The dma_pte_free_pagetable() function will only free a page table page
if it is asked to free the *entire* 2MiB range that it covers. So if a
page table page was used for one or more small mappings, it's likely to
end up still present in the page tables... but with no valid PTEs.

This was fine when we'd only be repopulating it with 4KiB PTEs anyway
but the same virtual address range can end up being reused for a
*large-page* mapping. And in that case were were trying to insert the
large page into the second-level page table, and getting a complaint
from the sanity check in __domain_mapping() because there was already a
corresponding entry. This was *relatively* harmless; it led to a memory
leak of the old page table page, but no other ill-effects.

Fix it by calling dma_pte_clear_range (hopefully redundant) and
dma_pte_free_pagetable() before setting up the new large page.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Tested-by: NRavi Murty <Ravi.Murty@intel.com>
Tested-by: NSudeep Dutt <sudeep.dutt@intel.com>
Cc: stable@kernel.org [3.0+]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We can't assume this device exists, fall back to the bridge itself.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Tested-by: NMatthew Thode <prometheanfire@gentoo.org>
Cc: stable@vger.kernel.org
Signed-off-by: NJoerg Roedel <joro@8bytes.org>

domain_update_iommu_coherency() currently defaults to setting domains
as coherent when the domain is not attached to any iommus.  This
allows for a window in domain_context_mapping_one() where such a
domain can update context entries non-coherently, and only after
update the domain capability to clear iommu_coherency.

This can be seen using KVM device assignment on VT-d systems that
do not support coherency in the ecap register.  When a device is
added to a guest, a domain is created (iommu_coherency = 0), the
device is attached, and ranges are mapped.  If we then hot unplug
the device, the coherency is updated and set to the default (1)
since no iommus are attached to the domain.  A subsequent attach
of a device makes use of the same dmar domain (now marked coherent)
updates context entries with coherency enabled, and only disables
coherency as the last step in the process.

To fix this, switch domain_update_iommu_coherency() to use the
safer, non-coherent default for domains not attached to iommus.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Tested-by: NDonald Dutile <ddutile@redhat.com>
Acked-by: NDonald Dutile <ddutile@redhat.com>
Acked-by: NChris Wright <chrisw@sous-sol.org>
Cc: stable@vger.kernel.org
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Introduce an inline function pci_pcie_type(dev) to extract PCIe
device type from pci_dev->pcie_flags_reg field, and prepare for
removing pci_dev->pcie_type.
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

SR-IOV can create buses without a bridge.  There may be other cases
where this happens as well.  In these cases skip to the parent bus
and continue testing devices there.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Tested-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Add missing free_domain_mem on failure path after alloc_domain.

A simplified version of the semantic match that finds this
problem is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@km exists@
local idexpression e;
expression e1,e2,e3;
type T,T1;
identifier f;
@@

* e = alloc_domain(...)
... when any
    when != e = e1
    when != e1 = (T)e
    when != e1(...,(T)e,...)
    when != &e->f
if(...) { ... when != e2(...,(T1)e,...)
                 when != e3 = e
                 when forall
(
             return <+...e...+>;
|
*             return ...;
) }
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Implement the attribute for the Intel IOMMU driver.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Work around broken devices and adhere to ACS support when determining
IOMMU grouping.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Add IOMMU group support to Intel VT-d code.  This driver sets up
devices ondemand, so make use of the add_device/remove_device
callbacks in IOMMU API to manage setting up the groups.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

IOMMU device groups are currently a rather vague associative notion
with assembly required by the user or user level driver provider to
do anything useful.  This patch intends to grow the IOMMU group concept
into something a bit more consumable.

To do this, we first create an object representing the group, struct
iommu_group.  This structure is allocated (iommu_group_alloc) and
filled (iommu_group_add_device) by the iommu driver.  The iommu driver
is free to add devices to the group using it's own set of policies.
This allows inclusion of devices based on physical hardware or topology
limitations of the platform, as well as soft requirements, such as
multi-function trust levels or peer-to-peer protection of the
interconnects.  Each device may only belong to a single iommu group,
which is linked from struct device.iommu_group.  IOMMU groups are
maintained using kobject reference counting, allowing for automatic
removal of empty, unreferenced groups.  It is the responsibility of
the iommu driver to remove devices from the group
(iommu_group_remove_device).

