On Mon, May 05, 2025 at 02:08:07PM -0300, Jason Gunthorpe wrote: > On Wed, Apr 30, 2025 at 12:58:47AM -0700, Nicolin Chen wrote: > > > > ... and I just hit a problem with it - this is basically guest BDFn > > > and it works as long as I'm hotplugging the TEE-IO VF into an SNP VM > > > but does not when I pass through via the QEMU cmdline - bus numbers > > > are not assigned yet. So I have to postpone the vdevice allocation > > > till run time, did I miss something here? Thanks, > > > > I have a similar case with QEMU ARM64's VM: so vDEVICE on ARM is > > allocated at runtime as well because the BDF number isn't ready > > at the boot time. > > Oh that's ugly then.. So you'll need to add some kind of 'modify > sid/bdf' operation I think.
But the initial vDEVICE would be still unusable. Its BDF number is literally 0 in my case. It can't be used for SID-based invalidation nor the reverse vSID lookup for fault injection.. > The bus numbers can be reassigned at any time on the fly by the guest > by reprogramming the PCI hierarchy. Yes. If we take some aggressive use case into account, where its BDF number could change multiple times, I think it's natural for VMM to simply destroy the previous vDEVICE and allocate a new one with a new BDF number, right? Thanks Nicolin
