Regarding upstream Linux, it should be addressed with https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=f24df84cbe05e4471c04ac4b921fc0340bbc7752

Although, I have no ETA on when it will land to distros.

@DustyArmstrong said:

@TeddyAstie yarp.

My bad, the VM has it as 00:08.0 but on the host it's actually 00:06.0, I just didn't think about the specifics of your request!

06:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Barcelo (rev c1) (prog-if 00 [VGA controller])
	Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device 1636
	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-
	Interrupt: pin A routed to IRQ 38
	Region 0: Memory at d0000000 (64-bit, prefetchable) [size=256M]
	Region 2: Memory at e0000000 (64-bit, prefetchable) [size=2M]
	Region 4: I/O ports at d000 [size=256]
	Region 5: Memory at fca00000 (32-bit, non-prefetchable) [size=512K]
	Capabilities: [48] Vendor Specific Information: Len=08 <?>
	Capabilities: [50] 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-
	Capabilities: [64] Express (v2) Legacy Endpoint, MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
			ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 256 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- UncorrErr+ FatalErr- UnsuppReq+ AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 8GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
			ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 8GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR-, OBFF Not Supported
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
		LnkCtl2: Target Link Speed: 8GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance De-emphasis: -6dB
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+, EqualizationPhase1+
			 EqualizationPhase2+, EqualizationPhase3+, LinkEqualizationRequest-
	Capabilities: [a0] MSI: Enable- Count=1/4 Maskable- 64bit+
		Address: 0000000000000000  Data: 0000
	Capabilities: [c0] MSI-X: Enable- Count=4 Masked-
		Vector table: BAR=5 offset=00042000
		PBA: BAR=5 offset=00043000
	Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
	Capabilities: [270 v1] #19
	Capabilities: [2a0 v1] Access Control Services
		ACSCap:	SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans-
		ACSCtl:	SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans-
	Capabilities: [2b0 v1] Address Translation Service (ATS)
		ATSCap:	Invalidate Queue Depth: 00
		ATSCtl:	Enable-, Smallest Translation Unit: 00
	Capabilities: [2c0 v1] Page Request Interface (PRI)
		PRICtl: Enable- Reset-
		PRISta: RF- UPRGI- Stopped+
		Page Request Capacity: 00000100, Page Request Allocation: 00000000
	Capabilities: [2d0 v1] Process Address Space ID (PASID)
		PASIDCap: Exec+ Priv+, Max PASID Width: 10
		PASIDCtl: Enable- Exec- Priv-
	Capabilities: [400 v1] #25
	Capabilities: [410 v1] #26
	Capabilities: [440 v1] #27
	Kernel driver in use: pciback

thanks.

So basically, there is a more annoying issue, as the device doesn't even have a ROMBAR, in this case, the VBIOS is likely in the VFCT ACPI table of host (which the guest can't see); which needs to be injected as a "fake" rombar for the guest to behave properly.

That doable on its own, but it's quite tricky to integrate (and you would e.g need to extract VBIOS from VFCT using external tools).

I just discussed with Xen/AMD people, and there are known issues regarding PCI Passthrough of integrated AMD GPUs (not specific to Xen AFAIU). There are some projects regarding alternative approaches to bring AMD GPUs to VMs (virtio-gpu native context) which is the current focus.

@gb.123 said in XCP-ng 8.3 updates announcements and testing:

Here is the summary:

If USB Keyboard & Mouse is passed-through along-with GPU:
The GPU gets stuck in D3 state (on Shutdown/Restart of VM) (Classic GPU reset problem)

If no vUSB is passed but GPU is passed through:
The GPU works correctly and resets correctly (on Shutdown/Restart of VM)

I have no clue what vUSB may change regarding GPU passthrough.

When I run :

$> lspci
Extract of Output (Partial):

07:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] Device 15b8

However, this controller does not show up when I run :
xe pci-list

Is it a bug that lspci & xe pci-list have different number of devices ?

How can I pass this controller since xe pci-list does not show it so I can't get the UUID ?
Will kernel parameters (like XCP-ng 8.2) work in this case ?