IOMMU groups also include a userspace representation in sysfs under
/sys/kernel/iommu_groups.  When allocated, each group is given a
dynamically assign ID (int).  The ID is managed by the core IOMMU group
code to support multiple heterogeneous iommu drivers, which could
potentially collide in group naming/numbering.  This also keeps group
IDs to small, easily managed values.  A directory is created under
/sys/kernel/iommu_groups for each group.  A further subdirectory named
"devices" contains links to each device within the group.  The iommu_group
file in the device's sysfs directory, which formerly contained a group
number when read, is now a link to the iommu group.  Example:

$ ls -l /sys/kernel/iommu_groups/26/devices/
total 0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:00:1e.0 ->
		../../../../devices/pci0000:00/0000:00:1e.0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:06:0d.0 ->
		../../../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:06:0d.1 ->
		../../../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.1

$ ls -l  /sys/kernel/iommu_groups/26/devices/*/iommu_group
[truncating perms/owner/timestamp]
/sys/kernel/iommu_groups/26/devices/0000:00:1e.0/iommu_group ->
					../../../kernel/iommu_groups/26
/sys/kernel/iommu_groups/26/devices/0000:06:0d.0/iommu_group ->
					../../../../kernel/iommu_groups/26
/sys/kernel/iommu_groups/26/devices/0000:06:0d.1/iommu_group ->
					../../../../kernel/iommu_groups/26

Groups also include several exported functions for use by user level
driver providers, for example VFIO.  These include:

iommu_group_get(): Acquires a reference to a group from a device
iommu_group_put(): Releases reference
iommu_group_for_each_dev(): Iterates over group devices using callback
iommu_group_[un]register_notifier(): Allows notification of device add
        and remove operations relevant to the group
iommu_group_id(): Return the group number

This patch also extends the IOMMU API to allow attaching groups to
domains.  This is currently a simple wrapper for iterating through
devices within a group, but it's expected that the IOMMU API may
eventually make groups a more integral part of domains.

Groups intentionally do not try to manage group ownership.  A user
level driver provider must independently acquire ownership for each
device within a group before making use of the group as a whole.
This may change in the future if group usage becomes more pervasive
across both DMA and IOMMU ops.

Groups intentionally do not provide a mechanism for driver locking
or otherwise manipulating driver matching/probing of devices within
the group.  Such interfaces are generic to devices and beyond the
scope of IOMMU groups.  If implemented, user level providers have
ready access via iommu_group_for_each_dev and group notifiers.

iommu_device_group() is removed here as it has no users.  The
replacement is:

	group = iommu_group_get(dev);
	id = iommu_group_id(group);
	iommu_group_put(group);

AMD-Vi & Intel VT-d support re-added in following patches.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Replace the struct pci_bus secondary/subordinate members with the
struct resource busn_res.  Later we'll build a resource tree of these
bus numbers.

[bhelgaas: changelog]
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Now we have four copies of this code, Linus "suggested" it was about time
we stopped copying it and turned it into a helper.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add device info into list before doing context mapping, because device
info will be used by iommu_enable_dev_iotlb(). Without it, ATS won't get
enabled as it should be.

ATS, while a dubious decision from a security point of view, can be very
important for performance.
Signed-off-by: NXudong Hao <xudong.hao@intel.com>
Signed-off-by: NXiantao Zhang <xiantao.zhang@intel.com>
Acked-by: NChris Wright <chrisw@sous-sol.org>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the file names consistent with the naming conventions of irq subsystem.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Make the code consistent with the naming conventions of irq subsystem.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

This patch introduces irq_remap_ops to hold implementation
specific function pointer to handle interrupt remapping. As
the first part the initialization functions for VT-d are
converted to these ops.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Adapt core x86 and IA64 architecture code for dma_map_ops changes: replace
alloc/free_coherent with generic alloc/free methods.
Signed-off-by: NAndrzej Pietrasiewicz <andrzej.p@samsung.com>
Acked-by: NKyungmin Park <kyungmin.park@samsung.com>
[removed swiotlb related changes and replaced it with wrappers,
 merged with IA64 patch to avoid inter-patch dependences in intel-iommu code]
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NTony Luck <tony.luck@intel.com>

