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SubjectRe: [PATCH 0/3] Add parameter for disabling ACS redirection for P2P
Am 24.05.2018 um 23:48 schrieb Logan Gunthorpe:
> Hi,
> As discussed in our PCI P2PDMA series, we'd like to add a kernel
> parameter for selectively disabling ACS redirection for select
> bridges. Seeing this turned out to be a small series in itself, we've
> decided to send this separately from the P2P work.
> This series generalizes the code already done for the resource_alignment
> option that already exists. The first patch creates a helper function
> to match PCI devices against strings based on the code that already
> existed in pci_specified_resource_alignment().
> The second patch expands the new helper to optionally take a path of
> PCI devfns. This is to address Alex's renumbering concern when using
> simple bus-devfns. The implementation is essentially how he described it and
> similar to the Intel VT-d spec (Section 8.3.1).
> The final patch adds the disable_acs_redir kernel parameter which takes
> a list of PCI devices and will disable the ACS P2P Request Redirect,
> ACS P2P Completion Redirect and ACS P2P Egress Control bits for the
> selected devices. This allows P2P traffic between selected bridges and
> seeing it's done at boot, before IOMMU group creating the IOMMU groups
> will be created correctly based on the bits.
> Thanks,
> Logan
> Logan Gunthorpe (3):
> PCI: Make specifying PCI devices in kernel parameters reusable
> PCI: Allow specifying devices using a base bus and path of devfns
> PCI: Introduce the disable_acs_redir parameter

Thanks a lot of taking care of it like that. It looks much cleaner to me
than just trying to disable ACS without a parameter.

Series is Acked-by: Christian König <>.


> Documentation/admin-guide/kernel-parameters.txt | 39 ++-
> drivers/pci/pci.c | 358 ++++++++++++++++++++----
> 2 files changed, 336 insertions(+), 61 deletions(-)
> --
> 2.11.0

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