"DMAR: DRHD: handling fault status reg 2" with vfio on kernel 6.13.11-200.fc41.x86_64, works with 6.13.9-200.fc41.x86_64 Description of problem: Since kernel 6.13.11-200.fc41.x86_64, I cannot use VFIO to pass an NVIDIA GeForce GTX 1070 card to a Windows guest. The same setup works just fine in 6.13.9-200.fc41.x86_64. The issue symptoms are the same regardless if I use kernel command line arguments to isolate cpus or not. Symptoms: - qemu logs show: ``` 2025-05-07T09:59:49.957891Z qemu-system-x86_64: vfio: Cannot reset device 0000:36:00.1, no available reset mechanism. 2025-05-07T09:59:49.958444Z qemu-system-x86_64: vfio: Cannot reset device 0000:36:00.0, no available reset mechanism. 2025-05-07T09:59:49.959119Z qemu-system-x86_64: vfio: Cannot reset device 0000:36:00.1, no available reset mechanism. 2025-05-07T09:59:49.959635Z qemu-system-x86_64: vfio: Cannot reset device 0000:36:00.0, no available reset mechanism. ``` - in dmesg I see: ``` kernel: DMAR: DRHD: handling fault status reg 2 kernel: DMAR: [INTR-REMAP] Request device [36:00.0] fault index 0x50 [fault reason 0x22] Present field in the IRTE entry is clear ``` - the VM hangs at boot (please see the notes below (*)). Steps to reproduce: Boot the same libvirt domain in kernel 6.13.9-200.fc41.x86_64 (works) and any other more recent kernel (>= 6.13.11-200.fc41.x86_64). Additional information: (*) Note that in a working kernel, the boot process is in any case finicky, and it shows these phases: 1. tianocore logo shows, and one single cpu is fully utilized by the guest 2. slowly, the loader find the Windows bootloader, and prints a message that it is loading and running it 3. some time passes, while cpus seem idle 4. finally the spinning wheel of the Windows bootloader appears Phase 1-3 can take anywhere from 0 to 60 seconds, in an apparently random manner. When running on the faulty kernels, it seems that the virtual machine gets stuck in phase 1, and I must use `virsh destroy` to interrupt it. lspci output: ``` -[0000:00]-+-00.0 Intel Corporation Tiger Lake-UP3/H35 4 cores Host Bridge/DRAM Registers +-02.0 Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics] +-04.0 Intel Corporation TigerLake-LP Dynamic Tuning Processor Participant +-06.0-[01]----00.0 Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 +-07.0-[02-33]-- +-0a.0 Intel Corporation Tigerlake Telemetry Aggregator Driver +-0d.0 Intel Corporation Tiger Lake-LP Thunderbolt 4 USB Controller +-0d.2 Intel Corporation Tiger Lake-LP Thunderbolt 4 NHI #0 +-14.0 Intel Corporation Tiger Lake-LP USB 3.2 Gen 2x1 xHCI Host Controller +-14.2 Intel Corporation Tiger Lake-LP Shared SRAM +-15.0 Intel Corporation Tiger Lake-LP Serial IO I2C Controller #0 +-15.1 Intel Corporation Tiger Lake-LP Serial IO I2C Controller #1 +-15.2 Intel Corporation Tiger Lake-LP Serial IO I2C Controller #2 +-16.0 Intel Corporation Tiger Lake-LP Management Engine Interface +-1c.0-[34]----00.0 Intel Corporation Wi-Fi 6 AX200 +-1c.5-[35]----00.0 Realtek Semiconductor Co., Ltd. RTS522A PCI Express Card Reader +-1d.0-[36]--+-00.0 NVIDIA Corporation GP104 [GeForce GTX 1070] | \-00.1 NVIDIA Corporation GP104 High Definition Audio Controller +-1f.0 Intel Corporation Tiger Lake-LP LPC Controller +-1f.3 Intel Corporation Tiger Lake-LP Smart Sound Technology Audio Controller +-1f.4 Intel Corporation Tiger Lake-LP SMBus Controller \-1f.5 Intel Corporation Tiger Lake-LP SPI Controller ``` kernel command line arguments (optimized with cpu isolation): ``` intel_pstate=per_cpu_perf_limits rd.driver.blacklist=nouveau modprobe.blacklist=nouveau module_blacklist=nouveau default_hugepagesz=1G hugepagesz=1G hugepages=13 i2c_i801.disable_features=0x10 rd.driver.pre=vfio_pci,vfio,vfio_iommu_type1 vfio-pci.ids=10de:1b81,10de:10f0 modprobe.blacklist=xpad systemd.unit=multi-user.target systemd.wants=bluetooth.service isolcpus=domain,managed_irq,1-3,5-7 rcu_nocbs=1-3,5-7 irqaffinity=0,4 nospectre_v2 ``` kernel command line arguments (without cpu isolation, same symptoms): ``` intel_pstate=per_cpu_perf_limits rd.driver.blacklist=nouveau modprobe.blacklist=nouveau module_blacklist=nouveau default_hugepagesz=1G hugepagesz=1G hugepages=13 rd.driver.pre=vfio_pci,vfio,vfio_iommu_type1 vfio-pci.ids=10de:1b81,10de:10f0 modprobe.blacklist=xpad systemd.unit=multi-user.target systemd.wants=bluetooth.service ```