The number of IOMMUs supported should be the same as the number
of IO APICS.  This limit comes into play when the IOMMUs are
identity mapped, thus the number of possible IOMMUs in the
"static identity" (si) domain should be this same number.
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NJack Steiner <steiner@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Daniel Rahn <drahn@suse.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>
[ Fixed printk format string, cleaned up the code ]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-ixcmp0hfp0a3b2lfv3uo0p0x@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>

With SandyBridge, Intel has changed these Socket PCI devices to
have a class type of "System Peripheral" & "Performance
counter", rather than "HostBridge".

So instead of using a "special" case to detect which devices will
not be doing DMA, use the fact that a device that is not associated
with an IOMMU, will not need an identity map.
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NMike Habeck <habeck@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Daniel Rahn <drahn@suse.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-018fywmjs3lmzfyzjlktg8dx@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>

Correct spelling "supportd" to "supported" in
drivers/iommu/intel-iommu.c

Signed-off-by: Masanari Iida<standby24x7@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

In i915 driver, we do not enable either rc6 or semaphores on SNB when dmar
is enabled. The new 'intel_iommu_enabled' variable signals when the
iommu code is in operation.

Cc: Ted Phelps <phelps@gnusto.com>
Cc: Peter <pab1612@gmail.com>
Cc: Lukas Hejtmanek <xhejtman@fi.muni.cz>
Cc: Andrew Lutomirski <luto@mit.edu>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NKeith Packard <keithp@keithp.com>

Now all ARCH_POPULATES_NODE_MAP archs select HAVE_MEBLOCK_NODE_MAP -
there's no user of early_node_map[] left.  Kill early_node_map[] and
replace ARCH_POPULATES_NODE_MAP with HAVE_MEMBLOCK_NODE_MAP.  Also,
relocate for_each_mem_pfn_range() and helper from mm.h to memblock.h
as page_alloc.c would no longer host an alternative implementation.

This change is ultimately one to one mapping and shouldn't cause any
observable difference; however, after the recent changes, there are
some functions which now would fit memblock.c better than page_alloc.c
and dependency on HAVE_MEMBLOCK_NODE_MAP instead of HAVE_MEMBLOCK
doesn't make much sense on some of them.  Further cleanups for
functions inside HAVE_MEMBLOCK_NODE_MAP in mm.h would be nice.

-v2: Fix compile bug introduced by mis-spelling
 CONFIG_HAVE_MEMBLOCK_NODE_MAP to CONFIG_MEMBLOCK_HAVE_NODE_MAP in
 mmzone.h.  Reported by Stephen Rothwell.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>

dmar_parse_rmrr_atsr_dev() calls rmrr_parse_dev() and
atsr_parse_dev() which are both marked as __init.

Section mismatch in reference from the function
dmar_parse_rmrr_atsr_dev() to the function
.init.text:dmar_parse_dev_scope() The function
dmar_parse_rmrr_atsr_dev() references the function __init
dmar_parse_dev_scope().

Section mismatch in reference from the function
dmar_parse_rmrr_atsr_dev() to the function
.init.text:dmar_parse_dev_scope() The function
dmar_parse_rmrr_atsr_dev() references the function __init
dmar_parse_dev_scope().
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: iommu@lists.linux-foundation.org
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Ohad Ben-Cohen <ohad@wizery.com>
Link: http://lkml.kernel.org/r/20111026154539.GA10103@swordfishSigned-off-by: NIngo Molnar <mingo@elte.hu>

The option iommu=group_mf indicates the that the iommu driver should
expose all functions of a multi-function PCI device as the same
iommu_device_group.  This is useful for disallowing individual functions
being exposed as independent devices to userspace as there are often
hidden dependencies.  Virtual functions are not affected by this option.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

We generally have BDF granularity for devices, so we just need
to make sure devices aren't hidden behind PCIe-to-PCI bridges.
We can then make up a group number that's simply the concatenated
seg|bus|dev|fn so we don't have to track them (not that users
should depend on that).
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-By: NDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Let the IOMMU core know we support arbitrary page sizes (as long as
they're an order of 4KiB).

