Re: [PATCH RFC 0/3] vfio/pci: Hide and optionally override the PCIe Device Serial Number

[Pranjal Shrivastava <praan@google.com>]

On Sat, Jun 13, 2026 at 11:13:35PM +0530, Pranjal Arya wrote:

Hi Pranjal,

> vfio-pci has no perm_bits entry for the PCIe Device Serial Number (DSN)
> Extended Capability, so guest reads of the serial
> number currently fall through to the physical device.  The DSN is a
> unique, persistent hardware serial number that identifies the physical
> component (the functions of a Multi-Function Device report the same
> value; Root Complex integrated Endpoints may implement it independently),
> so exposing it lets a guest fingerprint the host hardware and correlate
> it across VMs.  For multi-tenant passthrough this is an unnecessary
> host-identifier leak.
>

+ 1 to what Alex said here, QEMU / VMM should be able to trap and present
the desired values here, we shouldn't need this in the vconfig. Thus, I
believe this is better suited to QEMU (maybe this should be a patch to
QEMU?)

> 
> Signed-off-by: Pranjal Arya <pranjal.arya@oss.qualcomm.com>
> ---
> Pranjal Arya (3):
>       vfio/pci: Virtualize and scrub Device Serial Number from guests
>       vfio/pci: Allow userspace to set a virtual Device Serial Number
>       selftests/vfio: Add PCIe Device Serial Number test
> 
>  MAINTAINERS                                      |   6 +
>  drivers/vfio/pci/vfio_pci_config.c               |  98 +++++++++++
>  drivers/vfio/pci/vfio_pci_core.c                 |   2 +
>  drivers/vfio/pci/vfio_pci_priv.h                 |   2 +
>  include/uapi/linux/pci_regs.h                    |   5 +
>  include/uapi/linux/vfio.h                        |  18 ++
>  tools/testing/selftests/vfio/Makefile            |   1 +
>  tools/testing/selftests/vfio/vfio_pci_dsn_test.c | 206 +++++++++++++++++++++++
>  8 files changed, 338 insertions(+)
> ---
> base-commit: c425609d6ac4012c8bbf01ec2e10e801b1923a7b
> change-id: 20260613-pcie_vfio-48506602ec6a

A few minor things, we don't use change-id upstream and no need to add a
MAINTAINERS entry per test, we already have an entry to maintain
tools/testing/selftests/vfio.

Thanks,
Praan