Re: [RFC PATCH 0/5] hw/arm/virt: Add support for user-creatable nested SMMUv3

[Nathan Chen]

> > > >  >with an error message indicating DMA mapping failed for the
> > > > passthrough >devices.
> > > >
> > > > A correction - the message indicates UEFI failed to find a mapping for
> > > > the boot partition ("map: no mapping found"), not that DMA mapping
> > > > failed. But earlier EDK debug logs still show PCI host bridge resource
> > > > conflicts for the passthrough devices that seem related to the VM boot
> > > > failure.
> > >
> > > I have tried a 2023 version EFI which works. And for more recent tests I
> > am
> > > using a one built directly from,
> > > https://github.com/tianocore/edk2.git master
> > >
> > > Commit: 0f3867fa6ef0("UefiPayloadPkg/UefiPayloadEntry: Fix PT
> > protection
> > > in 5 level paging"
> > >
> > > With both, I don’t remember seeing any boot failure and the above UEFI
> > > related "map: no mapping found" error. But the Guest kernel at times
> > > complaints about pci bridge window memory assignment failures.
> > > ...
> > > pci 0000:10:01.0: bridge window [mem size 0x00200000 64bit pref]: can't
> > assign; no space
> > > pci 0000:10:01.0: bridge window [mem size 0x00200000 64bit pref]: failed
> > to assign
> > > pci 0000:10:00.0: bridge window [io  size 0x1000]:can't assign; no space
> > > ...
> > >
> > > But Guest still boots and worked fine so far.
> >
> > Hi Shameer,
> >
> > Just letting you know I resolved this by increasing the MMIO region size
> > in hw/arm/virt.c to support passing through GPUs with large BAR regions
> > (VIRT_HIGH_PCIE_MMIO). Thanks for taking a look.
>
> Ok. Thanks for that. Does that mean may be an optional property to specify
> the size for VIRT_HIGH_PCIE_MMIO is worth adding?

Yes, and actually we have a patch ready for the configurable highmem 
region size. Matt Ochs will send it out in the next day or so and CC you 
on the submission.

> adding  ""mem-reserve=X" and "io-reserve=X" to pcie-root-port helps

Ok, good to know - I'll keep that in mind for future testing.

Thanks,
Nathan