Re: [PATCH v2 0/3] xen: fix usage of devices behind a VMD bridge

[Bjorn Helgaas <helgaas@kernel.org>]

[+to Juergen, Nirmal, +cc Jonathan]

On Tue, Jan 14, 2025 at 11:33:10AM +0100, Roger Pau Monne wrote:
> Hello,
> 
> The following series should fix the usage of devices behind a VMD bridge
> when running Linux as a Xen PV hardware domain (dom0).  I've only been
> able to test PV. I think PVH should also work but I don't have hardware
> capable of testing it right now.
> 
> I don't expect the first two patches to be problematic, the last patch
> is likely to be more controversial.  I've tested it internally and
> didn't see any issues, but my testing of PV mode is mostly limited to
> dom0.
> 
> Thanks, Roger.
> 
> Roger Pau Monne (3):
>   xen/pci: do not register devices with segments >= 0x10000
>   vmd: disable MSI remapping bypass under Xen
>   pci/msi: remove pci_msi_ignore_mask
> 
>  arch/x86/pci/xen.c           |  8 ++------
>  drivers/pci/controller/vmd.c | 19 ++++++++++++++++++
>  drivers/pci/msi/msi.c        | 37 ++++++++++++++++++++----------------
>  drivers/xen/pci.c            | 19 ++++++++++++++++++
>  include/linux/msi.h          |  3 ++-
>  kernel/irq/msi.c             |  2 +-
>  6 files changed, 64 insertions(+), 24 deletions(-)

We got an ack from Thomas, so I'm fine with this from a PCI
perspective.  How should it be merged?  Via Xen or PCI?  I'm happy to
merge via PCI, but would also want acks from Juergen for the Xen
piece and Nirmal for the VMD piece.

I have a couple more trivial comments, will respond to those patches.