operation won't work" exactly mean here? Do you see any
IOMMU fault message? Or, something doesn't work as expected?
Keep hotplug devices with default static 1:1 iommu mapping in their default
domain after such hotplug devices are rescanned.
Signed-off-by: James Dong <xmd...@google.com>
Reported-by: Jis Ben <jis...@google.com>
---
drivers/iommu/intel-iommu.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 78188bf7e90d..4b02949e58ca 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5230,6 +5230,7 @@ static int intel_iommu_add_device(struct device *dev)
struct intel_iommu *iommu;
struct iommu_group *group;
u8 bus, devfn;
+ int ret = 0;
iommu = device_to_iommu(dev, &bus, &devfn);
if (!iommu)
@@ -5242,8 +5243,19 @@ static int intel_iommu_add_device(struct device *dev)
if (IS_ERR(group))
return PTR_ERR(group);
+ if (!iommu_group_default_domain(group) &&
+ !find_domain(dev) && iommu_should_identity_map(dev, 0)) {
+ ret = domain_add_dev_info(si_domain, dev);
+ if (!ret)
+ pr_info("identity mapping for device %s\n",
+ dev_name(dev));
+ else
+ pr_info("identity mapping failed (%d) for device %s\n",
+ ret, dev_name(dev));
+ }
+
I am not sure about whether this is a good place to fix this problem
before Intel IOMMU driver switches to default domain.
Do you mind checking this?
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 6ecdcf8fc8c0..f62f30bc1339 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2632,6 +2632,9 @@ static struct dmar_domain
*find_or_alloc_domain(struct device *dev, int gaw)
goto out;
}
+ if (!iommu_should_identity_map(dev, 0))
+ return si_domain;
+
/* Allocate and initialize new domain for the device */
domain = alloc_domain(0);
if (!domain)
Best regards,
Lu Baolu
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