Kernel 7.0.x regression: ACS violation on PCIe port 80:1b.4 causes VM freeze — Arrow Lake + Thunderbolt 5 + Intel Arc B50 passthrough

[edcoppen]

Hi all, following up from post #195 in the 7.0 opt-in thread as requested. Reposting the full details here with lspci -v output included.

Hardware

• CPU: Intel Arrow Lake-S (Arrow Lake-HX 8p+16e cores)
• Chipset: Intel 800 Series PCH
• GPU (passthrough): Intel Arc Pro B50 (Battlemage G21, 04:00.0)
• Thunderbolt: Intel JHL9580 Thunderbolt 5 Barlow Ridge (84:00.0 / 97:00.0)
• USB controller (passthrough): ASMedia ASM3242 USB 3.2 (06:00.0)
• NVMe (passthrough): Samsung S4LV008 Pascal (81:00.0)

Proxmox version: 9.2.3
Kernel boot parameters: intel_iommu=on iommu=pt split_lock_detect=off

VM Configuration

agent: 1
bios: ovmf
boot: order=ide0;hostpci0
cores: 8
cpu: host
hostpci0: 0000:81:00,pcie=1   # Samsung NVMe
hostpci1: 0000:06:00,pcie=1   # ASMedia USB 3.2
hostpci2: 0000:04:00,pcie=1   # Intel Arc B50 GPU
hostpci3: 0000:05:00,pcie=1   # Intel Arc B50 Audio
machine: pc-q35-10.1
memory: 30518
ostype: win11
vga: none

Symptom
The Windows 11 VM freezes shortly after the Arc GPU driver initialises on boot. Display output is lost, CPU pegs at 100%, and the VM becomes completely unresponsive. The host immediately enters a continuous AER error loop on PCIe root port 0000:80:1b.4 which persists even after force-stopping the VM and requires a full host reboot to clear. Keyboard and mouse (connected via the passed-through ASMedia USB controller) also stop responding at the point of freeze.

Root cause
The AER loop is triggered by an ACS violation on PCIe root port 80:1b.4 (device 8086:7f44), which is the upstream port for the Thunderbolt 5 subsystem. The violation appears to be triggered by DMA activity when the Arc GPU driver initialises, crossing an ACS boundary between sibling root ports 80:1b.0 and 80:1b.4.

dmesg (kernel 7.0.6-2-pve)

[  436.209061] pcieport 0000:80:1b.4: AER: Correctable error message received from 0000:80:1b.4
[  436.209134] pcieport 0000:80:1b.4:   device [8086:7f44] error status/mask=00300000/00000000
[  436.209138] pcieport 0000:80:1b.4:    [20] UnsupReq
[  436.209140] pcieport 0000:80:1b.4:    [21] ACSViol (First)
[  437.238805] thunderbolt 0000:84:00.0: AER: can't recover (no error_detected callback)
[  437.238815] xhci_hcd 0000:97:00.0: AER: can't recover (no error_detected callback)
[  437.238832] pcieport 0000:80:1b.4: AER: device recovery failed
... (repeats continuously until host reboot)

Kernels tested

• 6.17.13-13-pve — VM boots and runs normally
• 7.0.2-6-pve — freeze, ACS violation loop
• 7.0.2-7-pve — freeze, ACS violation loop
• 7.0.6-2-pve — freeze, ACS violation loop

Workaround
Pinned to 6.17.13-13-pve which resolves the issue completely.

lspci -v

00:00.0 Host bridge: Intel Corporation Arrow Lake-HX 8p+16e cores Host Bridge (rev 01)
Subsystem: Intel Corporation Device 7270
Flags: bus master, fast devsel, latency 0, IOMMU group 1
Capabilities: [e0] Vendor Specific Information: Len=14 <?>

00:02.0 VGA compatible controller: Intel Corporation Arrow Lake-S [Intel Graphics] (rev 06)
Subsystem: Intel Corporation Device 2212
Flags: bus master, fast devsel, latency 0, IRQ 208, IOMMU group 0
Kernel driver in use: i915

00:06.0 PCI bridge: Intel Corporation Arrow Lake-HX PCIe Root Port (rev 10)
Flags: bus master, fast devsel, latency 0, IRQ 125, IOMMU group 4
Bus: primary=00, secondary=02, subordinate=05
Kernel driver in use: pcieport

03:01.0 PCI bridge: Intel Corporation Device e2f0
Flags: bus master, fast devsel, latency 0, IOMMU group 15
Capabilities: [220] Access Control Services
Kernel driver in use: pcieport

03:02.0 PCI bridge: Intel Corporation Device e2f1
Flags: bus master, fast devsel, latency 0, IOMMU group 16
Capabilities: [220] Access Control Services
Kernel driver in use: pcieport

04:00.0 VGA compatible controller: Intel Corporation Battlemage G21 [Intel Graphics]
Subsystem: Intel Corporation Device 1114
Flags: bus master, fast devsel, latency 0, IRQ 227, IOMMU group 17
Kernel driver in use: vfio-pci

05:00.0 Audio device: Intel Corporation Device e2f7
Subsystem: Intel Corporation Device 1114
Flags: bus master, fast devsel, latency 0, IRQ 236, IOMMU group 18
Kernel driver in use: vfio-pci

06:00.0 USB controller: ASMedia Technology Inc. ASM3242 USB 3.2 Host Controller
Flags: bus master, fast devsel, latency 0, IRQ 16, IOMMU group 19
Kernel driver in use: vfio-pci

80:1b.0 PCI bridge: Intel Corporation 800 Series PCH PCIe Root Port (rev 10)
Flags: bus master, fast devsel, latency 0, IRQ 128, IOMMU group 24
Capabilities: [220] Access Control Services
Kernel driver in use: pcieport

80:1b.4 PCI bridge: Intel Corporation 800 Series PCH PCIe Root Port (rev 10)
Flags: bus master, fast devsel, latency 0, IRQ 129, IOMMU group 25
Bus: primary=80, secondary=82, subordinate=aa
Capabilities: [220] Access Control Services
Kernel driver in use: pcieport

81:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller S4LV008[Pascal]
Flags: bus master, fast devsel, latency 0, IRQ 16, IOMMU group 30
Kernel driver in use: vfio-pci

82:00.0 PCI bridge: Intel Corporation JHL9580 Thunderbolt 5 80/120G Bridge [Barlow Ridge Host 80G 2023] (rev 84)
Flags: bus master, fast devsel, latency 0, IRQ 16, IOMMU group 31
Kernel driver in use: pcieport

84:00.0 USB controller: Intel Corporation JHL9580 Thunderbolt 5 80/120G NHI [Barlow Ridge Host 80G 2023] (rev 84)
Flags: bus master, fast devsel, latency 0, IRQ 16, IOMMU group 36
Kernel driver in use: thunderbolt

97:00.0 USB controller: Intel Corporation JHL9580 Thunderbolt 5 80/120G USB Controller [Barlow Ridge Host 80G 2023]
Flags: fast devsel, IRQ 182, IOMMU group 37
Kernel driver in use: xhci_hcd

Full unabridged lspci -v output available on request.

Happy to provide any additional diagnostic output if helpful.