kernel/linux.git/drivers/iommu, branch v6.6.132

iommu/vt-d: Fix intel iommu iotlb sync hardlockup and retry

2026-03-25T10:06:04+00:00

commit fe89277c9ceb0d6af0aa665bcf24a41d8b1b79cd upstream. During the qi_check_fault process after an IOMMU ITE event, requests at odd-numbered positions in the queue are set to QI_ABORT, only satisfying single-request submissions. However, qi_submit_sync now supports multiple simultaneous submissions, and can't guarantee that the wait_desc will be at an odd-numbered position. Therefore, if an item times out, IOMMU can't re-initiate the request, resulting in an infinite polling wait. This modifies the process by setting the status of all requests already fetched by IOMMU and recorded as QI_IN_USE status (including wait_desc requests) to QI_ABORT, thus enabling multiple requests to be resubmitted. Fixes: 8a1d82462540 ("iommu/vt-d: Multiple descriptors per qi_submit_sync()") Cc: stable@vger.kernel.org Signed-off-by: Guanghui Feng Tested-by: Shuai Xue Reviewed-by: Shuai Xue Reviewed-by: Samiullah Khawaja Link: https://lore.kernel.org/r/20260306101516.3885775-1-guanghuifeng@linux.alibaba.com Signed-off-by: Lu Baolu Fixes: 8a1d82462540 ("iommu/vt-d: Multiple descriptors per qi_submit_sync()") Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman

iommu/vt-d: Flush dev-IOTLB only when PCIe device is accessible in scalable mode

2026-03-04T12:21:11+00:00

[ Upstream commit 10e60d87813989e20eac1f3eda30b3bae461e7f9 ] Commit 4fc82cd907ac ("iommu/vt-d: Don't issue ATS Invalidation request when device is disconnected") relies on pci_dev_is_disconnected() to skip ATS invalidation for safely-removed devices, but it does not cover link-down caused by faults, which can still hard-lock the system. For example, if a VM fails to connect to the PCIe device, "virsh destroy" is executed to release resources and isolate the fault, but a hard-lockup occurs while releasing the group fd. Call Trace: qi_submit_sync qi_flush_dev_iotlb intel_pasid_tear_down_entry device_block_translation blocking_domain_attach_dev __iommu_attach_device __iommu_device_set_domain __iommu_group_set_domain_internal iommu_detach_group vfio_iommu_type1_detach_group vfio_group_detach_container vfio_group_fops_release __fput Although pci_device_is_present() is slower than pci_dev_is_disconnected(), it still takes only ~70 µs on a ConnectX-5 (8 GT/s, x2) and becomes even faster as PCIe speed and width increase. Besides, devtlb_invalidation_with_pasid() is called only in the paths below, which are far less frequent than memory map/unmap. 1. mm-struct release 2. {attach,release}_dev 3. set/remove PASID 4. dirty-tracking setup The gain in system stability far outweighs the negligible cost of using pci_device_is_present() instead of pci_dev_is_disconnected() to decide when to skip ATS invalidation, especially under GDR high-load conditions. Fixes: 4fc82cd907ac ("iommu/vt-d: Don't issue ATS Invalidation request when device is disconnected") Cc: stable@vger.kernel.org Signed-off-by: Jinhui Guo Link: https://lore.kernel.org/r/20251211035946.2071-3-guojinhui.liam@bytedance.com Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/amd: move wait_on_sem() out of spinlock

2026-03-04T12:20:45+00:00

[ Upstream commit d2a0cac10597068567d336e85fa3cbdbe8ca62bf ] With iommu.strict=1, the existing completion wait path can cause soft lockups under stressed environment, as wait_on_sem() busy-waits under the spinlock with interrupts disabled. Move the completion wait in iommu_completion_wait() out of the spinlock. wait_on_sem() only polls the hardware-updated cmd_sem and does not require iommu->lock, so holding the lock during the busy wait unnecessarily increases contention and extends the time with interrupts disabled. Signed-off-by: Ankit Soni Reviewed-by: Vasant Hegde Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/arm-smmu-v3: Improve CMDQ lock fairness and efficiency