Question for @Team-XAPI-Network regarding the filtering on PCI IDs.
I don't think XAPI allows using arbitrary BDF, but I may be wrong.

Is it safe to run on XCP-ng host ?

 echo 1 > /sys/bus/pci/rescan

(I'm trying to find a way where the PCI card is reset by the host without complete reboot, though I am aware that the above command will not reset it.)

Probably. But it's not going to change anything as the device doesn't completely leave the Dom0 when passed-through.
FYI a function-level-reset is systematically performed by Xen when doing PCI passthrough, thus your device should be reset before entering another guest (aside reset bugs like you may have).

Also is it advisable to use :

xl pci-assignable-add 07:00.0

in XCP-ng 8.3 ? or is this method deprecated ?

I don't think XAPI supports this PCI passthrough approach.
This is a command which allows dynamically to remove a device from Dom0 and put it into "quarantine domain", so that it will be ready to passthrough it.

Current XAPI uses the approach of having a set of "passthrough-able" devices at boot time by modifying the xen-pciback.hide kernel parameter, which does the same but at boot time.

Hello !

I am looking to get some feedback and evaluation on a performance-related patch for Xen (XCP-ng 8.3 only).
This patch changes the memcpy implementation of Xen to use the "ERMS variant" (aka REP MOVSB) instead of the current REP MOVSQ+B implementation.
This is expected to perform better on the vast majority of Intel CPUs and modern AMD ones (Zen3+), but may perform worse on some older AMD CPUs.

This change may impact the performance of PV drivers (especially network).

You can find more details regarding this proposed change in : https://github.com/xcp-ng-rpms/xen/pull/54
This change may be reworked in the future to take more in account the specificities of each CPUs (e.g check presence of ERMS flag).

Keep in mind that this patched version is experimental and not officially supported.

Installation :

# Download repo file for XCP-ng 8.3
wget https://koji.xcp-ng.org/repos/user/8/8.3/xcpng-users.repo -O /etc/yum.repos.d/xcpng-users.repo

# Installing the patched Xen packages (you should see `.erms` packages)
yum update --enablerepo=xcp-ng-tae1

You can revert the changes by downgrading the Xen package with the ones in the default repos.

yum downgrade --disablerepo=xcp-ng-tae1 "xen-*"

TSnake41 opened this pull request in xcp-ng-rpms/xen

draft Use ERMS variant for memcpy #54

Xen Project covered this as XSA-489.

@plaidypus I don't know a lot about NUMA on Xen, but we have a part in the docs regarding that
https://docs.xcp-ng.org/compute/#numa-affinity

And also other documentation on the subject
https://xapi-project.github.io/new-docs/toolstack/features/NUMA/index.html
there was a design session regarding NUMA in latest Xen Summit : https://youtu.be/KoNwEYMlhyU?list=PLQMQQsKgvLnvjRgDnb-5T51e1kGHgs1SO

The rule is oddly written, and may conflict with another similar one that already exist in the distro (hence may not be useful to begin with).

The modern generic rule for doing vCPU hotplug is, which would be preferable to the current z10-xen-vcpu-hotplug.rules.
ACTION=="add", SUBSYSTEM=="cpu", ATTR{online}=="0", ATTR{online}="1"

@dcskinner @olivierlambert

You can read key/values from the xenstore, and write some (from VM to outside), but you cannot write values "in live" from outside the VM to the inside.

It is, but XAPI doesn't provide a interface for it.

do the guest tools quiesce the filesystems before snapshotting?

Tools are aware of a snapshot so you don't have blocks in flight.

do the guest tools quiesce the filesystems before snapshotting?

Guests kernel are aware, as it is them that are performing a "suspend" on toolstack request (thus quiece filesystems); although "tools" can only observe that the system has been suspended after the fact by measuring side effects, and not orchestrate it.

It's because suspend/resume operation doesn't come from "guest tools" actually, but instead from the kernel drivers. So userland tools has no say on it.

