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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?a1GoG5L9zsx6JWYQcLbqdQqRyq6iqJtQfSCiJu/xkh4IpNrZ4gUcRIhDtOYb?= =?us-ascii?Q?2Yjef0maWpiPD82u8qj8yHR4KJGl+e1SPwSUklhLyUCUPEZJlKmXbJESxTGo?= =?us-ascii?Q?5bQCQetx/UXmTL45mppsE6KUuGXmMiP3xhO36zJ6yV3cSJUwRATYxR+ACav2?= =?us-ascii?Q?34pQyjr01ogWJkIUHCOhZOD+4TQ3PicU66ebBM6ZCw+a3OCazj1RJ/c2ZMfl?= =?us-ascii?Q?I5u3U3zBhBCHfC4ZCreAnRgJzIpAqDLkjjjNj+TFV4eirIgnmtS8FQGllnSD?= =?us-ascii?Q?kuang3qi3tLtpT/cuuMhIFNmSEHsjGLf8PzXwlnKHKRB4Hy/UtqKJMG9NLnb?= =?us-ascii?Q?JnQ55nGOcCRX0Gxa2xDb/4I72Du8Jkh+draIRApcnLmaaI0sL7KsUJXfQ7XF?= =?us-ascii?Q?UgpdAbibD35MFzXm0zJv9jcRoHvKbigEloRw+kEt0aSpGYaDgzEHENLZg4l9?= =?us-ascii?Q?QLaxQcY9ltQiBOrUbEBYa3DUDchTjr8Klxx0fP1QteBH6KtJvLLfTBVwL7zq?= =?us-ascii?Q?CaJPFGy5jUaX1UDgtOByMIWjnjUYgwHVEHXN+X76oGtO0W2fWUgApTxLbL7v?= =?us-ascii?Q?2AMmawKWrtwXomRT7XhoyyJed5199TvnAqu/n9Cu8wSJvb9jtVvdeaexSJso?= =?us-ascii?Q?KNNn4JZCm99f+Y/jy8Gssd3Q3dsCzDdWF11mhFd6vT8vmKyeWydnHSidn6rU?= =?us-ascii?Q?vEJhiMj3gEkGBl9vZ710L6Uc0RO1E+QLr/8LlSeVYEK/pl5vlWNF1AJXRd/b?= =?us-ascii?Q?8jEtST4Rxqml6tvD/QOJO90qSW4ao+WvOJPtarTfEhoyhldvnWjdS3mvazlR?= =?us-ascii?Q?Tv3plImdVaNzHxQCPC8CPuiQljYXeu9MHoedXC/GmK2Nc4zC7C/zWNRJ3qKQ?= =?us-ascii?Q?pvGIMt9cTWWxDfRaPW/7T6c0Qm61mzXwV6EArXeJ69OO0U3vwvNA6KC4Ejmi?= =?us-ascii?Q?juIpG4gp7xrZRIjHefW3QpNiRRIKbWbsLzejitwYUb8N7dfGbjw0+Z5iyklj?= =?us-ascii?Q?O0tDYfCPd3aMLYXG5xcTQ8Q70Or4TX4o3vZsieO3HL0UWEVbcjyZwPod1obp?= =?us-ascii?Q?g/q6UAC5alzZbmoyw0+yZisuJiRYuPYLiPlWQB0cHZpMAmgu9sPVkMDRZhQM?= =?us-ascii?Q?TPVDdx/fuBSC+U5IoxFBoJOdc3YXfnUfWEYNN/+M9luRzsQq1i1BEvXg3aUz?= =?us-ascii?Q?21essnggnEncnDbNW5gImYz2jBDWaN1gf0I+3PbxkoNyu1o18STnn33NqZUL?= =?us-ascii?Q?SFoAmaxWhZ1Q07sT7A5p2WWdibMWOtETvTFvyrCTHCQ0WMKlx4a72zaWsmk+?= =?us-ascii?Q?ssgfoPie8hBU0BZTJlPGRdugYGYFcN1qdfbl/0Up7VK+q8u6PMs5rgdez9Iz?= =?us-ascii?Q?yhm6yEJmBBzUGaQvzR/dkWApynyAeIlVmVOBeSQ4uMYKVS5uAZehxt04zazC?= =?us-ascii?Q?x///zuwJEDLE0SEFXMHwUI8CpBlNbKDdJgXU9JUHbJx71Z81ooAcepH+5YAV?= =?us-ascii?Q?jLamwOUHEo+IuV1dV5qrkXfIEhSSWYa23dVQZisZP/UgtmAYPpS43Xg9kqTm?= =?us-ascii?Q?5lF+pG4DW+4PIyPfAvgu43iW88um/MEXqSYADfs6it76cgVzlwqWIqfaY/k3?= =?us-ascii?Q?5A+uYpDDgX5YJg3KcHiq7xPhQHF9zYhjJnsd1vwtUGx3+FOfvDRV9TSScIgg?= =?us-ascii?Q?SWYwpGmf3piXlgRwODqWnzyEIDtIJPAnw2kxztovBQkFU+gmjLOBl+wadb7B?