2026-03-04T12:20:44+00:00

[ Upstream commit df180b1a4cc51011c5f8c52c7ec02ad2e42962de ] The SMMU CMDQ lock is highly contentious when there are multiple CPUs issuing commands and the queue is nearly full. The lock has the following states: - 0: Unlocked - >0: Shared lock held with count - INT_MIN+N: Exclusive lock held, where N is the # of shared waiters - INT_MIN: Exclusive lock held, no shared waiters When multiple CPUs are polling for space in the queue, they attempt to grab the exclusive lock to update the cons pointer from the hardware. If they fail to get the lock, they will spin until either the cons pointer is updated by another CPU. The current code allows the possibility of shared lock starvation if there is a constant stream of CPUs trying to grab the exclusive lock. This leads to severe latency issues and soft lockups. Consider the following scenario where CPU1's attempt to acquire the shared lock is starved by CPU2 and CPU0 contending for the exclusive lock. CPU0 (exclusive) | CPU1 (shared) | CPU2 (exclusive) | `cmdq->lock` -------------------------------------------------------------------------- trylock() //takes | | | 0 | shared_lock() | | INT_MIN | fetch_inc() | | INT_MIN | no return | | INT_MIN + 1 | spins // VAL >= 0 | | INT_MIN + 1 unlock() | spins... | | INT_MIN + 1 set_release(0) | spins... | | 0 see[NOTE] (done) | (sees 0) | trylock() // takes | 0 | *exits loop* | cmpxchg(0, INT_MIN) | 0 | | *cuts in* | INT_MIN | cmpxchg(0, 1) | | INT_MIN | fails // != 0 | | INT_MIN | spins // VAL >= 0 | | INT_MIN | *starved* | | INT_MIN [NOTE] The current code resets the exclusive lock to 0 regardless of the state of the lock. This causes two problems: 1. It opens the possibility of back-to-back exclusive locks and the downstream effect of starving shared lock. 2. The count of shared lock waiters are lost. To mitigate this, we release the exclusive lock by only clearing the sign bit while retaining the shared lock waiter count as a way to avoid starving the shared lock waiters. Also deleted cmpxchg loop while trying to acquire the shared lock as it is not needed. The waiters can see the positive lock count and proceed immediately after the exclusive lock is released. Exclusive lock is not starved in that submitters will try exclusive lock first when new spaces become available. Reviewed-by: Mostafa Saleh Reviewed-by: Nicolin Chen Signed-off-by: Alexander Grest Signed-off-by: Jacob Pan Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

iommu/vt-d: Flush cache for PASID table before using it

2026-03-04T12:19:46+00:00

[ Upstream commit 22d169bdd2849fe6bd18c2643742e1c02be6451c ] When writing the address of a freshly allocated zero-initialized PASID table to a PASID directory entry, do that after the CPU cache flush for this PASID table, not before it, to avoid the time window when this PASID table may be already used by non-coherent IOMMU hardware while its contents in RAM is still some random old data, not zero-initialized. Fixes: 194b3348bdbb ("iommu/vt-d: Fix PASID directory pointer coherency") Signed-off-by: Dmytro Maluka Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20251221123508.37495-1-dmaluka@chromium.org Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

Revert "iommu/amd: Skip enabling command/event buffers for kdump"

2026-01-11T14:22:33+00:00

This reverts commit 44a764aec64b3f3235b9cbac2525222f69685418 which is commit 9be15fbfc6c5c89c22cf6e209f66ea43ee0e58bb upstream. This causes problems in older kernel trees as SNP host kdump is not supported in them, so drop it from the stable branches. Reported-by: Ashish Kalra Link: https://lore.kernel.org/r/dacdff7f-0606-4ed5-b056-2de564404d51@amd.com Cc: Vasant Hegde Cc: Sairaj Kodilkar Cc: Joerg Roedel Cc: Sasha Levin Signed-off-by: Greg Kroah-Hartman

