Commit Graph

213 Commits

Author SHA1 Message Date
Fenghua Yu
6ef0505158 iommu/vt-d: Fix a deadlock in intel_svm_drain_prq()
pasid_mutex and dev->iommu->param->lock are held while unbinding mm is
flushing IO page fault workqueue and waiting for all page fault works to
finish. But an in-flight page fault work also need to hold the two locks
while unbinding mm are holding them and waiting for the work to finish.
This may cause an ABBA deadlock issue as shown below:

	idxd 0000:00:0a.0: unbind PASID 2
	======================================================
	WARNING: possible circular locking dependency detected
	5.14.0-rc7+ #549 Not tainted [  186.615245] ----------
	dsa_test/898 is trying to acquire lock:
	ffff888100d854e8 (&param->lock){+.+.}-{3:3}, at:
	iopf_queue_flush_dev+0x29/0x60
	but task is already holding lock:
	ffffffff82b2f7c8 (pasid_mutex){+.+.}-{3:3}, at:
	intel_svm_unbind+0x34/0x1e0
	which lock already depends on the new lock.

	the existing dependency chain (in reverse order) is:

	-> #2 (pasid_mutex){+.+.}-{3:3}:
	       __mutex_lock+0x75/0x730
	       mutex_lock_nested+0x1b/0x20
	       intel_svm_page_response+0x8e/0x260
	       iommu_page_response+0x122/0x200
	       iopf_handle_group+0x1c2/0x240
	       process_one_work+0x2a5/0x5a0
	       worker_thread+0x55/0x400
	       kthread+0x13b/0x160
	       ret_from_fork+0x22/0x30

	-> #1 (&param->fault_param->lock){+.+.}-{3:3}:
	       __mutex_lock+0x75/0x730
	       mutex_lock_nested+0x1b/0x20
	       iommu_report_device_fault+0xc2/0x170
	       prq_event_thread+0x28a/0x580
	       irq_thread_fn+0x28/0x60
	       irq_thread+0xcf/0x180
	       kthread+0x13b/0x160
	       ret_from_fork+0x22/0x30

	-> #0 (&param->lock){+.+.}-{3:3}:
	       __lock_acquire+0x1134/0x1d60
	       lock_acquire+0xc6/0x2e0
	       __mutex_lock+0x75/0x730
	       mutex_lock_nested+0x1b/0x20
	       iopf_queue_flush_dev+0x29/0x60
	       intel_svm_drain_prq+0x127/0x210
	       intel_svm_unbind+0xc5/0x1e0
	       iommu_sva_unbind_device+0x62/0x80
	       idxd_cdev_release+0x15a/0x200 [idxd]
	       __fput+0x9c/0x250
	       ____fput+0xe/0x10
	       task_work_run+0x64/0xa0
	       exit_to_user_mode_prepare+0x227/0x230
	       syscall_exit_to_user_mode+0x2c/0x60
	       do_syscall_64+0x48/0x90
	       entry_SYSCALL_64_after_hwframe+0x44/0xae

	other info that might help us debug this:

	Chain exists of:
	  &param->lock --> &param->fault_param->lock --> pasid_mutex

	 Possible unsafe locking scenario:

	       CPU0                    CPU1
	       ----                    ----
	  lock(pasid_mutex);
				       lock(&param->fault_param->lock);
				       lock(pasid_mutex);
	  lock(&param->lock);

	 *** DEADLOCK ***

	2 locks held by dsa_test/898:
	 #0: ffff888100cc1cc0 (&group->mutex){+.+.}-{3:3}, at:
	 iommu_sva_unbind_device+0x53/0x80
	 #1: ffffffff82b2f7c8 (pasid_mutex){+.+.}-{3:3}, at:
	 intel_svm_unbind+0x34/0x1e0

