@redakula
First, thanks for chiming in. Second...I'll admit that I'm ignorant here. This is not an area that I have any real experience.
The Intel doc reference (paraphrasing here) "magic lspci" options that will truly show you that the GPU isn't really running in Gen1x1 and that deeper down, its truly working as intended. I wish they would have just included the super-secret magic lspci options needed to show this is the case...But they didn't.
The best I can see from lspci -vvxxxx is it still only shows Gen1x1
00:08.0 VGA compatible controller: Intel Corporation Battlemage G21 [Intel Graphics] (prog-if 00 [VGA controller])
Subsystem: Intel Corporation Device 1114
Physical Slot: 8
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Interrupt: pin ? routed to IRQ 79
Region 0: Memory at f1000000 (64-bit, prefetchable) [size=16M]
Region 2: Memory at 400000000 (64-bit, prefetchable) [size=16G]
Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express (v2) Endpoint, IntMsgNum 0
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s unlimited, L1 unlimited
ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 0W TEE-IO-
DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
MaxPayload 128 bytes, MaxReadReq 512 bytes
DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
LnkCtl: ASPM Disabled; RCB 64 bytes, LnkDisable- CommClk-
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x1
TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Range B, TimeoutDis+ NROPrPrP- LTR+
10BitTagComp+ 10BitTagReq+ OBFF Not Supported, ExtFmt+ EETLPPrefix-
EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
FRS- TPHComp- ExtTPHComp-
AtomicOpsCap: 32bit- 64bit- 128bitCAS-
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-
AtomicOpsCtl: ReqEn-
IDOReq- IDOCompl- LTR- EmergencyPowerReductionReq-
10BitTagReq- OBFF Disabled, EETLPPrefixBlk-
LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
Retimer- 2Retimers- CrosslinkRes: unsupported
Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit+
Address: 00000000feed7000 Data: 0700
Capabilities: [d0] Power Management version 3
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Kernel driver in use: xe
Kernel modules: xe
00: 86 80 12 e2 07 04 10 00 00 00 00 03 00 00 00 00
10: 0c 00 00 f1 00 00 00 00 0c 00 00 00 04 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 14 11
30: 00 00 00 f2 40 00 00 00 00 00 00 00 ff 00 00 00
40: 09 70 0c 01 0b 00 00 00 00 00 00 00 00 00 00 00
50: c0 f9 00 00 00 00 00 00 00 40 00 00 00 00 00 00
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 10 ac 02 00 e1 8f 00 00 10 29 00 00 11 0c 40 00
80: 00 00 11 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 12 08 13 00 00 00 00 00 02 00 00 00
a0: 01 00 00 00 00 00 00 00 00 00 00 00 05 d0 81 00
b0: 00 70 ed fe 00 00 00 00 00 07 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 01 00 03 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: c7 21 80 ff 03 00 00 00 00 00 00 00 00 00 00 00
When I ask the system what it thinks the capabilities are, again I get Gen1x1:
cat /sys/bus/pci/devices/0000:00:08.0/current_link_speed
2.5 GT/s PCIe
cat /sys/bus/pci/devices/0000:00:08.0/current_link_width
1
cat /sys/bus/pci/devices/0000:00:08.0/max_link_speed
2.5 GT/s PCIe
cat /sys/bus/pci/devices/0000:00:08.0/max_link_width
1
I know I'm a bit out in uncharted territory here. I don't think XCP-ng supports ReBAR via pass-through (I think that's on the road-map for XenServer9 and maybe XCP-ng 9 as well), current gen GPUs all want ReBAR support, Intel GPU's are in a mostly experimental/developmental mode and might be having a murky future anyway...
Anyway...From my completely uninformed and ignorant position, it doesn't look like it's negotiating PCIe properly through XCP-ng.
