On Sun, 29 Dec 2019, 'awokd' via qubes-users wrote: > Claudia: > > December 26, 2019 12:59 PM, "awokd' via qubes-users" > > <[email protected]> wrote: > > > >> Claudia: > >> > >> TLDR; check bottom of https://community.amd.com/thread/241650, looks > >> like there was a recently released related updated. Not sure if > >> applicable to your situation. > > > > Thanks for the link! I'm not sure if it affects me or not. I did > > install a Dell BIOS update dated March 2019, so it sounds like that > > could have contained this Agesa update. So downgrading might fix the > > grouping issue, but this update also contained an "urgent" security > > update which I'd have to look into before downgrading. > > I'd assumed AGESA version numbers were from a common code base, but > apparently not. The one mentioned in that thread was released around > Oct. 2019, but may not be applicable to your hardware. They also don't > specifically reference USB controller grouping in that thread, so it > might do nothing for you even if it is applicable. > > > I sort of blame Xen for not enforcing IOMMU grouping, especially > > considering that it hides that > > info from the OS. KVM does enforce IOMMU grouping rules, so I don't see why > > Xen wouldn't. Xen > > leaves it up to the user software to be careful what it passes where, but > > that's kind of hard when > > you don't have /sys/kernel/iommu_groups for a hint. > > I am a bit fuzzy here too. It seems like if ACS is working correctly, > you can get better granularity within IOMMU groups. It would be > disappointing if it does not on recently released hardware. In your > case, the USB controller appears as a different function of the same PCI > device, which could be the case from a hardware perspective. This is > even worse for a passthrough scenario than IOMMU grouping. There is a > Realtek controller that often comes up on the list that makes people > passthrough the SD card controller to their sys-net along with WIFI for > the same reason.
I got an impression from somewhere, that AMD platform itself should support really good IOMMU grouping but that there's then a BIOS option to enable it (like "IOMMU: auto/enabled", where "auto" got you the default conflicting groups; I read two lspcis from the same HW somewhere with very different PCI dev layouting where the other was with the "enabled" setting but I guess it was a desktop MB). I suspect, however, laptop vendors may not be putting that much effort on including such options. -- i. -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/alpine.DEB.2.20.1912291951080.10565%40whs-18.cs.helsinki.fi.
