KVM broken on 6.18.12?

Message

cmpxchg8b · Post by **cmpxchg8b** » Fri Feb 27, 2026 7:46 pm

Greetings to all.

I've got a dual processor Xeon E5-2690v4 machine here that recently started to refuse to run anything KVM related.

When I try to run qemu with `-accel kvm`, I simply get the following error message:

Create kernel irqchip failed: Inappropriate ioctl for device

That's it, nothing else.

Everything worked fine on 6.12.58, but after upgrading nothing seems to work on 6.18.12.

KVM modules appear to be loaded and show up just fine in lsmod. Nothing shows up in dmesg. Kernel command line doesn't contain anything funky and my config didn't change between 6.12.58 and 6.18.12 apart from dropping some CONFIG lines that were removed from the kernel. /dev/kvm is present and appears to have the correct ownership and permissions, plus I'm also a member of the kvm group. Same thing happens with root though so I don't think it's a user issue.

The only other oddity I've noticed is that the QLED code on my motherboard used to read "00" when booted, and now it reads "AA" instead. I haven't changed anything in the BIOS though and everything else is exactly the same as before.

-CMPX

cmpxchg8b · Post by **cmpxchg8b** » Sat Feb 28, 2026 4:12 am

Fixed it.

Seems like the problem was related to missing CONFIG_IRQ_REMAP in my config.

Why this applies to 6.18.12 and not 6.12.58, I'm not really sure. I can't find any mention of it online anywhere, but I guess IRQ remapping is now a hard requirement for the KVM_CREATE_IRQCHIP IOCTL to succeed (which is what was failing as per strace).

-CMPX

Post by **Banana** » Sat Feb 28, 2026 10:05 am

Thank you for posting the solution to your problem

vijayphadke · Post by **vijayphadke** » Mon Mar 30, 2026 10:03 pm

cmpxchg8b wrote:Fixed it.

Seems like the problem was related to missing CONFIG_IRQ_REMAP in my config.

Why this applies to 6.18.12 and not 6.12.58, I'm not really sure. I can't find any mention of it online anywhere, but I guess IRQ remapping is now a hard requirement for the KVM_CREATE_IRQCHIP IOCTL to succeed (which is what was failing as per strace).

-CMPX

Likewise iptables config was also broken!
Pay attention to the kernel config option (when making oldconfig), the default for iptables support is No (N)!! Don't forget to select 'y' explicitly, else your scripts using iptables will break.

Another thing is that I abandoned 6.18.18, it is showing some core dump/crash in boot messages (dmesg) which doesn't happen when you boot with 6.12.x kernel. I am not an expert but things seem to be broken, be careful while upgrading.