PCI-Passthrough without "iommu=soft" possible?

["J. Roeleveld" <joost@xxxxxxxxxxxx>]

Hi all,

When trying to boot a guest domain with 2 HBA's assigned via PCI-passthrough I 
get a kernel-panic with 5.15.72.
If I add "iommu=soft" to the kernel command line it works, but locks up 
quickly with messages like:
[Sun Oct 16 20:33:36 2022] mpt3sas 0000:81:00.0: swiotlb buffer is full (sz: 
319488 bytes), total 32768 (slots), used 68 (slots)
[Sun Oct 16 20:33:36 2022] sd 0:0:26:0: scsi_dma_map failed: request for 
708608 bytes!

in the logs (dmesg)

If I stay with 5.15.59 (without "iommu=soft", it is running stable, but I 
would like to upgrade to newer kernels when possible.

I am currently running Xen 4.15.3

Is there an additional setting I need to add or any other options I haven't 
been able to find through a few days of google-searches that are advised?

Many thanks,

Joost Roeleveld