	stack backtrace:
	CPU: 2 PID: 898 Comm: dsa_test Not tainted 5.14.0-rc7+ #549
	Hardware name: Intel Corporation Kabylake Client platform/KBL S
	DDR4 UD IMM CRB, BIOS KBLSE2R1.R00.X050.P01.1608011715 08/01/2016
	Call Trace:
	 dump_stack_lvl+0x5b/0x74
	 dump_stack+0x10/0x12
	 print_circular_bug.cold+0x13d/0x142
	 check_noncircular+0xf1/0x110
	 __lock_acquire+0x1134/0x1d60
	 lock_acquire+0xc6/0x2e0
	 ? iopf_queue_flush_dev+0x29/0x60
	 ? pci_mmcfg_read+0xde/0x240
	 __mutex_lock+0x75/0x730
	 ? iopf_queue_flush_dev+0x29/0x60
	 ? pci_mmcfg_read+0xfd/0x240
	 ? iopf_queue_flush_dev+0x29/0x60
	 mutex_lock_nested+0x1b/0x20
	 iopf_queue_flush_dev+0x29/0x60
	 intel_svm_drain_prq+0x127/0x210
	 ? intel_pasid_tear_down_entry+0x22e/0x240
	 intel_svm_unbind+0xc5/0x1e0
	 iommu_sva_unbind_device+0x62/0x80
	 idxd_cdev_release+0x15a/0x200

pasid_mutex protects pasid and svm data mapping data. It's unnecessary
to hold pasid_mutex while flushing the workqueue. To fix the deadlock
issue, unlock pasid_pasid during flushing the workqueue to allow the works
to be handled.

Fixes: d5b9e4bfe0 ("iommu/vt-d: Report prq to io-pgfault framework")
Reported-and-tested-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20210826215918.4073446-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210828070622.2437559-3-baolu.lu@linux.intel.com
[joro: Removed timing information from kernel log messages]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-09-09 13:18:07 +02:00
Fenghua Yu
a21518cb23 iommu/vt-d: Fix PASID leak in intel_svm_unbind_mm()
The mm->pasid will be used in intel_svm_free_pasid() after load_pasid()
during unbinding mm. Clearing it in load_pasid() will cause PASID cannot
be freed in intel_svm_free_pasid().

Additionally mm->pasid was updated already before load_pasid() during pasid
allocation. No need to update it again in load_pasid() during binding mm.
Don't update mm->pasid to avoid the issues in both binding mm and unbinding
mm.

Fixes: 4048377414 ("iommu/vt-d: Use iommu_sva_alloc(free)_pasid() helpers")
Reported-and-tested-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20210826215918.4073446-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210828070622.2437559-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-09-09 13:18:06 +02:00
Joerg Roedel
d8768d7eb9 Merge branches 'apple/dart', 'arm/smmu', 'iommu/fixes', 'x86/amd', 'x86/vt-d' and 'core' into next 2021-08-20 17:14:35 +02:00
Liu Yi L
423d39d851 iommu/vt-d: Add present bit check in pasid entry setup helpers
The helper functions should not modify the pasid entries which are still
in use. Add a check against present bit.

Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20210817042425.1784279-1-yi.l.liu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210818134852.1847070-10-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Liu Yi L
8123b0b868 iommu/vt-d: Use pasid_pte_is_present() helper function
Use the pasid_pte_is_present() helper for present bit check in the
intel_pasid_tear_down_entry().

Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20210817042425.1784279-1-yi.l.liu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210818134852.1847070-9-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Andy Shevchenko
9ddc348214 iommu/vt-d: Drop the kernel doc annotation
Kernel doc validator is unhappy with the following

.../perf.c:16: warning: Function parameter or member 'latency_lock' not described in 'DEFINE_SPINLOCK'
.../perf.c:16: warning: expecting prototype for perf.c(). Prototype was for DEFINE_SPINLOCK() instead

