mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-04-29 12:28:27 +02:00
Mingcong Bai
677714d779
commit2c8a7c66c9upstream. On the Lenovo ThinkPad X201, when Intel VT-d is enabled in the BIOS, the kernel boots with errors related to DMAR, the graphical interface appeared quite choppy, and the system resets erratically within a minute after it booted: DMAR: DRHD: handling fault status reg 3 DMAR: [DMA Write NO_PASID] Request device [00:02.0] fault addr 0xb97ff000 [fault reason 0x05] PTE Write access is not set Upon comparing boot logs with VT-d on/off, I found that the Intel Calpella quirk (`quirk_calpella_no_shadow_gtt()') correctly applied the igfx IOMMU disable/quirk correctly: pci 0000:00:00.0: DMAR: BIOS has allocated no shadow GTT; disabling IOMMU for graphics Whereas with VT-d on, it went into the "else" branch, which then triggered the DMAR handling fault above: ... else if (!disable_igfx_iommu) { /* we have to ensure the gfx device is idle before we flush */ pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n"); iommu_set_dma_strict(); } Now, this is not exactly scientific, but moving 0x0044 to quirk_iommu_igfx seems to have fixed the aforementioned issue. Running a few `git blame' runs on the function, I have found that the quirk was originally introduced as a fix specific to ThinkPad X201: commit9eecabcb9a("intel-iommu: Abort IOMMU setup for igfx if BIOS gave no shadow GTT space") Which was later revised twice to the "else" branch we saw above: - 2011: commit6fbcfb3e46("intel-iommu: Workaround IOTLB hang on Ironlake GPU") - 2024: commitba00196ca4("iommu/vt-d: Decouple igfx_off from graphic identity mapping") I'm uncertain whether further testings on this particular laptops were done in 2011 and (honestly I'm not sure) 2024, but I would be happy to do some distro-specific testing if that's what would be required to verify this patch. P.S., I also see IDs 0x0040, 0x0062, and 0x006a listed under the same `quirk_calpella_no_shadow_gtt()' quirk, but I'm not sure how similar these chipsets are (if they share the same issue with VT-d or even, indeed, if this issue is specific to a bug in the Lenovo BIOS). With regards to 0x0062, it seems to be a Centrino wireless card, but not a chipset? I have also listed a couple (distro and kernel) bug reports below as references (some of them are from 7-8 years ago!), as they seem to be similar issue found on different Westmere/Ironlake, Haswell, and Broadwell hardware setups. Cc: stable@vger.kernel.org Fixes:6fbcfb3e46("intel-iommu: Workaround IOTLB hang on Ironlake GPU") Fixes:ba00196ca4("iommu/vt-d: Decouple igfx_off from graphic identity mapping") Link: https://groups.google.com/g/qubes-users/c/4NP4goUds2c?pli=1 Link: https://bugs.archlinux.org/task/65362 Link: https://bbs.archlinux.org/viewtopic.php?id=230323 Reported-by: Wenhao Sun <weiguangtwk@outlook.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=197029 Signed-off-by: Mingcong Bai <jeffbai@aosc.io> Link: https://lore.kernel.org/r/20250415133330.12528-1-jeffbai@aosc.io Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>