After a power outage I'm facing this issue: TASK ERROR: cannot prepare PCI pass-through, IOMMU not present

[Nuokaneco]

Hello I'm facing this issue or error message when I try to power on the Virtual machine after a power outage
Task viewer: VM 100 - Start

OutputStatus

Stop
TASK ERROR: cannot prepare PCI pass-through, IOMMU not present

How can I solve this?

Thank you advance for your help and support

 

[leesteken]

Enable IOMMU or VT-d in your motherboard BIOS again. Maybe the battery is low and the BIOS settings got lost when the power went out.
It's unlikely that the Proxmox configuration changed because of the power loss but check cat /proc/cmdline to make sure (if you are using an Intel system).

 

[Nuokaneco]

All the virtualizations options are enable in the bios

 

[Nuokaneco]

Enable IOMMU or VT-d in your motherboard BIOS again. Maybe the battery is low and the BIOS settings got lost when the power went out.
It's unlikely that the Proxmox configuration changed because of the power loss but check cat /proc/cmdline to make sure (if you are using an Intel system).

Thank you for your reply !

All the Virtualizations options are enable but ok i will disable an enable it again to test

The output command:

root@pve:~# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.15.83-1-pve root=/dev/mapper/pve-root ro quiet
root@pve:~#

 

[Nuokaneco]

 

[Nuokaneco]

Enable IOMMU or VT-d in your motherboard BIOS again. Maybe the battery is low and the BIOS settings got lost when the power went out.
It's unlikely that the Proxmox configuration changed because of the power loss but check cat /proc/cmdline to make sure (if you are using an Intel system).

I try disable and enable again all the Virtualization options seething's in the Bios

And the problem persists

 

[Nuokaneco]

I think I have discovered the issue, when i execute the following command

dmesg | grep -e DMAR -e IOMMU


dd800000-0x00000000dfffffff], contact BIOS vendor for fixes
[ 0.114325] DMAR: [Firmware Bug]: Your BIOS is broken; bad RMRR [0x00000000dd800000-0x00000000dfffffff]
[ 0.114329] DMAR-IR: IOAPIC id 2 under DRHD base 0xfed91000 IOMMU 1
[ 0.114330] DMAR-IR: HPET id 0 under DRHD base 0xfed91000

I will try to update the bios in order to try fix this issue ...

 

[leesteken]

root@pve:~# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.15.83-1-pve root=/dev/mapper/pve-root ro quiet

There is no intel_iommu=on. The Proxmox manual describes where to make the change and how to apply them so they take effect.
Note that Proxmox can use either GRUB or systemd-boot. If you switched your system from legacy boot to UEFI or the other way around, you may have to add intel_iommu=on again.

I think I have discovered the issue, when i execute the following command

dmesg | grep -e DMAR -e IOMMU


dd800000-0x00000000dfffffff], contact BIOS vendor for fixes
[ 0.114325] DMAR: [Firmware Bug]: Your BIOS is broken; bad RMRR [0x00000000dd800000-0x00000000dfffffff]
[ 0.114329] DMAR-IR: IOAPIC id 2 under DRHD base 0xfed91000 IOMMU 1
[ 0.114330] DMAR-IR: HPET id 0 under DRHD base 0xfed91000

I will try to update the bios in order to try fix this issue ...

I assumed that IOMMU was working before the power outage. Did it work before the power outage? I don't understand why your motherboard BIOS might be broken suddenly. Maybe it only works in UEFI boot mode and not in legacy boot mode, or the other way around?

 

[Nuokaneco]

There is no intel_iommu=on. The Proxmox manual describes where to make the change and how to apply them so they take effect.
Note that Proxmox can use either GRUB or systemd-boot. If you switched your system from legacy boot to UEFI or the other way around, you may have to add intel_iommu=on again.

I assumed that IOMMU was working before the power outage. Did it work before the power outage? I don't understand why your motherboard BIOS might be broken suddenly. Maybe it only works in UEFI boot mode and not in legacy boot mode, or the other way around?

Yes it's working until the power outage without any problem

I tried to added the: intel_iommu=on

on the following config file : nano /etc/default/grub



after this I executed the command:

proxmox-boot-tool refresh

But I still facing the same issue

Thank you for your support

 

[leesteken]

If this worked before then it is best to not make changes to Proxmox. Instead, find out why your system is booting different than before and change the motherboard BIOS (boot) settings back to what they were before. Hopefully, that will fix the "your BIOS is broken" problem as well.
Your Proxmox did not boot with GRUB before, so it must have been using systemd-boot. That also means that it booted in UEFI mode. Probably your system is booting in Legacy mode now and you need to switch it back to UEFI boot mode. (But I don't know how.)

 

[Nuokaneco]

If this worked before then it is best to not make changes to Proxmox. Instead, find out why your system is booting different than before and change the motherboard BIOS (boot) settings back to what they were before. Hopefully, that will fix the "your BIOS is broken" problem as well.
Your Proxmox did not boot with GRUB before, so it must have been using systemd-boot. That also means that it booted in UEFI mode. Probably your system is booting in Legacy mode now and you need to switch it back to UEFI boot mode. (But I don't know how.)

I reverted all changes that I mentioned before right now. I'm trying to fix the BIOS broken in order to try solve this issue...

Once again thank you for your support and best regards