Drop kernel doc annotation since the top comment is not in the required format.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210729163538.40101-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210818134852.1847070-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Lu Baolu
48811c4434 iommu/vt-d: Allow devices to have more than 32 outstanding PRs
The minimum per-IOMMU PRQ queue size is one 4K page, this is more entries
than the hardcoded limit of 32 in the current VT-d code. Some devices can
support up to 512 outstanding PRQs but underutilized by this limit of 32.
Although, 32 gives some rough fairness when multiple devices share the same
IOMMU PRQ queue, but far from optimal for customized use case. This extends
the per-IOMMU PRQ queue size to four 4K pages and let the devices have as
many outstanding page requests as they can.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720013856.4143880-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210818134852.1847070-7-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Lu Baolu
289b3b005c iommu/vt-d: Preset A/D bits for user space DMA usage
We preset the access and dirty bits for IOVA over first level usage only
for the kernel DMA (i.e., when domain type is IOMMU_DOMAIN_DMA). We should
also preset the FL A/D for user space DMA usage. The idea is that even the
user space A/D bit memory write is unnecessary. We should avoid it to
minimize the overhead.

Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720013856.4143880-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210818134852.1847070-6-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Lu Baolu
792fb43ce2 iommu/vt-d: Enable Intel IOMMU scalable mode by default
The commit 8950dcd83a ("iommu/vt-d: Leave scalable mode default off")
leaves the scalable mode default off and end users could turn it on with
"intel_iommu=sm_on". Using the Intel IOMMU scalable mode for kernel DMA,
user-level device access and Shared Virtual Address have been enabled.
This enables the scalable mode by default if the hardware advertises the
support and adds kernel options of "intel_iommu=sm_on/sm_off" for end
users to configure it through the kernel parameters.

Suggested-by: Ashok Raj <ashok.raj@intel.com>
Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210720013856.4143880-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210818134852.1847070-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Lu Baolu
01dac2d9d2 iommu/vt-d: Refactor Kconfig a bit
Put all sub-options inside a "if INTEL_IOMMU" so that they don't need to
always depend on INTEL_IOMMU. Use IS_ENABLED() instead of #ifdef as well.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720013856.4143880-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210818134852.1847070-4-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Zhen Lei
5e41c99894 iommu/vt-d: Remove unnecessary oom message
Fixes scripts/checkpatch.pl warning:
WARNING: Possible unnecessary 'out of memory' message

Remove it can help us save a bit of memory.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20210609124937.14260-1-thunder.leizhen@huawei.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210818134852.1847070-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Lu Baolu
4d99efb229 iommu/vt-d: Update the virtual command related registers
The VT-d spec Revision 3.3 updated the virtual command registers, virtual
command opcode B register, virtual command response register and virtual
command capability register (Section 10.4.43, 10.4.44, 10.4.45, 10.4.46).
This updates the virtual command interface implementation in the Intel
IOMMU driver accordingly.

Fixes: 24f27d32ab ("iommu/vt-d: Enlightened PASID allocation")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Sanjay Kumar <sanjay.k.kumar@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210713042649.3547403-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210818134852.1847070-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-19 10:41:08 +02:00
Robin Murphy
78ca078459 iommu/vt-d: Prepare for multiple DMA domain types
In preparation for the strict vs. non-strict decision for DMA domains
to be expressed in the domain type, make sure we expose our flush queue
awareness by accepting the new domain type, and test the specific
feature flag where we want to identify DMA domains in general. The DMA
ops reset/setup can simply be made unconditional, since iommu-dma
already knows only to touch DMA domains.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/31a8ef868d593a2f3826a6a120edee81815375a7.1628682049.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-18 13:27:49 +02:00
Robin Murphy
f297e27f83 iommu/vt-d: Drop IOVA cookie management
The core code bakes its own cookies now.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/e9dbe3b6108f8538e17e0c5f59f8feeb714f51a4.1628682048.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-18 13:25:31 +02:00
Liu Yi L
8798d36411 iommu/vt-d: Fix incomplete cache flush in intel_pasid_tear_down_entry()
This fixes improper iotlb invalidation in intel_pasid_tear_down_entry().
When a PASID was used as nested mode, released and reused, the following
error message will appear:

[  180.187556] Unexpected page request in Privilege Mode
[  180.187565] Unexpected page request in Privilege Mode
[  180.279933] Unexpected page request in Privilege Mode
[  180.279937] Unexpected page request in Privilege Mode

Per chapter 6.5.3.3 of VT-d spec 3.3, when tear down a pasid entry, the
software should use Domain selective IOTLB flush if the PGTT of the pasid
entry is SL only or Nested, while for the pasid entries whose PGTT is FL
only or PT using PASID-based IOTLB flush is enough.

