Failing SAS Passthrough on Proxmox 9 with 8.14 kernel

[Mindbang]

Hey folks,
I've recently updated my cluster to Proxmox 9. Most things went without issues, but I'm stuck on one problem.
In one machine I have a LSI 9207-8i that I'm passing through to a VM. On Proxmox 8 with a 6.8 kernel this is working fine.
After upgrading to Proxmox 9 with kernel 6.14.8-2-pve the passthrough is eventually failing. The issue is somewhere in the handoff of the controller to the VM (See the attached screenshot for the errors).

I've done a bit of digging and there's been some movement in the mpt3sas driver in the kernel (https://github.com/torvalds/linux/commits/master/drivers/scsi/mpt3sas), with some interesting commits that could potentially relate:
- https://github.com/torvalds/linux/commit/3f5eb062e8aa335643181c480e6c590c6cedfd22
- https://github.com/torvalds/linux/commit/5612d6d51ed2634a033c95de2edec7449409cbb9

Long story short, I'm on Proxmox 9, but I've pinned the kernel to 6.8.12-13-pve. Things are working fine. But that's running everything in an unsupported configuration, which I don't like.

Has anybody else run into this issue or has some pointers or where I better go digging?

 

[Mindbang]

Does anybody have any ideas? Pretty please?

 

[Mindbang]

I build a few custom patches for the mpt3sas driver before I realized that this is not the right approach, since the host machine isn't using the hardware, but it's passed through. The issue is somewhere in the vfio, iommu or kvm subsystems. Probably gonna try to bisect it by going the kernel versions up. 6.11 minor also works.

 

[Mindbang]

I think this is a regression introduced with this patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f9e54c3a2f5b
The whole functionality can be disabled using the kernel parameter "transparent_hugepage=never". With this set, things work again.