I finally got access to a machine with Intel Arc machine.
There are issues around hvm-pirq, hence hvm-pirq=0 is required (see https://docs.xcp-ng.org/troubleshooting/common-problems/#pci-passthrough-error-unsupported-msi-delivery-mode-7).
For some reason, Fedora Workstation has a issue with this GPU (a Fedora bug I guess), but CachyOS (desktop iso) works fine.
Ran a clpeak bench, and performance looks normal for this class of GPU.
Host-device transfer is a bit slower than "theorical", but definetely not PCIe 1x1 and more PCIe 3x8-ish (matching reality as it's plugged as PCIe 3.0).
in-VM inxi -CGM
Machine:
Type: Xen System: Xen product: HVM domU v: 4.17 serial: 2c66cb09-57db-340c-ad8e-f505eb25ca3e
Mobo: N/A model: N/A serial: N/A Firmware: UEFI vendor: Xen v: 4.17 date: 10/06/2026
CPU:
Info: 6x 1-core model: Intel Xeon Silver 4112 bits: 64 type: SMP cache: L2: 6x 1024 KiB (6 MiB)
Speed (MHz): avg: 2594 min/max: N/A cores: 1: 2594 2: 2594 3: 2594 4: 2594 5: 2594 6: 2594
Graphics:
Device-1: driver: bochs-drm v: N/A
Device-2: Intel Battlemage G21 [Arc Pro B50] driver: xe v: kernel
Display: unspecified server: Xwayland v: 24.1.13 driver: gpu: bochs-drm tty: 212x48
API: EGL v: 1.5 drivers: iris,swrast platforms: gbm,surfaceless,device
API: OpenGL v: 4.6 vendor: mesa v: 26.1.6-arch3.1 note: console (EGL sourced) renderer: Mesa
Intel Arc Pro B50 Graphics (BMG G21), llvmpipe (LLVM 22.1.8 256 bits)
API: Vulkan v: 1.4.357 drivers: intel surfaces: N/A
Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo de: kscreen-console,kscreen-doctor
gpu: gputop, intel_gpu_top, lsgpu, nvidia-smi wl: wayland-info x11: xdpyinfo, xprop, xrandr
Raw numbers
Backend: Vulkan
Device 0: Intel(R) Arc(tm) Pro B50 Graphics (BMG G21)
Driver version : 26.2.4
API version : 1.4.354
VRAM : 16048 MB
Single-precision compute
float : 9.47 TFLOPS
float2 : 9.48 TFLOPS
float4 : 9.52 TFLOPS
Half-precision compute fp16xfp16+fp16
half : 18.3 TFLOPS
half2 : 18.8 TFLOPS
half4 : 19.1 TFLOPS
Double-precision compute
double : 650 GFLOPS
double2 : 647 GFLOPS
double4 : 640 GFLOPS
Mixed-precision compute fp16xfp16+fp32
mp : 9.31 TFLOPS
mp2 : 9.32 TFLOPS
mp4 : 9.42 TFLOPS
BF16 compute bf16xbf16+fp32
bf16 : 9.17 TFLOPS
bf16_2 : 9.30 TFLOPS
bf16_4 : 9.28 TFLOPS
Integer compute int32
int : 1.81 TOPS
int2 : 1.88 TOPS
int4 : 1.82 TOPS
INT8 dot-product compute
int8_dp : 28.0 TOPS
int8_dp2 : 26.3 TOPS
int8_dp4 : 27.1 TOPS
Cooperative matrix
fp16 : 67.3 TFLOPS
fp16 f16acc : 68.9 TFLOPS
bf16 : 68.9 TFLOPS
int8 : 141 TOPS
Global memory bandwidth
float : 196 GB/s
float2 : 206 GB/s
float4 : 212 GB/s
Local memory bandwidth
float : 2.55 TB/s
float2 : 3.65 TB/s
float4 : 4.23 TB/s
Image memory bandwidth
float4 : 213 GB/s
Transfer bandwidth
h2d : 4.81 GB/s
d2h : 5.48 GB/s
Kernel launch latency
dispatch : 48.7 us
roundtrip : 113 us
Real performance is much higher than the "displayed" Speed 2.5GT/s, Width x1.