Fixes: 2cd1311a26 ("iommu/vt-d: Add set domain DOMAIN_ATTR_NESTING attr")
Signed-off-by: Kumar Sanjay K <sanjay.k.kumar@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Tested-by: Yi Sun <yi.y.sun@intel.com>
Link: https://lore.kernel.org/r/20210817042425.1784279-1-yi.l.liu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210817124321.1517985-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-18 13:15:58 +02:00
Fenghua Yu
62ef907a04 iommu/vt-d: Fix PASID reference leak
A PASID reference is increased whenever a device is bound to an mm (and
its PASID) successfully (i.e. the device's sdev user count is increased).
But the reference is not dropped every time the device is unbound
successfully from the mm (i.e. the device's sdev user count is decreased).
The reference is dropped only once by calling intel_svm_free_pasid() when
there isn't any device bound to the mm. intel_svm_free_pasid() drops the
reference and only frees the PASID on zero reference.

Fix the issue by dropping the PASID reference and freeing the PASID when
no reference on successful unbinding the device by calling
intel_svm_free_pasid() .

Fixes: 4048377414 ("iommu/vt-d: Use iommu_sva_alloc(free)_pasid() helpers")
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20210813181345.1870742-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210817124321.1517985-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-08-18 13:15:58 +02:00
Lu Baolu
75cc1018a9 iommu/vt-d: Move clflush'es from iotlb_sync_map() to map_pages()
As the Intel VT-d driver has switched to use the iommu_ops.map_pages()
callback, multiple pages of the same size will be mapped in a call.
There's no need to put the clflush'es in iotlb_sync_map() callback.
Move them back into __domain_mapping() to simplify the code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720020615.4144323-4-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:56:25 +02:00
Lu Baolu
3f34f12597 iommu/vt-d: Implement map/unmap_pages() iommu_ops callback
Implement the map_pages() and unmap_pages() callback for the Intel IOMMU
driver to allow calls from iommu core to map and unmap multiple pages of
the same size in one call. With map/unmap_pages() implemented, the prior
map/unmap callbacks are deprecated.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720020615.4144323-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:56:25 +02:00
Lu Baolu
a886d5a7e6 iommu/vt-d: Report real pgsize bitmap to iommu core
The pgsize bitmap is used to advertise the page sizes our hardware supports
to the IOMMU core, which will then use this information to split physically
contiguous memory regions it is mapping into page sizes that we support.

Traditionally the IOMMU core just handed us the mappings directly, after
making sure the size is an order of a 4KiB page and that the mapping has
natural alignment. To retain this behavior, we currently advertise that we
support all page sizes that are an order of 4KiB.

We are about to utilize the new IOMMU map/unmap_pages APIs. We could change
this to advertise the real page sizes we support.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720020615.4144323-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:56:25 +02:00
John Garry
308723e358 iommu: Remove mode argument from iommu_set_dma_strict()
We only ever now set strict mode enabled in iommu_set_dma_strict(), so
just remove the argument.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/1626088340-5838-7-git-send-email-john.garry@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:27:38 +02:00
Zhen Lei
d0e108b8e9 iommu/vt-d: Add support for IOMMU default DMA mode build options
Make IOMMU_DEFAULT_LAZY default for when INTEL_IOMMU config is set,
as is current behaviour.

Also delete global flag intel_iommu_strict:
- In intel_iommu_setup(), call iommu_set_dma_strict(true) directly. Also
  remove the print, as iommu_subsys_init() prints the mode and we have
  already marked this param as deprecated.

- For cap_caching_mode() check in intel_iommu_setup(), call
  iommu_set_dma_strict(true) directly; also reword the accompanying print
  with a level downgrade and also add the missing '\n'.

- For Ironlake GPU, again call iommu_set_dma_strict(true) directly and
  keep the accompanying print.

