{"id":2226655,"url":"http://patchwork.ozlabs.org/api/covers/2226655/?format=json","web_url":"http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260422180616.336474-1-mehmet.basaran@canonical.com/","project":{"id":15,"url":"http://patchwork.ozlabs.org/api/projects/15/?format=json","name":"Ubuntu Kernel","link_name":"ubuntu-kernel","list_id":"kernel-team.lists.ubuntu.com","list_email":"kernel-team@lists.ubuntu.com","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260422180616.336474-1-mehmet.basaran@canonical.com>","list_archive_url":null,"date":"2026-04-22T18:06:15","name":"[SRU,N,0/1] Revert \"iommu: disable SVA when CONFIG_X86 is set\"","submitter":{"id":89305,"url":"http://patchwork.ozlabs.org/api/people/89305/?format=json","name":"Mehmet Basaran","email":"mehmet.basaran@canonical.com"},"mbox":"http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260422180616.336474-1-mehmet.basaran@canonical.com/mbox/","series":[{"id":501061,"url":"http://patchwork.ozlabs.org/api/series/501061/?format=json","web_url":"http://patchwork.ozlabs.org/project/ubuntu-kernel/list/?series=501061","date":"2026-04-22T18:06:15","name":"Revert \"iommu: disable SVA when CONFIG_X86 is set\"","version":1,"mbox":"http://patchwork.ozlabs.org/series/501061/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/covers/2226655/comments/","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=e+3n+xMq;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; 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charset=\"utf-8\"","Content-Transfer-Encoding":"base64","Errors-To":"kernel-team-bounces@lists.ubuntu.com","Sender":"\"kernel-team\" "},"content":"BugLink: https://bugs.launchpad.net/bugs/2149766\n\n[Impact]\n \nThe issue has been brought to our attention when questing (6.17)\nkernels were unable to load amd_xdna drivers. However, this commit,\nin addition to NPUs, also affects PCIe cards which make use of\nunified memory (GPUs, Accelerators, NICs). With this commit, PCIe\ndevices will revert to using legacy method (pinning) instead of\nunified memory. As a result,\n - arguably it will be less secure,\n - there can be performance drops.\n\nCurrently, this commit is part of an 8 commit patch series:\n\"Fix stale IOTLB entries for kernel address space\", v7.\n [PATCH v7 1/8] iommu: Disable SVA when CONFIG_X86 is set\n [PATCH v7 2/8] mm: Add a ptdesc flag to mark kernel page tables\n [PATCH v7 3/8] mm: Actually mark kernel page table pages\n [PATCH v7 4/8] x86/mm: Use 'ptdesc' when freeing PMD pages\n [PATCH v7 5/8] mm: Introduce pure page table freeing function\n [PATCH v7 6/8] x86/mm: Use pagetable_free()\n [PATCH v7 7/8] mm: Introduce deferred freeing for kernel page tables\n [PATCH v7 8/8] iommu/sva: Invalidate stale IOTLB entries for kernel address space\n\nwhere \"iommu: disable SVA when CONFIG_X86 is set\" is undone by\nthe 8th commit. We only have this commit from the whole patchset.\nIdeally we should have the whole patchset applied.\n\n[Fix]\n\nThis commit fixes the following issue which is old,\n26b25a2b98e4 (\"iommu: Bind process address spaces to devices\")\nand we applied this commit recently. So, reverting this commit\nwon't be introducing regressions. Affected kernel versions are:\n - 6.8 due to the reasons above.\n - 6.17 due to both the reasons above and the amd_xdna issue.\n\n[Test Plan]\n\nOur regression test suite doesn't catch this issue. However,\nwe will run it again to see it doesn't cause anything else.\n\n[Where problems could occur]\n\nReverted commit is a fix for a security vulnerability related to\nIOMMU Shared Virtual Addressing (SVA). In an SVA context, an \nIOMMU can cache kernel page table entries. When a kernel page \ntable page is freed and reallocated for another purpose, the \nIOMMU might still hold stale, incorrect entries. This can be \nexploited to cause a use-after-free or write-after-free condition,\npotentially leading to privilege escalation or data corruption.\n\nMehmet Basaran (1):\n Revert \"iommu: disable SVA when CONFIG_X86 is set\"\n\n drivers/iommu/iommu-sva.c | 3 ---\n 1 file changed, 3 deletions(-)"}