= =?us-ascii?Q?GKVZ1GCnnw=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: cc27e4d4-19d7-438a-7a64-08de5a8edb84 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Jan 2026 14:51:15.0621 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: c3FMv8nbsRaDeuV3rUYMbb2B14ZI2P++TD9ncipynDRaoKsxkxQxlevJXBmwjGHy X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN7PPF39B20C1D8 On Fri, Jan 23, 2026 at 09:49:43AM +0800, Wei Wang wrote: > The enhanced ACS controls introduced by PCIe Gen 5 ensures better device > isolation. On devices that support the PCI_ACS_ECAP capability, the > controls are required to be enabled properly: > - ACS I/O Request Blocking needs to be enabled to avoid unintended > upstream I/O requests. > - ACS DSP and USP Memory Target Access Control needs to be set with > Request Redirect or Request Blocking to ensure the Downstream and > and Upstream Port memory resource ranges are not accessed by upstream > memory requests. > - ACS Unclaimed Request Redirect needs to be enabled to ensure accesses to > areas that lies within a Switch's Upstream Port memory apertures but not > within any Downstream Port memory apertures get redirected. > > To maintain compatibility with legacy devices that lack PCI_ACS_ECAP > support, pci_acs_enabled() skips checking for the capability and logs a > warning to indicate that isolation may be incomplete. That's every existing system, please don't do that. The issue with ECAP is the way PCI SIG re-defined what Linux has been doing forever as unsafe. Jason > > Signed-off-by: Wei Wang > --- > drivers/pci/pci.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 67 insertions(+) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index c4cf835ec8ba..ff974ced90aa 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3527,6 +3527,56 @@ void pci_configure_ari(struct pci_dev *dev) > } > } > > +static bool pci_dev_has_memory_bars(struct pci_dev *pdev) > +{ > + int i; > + > + for (i = 0; i <= PCI_ROM_RESOURCE; i++) { > + if (pci_resource_flags(pdev, i) & IORESOURCE_MEM) > + return true; > + } > + > + return false; > +} > + > +static bool pci_acs_ecap_enabled(struct pci_dev *pdev, u16 ctrl) > +{ > + struct pci_dev *usp_pdev = pci_upstream_bridge(pdev); > + u16 mask = PCI_ACS_DMAC_RB | PCI_ACS_DMAC_RR; > + > + /* > + * For ACS DSP/USP Memory Target Access Control, either Request > + * Redirect or Request Blocking must be enabled to enforce isolation. > + * According to PCIe spec 6.2, the DSP Memory Target Access is > + * applicable to both Root Ports and Switch Upstream Ports that have > + * applicable Memory BAR space to protect. So if the device does not > + * have a Memory BAR, it skips the check. > + */ This doesn't make sense, the special cases PCI sig clarified only have to do with switches that have MMIO on their USP/DSP and a case where the DSP aperture isn't covered by all the USPs. These tests shouldn't be done outside a usp/dsp context. You can look at what I drafted earlier here: https://lore.kernel.org/all/0-v3-8827cc7fc4e0+23f-pcie_switch_groups_jgg@nvidia.com/ Jason