[jpg: Remove intel_iommu_strict]

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/1626088340-5838-5-git-send-email-john.garry@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:27:38 +02:00
John Garry
1d479f160c iommu: Deprecate Intel and AMD cmdline methods to enable strict mode
Now that the x86 drivers support iommu.strict, deprecate the custom
methods.

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/1626088340-5838-2-git-send-email-john.garry@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-26 13:27:38 +02:00
Lu Baolu
474dd1c650 iommu/vt-d: Fix clearing real DMA device's scalable-mode context entries
The commit 2b0140c696 ("iommu/vt-d: Use pci_real_dma_dev() for mapping")
fixes an issue of "sub-device is removed where the context entry is cleared
for all aliases". But this commit didn't consider the PASID entry and PASID
table in VT-d scalable mode. This fix increases the coverage of scalable
mode.

Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Fixes: 8038bdb855 ("iommu/vt-d: Only clear real DMA device's context entries")
Fixes: 2b0140c696 ("iommu/vt-d: Use pci_real_dma_dev() for mapping")
Cc: stable@vger.kernel.org # v5.6+
Cc: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210712071712.3416949-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-14 12:58:07 +02:00
Sanjay Kumar
37764b952e iommu/vt-d: Global devTLB flush when present context entry changed
This fixes a bug in context cache clear operation. The code was not
following the correct invalidation flow. A global device TLB invalidation
should be added after the IOTLB invalidation. At the same time, it
uses the domain ID from the context entry. But in scalable mode, the
domain ID is in PASID table entry, not context entry.

Fixes: 7373a8cc38 ("iommu/vt-d: Setup context and enable RID2PASID support")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210712071315.3416543-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-14 12:57:39 +02:00
Joerg Roedel
2b9d8e3e9a Merge branches 'iommu/fixes', 'arm/rockchip', 'arm/smmu', 'x86/vt-d', 'x86/amd', 'virtio' and 'core' into next 2021-06-25 15:23:25 +02:00
Jean-Philippe Brucker
ac6d704679 iommu/dma: Pass address limit rather than size to iommu_setup_dma_ops()
Passing a 64-bit address width to iommu_setup_dma_ops() is valid on
virtual platforms, but isn't currently possible. The overflow check in
iommu_dma_init_domain() prevents this even when @dma_base isn't 0. Pass
a limit address instead of a size, so callers don't have to fake a size
to work around the check.

The base and limit parameters are being phased out, because:
* they are redundant for x86 callers. dma-iommu already reserves the
  first page, and the upper limit is already in domain->geometry.
* they can now be obtained from dev->dma_range_map on Arm.
But removing them on Arm isn't completely straightforward so is left for
future work. As an intermediate step, simplify the x86 callers by
passing dummy limits.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20210618152059.1194210-5-jean-philippe@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-25 15:02:43 +02:00
Colin Ian King
934ed4580c iommu/vt-d: Fix dereference of pointer info before it is null checked
The assignment of iommu from info->iommu occurs before info is null checked
hence leading to a potential null pointer dereference issue. Fix this by
assigning iommu and checking if iommu is null after null checking info.

Addresses-Coverity: ("Dereference before null check")
Fixes: 4c82b88696 ("iommu/vt-d: Allocate/register iopf queue for sva devices")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210611135024.32781-1-colin.king@canonical.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-18 15:19:50 +02:00
Joerg Roedel
d6a9642bd6 iommu/vt-d: Fix linker error on 32-bit
A recent commit broke the build on 32-bit x86. The linker throws these
messages:

	ld: drivers/iommu/intel/perf.o: in function `dmar_latency_snapshot':
	perf.c:(.text+0x40c): undefined reference to `__udivdi3'
	ld: perf.c:(.text+0x458): undefined reference to `__udivdi3'

The reason are the 64-bit divides in dmar_latency_snapshot(). Use the
div_u64() helper function for those.

