Re: [PATCH v2] ACPI: VIOT: Fix ACS setup

[Jean-Philippe Brucker]

On Thu, Jun 30, 2022 at 11:40:59AM +0200, Eric Auger wrote:
> Currently acpi_viot_init() gets called after the pci
> device has been scanned and pci_enable_acs() has been called.
> So pci_request_acs() fails to be taken into account leading
> to wrong single iommu group topologies when dealing with
> multi-function root ports for instance.
> 
> We cannot simply move the acpi_viot_init() earlier, similarly
> as the IORT init because the VIOT parsing relies on the pci
> scan. However we can detect VIOT is present earlier and in
> such a case, request ACS. Introduce a new acpi_viot_early_init()
> routine that allows to call pci_request_acs() before the scan.
> 
> While at it, guard the call to pci_request_acs() with #ifdef
> CONFIG_PCI.
> 
> Fixes: 3cf485540e7b ("ACPI: Add driver for the VIOT table")
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Reported-by: Jin Liu <jinl@xxxxxxxxxx>

Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Tested-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>