Hello,

Make sure Intel VMD is disabled (this is the hardware RAID feature of Intel, and it doesn't currently work on XCP-ng; you probably don't need it unless you are looking to make a RAID). We found some modern platforms enabling by default (which also causes issues with Windows).

@tuxen said (https://xcp-ng.org/forum/topic/3652/no-free-virtual-function-found-vgpu-s7150/4?_=1731502751059)

After some digging, could be the case of a GPU firmware being incompatible with UEFI. Do you have any spare server for testing XCP-ng boot in legacy/BIOS with this GPU?

Perhaps it is the issue ?

@JamesG Can you try having a workload on the GPU (and also checking if the performance is lower, or if it's just display) ?

@JamesG said:

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

This information is actually crafted by QEMU, it doesn't represent the actual real device PCI state; you should check this from Dom0 which should be closer to reality.

@JamesG

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...

XCP-ng guest firmware have a very "legacy" initial BAR placement (i.e thus no explicit support for Resizable BAR, everything below 4G, ...), but the guest operating system can still replace the location of BAR itself if the hardware allows it (in particular Linux will try it, but I'm not sure Windows does).

In your case, the GPU VRAM BAR is 16 GB, so it's obviously resized. And according to xe, you should see in dmesg something like BAR2 resized to 16384MiB

@Andrew said:
HP DL G8 Intel E5-2673 v2 shows 64 CPUs. The actual CPUs show correctly, the higher ones (that don't exist) show [CPUxx] Unable to fetch temperature (19 - No such device)

Machines with hotpluggable CPUs are a pretty tricky case, the logic tries up to "maximum possible CPU" and fails here because the CPU is not online (No such device error). That doesn't prevent the temperature from getting fetched for CPU that exists.
I can try to add a check to hide this specific error, so it's doesn't create noise for offline CPUs on such machines.

@acebmxer said:

@rzr

Just installed updates on host 1. Once host rebooted it took an extra min or two to reconnect to xo, but did finally connect. Applying updates on host 2 now.

Update - host2 no issues. Once reboot complete it connected to xo as expected without delay.

I see these updates include -

• xen: Add support for xenpm get-core-temp to query CPU temperature on Intel platforms.

• Use xenpm get-core-temp to get the temperature on Intel's CPU, to fallback unsupported coretemp. Doc update being reviewed .

My host are AMD so can verify these. I might be able to deploy a Intel host later tonight. Will this come to AMD later?

AMD rely on a different method to expose the temperature, that don't require this xenpm-based approach. In principle, it should already work with plain sensors (through k10temp), but our driver may not be up to date for recent AMD CPUs.

Regarding upstream Linux, it should be addressed with https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=f24df84cbe05e4471c04ac4b921fc0340bbc7752

Although, I have no ETA on when it will land to distros.

@TrapoSAMA https://updates.xcp-ng.org/isos/8.2/
And https://updates.xcp-ng.org/8/8.2/ appears fine.

The rule is oddly written, and may conflict with another similar one that already exist in the distro (hence may not be useful to begin with).

The modern generic rule for doing vCPU hotplug is, which would be preferable to the current z10-xen-vcpu-hotplug.rules.
ACTION=="add", SUBSYSTEM=="cpu", ATTR{online}=="0", ATTR{online}="1"

@MajorP93 said:
Do you think it is possible to fix this on hypervisor level while still having live migration etc. enabled or do we have to wait for an upstream fix within Linux kernel tree?

Yes it's possible to fix it on the hypervisor level (Invariant TSC in guest), but it's quite a bit of work that still needs to be done. A Linux upstream fix for the underlying bug should come at some point hopefully.

@majorp93 @henri9813 @acebmxer
Do you observe the same behavior after setting this for the VM ?

xe vm-param-add uuid=$UUID param-name=platform tsc_mode=2
xe vm-param-add uuid=$UUID param-name=platform nomigrate=true

(beware you lose live migration support doing this, you can cancel these changes with matching vm-param-remove like xe vm-param-remove uuid=$UUID param-name=platform param-key=nomigrate)