Fixes: 55ee5e67a5 ("iommu/vt-d: Add common code for dmar latency performance monitors")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20210610083120.29224-1-joro@8bytes.org
2021-06-10 10:33:14 +02:00
Parav Pandit
7a0f06c197 iommu/vt-d: No need to typecast
Page directory assignment by alloc_pgtable_page() or phys_to_virt()
doesn't need typecasting as both routines return void*. Hence, remove
typecasting from both the calls.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-24-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:14 +02:00
Parav Pandit
cee57d4fe7 iommu/vt-d: Remove unnecessary braces
No need for braces for single line statement under if() block.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-22-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:14 +02:00
Parav Pandit
74f6d776ae iommu/vt-d: Removed unused iommu_count in dmar domain
DMAR domain uses per DMAR refcount. It is indexed by iommu seq_id.
Older iommu_count is only incremented and decremented but no decisions
are taken based on this refcount. This is not of much use.

Hence, remove iommu_count and further simplify domain_detach_iommu()
by returning void.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-21-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:14 +02:00
Parav Pandit
1f106ff0ea iommu/vt-d: Use bitfields for DMAR capabilities
IOTLB device presence, iommu coherency and snooping are boolean
capabilities. Use them as bits and keep them adjacent.

Structure layout before the reorg.
$ pahole -C dmar_domain drivers/iommu/intel/dmar.o
struct dmar_domain {
        int                        nid;                  /*     0     4 */
        unsigned int               iommu_refcnt[128];    /*     4   512 */
        /* --- cacheline 8 boundary (512 bytes) was 4 bytes ago --- */
        u16                        iommu_did[128];       /*   516   256 */
        /* --- cacheline 12 boundary (768 bytes) was 4 bytes ago --- */
        bool                       has_iotlb_device;     /*   772     1 */

        /* XXX 3 bytes hole, try to pack */

        struct list_head           devices;              /*   776    16 */
        struct list_head           subdevices;           /*   792    16 */
        struct iova_domain         iovad __attribute__((__aligned__(8)));
							 /*   808  2320 */
        /* --- cacheline 48 boundary (3072 bytes) was 56 bytes ago --- */
        struct dma_pte *           pgd;                  /*  3128     8 */
        /* --- cacheline 49 boundary (3136 bytes) --- */
        int                        gaw;                  /*  3136     4 */
        int                        agaw;                 /*  3140     4 */
        int                        flags;                /*  3144     4 */
        int                        iommu_coherency;      /*  3148     4 */
        int                        iommu_snooping;       /*  3152     4 */
        int                        iommu_count;          /*  3156     4 */
        int                        iommu_superpage;      /*  3160     4 */

        /* XXX 4 bytes hole, try to pack */

        u64                        max_addr;             /*  3168     8 */
        u32                        default_pasid;        /*  3176     4 */

        /* XXX 4 bytes hole, try to pack */

        struct iommu_domain        domain;               /*  3184    72 */

        /* size: 3256, cachelines: 51, members: 18 */
        /* sum members: 3245, holes: 3, sum holes: 11 */
        /* forced alignments: 1 */
        /* last cacheline: 56 bytes */
} __attribute__((__aligned__(8)));

After arranging it for natural padding and to make flags as u8 bits, it
saves 8 bytes for the struct.

struct dmar_domain {
        int                        nid;                  /*     0     4 */
        unsigned int               iommu_refcnt[128];    /*     4   512 */
        /* --- cacheline 8 boundary (512 bytes) was 4 bytes ago --- */
        u16                        iommu_did[128];       /*   516   256 */
        /* --- cacheline 12 boundary (768 bytes) was 4 bytes ago --- */
        u8                         has_iotlb_device:1;   /*   772: 0  1 */
        u8                         iommu_coherency:1;    /*   772: 1  1 */
        u8                         iommu_snooping:1;     /*   772: 2  1 */

        /* XXX 5 bits hole, try to pack */
        /* XXX 3 bytes hole, try to pack */

        struct list_head           devices;              /*   776    16 */
        struct list_head           subdevices;           /*   792    16 */
        struct iova_domain         iovad __attribute__((__aligned__(8)));
							 /*   808  2320 */
        /* --- cacheline 48 boundary (3072 bytes) was 56 bytes ago --- */
        struct dma_pte *           pgd;                  /*  3128     8 */
        /* --- cacheline 49 boundary (3136 bytes) --- */
        int                        gaw;                  /*  3136     4 */
        int                        agaw;                 /*  3140     4 */
        int                        flags;                /*  3144     4 */
        int                        iommu_count;          /*  3148     4 */
        int                        iommu_superpage;      /*  3152     4 */

