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authorAlex Williamson <alex.williamson@redhat.com>2011-10-21 15:56:05 -0400
committerJoerg Roedel <joerg.roedel@amd.com>2011-11-15 12:22:23 +0100
commit1460432cb513f0c16136ed132c20ecfbf8ccf942 (patch)
treef9802b729aa47d9c95fe2de5f41c511d3db7df4c /drivers/iommu
parent1ea6b8f48918282bdca0b32a34095504ee65bab5 (diff)
downloadlinux-1460432cb513f0c16136ed132c20ecfbf8ccf942.tar.bz2
iommu: Add iommu_device_group callback and iommu_group sysfs entry
An IOMMU group is a set of devices for which the IOMMU cannot distinguish transactions. For PCI devices, a group often occurs when a PCI bridge is involved. Transactions from any device behind the bridge appear to be sourced from the bridge itself. We leave it to the IOMMU driver to define the grouping restraints for their platform. Using this new interface, the group for a device can be retrieved using the iommu_device_group() callback. Users will compare the value returned against the value returned for other devices to determine whether they are part of the same group. Devices with no group are not translated by the IOMMU. There should be no expectations about the group numbers as they may be arbitrarily assigned by the IOMMU driver and may not be persistent across boots. We also provide a sysfs interface to the group numbers here so that userspace can understand IOMMU dependencies between devices for managing safe, userspace drivers. [Some code changes by Joerg Roedel <joerg.roedel@amd.com>] Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/iommu.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 2fb2963df553..9c35be4b333f 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -25,8 +25,59 @@
#include <linux/errno.h>
#include <linux/iommu.h>
+static ssize_t show_iommu_group(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ unsigned int groupid;
+
+ if (iommu_device_group(dev, &groupid))
+ return 0;
+
+ return sprintf(buf, "%u", groupid);
+}
+static DEVICE_ATTR(iommu_group, S_IRUGO, show_iommu_group, NULL);
+
+static int add_iommu_group(struct device *dev, void *data)
+{
+ unsigned int groupid;
+
+ if (iommu_device_group(dev, &groupid) == 0)
+ return device_create_file(dev, &dev_attr_iommu_group);
+
+ return 0;
+}
+
+static int remove_iommu_group(struct device *dev)
+{
+ unsigned int groupid;
+
+ if (iommu_device_group(dev, &groupid) == 0)
+ device_remove_file(dev, &dev_attr_iommu_group);
+
+ return 0;
+}
+
+static int iommu_device_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct device *dev = data;
+
+ if (action == BUS_NOTIFY_ADD_DEVICE)
+ return add_iommu_group(dev, NULL);
+ else if (action == BUS_NOTIFY_DEL_DEVICE)
+ return remove_iommu_group(dev);
+
+ return 0;
+}
+
+static struct notifier_block iommu_device_nb = {
+ .notifier_call = iommu_device_notifier,
+};
+
static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
{
+ bus_register_notifier(bus, &iommu_device_nb);
+ bus_for_each_dev(bus, NULL, NULL, add_iommu_group);
}
/**
@@ -186,3 +237,12 @@ int iommu_unmap(struct iommu_domain *domain, unsigned long iova, int gfp_order)
return domain->ops->unmap(domain, iova, gfp_order);
}
EXPORT_SYMBOL_GPL(iommu_unmap);
+
+int iommu_device_group(struct device *dev, unsigned int *groupid)
+{
+ if (iommu_present(dev->bus) && dev->bus->iommu_ops->device_group)
+ return dev->bus->iommu_ops->device_group(dev, groupid);
+
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(iommu_device_group);