[{"id":3680748,"web_url":"http://patchwork.ozlabs.org/comment/3680748/","msgid":"<875x5iswe9.fsf@gmail.com>","list_archive_url":null,"date":"2026-04-22T18:05:50","subject":"NACK: [SRU][N][PATCH 0/1] Revert \"iommu: disable SVA when\n CONFIG_X86 is set\"","submitter":{"id":89305,"url":"http://patchwork.ozlabs.org/api/people/89305/","name":"Mehmet Basaran","email":"mehmet.basaran@canonical.com"},"content":"Nacked-by: Mehmet Basaran \nMehmet Basaran writes:\n\n> BugLink: https://bugs.launchpad.net/bugs/2149766\n>\n> [Impact]\n> \n> The issue has been brought to our attention when questing (6.17)\n> kernels were unable to load amd_xdna drivers. However, this commit,\n> in addition to NPUs, also affects PCIe cards which make use of\n> unified memory (GPUs, Accelerators, NICs). With this commit, PCIe\n> devices will revert to using legacy method (pinning) instead of\n> unified memory. As a result,\n> - arguably it will be less secure,\n> - there can be performance drops.\n>\n> Currently, 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>\n> where \"iommu: disable SVA when CONFIG_X86 is set\" is undone by\n> the 8th commit. We only have this commit from the whole patchset.\n> Ideally we should have the whole patchset applied.\n>\n> [Fix]\n>\n> This commit fixes the following issue which is old,\n> 26b25a2b98e4 (\"iommu: Bind process address spaces to devices\")\n> and we applied this commit recently. So, reverting this commit\n> won'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>\n> Our regression test suite doesn't catch this issue. However,\n> we will run it again to see it doesn't cause anything else.\n>\n> [Where problems could occur]\n>\n> Reverted commit is a fix for a security vulnerability related to\n> IOMMU Shared Virtual Addressing (SVA). In an SVA context, an \n> IOMMU can cache kernel page table entries. When a kernel page \n> table page is freed and reallocated for another purpose, the \n> IOMMU might still hold stale, incorrect entries. This can be \n> exploited to cause a use-after-free or write-after-free condition,\n> potentially leading to privilege escalation or data corruption.\n>\n> Mehmet 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(-)\n>\n> -- \n> 2.43.0","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=NVlIL2xg;\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; helo=lists.ubuntu.com;\n envelope-from=kernel-team-bounces@lists.ubuntu.com;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g16bf0GgTz1y2d\n\tfor ; Thu, 23 Apr 2026 04:06:06 +1000 (AEST)","from localhost ([127.0.0.1] helo=lists.ubuntu.com)\n\tby lists.ubuntu.com with esmtp (Exim 4.86_2)\n\t(envelope-from )\n\tid 1wFbxU-0001BV-3R; Wed, 22 Apr 2026 18:05:56 +0000","from smtp-relay-internal-0.internal ([10.131.114.225]\n helo=smtp-relay-internal-0.canonical.com)\n by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.86_2) (envelope-from )\n id 1wFbxT-0001BA-CK\n for kernel-team@lists.ubuntu.com; Wed, 22 Apr 2026 18:05:55 +0000","from mail-wm1-f72.google.com (mail-wm1-f72.google.com\n [209.85.128.72])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest\n SHA256)\n (No client certificate requested)\n by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 3B8C83F2A0\n for ; Wed, 22 Apr 2026 18:05:55 +0000 (UTC)","by mail-wm1-f72.google.com with SMTP id\n 5b1f17b1804b1-48a588ff84eso13409385e9.1\n for ; Wed, 22 Apr 2026 11:05:55 -0700 (PDT)","from localhost ([149.86.141.144]) by smtp.gmail.com with