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X-CSE-ConnectionGUID: RGW+ok76Thm38mIoc/u8dA== X-CSE-MsgGUID: HhIJZmwqQTSbaVTSnCbKbA== X-IronPort-AV: E=McAfee;i="6800,10657,11677"; a="87615486" X-IronPort-AV: E=Sophos;i="6.21,242,1763452800"; d="scan'208";a="87615486" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 23:32:50 -0800 X-CSE-ConnectionGUID: cc8N6P4jTiiViNi17R1B7A== X-CSE-MsgGUID: jWepoUefS7Ca/BNWogF4ig== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,242,1763452800"; d="scan'208";a="205513188" Received: from allen-sbox.sh.intel.com (HELO [10.239.159.30]) ([10.239.159.30]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 23:32:48 -0800 Message-ID: Date: Wed, 21 Jan 2026 15:32:42 +0800 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: IOMMU regression in linux-6.18.y To: Greg KH Cc: Mario Limonciello , Mario Limonciello , regressions , stable@vger.kernel.org, iommu@lists.linux.dev, "Hegde, Vasant" , "Hou, Lizhi" References: <870872aa-28e9-412a-bac6-8020bf560e4f@amd.com> <3fccd233-c5cf-4252-98ea-61f240f82695@linux.intel.com> <2026012112-phantom-music-f6e8@gregkh> Content-Language: en-US From: Baolu Lu In-Reply-To: <2026012112-phantom-music-f6e8@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/21/26 15:26, Greg KH wrote: > On Wed, Jan 21, 2026 at 03:14:42PM +0800, Baolu Lu wrote: >> On 1/21/26 13:26, Mario Limonciello wrote: >>> >>> >>> On 1/20/26 8:08 PM, Mario Limonciello wrote: >>>> Hi, >>>> >>>> Recently I found out that amdxdna stopped working in linux-6.18.4. >>>> This is because of this commit in linux-6.18.y: >>>> >>>> commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set") >>>> >>>> That was originally backported from upstream: >>>> >>>> commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set") >>>> >>>> --- >>>> >>>> SVA support is a requirement for amdxdna. >>>> >>>> The series that this commit came from was part of a larger 8 patch >>>> series, but this was the only commit that was CC'ed to stable. >>>> >>>> As a result this is not broken in 6.19-rc, but it is broken in >>>> linux-6.18.y (and presumably any older stable kernels still around >>>> that picked it up). >>>> >>>> So there are two options I see: >>>> >>>> 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel >>>> that picked it up but has amdxdna) >>>> >>>> 2) Bring the entire 8 patch series to linux-6.18.y. >>>> >>>> This is the entire series (I didn't look up the hashes from >>>> mainline, but they should have all landed): >>>> https://lore.kernel.org/linux-iommu/20251022082635.2462433-1- >>>> baolu.lu@linux.intel.com/ >>>> >>>> What should we do? >>>> >>> >>> If the decision is to take the remaining commits to 6.18.y to fix this I >>> did confirm they cleanly cherry pick and build.  Here are the hashes. >>> >>> commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables") >>> commit 977870522af3 ("mm: actually mark kernel page table pages") >>> commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages") >>> commit 018942956723 ("mm: introduce pure page table freeing function") >>> commit bf9e4e30f353 ("x86/mm: use pagetable_free()") >>> commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page >>> tables") >>> commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for >>> kernel address space") >>> >> >> Yes. These patches fix a security issue in iommu/sva on x86 and restore >> the SVA functionality. > > So all should be backported? If so, great, but why were they not tagged > as such? Yes, they should be backported. I am sorry; we should have tagged them at the time we upstreamed them. > > thanks, > > greg k-h > Thanks, baolu