        /* XXX 4 bytes hole, try to pack */

        u64                        max_addr;             /*  3160     8 */
        u32                        default_pasid;        /*  3168     4 */

        /* XXX 4 bytes hole, try to pack */

        struct iommu_domain        domain;               /*  3176    72 */

        /* size: 3248, cachelines: 51, members: 18 */
        /* sum members: 3236, holes: 3, sum holes: 11 */
        /* sum bitfield members: 3 bits, bit holes: 1, sum bit holes: 5 bits */
        /* forced alignments: 1 */
        /* last cacheline: 48 bytes */
} __attribute__((__aligned__(8)));

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-20-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
YueHaibing
3bc770b0e9 iommu/vt-d: Use DEVICE_ATTR_RO macro
Use DEVICE_ATTR_RO() helper instead of plain DEVICE_ATTR(),
which makes the code a bit shorter and easier to read.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210528130229.22108-1-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20210610020115.1637656-19-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Gustavo A. R. Silva
606636dcbd iommu/vt-d: Fix out-bounds-warning in intel/svm.c
Replace a couple of calls to memcpy() with simple assignments in order
to fix the following out-of-bounds warning:

drivers/iommu/intel/svm.c:1198:4: warning: 'memcpy' offset [25, 32] from
    the object at 'desc' is out of the bounds of referenced subobject
    'qw2' with type 'long long unsigned int' at offset 16 [-Warray-bounds]

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy(). This causes a legitimate compiler warning because memcpy()
overruns the length of &desc.qw2 and &resp.qw2, respectively.

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210414201403.GA392764@embeddedor
Link: https://lore.kernel.org/r/20210610020115.1637656-18-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
0f4834ab25 iommu/vt-d: Add PRQ handling latency sampling
The execution time for page fault request handling is performance critical
and needs to be monitored. This adds code to sample the execution time of
page fault request handling.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-17-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
74eb87a0f9 iommu/vt-d: Add cache invalidation latency sampling
Queued invalidation execution time is performance critical and needs
to be monitored. This adds code to sample the execution time of IOTLB/
devTLB/ICE cache invalidation.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-16-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
456bb0b97f iommu/vt-d: Expose latency monitor data through debugfs
A debugfs interface /sys/kernel/debug/iommu/intel/dmar_perf_latency is
created to control and show counts of execution time ranges for various
types per DMAR. The interface may help debug any potential performance
issue.

By default, the interface is disabled.

Possible write value of /sys/kernel/debug/iommu/intel/dmar_perf_latency
  0 - disable sampling all latency data
  1 - enable sampling IOTLB invalidation latency data
  2 - enable sampling devTLB invalidation latency data
  3 - enable sampling intr entry cache invalidation latency data
  4 - enable sampling prq handling latency data

Read /sys/kernel/debug/iommu/intel/dmar_perf_latency gives a snapshot
of sampling result of all enabled monitors.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-15-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
55ee5e67a5 iommu/vt-d: Add common code for dmar latency performance monitors
The execution time of some operations is very performance critical, such
as cache invalidation and PRQ processing time. This adds some common code
to monitor the execution time range of those operations. The interfaces
include enabling/disabling, checking status, updating sampling data and
providing a common string format for users.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-14-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
e93a67f5a0 iommu/vt-d: Add prq_report trace event
This adds a new trace event to track the page fault request report.
This event will provide almost all information defined in a page
request descriptor.