ESMTPSA id\n 5b1f17b1804b1-48a4b329542sm336712155e9.3.2026.04.22.11.05.52\n for \n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Wed, 22 Apr 2026 11:05:52 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com;\n s=20251003; t=1776881155;\n bh=1ohQ8RoAf7Eai4jEzgvubUpDWnf05WDaMOWhfPJ33qE=;\n h=From:To:Subject:In-Reply-To:References:Date:Message-ID:\n MIME-Version:Content-Type;\n b=NVlIL2xglli65K1pq62AAvOYR8N9X/Vrwn9DsANjMliENqAKbvsPX1Cn+cKTolPH3\n IwasQ//h9qLzQRRKts4SkjUIlPCEOSDUW5xh1UatOE0F3BXo/ugqmIquTjQr3N/uxn\n fHmKwc8qgIS2F6Q9rk8SBR0Ko5G/u5bwUB3SeskqLTBHzioeskDrThkYp4cdkuFH9o\n lpgeQBCNm2Z4GyT1Ibb3g3frHxCy/x9j9i1l/OYOk1eEhMHiiTYHQOQytanF/KOTqB\n 15jcHY7q9SQKjGQb/XtTET/ELXBwzCvL8tlBsqRSnUsk0JlMABUYnIUiWYgkFdCP9w\n 9EEPqtll+SvgoRA95O/SE83FfDsm8iF/ZcRDa7hSL5x3gd2g9ZfnoFgBslhig1qj05\n gAKVBhVvLgv++3oQpDdrAULefkQ/o0+Daw9SG8oNELhb7RUSEogtXapY+BUek/8Sav\n yEpII6dnPRWLs5UhePqN2FQanmYCLV7qCg5EDa38vaqzs1zNCC649ids5WETnEXeO+\n 8pbs+UV4LCyIRppluhW+xcqJlSvz508FQqfQRgcbs9yXd1u9WL4DEb7QWCsg+eoyGS\n xITZkKRUW9RKTdeWiCGsAIeFrseutPleXgvH1lbYchY1a2Z0zFbDV1va9CKMITcp3Z\n yOFZE1D9pVWHXeXRih02SkXA=","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1776881154; x=1777485954;\n h=mime-version:message-id:date:references:in-reply-to:subject:to:from\n :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id\n :reply-to;\n bh=1ohQ8RoAf7Eai4jEzgvubUpDWnf05WDaMOWhfPJ33qE=;\n b=bbMEXtp0THNVd0VjvrM9KK3n9Q4nbZXidevKVRrh9nIPFc/+1wfdQw2XXEmSuQFpMA\n svA7IiSnImdlh2n8gZy+qmQpWfqyGOCnsStxuMQTI6H9E6mRb/jQEDIPi7/XfXW8Zrmw\n WVThr/IGSzdilx276x0pXchpcKveTL+Xx/H2MhoRULh1Bi2W/wHBK2OjXln8t7lBXcVz\n 4XqemdigM+eXs2RKtT1TQKNrVMMzc1wK3zeOBtMPgnaBMeXm9q949FwuWob4ce6a2cwJ\n p5OfFoay8mMjkKrkuSZOh/9zRWpcpnlfxmWf0ZXN8k70QEVWn4H2n86NvcP1b/oTXYbW\n u8mw==","X-Gm-Message-State":"AOJu0YwsnXUgjZXbnOap/ZMG81/WLaQB4EkktulJnknxxb07rlhYxWq3\n ATbF1/dsZQUL+KWe4WpMwVQkXdN2YEQuzK1ha2CVmfInsL3Y/dAGC+p68TzHDatZIIl4Ig8F2ev\n TYGUVmLmUah2R3/Ro5hMyywHLBkHs2oVV7aGPc2HsQALZdMx97mCFPrQi0ZVa92s2vFLaw+5syu\n /mi2qAODW8TjuzStvC","X-Gm-Gg":"AeBDiesGwoLoNmHxgQl74uS1G9kl+yoo5T4RUSNkMs/lkWKH3advi22B94zqqrmBYhW\n ZErLogIo+hmHH8h3ITYIn107Q6+alD4DfLSHgE66PV630RiZq3tvG86c0UyG0XdxTc6A1KD3s2h\n 9ePZr8omIBu1UMKC636evS2Ex14Dj5FcSbf3co2D5TpggvMCr+kHcnqzi+x0nBvx5fLWpfUoxjp\n 3dBcTmU+QnnmfwT1NCuNyqHjdNR0oAjFq0cqNiVmQ5FeyQE498RXUxENYyMiVaNNjw8bduaZimN\n l/98uwMyuIZ3n4EgfOztE63ov3cd8bCz7J6yrmC/mKSKs7cs3B90mAs4Xrcij+nhoxBbqKtEAES\n MufcoUWTDV9LLgNxs16uzTT/ykfhMMFDroV/3uh2mjg==","X-Received":["by 2002:a05:600c:c4a1:b0:488:c014:34da with SMTP id\n 5b1f17b1804b1-488fb77ed1bmr322659605e9.26.1776881154268;\n Wed, 22 Apr 2026 11:05:54 -0700 (PDT)","by 2002:a05:600c:c4a1:b0:488:c014:34da with SMTP id\n 5b1f17b1804b1-488fb77ed1bmr322659225e9.26.1776881153843;\n Wed, 22 Apr 2026 11:05:53 -0700 (PDT)"],"From":"Mehmet Basaran ","To":"kernel-team@lists.ubuntu.com","Subject":"NACK: [SRU][N][PATCH 0/1] Revert \"iommu: disable SVA when\n CONFIG_X86 is set\"","In-Reply-To":"<20260422175746.329799-1-mehmet.basaran@canonical.com>","References":"<20260422175746.329799-1-mehmet.basaran@canonical.com>","Date":"Wed, 22 Apr 2026 21:05:50 +0300","Message-ID":"<875x5iswe9.fsf@gmail.com>","MIME-Version":"1.0","Content-Type":"multipart/mixed; boundary=\"=-=-=\"","X-BeenThere":"kernel-team@lists.ubuntu.com","X-Mailman-Version":"2.1.20","Precedence":"list","List-Id":"Kernel team discussions ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"kernel-team-bounces@lists.ubuntu.com","Sender":"\"kernel-team\" "}}]