This way the IOMMU core will retain the existing behavior we're used to;
it will let us map regions that:
- their size is an order of 4KiB
- they are naturally aligned

Note: Intel IOMMU hardware doesn't support arbitrary page sizes,
but the driver does (it splits arbitrary-sized mappings into
the pages supported by the hardware).

To make everything simpler for now, though, this patch effectively tells
the IOMMU core to keep giving this driver the same memory regions it did
before, so nothing is changed as far as it's concerned.

At this point, the page sizes announced remain static within the IOMMU
core. To correctly utilize the pgsize-splitting of the IOMMU core by
this driver, it seems that some core changes should still be done,
because Intel's IOMMU page size capabilities seem to have the potential
to be different between different DMA remapping devices.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Express sizes in bytes rather than in page order, to eliminate the
size->order->size conversions we have whenever the IOMMU API is calling
the low level drivers' map/unmap methods.

Adopt all existing drivers.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <Joerg.Roedel@amd.com>
Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Cc: KyongHo Cho <pullip.cho@samsung.com>
Cc: Hiroshi DOYU <hdoyu@nvidia.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Convert the Intel IOMMU driver to use the new interface for
publishing the iommu_ops.

Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

We really don't want this to work in the general case; device drivers
*shouldn't* care whether they are behind an IOMMU or not. But the
integrated graphics is a special case, because the IOMMU and the GTT are
all kind of smashed into one and generally horrifically buggy, so it's
reasonable for the graphics driver to want to know when the IOMMU is
active for the graphics hardware.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NKeith Packard <keithp@keithp.com>

To work around a hardware issue, we have to submit IOTLB flushes while
the graphics engine is idle. The graphics driver will (we hope) go to
great lengths to ensure that it gets that right on the affected
chipset(s)... so let's not screw it over by deferring the unmap and
doing it later. That wouldn't be very helpful.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NKeith Packard <keithp@keithp.com>

If target_level == 0, current code breaks out of the while-loop if
SUPERPAGE bit is set. We should also break out if PTE is not present.
If we don't do this, KVM calls to iommu_iova_to_phys() will cause
pfn_to_dma_pte() to create mapping for 4KiB pages.
Signed-off-by: NAllen Kay <allen.m.kay@intel.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

set dmar->iommu_superpage field to the smallest common denominator
of super page sizes supported by all active VT-d engines.  Initialize
this field in intel_iommu_domain_init() API so intel_iommu_map() API
will be able to use iommu_superpage field to determine the appropriate
super page size to use.
Signed-off-by: NAllen Kay <allen.m.kay@intel.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

iommu_unmap() API expects IOMMU drivers to return the actual page order
of the address being unmapped.  Previous code was just returning page
order passed in from the caller.  This patch fixes this problem.
Signed-off-by: NAllen Kay <allen.m.kay@intel.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

We really don't want this to work in the general case; device drivers
*shouldn't* care whether they are behind an IOMMU or not. But the
integrated graphics is a special case, because the IOMMU and the GTT are
all kind of smashed into one and generally horrifically buggy, so it's
reasonable for the graphics driver to want to know when the IOMMU is
active for the graphics hardware.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

To work around a hardware issue, we have to submit IOTLB flushes while
the graphics engine is idle. The graphics driver will (we hope) go to
great lengths to ensure that it gets that right on the affected
chipset(s)... so let's not screw it over by deferring the unmap and
doing it later. That wouldn't be very helpful.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

When unbinding a device so that I could pass it through to a KVM VM, I
got the lockdep report below.  It looks like a legitimate lock
ordering problem:

 - domain_context_mapping_one() takes iommu->lock and calls
   iommu_support_dev_iotlb(), which takes device_domain_lock (inside
   iommu->lock).

 - domain_remove_one_dev_info() starts by taking device_domain_lock
   then takes iommu->lock inside it (near the end of the function).

So this is the classic AB-BA deadlock.  It looks like a safe fix is to
simply release device_domain_lock a bit earlier, since as far as I can
tell, it doesn't protect any of the stuff accessed at the end of
domain_remove_one_dev_info() anyway.

