iommu/vt-d: Make use of IOMMU sysfs support

Register our DRHD IOMMUs, cross link devices, and provide a base set
of attributes for the IOMMU.  Note that IRQ remapping support parses
the DMAR table very early in boot, well before the iommu_class can
reasonably be setup, so our registration is split between
intel_iommu_init(), which occurs later, and alloc_iommu(), which
typically occurs much earlier, but may happen at any time later
with IOMMU hot-add support.

On a typical desktop system, this provides the following (pruned):

$ find /sys | grep dmar
/sys/devices/virtual/iommu/dmar0
/sys/devices/virtual/iommu/dmar0/devices
/sys/devices/virtual/iommu/dmar0/devices/0000:00:02.0
/sys/devices/virtual/iommu/dmar0/intel-iommu
/sys/devices/virtual/iommu/dmar0/intel-iommu/cap
/sys/devices/virtual/iommu/dmar0/intel-iommu/ecap
/sys/devices/virtual/iommu/dmar0/intel-iommu/address
/sys/devices/virtual/iommu/dmar0/intel-iommu/version
/sys/devices/virtual/iommu/dmar1
/sys/devices/virtual/iommu/dmar1/devices
/sys/devices/virtual/iommu/dmar1/devices/0000:00:00.0
/sys/devices/virtual/iommu/dmar1/devices/0000:00:01.0
/sys/devices/virtual/iommu/dmar1/devices/0000:00:16.0
/sys/devices/virtual/iommu/dmar1/devices/0000:00:1a.0
/sys/devices/virtual/iommu/dmar1/devices/0000:00:1b.0
/sys/devices/virtual/iommu/dmar1/devices/0000:00:1c.0
...
/sys/devices/virtual/iommu/dmar1/intel-iommu
/sys/devices/virtual/iommu/dmar1/intel-iommu/cap
/sys/devices/virtual/iommu/dmar1/intel-iommu/ecap
/sys/devices/virtual/iommu/dmar1/intel-iommu/address
/sys/devices/virtual/iommu/dmar1/intel-iommu/version
/sys/class/iommu/dmar0
/sys/class/iommu/dmar1

(devices also link back to the dmar units)

This makes address, version, capabilities, and extended capabilities
available, just like printed on boot.  I've tried not to duplicate
data that can be found in the DMAR table, with the exception of the
address, which provides an easy way to associate the sysfs device with
a DRHD entry in the DMAR.  It's tempting to add scopes and RMRR data
here, but the full DMAR table is already exposed under /sys/firmware/
and therefore already provides a way for userspace to learn such
details.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 32 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-iommu-intel-iommu b/Documentation/ABI/testing/sysfs-class-iommu-intel-iommu
new file mode 100644
index 00000000000..258cc246d98
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-iommu-intel-iommu
@@ -0,0 +1,32 @@
+What:		/sys/class/iommu/<iommu>/intel-iommu/address
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	Alex Williamson <alex.williamson@redhat.com>
+Description:
+		Physical address of the VT-d DRHD for this IOMMU.
+		Format: %llx.  This allows association of a sysfs
+		intel-iommu with a DMAR DRHD table entry.
+
+What:		/sys/class/iommu/<iommu>/intel-iommu/cap
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	Alex Williamson <alex.williamson@redhat.com>
+Description:
+		The cached hardware capability register value
+		of this DRHD unit.  Format: %llx.
+
+What:		/sys/class/iommu/<iommu>/intel-iommu/ecap
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	Alex Williamson <alex.williamson@redhat.com>
+Description:
+		The cached hardware extended capability register
+		value of this DRHD unit.  Format: %llx.
+
+What:		/sys/class/iommu/<iommu>/intel-iommu/version
+Date:		June 2014
+KernelVersion:	3.17
+Contact:	Alex Williamson <alex.williamson@redhat.com>
+Description:
+		The architecture version as reported from the
+		VT-d VER_REG.  Format: %d:%d, major:minor