iommu: disable SVA when CONFIG_X86 is set

2026-01-11T14:22:12+00:00

commit 72f98ef9a4be30d2a60136dd6faee376f780d06c upstream. Patch series "Fix stale IOTLB entries for kernel address space", v7. This proposes a fix for a security vulnerability related to IOMMU Shared Virtual Addressing (SVA). In an SVA context, an IOMMU can cache kernel page table entries. When a kernel page table page is freed and reallocated for another purpose, the IOMMU might still hold stale, incorrect entries. This can be exploited to cause a use-after-free or write-after-free condition, potentially leading to privilege escalation or data corruption. This solution introduces a deferred freeing mechanism for kernel page table pages, which provides a safe window to notify the IOMMU to invalidate its caches before the page is reused. This patch (of 8): In the IOMMU Shared Virtual Addressing (SVA) context, the IOMMU hardware shares and walks the CPU's page tables. The x86 architecture maps the kernel's virtual address space into the upper portion of every process's page table. Consequently, in an SVA context, the IOMMU hardware can walk and cache kernel page table entries. The Linux kernel currently lacks a notification mechanism for kernel page table changes, specifically when page table pages are freed and reused. The IOMMU driver is only notified of changes to user virtual address mappings. This can cause the IOMMU's internal caches to retain stale entries for kernel VA. Use-After-Free (UAF) and Write-After-Free (WAF) conditions arise when kernel page table pages are freed and later reallocated. The IOMMU could misinterpret the new data as valid page table entries. The IOMMU might then walk into attacker-controlled memory, leading to arbitrary physical memory DMA access or privilege escalation. This is also a Write-After-Free issue, as the IOMMU will potentially continue to write Accessed and Dirty bits to the freed memory while attempting to walk the stale page tables. Currently, SVA contexts are unprivileged and cannot access kernel mappings. However, the IOMMU will still walk kernel-only page tables all the way down to the leaf entries, where it realizes the mapping is for the kernel and errors out. This means the IOMMU still caches these intermediate page table entries, making the described vulnerability a real concern. Disable SVA on x86 architecture until the IOMMU can receive notification to flush the paging cache before freeing the CPU kernel page table pages. Link: https://lkml.kernel.org/r/20251022082635.2462433-1-baolu.lu@linux.intel.com Link: https://lkml.kernel.org/r/20251022082635.2462433-2-baolu.lu@linux.intel.com Fixes: 26b25a2b98e4 ("iommu: Bind process address spaces to devices") Signed-off-by: Lu Baolu Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Cc: Alistair Popple Cc: Andy Lutomirski Cc: Borislav Betkov Cc: Dave Hansen Cc: David Hildenbrand Cc: Ingo Molnar Cc: Jann Horn Cc: Jean-Philippe Brucker Cc: Joerg Roedel Cc: Kevin Tian Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Peter Zijlstra Cc: Robin Murohy Cc: Thomas Gleinxer Cc: "Uladzislau Rezki (Sony)" Cc: Vasant Hegde Cc: Vinicius Costa Gomes Cc: Vlastimil Babka Cc: Will Deacon Cc: Yi Lai Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

iommu/tegra: fix device leak on probe_device()

2026-01-11T14:22:12+00:00

commit c08934a61201db8f1d1c66fcc63fb2eb526b656d upstream. Make sure to drop the reference taken to the iommu platform device when looking up its driver data during probe_device(). Note that commit 9826e393e4a8 ("iommu/tegra-smmu: Fix missing put_device() call in tegra_smmu_find") fixed the leak in an error path, but the reference is still leaking on success. Fixes: 891846516317 ("memory: Add NVIDIA Tegra memory controller support") Cc: stable@vger.kernel.org # 3.19: 9826e393e4a8 Cc: Miaoqian Lin Acked-by: Robin Murphy Acked-by: Thierry Reding Signed-off-by: Johan Hovold Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman

iommu/sun50i: fix device leak on of_xlate()

2026-01-11T14:22:11+00:00

commit f916109bf53864605d10bf6f4215afa023a80406 upstream. Make sure to drop the reference taken to the iommu platform device when looking up its driver data during of_xlate(). Fixes: 4100b8c229b3 ("iommu: Add Allwinner H6 IOMMU driver") Cc: stable@vger.kernel.org # 5.8 Cc: Maxime Ripard Acked-by: Robin Murphy Signed-off-by: Johan Hovold Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman

iommu/qcom: fix device leak on of_xlate()

2026-01-11T14:22:11+00:00

commit 6a3908ce56e6879920b44ef136252b2f0c954194 upstream. Make sure to drop the reference taken to the iommu platform device when looking up its driver data during of_xlate(). Note that commit e2eae09939a8 ("iommu/qcom: add missing put_device() call in qcom_iommu_of_xlate()") fixed the leak in a couple of error paths, but the reference is still leaking on success and late failures. Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu") Cc: stable@vger.kernel.org # 4.14: e2eae09939a8 Cc: Rob Clark Cc: Yu Kuai Acked-by: Robin Murphy Signed-off-by: Johan Hovold Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman