Re: [PATCH v8 08/12] PCI: liveupdate: Adopt ACS controls in incoming preserved devices

[Pranjal Shrivastava]

On Tue, Jul 28, 2026 at 10:10:02PM +0000, David Matlack wrote:
> Adopt Access Control Services (ACS) controls on all incoming preserved
> devices (endpoints and upstream bridges) during a Live Update.
> 
> Inheriting ACS flags avoids changing routing rules while memory
> transactions are in flight from preserved devices. This is also strictly
> necessary to ensure that IOMMU group assignments do not change during or
> after Live Update.
> 
> Cache the inherited ACS controls established by the previous kernel in
> struct pci_dev so that ACS controls do not change after a reset
> (pci_restore_state() calls pci_enable_acs()).
> 
> To simplify ACS inheritance, reject preserving any devices that require
> quirks to enable ACS as those quirks would also have to take Live Update
> into account.
> 
> Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>

Reviewed-by: Pranjal Shrivastava <praan@xxxxxxxxxx>

Thanks,
Praan