Re: Issue with PCI passthrough ("swiotlb buffer is full") after Debian Dom0 kernel update to 5.10.178-3

[Paul Leiber <paul@xxxxxxxxxxxxxxxx>]

Am 06.05.2023 um 01:37 schrieb zithro:
> On 05 May 2023 21:32, Paul Leiber wrote:
> > Hi list,
> >
> > Since a Debian update of package linux-image-amd64 to version 
> > 5.10.0-22 (kernel 5.10.178-3), I am experiencing an issue with PCI 
> > passthrough.
> You lucky, I can't even BOOT dom0 with this kernel !
> (and no serial console avail for now, so dunno where it is bugging ...).
>
> Also, I found a few users having problems with the new kernel and 
> virtualization on the debian-users mailing list.
> Maybe the kernel is ill-fated ?
Thanks for this info.

> Quick notes:
> - did you try swiotlb buffer==64k (swiotlb=65536) ? (from memory it 
> helped for a WLAN NIC, as I told you in our previous exchanges)
Tried swiotlb=65536, same result as with swiotlb=8192, the physical 
machine crashed.
> - most of the updates you linked are about APIC, so you may try adding 
> in Xen cmdline : "apic_verbosity=debug"
> - another one, not sure about the syntax but I et more info with 
> "iommu=debug,verbose" (maybe in your case "iommu=debug,verbose,soft" ?)
Will perhaps give it a try later

> - you have "permissive=1" in your domU config for the PCI device, is 
> that normal ? I've never needed that and iirc is not recommended 
> (check man pages though, corrupted brain memory here ^^)
Before the kernel update, the PCI passthrough was working well without 
"permissive=1". I added this parameter during my tests, because Dom0 
dmesg said that the driver for the device tried to access a restricted 
area. Adding this parameter didn't change anything for better or worse, 
AFAICT. In my other Xen system, I have passed through a DVB-T2 tv card 
with this option, and it is working well.
> As for the rest of your post, I need some rest :p
> (if I ever make some sense from it ^^)
You ask for logs, logs you get. :-D No, seriously, thanks for your time.