BTW, the use of device_domain_lock looks a bit unsafe to me... it's
at least not obvious to me why we aren't vulnerable to the race below:

  iommu_support_dev_iotlb()
                                          domain_remove_dev_info()

  lock device_domain_lock
    find info
  unlock device_domain_lock

                                          lock device_domain_lock
                                            find same info
                                          unlock device_domain_lock

                                          free_devinfo_mem(info)

  do stuff with info after it's free

However I don't understand the locking here well enough to know if
this is a real problem, let alone what the best fix is.

Anyway here's the full lockdep output that prompted all of this:

     =======================================================
     [ INFO: possible circular locking dependency detected ]
     2.6.39.1+ #1
     -------------------------------------------------------
     bash/13954 is trying to acquire lock:
      (&(&iommu->lock)->rlock){......}, at: [<ffffffff812f6421>] domain_remove_one_dev_info+0x121/0x230

     but task is already holding lock:
      (device_domain_lock){-.-...}, at: [<ffffffff812f6508>] domain_remove_one_dev_info+0x208/0x230

     which lock already depends on the new lock.

     the existing dependency chain (in reverse order) is:

     -> #1 (device_domain_lock){-.-...}:
            [<ffffffff8109ca9d>] lock_acquire+0x9d/0x130
            [<ffffffff81571475>] _raw_spin_lock_irqsave+0x55/0xa0
            [<ffffffff812f8350>] domain_context_mapping_one+0x600/0x750
            [<ffffffff812f84df>] domain_context_mapping+0x3f/0x120
            [<ffffffff812f9175>] iommu_prepare_identity_map+0x1c5/0x1e0
            [<ffffffff81ccf1ca>] intel_iommu_init+0x88e/0xb5e
            [<ffffffff81cab204>] pci_iommu_init+0x16/0x41
            [<ffffffff81002165>] do_one_initcall+0x45/0x190
            [<ffffffff81ca3d3f>] kernel_init+0xe3/0x168
            [<ffffffff8157ac24>] kernel_thread_helper+0x4/0x10

     -> #0 (&(&iommu->lock)->rlock){......}:
            [<ffffffff8109bf3e>] __lock_acquire+0x195e/0x1e10
            [<ffffffff8109ca9d>] lock_acquire+0x9d/0x130
            [<ffffffff81571475>] _raw_spin_lock_irqsave+0x55/0xa0
            [<ffffffff812f6421>] domain_remove_one_dev_info+0x121/0x230
            [<ffffffff812f8b42>] device_notifier+0x72/0x90
            [<ffffffff8157555c>] notifier_call_chain+0x8c/0xc0
            [<ffffffff81089768>] __blocking_notifier_call_chain+0x78/0xb0
            [<ffffffff810897b6>] blocking_notifier_call_chain+0x16/0x20
            [<ffffffff81373a5c>] __device_release_driver+0xbc/0xe0
            [<ffffffff81373ccf>] device_release_driver+0x2f/0x50
            [<ffffffff81372ee3>] driver_unbind+0xa3/0xc0
            [<ffffffff813724ac>] drv_attr_store+0x2c/0x30
            [<ffffffff811e4506>] sysfs_write_file+0xe6/0x170
            [<ffffffff8117569e>] vfs_write+0xce/0x190
            [<ffffffff811759e4>] sys_write+0x54/0xa0
            [<ffffffff81579a82>] system_call_fastpath+0x16/0x1b

     other info that might help us debug this:

     6 locks held by bash/13954:
      #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff811e4464>] sysfs_write_file+0x44/0x170
      #1:  (s_active#3){++++.+}, at: [<ffffffff811e44ed>] sysfs_write_file+0xcd/0x170
      #2:  (&__lockdep_no_validate__){+.+.+.}, at: [<ffffffff81372edb>] driver_unbind+0x9b/0xc0
      #3:  (&__lockdep_no_validate__){+.+.+.}, at: [<ffffffff81373cc7>] device_release_driver+0x27/0x50
      #4:  (&(&priv->bus_notifier)->rwsem){.+.+.+}, at: [<ffffffff8108974f>] __blocking_notifier_call_chain+0x5f/0xb0
      #5:  (device_domain_lock){-.-...}, at: [<ffffffff812f6508>] domain_remove_one_dev_info+0x208/0x230

     stack backtrace:
     Pid: 13954, comm: bash Not tainted 2.6.39.1+ #1
     Call Trace:
      [<ffffffff810993a7>] print_circular_bug+0xf7/0x100
      [<ffffffff8109bf3e>] __lock_acquire+0x195e/0x1e10
      [<ffffffff810972bd>] ? trace_hardirqs_off+0xd/0x10
      [<ffffffff8109d57d>] ? trace_hardirqs_on_caller+0x13d/0x180
      [<ffffffff8109ca9d>] lock_acquire+0x9d/0x130
      [<ffffffff812f6421>] ? domain_remove_one_dev_info+0x121/0x230
      [<ffffffff81571475>] _raw_spin_lock_irqsave+0x55/0xa0
      [<ffffffff812f6421>] ? domain_remove_one_dev_info+0x121/0x230
      [<ffffffff810972bd>] ? trace_hardirqs_off+0xd/0x10
      [<ffffffff812f6421>] domain_remove_one_dev_info+0x121/0x230
      [<ffffffff812f8b42>] device_notifier+0x72/0x90
      [<ffffffff8157555c>] notifier_call_chain+0x8c/0xc0
      [<ffffffff81089768>] __blocking_notifier_call_chain+0x78/0xb0
      [<ffffffff810897b6>] blocking_notifier_call_chain+0x16/0x20
      [<ffffffff81373a5c>] __device_release_driver+0xbc/0xe0
      [<ffffffff81373ccf>] device_release_driver+0x2f/0x50
      [<ffffffff81372ee3>] driver_unbind+0xa3/0xc0
      [<ffffffff813724ac>] drv_attr_store+0x2c/0x30
      [<ffffffff811e4506>] sysfs_write_file+0xe6/0x170
      [<ffffffff8117569e>] vfs_write+0xce/0x190
      [<ffffffff811759e4>] sys_write+0x54/0xa0
      [<ffffffff81579a82>] system_call_fastpath+0x16/0x1b
Signed-off-by: NRoland Dreier <roland@purestorage.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

Change the CONFIG_DMAR to CONFIG_INTEL_IOMMU to be consistent
with the other IOMMU options.

Rename the CONFIG_INTR_REMAP to CONFIG_IRQ_REMAP to match the
irq subsystem name.

And define the CONFIG_DMAR_TABLE for the common ACPI DMAR
routines shared by both CONFIG_INTEL_IOMMU and CONFIG_IRQ_REMAP.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: yinghai@kernel.org
Cc: youquan.song@intel.com
Cc: joerg.roedel@amd.com
Cc: tony.luck@intel.com
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/20110824001456.558630224@sbsiddha-desk.sc.intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Move the IOMMU specific routines to intel-iommu.c leaving the
dmar.c to the common ACPI dmar code shared between DMA-remapping
and Interrupt-remapping.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: yinghai@kernel.org
Cc: youquan.song@intel.com
Cc: joerg.roedel@amd.com
Cc: tony.luck@intel.com
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/20110824001456.282401285@sbsiddha-desk.sc.intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Both DMA-remapping aswell as Interrupt-remapping depend on the
dmar dev scope to be initialized. When both DMA and
IRQ-remapping are enabled, we depend on DMA-remapping init code
to call dmar_dev_scope_init(). This resulted in not doing this
init when DMA-remapping was turned off but interrupt-remapping
turned on in the kernel config.

This caused interrupt routing to break with CONFIG_INTR_REMAP=y
and CONFIG_DMAR=n.

This issue was introduced by this commit:

 | commit 9d5ce73a
 | Author: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 | Date:   Tue Nov 10 19:46:16 2009 +0900
 |
 |    x86: intel-iommu: Convert detect_intel_iommu to use iommu_init hook

Fix this by calling dmar_dev_scope_init() explicitly from the
interrupt remapping code too.
Reported-by: NAndrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: yinghai@kernel.org
Cc: youquan.song@intel.com
Cc: joerg.roedel@amd.com
Cc: tony.luck@intel.com
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/20110824001456.229207526@sbsiddha-desk.sc.intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>