A sample output:
| prq_report: dmar0/0000:00:0a.0 seq# 1: rid=0x50 addr=0x559ef6f97 r---- pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 2: rid=0x50 addr=0x559ef6f9c rw--l pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 3: rid=0x50 addr=0x559ef6f98 r---- pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 4: rid=0x50 addr=0x559ef6f9d rw--l pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 5: rid=0x50 addr=0x559ef6f99 r---- pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 6: rid=0x50 addr=0x559ef6f9e rw--l pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 7: rid=0x50 addr=0x559ef6f9a r---- pasid=0x2 index=0x1
| prq_report: dmar0/0000:00:0a.0 seq# 8: rid=0x50 addr=0x559ef6f9f rw--l pasid=0x2 index=0x1

This will be helpful for I/O page fault related debugging.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-13-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
d5b9e4bfe0 iommu/vt-d: Report prq to io-pgfault framework
Let the IO page fault requests get handled through the io-pgfault
framework.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-12-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
4c82b88696 iommu/vt-d: Allocate/register iopf queue for sva devices
This allocates and registers the iopf queue infrastructure for devices
which want to support IO page fault for SVA.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-11-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
ae7f09b14b iommu/vt-d: Refactor prq_event_thread()
Refactor prq_event_thread() by moving handling single prq event out of
the main loop.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-10-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
9e52cc0fed iommu/vt-d: Use common helper to lookup svm devices
It's common to iterate the svm device list and find a matched device. Add
common helpers to do this and consolidate the code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-9-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:13 +02:00
Lu Baolu
4048377414 iommu/vt-d: Use iommu_sva_alloc(free)_pasid() helpers
Align the pasid alloc/free code with the generic helpers defined in the
iommu core. This also refactored the SVA binding code to improve the
readability.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Lu Baolu
100b8a14a3 iommu/vt-d: Add pasid private data helpers
We are about to use iommu_sva_alloc/free_pasid() helpers in iommu core.
That means the pasid life cycle will be managed by iommu core. Use a
local array to save the per pasid private data instead of attaching it
the real pasid.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210520031531.712333-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-7-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Lu Baolu
521f546b4e iommu/vt-d: Support asynchronous IOMMU nested capabilities
Current VT-d implementation supports nested translation only if all
underlying IOMMUs support the nested capability. This is unnecessary
as the upper layer is allowed to create different containers and set
them with different type of iommu backend. The IOMMU driver needs to
guarantee that devices attached to a nested mode iommu_domain should
support nested capabilility.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210517065701.5078-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-6-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Lu Baolu
879fcc6bda iommu/vt-d: Select PCI_ATS explicitly
The Intel VT-d implementation supports device TLB management. Select
PCI_ATS explicitly so that the pci_ats helpers are always available.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210512065313.3441309-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Lu Baolu
719a193356 iommu/vt-d: Tweak the description of a DMA fault
The Intel IOMMU driver reports the DMA fault reason in a decimal number
while the VT-d specification uses a hexadecimal one. It's inconvenient
that users need to covert them everytime before consulting the spec.
Let's use hexadecimal number for a DMA fault reason.

The fault message uses 0xffffffff as PASID for DMA requests w/o PASID.
This is confusing. Tweak this by adding "NO_PASID" explicitly.

Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210517065425.4953-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210610020115.1637656-4-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Aditya Srivastava
367f82de5a iommu/vt-d: Fix kernel-doc syntax in file header
The opening comment mark '/**' is used for highlighting the beginning of
kernel-doc comments.
The header for drivers/iommu/intel/pasid.c follows this syntax, but
the content inside does not comply with kernel-doc.

This line was probably not meant for kernel-doc parsing, but is parsed
due to the presence of kernel-doc like comment syntax(i.e, '/**'), which
causes unexpected warnings from kernel-doc:
warning: Function parameter or member 'fmt' not described in 'pr_fmt'

Provide a simple fix by replacing this occurrence with general comment
format, i.e. '/*', to prevent kernel-doc from parsing it.

Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210523143245.19040-1-yashsri421@gmail.com
Link: https://lore.kernel.org/r/20210610020115.1637656-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00
Colin Ian King
05d2cbf969 iommu/vt-d: Remove redundant assignment to variable agaw
The variable agaw is initialized with a value that is never read and it
is being updated later with a new value as a counter in a for-loop. The
initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210416171826.64091-1-colin.king@canonical.com
Link: https://lore.kernel.org/r/20210610020115.1637656-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-06-10 09:06:12 +02:00