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

[Alex Williamson]

On Sat, Jun 13, 2026, at 11:43 AM, Pranjal Arya wrote:
> 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.

This sounds like a userspace problem, QEMU can virtualize the capability and manipulate it as it sees fit.  Thanks,

Alex