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

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

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/amd: Fix pci_segment memleak in alloc_pci_segment()

2026-01-11T14:22:10+00:00

commit 75ba146c2674ba49ed8a222c67f9abfb4a4f2a4f upstream. Fix a memory leak of struct amd_iommu_pci_segment in alloc_pci_segment() when system memory (or contiguous memory) is insufficient. Fixes: 04230c119930 ("iommu/amd: Introduce per PCI segment device table") Fixes: eda797a27795 ("iommu/amd: Introduce per PCI segment rlookup table") Fixes: 99fc4ac3d297 ("iommu/amd: Introduce per PCI segment alias_table") Cc: stable@vger.kernel.org Signed-off-by: Jinhui Guo Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman

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

2025-11-24T09:29:34+00:00

[ Upstream commit 9be15fbfc6c5c89c22cf6e209f66ea43ee0e58bb ] After a panic if SNP is enabled in the previous kernel then the kdump kernel boots with IOMMU SNP enforcement still enabled. IOMMU command buffers and event buffer registers remain locked and exclusive to the previous kernel. Attempts to enable command and event buffers in the kdump kernel will fail, as hardware ignores writes to the locked MMIO registers as per AMD IOMMU spec Section 2.12.2.1. Skip enabling command buffers and event buffers for kdump boot as they are already enabled in the previous kernel. Reviewed-by: Vasant Hegde Tested-by: Sairaj Kodilkar Signed-off-by: Ashish Kalra Link: https://lore.kernel.org/r/576445eb4f168b467b0fc789079b650ca7c5b037.1756157913.git.ashish.kalra@amd.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/amd/pgtbl: Fix possible race while increase page table level

2025-09-25T09:00:10+00:00

[ Upstream commit 1e56310b40fd2e7e0b9493da9ff488af145bdd0c ] The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), starting with a 3-level configuration that expands based on IOVA address. The kernel maintains a root pointer and current page table level to enable proper page table walks in alloc_pte()/fetch_pte() operations. The IOMMU IOVA allocator initially starts with 32-bit address and onces its exhuasted it switches to 64-bit address (max address is determined based on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU driver increases page table level. But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads pgtable->[root/mode] without lock. So its possible that in exteme corner case, when increase_address_space() is updating pgtable->[root/mode], fetch_pte() reads wrong page table level (pgtable->mode). It does compare the value with level encoded in page table and returns NULL. This will result is iommu_unmap ops to fail and upper layer may retry/log WARN_ON. CPU 0 CPU 1 ------ ------ map pages unmap pages alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte() pgtable->root = pte (new root value) READ pgtable->[mode/root] Reads new root, old mode Updates mode (pgtable->mode += 1) Since Page table level updates are infrequent and already synchronized with a spinlock, implement seqcount to enable lock-free read operations on the read path. Fixes: 754265bcab7 ("iommu/amd: Fix race in increase_address_space()") Reported-by: Alejandro Jimenez Cc: stable@vger.kernel.org Cc: Joao Martins Cc: Suravee Suthikulpanit Signed-off-by: Vasant Hegde Signed-off-by: Joerg Roedel [ Adapted pgtable->mode and pgtable->root to use domain->iop.mode and domain->iop.root ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

iommu/amd: Avoid stack buffer overflow from kernel cmdline

2025-08-28T14:28:48+00:00

[ Upstream commit 8503d0fcb1086a7cfe26df67ca4bd9bd9e99bdec ] While the kernel command line is considered trusted in most environments, avoid writing 1 byte past the end of "acpiid" if the "str" argument is maximum length. Reported-by: Simcha Kosman Closes: https://lore.kernel.org/all/AS8P193MB2271C4B24BCEDA31830F37AE84A52@AS8P193MB2271.EURP193.PROD.OUTLOOK.COM Fixes: b6b26d86c61c ("iommu/amd: Add a length limitation for the ivrs_acpihid command-line parameter") Signed-off-by: Kees Cook Reviewed-by: Ankit Soni Link: https://lore.kernel.org/r/20250804154023.work.970-kees@kernel.org Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/amd: Fix geometry.aperture_end for V2 tables

2025-08-15T10:08:48+00:00

[ Upstream commit 8637afa79cfa6123f602408cfafe8c9a73620ff1 ] The AMD IOMMU documentation seems pretty clear that the V2 table follows the normal CPU expectation of sign extension. This is shown in Figure 25: AMD64 Long Mode 4-Kbyte Page Address Translation Where bits Sign-Extend [63:57] == [56]. This is typical for x86 which would have three regions in the page table: lower, non-canonical, upper. The manual describes that the V1 table does not sign extend in section 2.2.4 Sharing AMD64 Processor and IOMMU Page Tables GPA-to-SPA Further, Vasant has checked this and indicates the HW has an addtional behavior that the manual does not yet describe. The AMDv2 table does not have the sign extended behavior when attached to PASID 0, which may explain why this has gone unnoticed. The iommu domain geometry does not directly support sign extended page tables. The driver should report only one of the lower/upper spaces. Solve this by removing the top VA bit from the geometry to use only the lower space. This will also make the iommu_domain work consistently on all PASID 0 and PASID != 1. Adjust dma_max_address() to remove the top VA bit. It now returns: 5 Level: Before 0x1ffffffffffffff After 0x0ffffffffffffff 4 Level: Before 0xffffffffffff After 0x7fffffffffff Fixes: 11c439a19466 ("iommu/amd/pgtbl_v2: Fix domain max address") Link: https://lore.kernel.org/all/8858d4d6-d360-4ef0-935c-bfd13ea54f42@amd.com/ Signed-off-by: Jason Gunthorpe Reviewed-by: Vasant Hegde Reviewed-by: Lu Baolu Link: https://lore.kernel.org/r/0-v2-0615cc99b88a+1ce-amdv2_geo_jgg@nvidia.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

iommu/amd: Ensure GA log notifier callbacks finish running before module unload

2025-06-27T10:08:55+00:00

[ Upstream commit 94c721ea03c7078163f41dbaa101ac721ddac329 ] Synchronize RCU when unregistering KVM's GA log notifier to ensure all in-flight interrupt handlers complete before KVM-the module is unloaded. Signed-off-by: Sean Christopherson Link: https://lore.kernel.org/r/20250315031048.2374109-1-seanjc@google.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/amd/pgtbl_v2: Improve error handling

2025-06-04T12:42:01+00:00

[ Upstream commit 36a1cfd497435ba5e37572fe9463bb62a7b1b984 ] Return -ENOMEM if v2_alloc_pte() fails to allocate memory. Signed-off-by: Vasant Hegde Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20250227162320.5805-4-vasant.hegde@amd.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

iommu/amd: Fix potential buffer overflow in parse_ivrs_acpihid

2025-05-09T07:43:52+00:00

commit 8dee308e4c01dea48fc104d37f92d5b58c50b96c upstream. There is a string parsing logic error which can lead to an overflow of hid or uid buffers. Comparing ACPIID_LEN against a total string length doesn't take into account the lengths of individual hid and uid buffers so the check is insufficient in some cases. For example if the length of hid string is 4 and the length of the uid string is 260, the length of str will be equal to ACPIID_LEN + 1 but uid string will overflow uid buffer which size is 256. The same applies to the hid string with length 13 and uid string with length 250. Check the length of hid and uid strings separately to prevent buffer overflow. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: ca3bf5d47cec ("iommu/amd: Introduces ivrs_acpihid kernel parameter") Cc: stable@vger.kernel.org Signed-off-by: Pavel Paklov Link: https://lore.kernel.org/r/20250325092259.392844-1-Pavel.Paklov@cyberprotect.ru Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman