[PATCH v7 08/19] iommu: Implement reserved_regions iommu-group sysfs file

Eric Auger
2017-01-09T13:47:05Z

A new iommu-group sysfs attribute file is introduced. It contains
the list of reserved regions for the iommu-group. Each reserved
region is described on a separate line:
- first field is the start IOVA address,
- second is the end IOVA address,
- third is the type.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
v6 -> v7:
- also report the type of the reserved region as a string
- updated ABI documentation

v3 -> v4:
- add cast to long long int when printing to avoid warning on
i386
- change S_IRUGO into 0444
- remove sort. The list is natively sorted now.

The file layout is inspired of /sys/bus/pci/devices/BDF/resource.
I also read Documentation/filesystems/sysfs.txt so I expect this
to be frowned upon.
---
.../ABI/testing/sysfs-kernel-iommu_groups | 12 +++++++
drivers/iommu/iommu.c | 38 ++++++++++++++++++++++
2 files changed, 50 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-iommu_groups b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
index 9b31556..35c64e0 100644
--- a/Documentation/ABI/testing/sysfs-kernel-iommu_groups
+++ b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
@@ -12,3 +12,15 @@ Description: /sys/kernel/iommu_groups/ contains a number of sub-
file if the IOMMU driver has chosen to register a more
common name for the group.
Users:
+
+What: /sys/kernel/iommu_groups/reserved_regions
+Date: January 2017
+KernelVersion: v4.11
+Contact: Eric Auger <eric.auger@redhat.com>
+Description: /sys/kernel/iommu_groups/reserved_regions list IOVA
+ regions that are reserved. Not necessarily all
+ reserved regions are listed. This is typically used to
+ output direct-mapped, MSI, non mappable regions. Each
+ region is described on a single line: the 1st field is
+ the base IOVA, the second is the end IOVA and the third
+ field describes the type of the region.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 640056b..0123daa 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -68,6 +68,12 @@ struct iommu_group_attribute {
const char *buf, size_t count);
};

+static const char * const iommu_group_resv_type_string[] = {
+ [IOMMU_RESV_DIRECT] = "direct",
+ [IOMMU_RESV_RESERVED] = "reserved",
+ [IOMMU_RESV_MSI] = "msi",
+};
+
#define IOMMU_GROUP_ATTR(_name, _mode, _show, _store) \
struct iommu_group_attribute iommu_group_attr_##_name = \
__ATTR(_name, _mode, _show, _store)
@@ -231,8 +237,33 @@ int iommu_get_group_resv_regions(struct iommu_group *group,
}
EXPORT_SYMBOL_GPL(iommu_get_group_resv_regions);

+static ssize_t iommu_group_show_resv_regions(struct iommu_group *group,
+ char *buf)
+{
+ struct iommu_resv_region *region, *next;
+ struct list_head group_resv_regions;
+ char *str = buf;
+
+ INIT_LIST_HEAD(&group_resv_regions);
+ iommu_get_group_resv_regions(group, &group_resv_regions);
+
+ list_for_each_entry_safe(region, next, &group_resv_regions, list) {
+ str += sprintf(str, "0x%016llx 0x%016llx %s\n",
+ (long long int)region->start,
+ (long long int)(region->start +
+ region->length - 1),
+ iommu_group_resv_type_string[region->type]);
+ kfree(region);
+ }
+
+ return (str - buf);
+}
+
static IOMMU_GROUP_ATTR(name, S_IRUGO, iommu_group_show_name, NULL);

+static IOMMU_GROUP_ATTR(reserved_regions, 0444,
+ iommu_group_show_resv_regions, NULL);
+
static void iommu_group_release(struct kobject *kobj)
{
struct iommu_group *group = to_iommu_group(kobj);
@@ -247,6 +278,8 @@ static void iommu_group_release(struct kobject *kobj)
if (group->default_domain)
iommu_domain_free(group->default_domain);

+ iommu_group_remove_file(group, &iommu_group_attr_reserved_regions);
+
kfree(group->name);
kfree(group);
}
@@ -310,6 +343,11 @@ struct iommu_group *iommu_group_alloc(void)
*/
kobject_put(&group->kobj);

+ ret = iommu_group_create_file(group,
+ &iommu_group_attr_reserved_regions);
+ if (ret)
+ return ERR_PTR(ret);
+
pr_debug("Allocated group %d\n", group->id);

return group;
--
1.9.1