[Deepin-Kernel-SIG] [deepin] PCI: Add ACS override support for debug #396
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为什么这个东西没有被上游化？ |
also used in other distro kernel like fedroa and zen Link:https://lkml.org/lkml/2013/5/30/513 Source: https://gitlab.com/Queuecumber/linux-acs-override/-/raw/master/workspaces/5.10.4/acso.patch PCIe ACS (Access Control Services) is the PCIe 2.0+ feature that allows us to control whether transactions are allowed to be redirected in various subnodes of a PCIe topology. For instance, if two endpoints are below a root port or downsteam switch port, the downstream port may optionally redirect transactions between the devices, bypassing upstream devices. The same can happen internally on multifunction devices. The transaction may never be visible to the upstream devices. One upstream device that we particularly care about is the IOMMU. If a redirection occurs in the topology below the IOMMU, then the IOMMU cannot provide isolation between devices. This is why the PCIe spec encourages topologies to include ACS support. Without it, we have to assume peer-to-peer DMA within a hierarchy can bypass IOMMU isolation. Unfortunately, far too many topologies do not support ACS to make this a steadfast requirement. Even the latest chipsets from Intel are only sporadically supporting ACS. We have trouble getting interconnect vendors to include the PCIe spec required PCIe capability, let alone suggested features. Therefore, we need to add some flexibility. The pcie_acs_override= boot option lets users opt-in specific devices or sets of devices to assume ACS support. The "downstream" option assumes full ACS support on root ports and downstream switch ports. The "multifunction" option assumes the subset of ACS features available on multifunction endpoints and upstream switch ports are supported. The "id:nnnn:nnnn" option enables ACS support on devices matching the provided vendor and device IDs, allowing more strategic ACS overrides. These options may be combined in any order. A maximum of 16 id specific overrides are available. It's suggested to use the most limited set of options necessary to avoid completely disabling ACS across the topology. Note to hardware vendors, we have facilities to permanently quirk specific devices which enforce isolation but not provide an ACS capability. Please contact me to have your devices added and save your customers the hassle of this boot option. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
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看邮件列表里面的意思是用户配置不正确可能影响内核稳定性 |
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also used in other distro kernel like fedroa and zen
Link:https://lkml.org/lkml/2013/5/30/513
Source: https://gitlab.com/Queuecumber/linux-acs-override/-/raw/master/workspaces/5.10.4/acso.patch